Metals

13 pages, 14317 KB

Open AccessEditor’s ChoiceArticle

Crystal Plasticity Analysis of Microstructure and Texture Evolution in Cold-Rolled High-Strength Interstitial-Free Steel

by Jibin Pei, Yibo Wang, Danyu Yin, Wei Li, Yaru Zhu, Luyang Miao and Chi Zhang

Metals 2026, 16(7), 688; https://doi.org/10.3390/met16070688 - 24 Jun 2026

Viewed by 302

Abstract

After cold rolling of high-strength interstitial-free (IF) steel, the ferrite grains undergo plastic deformation associated with the formation of substructures and intense cold-rolling texture, which affects the microstructure and texture in the subsequent annealing process and determines the formability of the final sheet. [...] Read more.

After cold rolling of high-strength interstitial-free (IF) steel, the ferrite grains undergo plastic deformation associated with the formation of substructures and intense cold-rolling texture, which affects the microstructure and texture in the subsequent annealing process and determines the formability of the final sheet. To clarify the mechanisms of microstructure and texture formation during cold rolling of IF steel, a polycrystalline model was constructed based on the measured microstructure and texture features. A crystal plasticity model, along with a remeshing technique, was developed for IF steel. The model can calculate the deformation of the polycrystal after 70% cold rolling reduction, in which the calculated microstructure and texture features are consistent with the results from electron backscatter diffraction (EBSD). The results show that the deformed microstructure and texture are closely related to the initial crystal orientation, the interaction between neighbouring grains, and the cold rolling reduction. Grains with an initial texture orientation near <001>//ND are more stable during deformation and tend to retain their orientations after cold rolling. In contrast, grains initially deviating from the γ-fiber tend to rotate towards the <111>//ND orientation, while near-γ-fiber grains mainly retain their γ-fiber characteristics with intragranular orientation spreading during cold rolling. Multiple slip systems induce the formation of ingrain shear bands. These results establish a grain-scale link between initial orientation, intragranular substructure formation, and cold rolling texture evolution, and provide a mechanistic basis for optimizing cold rolling texture control and improving the formability of high-strength IF steel sheets. Full article

(This article belongs to the Special Issue Research Progress of Crystal in Metallic Materials, 2nd Edition)

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15 pages, 4458 KB

Open AccessEditor’s ChoiceArticle

Nozzle Shape Suitable for Vertical-Type High-Speed Twin-Roll Casting of Al-5%Mg Alloy Strip

by Toshio Haga and Tomonori Yasukawa

Metals 2026, 16(7), 689; https://doi.org/10.3390/met16070689 - 24 Jun 2026

Viewed by 260

Abstract

A vertical-type high-speed twin-roll caster can cast strips at a speed of 60 m/min. However, ripple marks, which are typical surface defects on strips cast using a twin-roll caster, also appear on strips cast using this caster. In the present study, Al-5%Mg was [...] Read more.

A vertical-type high-speed twin-roll caster can cast strips at a speed of 60 m/min. However, ripple marks, which are typical surface defects on strips cast using a twin-roll caster, also appear on strips cast using this caster. In the present study, Al-5%Mg was used because severe ripple marks occur on Al-5%Mg strips. The influences of the molten-metal head (50, 100, and 150 mm), which is a characteristic parameter for this caster, the molten-metal temperature (645, 685, and 735 °C), and the nozzle thickness on ripple marks were investigated. The nozzle thickness was an important factor in eliminating ripple marks, and a nozzle thickness of 3 mm was suitable for eliminating them. No relationship was found between ripple marks and surface cracks. The surface cracks decreased as the roll load decreased, and a roll load of 5 N/mm was suitable. Based on the obtained results, the optimum nozzle shape and casting conditions for casting strips without ripple marks or cracks were clarified. Full article

(This article belongs to the Special Issue Preparation, Formation and Application of Light Alloys and Their Composites)

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21 pages, 18430 KB

Open AccessEditor’s ChoiceArticle

Effect of Load Partitioning Under Different Pressing Temperature Conditions During 2P1A Compaction on the Densification Behavior and Electromagnetic Properties of Fe–5.0 wt.%Si SMC Core

by Minseop Sim and Seonbong Lee

Metals 2026, 16(6), 669; https://doi.org/10.3390/met16060669 - 17 Jun 2026

Viewed by 407

Abstract

Soft magnetic composites (SMCs) are attracting increasing attention for electromagnetic applications owing to their three-dimensional shape flexibility and reduced eddy current loss. In this study, the 2-Pressing 1-Annealing (2P1A) process was applied to Fe–5.0 wt.%Si SMC toroidal cores to investigate the effects of [...] Read more.

Soft magnetic composites (SMCs) are attracting increasing attention for electromagnetic applications owing to their three-dimensional shape flexibility and reduced eddy current loss. In this study, the 2-Pressing 1-Annealing (2P1A) process was applied to Fe–5.0 wt.%Si SMC toroidal cores to investigate the effects of pressing temperature and 1st pressing level on densification behavior, interparticle insulation structure, and frequency-dependent electromagnetic response. DEFORM-3D FEM simulations compared relative density distribution, hydrostatic stress, effective strain, and reaction load under single-press and 2P1A conditions. The 1st pressing stage was conducted at 350 °C with 30%, 50%, and 70% pressing levels, followed by final densification at 550 °C. Increasing compaction temperature reduced reaction load and hydrostatic stress range, while the 1st pressing level affected the final density distribution and stress state after 2nd pressing. TEM-EDS confirmed continuous interparticle insulation layers, and thickness measurements were used to compare local boundary structures. Among the 2P1A conditions, the 50% → 100% condition showed the smallest upper/lower relative density difference and the narrowest insulation-layer thickness range, indicating the most balanced condition in terms of densification uniformity and interparticle boundary structure. Compared with the 550 °C single-press condition, the 2P1A compacts showed higher permeability retention and Q-factor values in the 5–20 kHz range. These results indicate that the 1st pressing level influences staged densification behavior, interparticle boundary structure, and frequency-dependent electromagnetic response in Fe–5.0 wt.%Si SMC cores. Full article

(This article belongs to the Section Powder Metallurgy)

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14 pages, 1979 KB

Open AccessEditor’s ChoiceArticle

Phase Evolution and Deuterium Storage Properties of TiVNbZrCr High-Entropy Alloy: A Temperature-Resolved Synchrotron X-Ray Diffraction Study

by Karel Saksl, Katarína Kušnírová, Lenka Oroszová, Katarína Nigutová, Jakub Kubaško, Jens Möllmer, Marcus Lange and Mária Podobová

Metals 2026, 16(6), 664; https://doi.org/10.3390/met16060664 - 16 Jun 2026

Viewed by 352

Abstract

TiVNbZrCr high-entropy intermetallic alloy was investigated as a deuterium storage material using gravimetric sorption measurements, thermogravimetric analysis, and temperature-resolved synchrotron X-ray diffraction during deuterium desorption. The as-prepared alloy had an experimentally determined composition of Ti₁₇V₁₉Zr₁₉Nb₂₂Cr [...] Read more.

TiVNbZrCr high-entropy intermetallic alloy was investigated as a deuterium storage material using gravimetric sorption measurements, thermogravimetric analysis, and temperature-resolved synchrotron X-ray diffraction during deuterium desorption. The as-prepared alloy had an experimentally determined composition of Ti₁₇V₁₉Zr₁₉Nb₂₂Cr₂₃ and a density of 6.59 g·cm⁻³. Empirical alloy-design parameters indicate that the alloy is not a single-phase bcc solid solution, but rather a compositionally complex intermetallic alloy. The calculated hydrogen-affinity descriptors suggest a strong thermodynamic driving force for deuteride formation. Under 5 MPa D₂, the alloy absorbed 3.28 wt.% D, corresponding to D/M = 1.1. After ex situ deuteration, additional diffraction reflections were indexed using tetragonal deuteride reference structures corresponding to ZrV₂D_2.35 and TiD₂, while the Cr-rich bcc phase remained comparatively stable. Thermal desorption released 2.28 wt.% D up to 600 °C in three partially overlapping steps. These results demonstrate that deuterium storage in TiVNbZrCr is governed by phase-selective deuteride formation and decomposition rather than by homogeneous bcc lattice expansion. Full article

(This article belongs to the Special Issue Advances in the Study of Metal Crystals)

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19 pages, 10264 KB

Open AccessEditor’s ChoiceArticle

Effects of Cathodic Hydrogen Charging on the Mechanical Properties and Fracture Behaviour of Wire Arc Additively Manufactured AA2319

by Tinashe Mazarire, Alexander Galloway and Athanasios Toumpis

Metals 2026, 16(6), 647; https://doi.org/10.3390/met16060647 - 12 Jun 2026

Viewed by 430

Abstract

The growing adoption of wire arc additive manufacturing (WAAM) requires an understanding of how WAAM-fabricated aluminium alloys respond to environmental factors that may degrade mechanical performance. This study investigates the effects of cathodic charging on the mechanical properties and fracture behaviour of WAAM [...] Read more.

The growing adoption of wire arc additive manufacturing (WAAM) requires an understanding of how WAAM-fabricated aluminium alloys respond to environmental factors that may degrade mechanical performance. This study investigates the effects of cathodic charging on the mechanical properties and fracture behaviour of WAAM AA2319 aluminium alloy. Cathodic charging was conducted in an electrolyte containing 3.5 wt.% NaCl and 3 g/L ammonium thiocyanate using different applied current densities. The resulting changes in mechanical performance were assessed through uniaxial tensile and Charpy impact toughness tests. The results demonstrate that cathodic charging led to a progressive reduction in ductility with increasing current density. Elongation decreased by up to approximately 45% relative to the uncharged condition, while ultimate tensile strength and yield strength were marginally affected. Charpy impact testing revealed a corresponding reduction in impact toughness of approximately 40% following hydrogen charging. Fractographic analysis showed a transition from ductile fracture dominated by microvoid coalescence in the uncharged material, to a mixed ductile–brittle fracture in hydrogen-charged specimens, characterised by shallow dimples and quasi-cleavage features. The observed changes in mechanical behaviour and fracture morphology suggest that cathodic charging promoted hydrogen-assisted mechanical degradation, with features consistent with hydrogen-enhanced localised plasticity (HELP) and hydrogen-enhanced decohesion (HEDE). Full article

(This article belongs to the Special Issue Advanced Metallic Materials for Hydrogen Production, Storage and Transportation: Design, Degradation and Reliability)

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23 pages, 4149 KB

Open AccessEditor’s ChoiceArticle

Effect of Oxygen on Growth Mechanism of SiO₂ Inclusions in Non-Agitated Melts

by Suwam Kumar, Angshuman Podder, Muhammad Nabeel, André B. Phillion and Neslihan Dogan

Metals 2026, 16(6), 616; https://doi.org/10.3390/met16060616 - 4 Jun 2026

Viewed by 579

Abstract

This study investigates the growth and evolution of SiO₂-based inclusions in Si-killed steel under stagnant conditions and varying oxygen levels. Deoxidation experiments were conducted in a high-temperature furnace using commercial FeSi, with systematic variations in holding time and total oxygen content. [...] Read more.

This study investigates the growth and evolution of SiO₂-based inclusions in Si-killed steel under stagnant conditions and varying oxygen levels. Deoxidation experiments were conducted in a high-temperature furnace using commercial FeSi, with systematic variations in holding time and total oxygen content. Automated SEM–EDS analysis was employed to quantify inclusion size, number density, and chemical composition. Under stagnant conditions, SiO₂ inclusions were observed to grow and coarsen in the absence of melt agitation, following a t^1/3 scaling law. In high-oxygen melts, rapid inclusion growth was dominated by Stokes collision mechanisms, resulting in the formation of inclusions in the size range of 1–5 μm, which were subsequently removed by flotation. In contrast, low-oxygen melts exhibited slower growth kinetics governed primarily by Brownian motion and Ostwald ripening, producing smaller inclusions with characteristic sizes of 1–2 μm. These results demonstrate that the initial oxygen content plays a decisive role in controlling the dominant growth mechanisms and the extent of inclusion coarsening in non-agitated steel. Full article

(This article belongs to the Special Issue Recent Developments and Research on Ironmaking and Steelmaking)

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18 pages, 24710 KB

Open AccessEditor’s ChoiceArticle

Development and Characterization of CoCrMo/xCu Composites Fabricated by Powder Metallurgy

by Luis Olmos, Armando Michel Garcia-Carrillo, Jose Lemus-Ruiz, Omar Jiménez, Dante Arteaga, Julio Cesar Villalobos-Brito and Melina Velasco-Plascencia

Metals 2026, 16(6), 572; https://doi.org/10.3390/met16060572 - 23 May 2026

Viewed by 399

Abstract

This study aims to develop CoCrMo/xCu composites through liquid phase sintering. The primary focus is on investigating how the addition of copper influences sintering kinetics, microstructure, and mechanical properties. The copper volume fraction ranged from 10 to 25 wt.% relative to CoCrMo. Sintering [...] Read more.

This study aims to develop CoCrMo/xCu composites through liquid phase sintering. The primary focus is on investigating how the addition of copper influences sintering kinetics, microstructure, and mechanical properties. The copper volume fraction ranged from 10 to 25 wt.% relative to CoCrMo. Sintering was conducted at 1150 °C under an argon atmosphere. Characterization methods included scanning electron microscopy, computed microtomography, and X-ray diffraction analysis. It was observed that molten copper, which forms upon reaching its melting temperature, can fill the interparticle spaces left by CoCrMo particles in the green compacts. During sintering, densification is further enhanced by the dissolution of CoCrMo, resulting in the formation of intermetallic phases enriched in Cr and Mo, as well as a ternary Co-Cr-Cu compound. Both densification and intermetallic formation contribute to increased microhardness as Cu content rises. It is concluded that the CoCrMo/25Cu composite exhibits the best mechanical and corrosion properties because its densification was improved by the Cu liquid. Full article

(This article belongs to the Special Issue Preparation, Microstructure, and Mechanical Properties of Biomedical Metallic Materials)

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20 pages, 5260 KB

Open AccessEditor’s ChoiceArticle

Physics-Informed Neural Network Modelling of Hydrogen Diffusion and Trapping in Microalloyed Steels: A Data-Driven Synthesis Across Multiple Alloy Systems

by Saurabh Tiwari, Nokeun Park and Nagireddy Gari Subba Reddy

Metals 2026, 16(5), 546; https://doi.org/10.3390/met16050546 - 18 May 2026

Viewed by 548

Abstract

Hydrogen embrittlement is a critical degradation mechanism in microalloyed and pipeline steels used in hydrogen-economy infrastructure. We present a physics-informed neural network (PINN) framework that embeds Fick’s second law and the Arrhenius temperature dependence directly into the loss function, trained on 22 temperature-dependent [...] Read more.

Hydrogen embrittlement is a critical degradation mechanism in microalloyed and pipeline steels used in hydrogen-economy infrastructure. We present a physics-informed neural network (PINN) framework that embeds Fick’s second law and the Arrhenius temperature dependence directly into the loss function, trained on 22 temperature-dependent data points spanning pure α-Fe and API X65 pipeline steels (modern and vintage microstructures). The PINN recovered the pure-iron activation energy (4.2 kJ mol⁻¹ vs. literature 4.15 kJ mol⁻¹, R² = 1.00) and yielded Arrhenius activation energies of 28.5 and 45.2 kJ mol⁻¹ for modern and vintage X65, respectively, indicating substantially stronger trapping in older microstructures. McNabb–Foster analysis of ten ternary Fe–Me–C,N alloys revealed flat-trap binding enthalpies of 19 ± 2 kJ mol⁻¹ and deep-trap free energies of 57 ± 2 kJ mol⁻¹, with effective diffusivities spanning three orders of magnitude governed primarily by flat-trap density. The framework provides a computationally efficient and physically consistent tool for hydrogen transport prediction, with a clear roadmap for multi-feature extension incorporating compositional and microstructural descriptors. Full article

(This article belongs to the Special Issue Hydrogen Embrittlement of Metals and Alloys)

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24 pages, 7664 KB

Open AccessEditor’s ChoiceArticle

Mechanism of Ring Formation in Nickel Ore During Rotary Kiln Processing and Its Mitigation Strategies

by Kyu-Dong Lee, Wi-Geol Seo, Aman Gupta and Shi-Hoon Choi

Metals 2026, 16(5), 545; https://doi.org/10.3390/met16050545 - 18 May 2026

Viewed by 489

Abstract

Ring formation in rotary kilns is a major operational problem in the ferronickel dry smelting process, in which nickel laterite ore undergoes drying, calcination, and partial reduction. Excessive ring accretion reduces thermal efficiency and disrupts stable kiln operation. In this study, the mechanism [...] Read more.

Ring formation in rotary kilns is a major operational problem in the ferronickel dry smelting process, in which nickel laterite ore undergoes drying, calcination, and partial reduction. Excessive ring accretion reduces thermal efficiency and disrupts stable kiln operation. In this study, the mechanism of ring formation was investigated through a combined approach integrating laboratory-scale experiments and long-term operational data obtained from a large-scale industrial rotary kiln. The effects of ore composition, particle size, and temperature on melting and sintering behavior were examined, and their correlations with operating variables such as fuel input and kiln rotational speed were analyzed. The results show that ring formation is governed by the selective melting and adhesion of low-melting constituents, particularly in ores with low basicity (MgO/SiO₂ < 0.55) and high Fe content (>14 wt.%). A high fraction of fine particles (<75 μm) further promotes adhesion due to their lower melting temperature and enhanced mechanical retention on the refractory surface. In industrial operation, localized overheating near the burner zone and low kiln rotational speeds (0.9–1.1 rpm) significantly accelerate ring growth. These findings provide a mechanistic understanding of ring formation and suggest that appropriate ore blending and optimized control of fuel input and kiln rotation are effective strategies for mitigating ring accretion in commercial ferronickel rotary kilns. Full article

(This article belongs to the Section Extractive Metallurgy)

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47 pages, 6646 KB

Open AccessEditor’s ChoiceReview

Heat-Assisted Metal Spinning: Review

by Sergio Elizalde, Mohammad Jahazi and Henri Champliaud

Metals 2026, 16(5), 483; https://doi.org/10.3390/met16050483 - 29 Apr 2026

Cited by 1 | Viewed by 1312

Abstract

Heat-assisted metal spinning comprises incremental forming routes, conventional spinning, shear spinning and flow forming, performed at elevated temperature to increase formability. This review consolidates the main advances of the last fifteen years. It outlines spinning mechanics and the rationale for heating (higher ductility, [...] Read more.

Heat-assisted metal spinning comprises incremental forming routes, conventional spinning, shear spinning and flow forming, performed at elevated temperature to increase formability. This review consolidates the main advances of the last fifteen years. It outlines spinning mechanics and the rationale for heating (higher ductility, lower forming forces and microstructure control), then compares global and local heating strategies (furnace, flame, induction, laser and hot-gas convection) in terms of temperature uniformity, industrial practicality, energy efficiency and cost. Key process parameters (spindle speed, feed rate and thickness reduction) are discussed with respect to defect formation, and representative windows for defect mitigation are reported. Progress in modeling is reviewed, including coupled thermo-mechanical finite element simulations, damage/formability prediction and emerging data-driven optimization. The review also summarizes microstructural evolution under heat-assisted conditions, phase transformation, dynamic recrystallisation and grain growth, and its impact on final properties. Across more than 100 studies, evidence shows that robust thermal management can roughly double achievable deformation before failure and enables property tailoring in difficult-to-form alloys (Ni-based alloys, high-strength steels, Al, Mg and Ti). Remaining challenges include reliable in situ temperature measurement/control and improved predictive fidelity of simulations. Future opportunities include digital twins, real-time sensing and adaptive, machine-learning-assisted control. Full article

(This article belongs to the Special Issue Advanced Metallic Materials and Forming Technologies)

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16 pages, 7104 KB

Open AccessEditor’s ChoiceArticle

Phase Field Simulation Study of Competitive Growth of Polycrystalline in Directional Solidification Under Natural Convection Conditions

by Qiao Yin, Huaxiang Zha, Chunwen Guo, Junjie Li, Hongliang Zhao, Shuya Zhang, Xianglei Dong and Yuheng Fan

Metals 2026, 16(5), 454; https://doi.org/10.3390/met16050454 - 22 Apr 2026

Viewed by 566

Abstract

Directional solidification technology is the core process for manufacturing single-crystal blades in aero-engines, but transverse grain boundaries caused by the competitive growth of polycrystals severely degrade blade performance. To gain a deeper understanding of polycrystalline competitive growth behavior, this study investigates the competitive [...] Read more.

Directional solidification technology is the core process for manufacturing single-crystal blades in aero-engines, but transverse grain boundaries caused by the competitive growth of polycrystals severely degrade blade performance. To gain a deeper understanding of polycrystalline competitive growth behavior, this study investigates the competitive growth of polycrystals during directional solidification under natural convection based on the phase field and lattice Boltzmann coupling model. By adjusting the solutal expansion coefficient, grain configuration, and pulling velocity, the influence of the flow field on polycrystalline competitive growth is analyzed. The results indicate that changes in the solutal expansion coefficient affect the dendritic competition process and outcome, particularly for dendrites with larger favorably oriented (FO) angles, which are more likely to be eliminated at higher solutal expansion coefficients. Additionally, grain configurations with greater orientation differences between adjacent dendrites are more sensitive to changes in the solutal expansion coefficient, whereas configurations with smaller orientation differences are less affected. It was also found that as the pulling velocity increases, the primary dendrite arm spacing decreases and the growth direction of the dendrites deflects towards the temperature gradient direction. This leads to a reduction in vortices at the dendrite tips and grain boundaries, thereby decreasing the overall flow field intensity. During dendrite growth, solute is rejected from the solid phase, creating a concentration gradient between the dendrite tips and the liquid region. This induces convection in the liquid phase. The interaction between the flow field and the solute concentration in the liquid phase causes the flow field strength and solute concentration to exhibit periodic fluctuations. Full article

(This article belongs to the Special Issue Modeling and Simulation of Microstructural Evolution in Metallic Materials)

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23 pages, 7594 KB

Open AccessEditor’s ChoiceArticle

Hydrogen Reduction Behavior and Kinetic Modeling of a High-Barium Manganese Ore: Effect of Calcination

by Alok Sarkar, Elias Trondsen Dahl and Jafar Safarian

Metals 2026, 16(4), 434; https://doi.org/10.3390/met16040434 - 17 Apr 2026

Viewed by 768

Abstract

Hydrogen-based reduction of manganese ores has attracted increasing attention as a promising route for low-carbon manganese production. In this study, the reduction behavior, microstructural evolution, and kinetics of a high-barium-rich manganese ore were investigated in both dried and calcined states under isothermal hydrogen [...] Read more.

Hydrogen-based reduction of manganese ores has attracted increasing attention as a promising route for low-carbon manganese production. In this study, the reduction behavior, microstructural evolution, and kinetics of a high-barium-rich manganese ore were investigated in both dried and calcined states under isothermal hydrogen atmospheres at 600–800 °C. The ore was characterized using XRF, XRD, optical microscopy, SEM-EDS, and porosity measurements to evaluate mineralogical and structural changes during calcination and reduction. Calcination at 900 °C transformed MnO₂ into Mn₂O₃/Mn₃O₄, removed volatile components, and generated micro-porosity that improved gas accessibility. Isothermal reduction experiments revealed a rapid initial reduction stage followed by a slower reaction regime, with increasing temperature significantly accelerating the reduction rate. Despite isothermal furnace conditions, a temporary rise in sample temperature was observed due to the exothermic nature of manganese oxide reduction by hydrogen. XRD analysis confirmed that manganese oxides were predominantly reduced to MnO, while iron oxides were converted to metallic Fe. Porosity measurements showed significant pore development during reduction at moderate temperatures due to oxygen removal and gas evolution; however, at higher temperatures, partial sintering led to pore coalescence and densification, reducing the overall porosity. Kinetic analysis showed that the Johnson–Mehl–Avrami–Kolmogorov (JMAK) model effectively describes the reduction behavior. The apparent activation energies were 21.92 kJ.mol⁻¹ for dried ore and 17.40 kJ.mol⁻¹ for calcined ore, indicating diffusion-influenced kinetics. The results demonstrate that calcination enhances hydrogen reducibility by improving gas accessibility and reducing kinetic resistance, highlighting its importance for hydrogen-based manganese pre-reduction processes. Full article

(This article belongs to the Special Issue Green Technologies in Metal Recovery)

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22 pages, 40292 KB

Open AccessEditor’s ChoiceArticle

Maritime Applications as Motivation for Analytical Calculation of Thermal History in Low-Carbon Mild Steel WAAM Cylinders

by Eleftherios Lampros and Anna D. Zervaki

Metals 2026, 16(2), 192; https://doi.org/10.3390/met16020192 - 5 Feb 2026

Cited by 3 | Viewed by 1283

Abstract

This study reviews the application of wire arc additive manufacturing (WAAM) technology in maritime engineering and investigates an experimentally driven analytical approach for prediction of thermal distributions based on the Rosenthal solution. Two ER70S-6 low-carbon steel WAAM cylinders were fabricated using gas metal [...] Read more.

This study reviews the application of wire arc additive manufacturing (WAAM) technology in maritime engineering and investigates an experimentally driven analytical approach for prediction of thermal distributions based on the Rosenthal solution. Two ER70S-6 low-carbon steel WAAM cylinders were fabricated using gas metal arc welding (GMAW) and plasma arc welding (PAW) processes, with interlayer temperatures of 453 °C and 250 °C, respectively. Accurately measuring the temperature field to tailor the microstructure has long been a challenge. The results indicated a significant deviation between the analytical predictions and the experimental data. To address this discrepancy, a hybrid approach combining analytical and experimental results was implemented. Time intervals between layers, extracted from the experimental data, were incorporated into the Rosenthal equation to improve the accuracy of temperature field predictions. The microstructure at the bottom, middle, and top regions of the WAAM components was examined using optical microscopy. Tensile testing and Vickers microhardness measurements were conducted to evaluate mechanical properties. Scanning electron microscopy (SEM) was used to analyze fracture surfaces and identify fracture modes. The results were consistent with those reported for other ER70S-6 cylindrical WAAM components. This work highlights limitations of the Rosenthal solution and emphasizes the need for thermal models in WAAM applications. Full article

(This article belongs to the Special Issue Advanced Additive Manufacturing of Metallic Materials)

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13 pages, 4564 KB

Open AccessEditor’s ChoiceArticle

Microstructure and Mechanical Properties of Ultrafine-Grained CrMnFeCoNi High-Entropy Alloy Prepared via Powder Metallurgy

by Sunghyuk Jang, Seonghyun Park and Jae-Gil Jung

Metals 2026, 16(2), 170; https://doi.org/10.3390/met16020170 - 1 Feb 2026

Cited by 1 | Viewed by 1122

Abstract

We studied the microstructural evolution and mechanical properties of ultrafine-grained CrMnFeCoNi high-entropy alloys fabricated by mechanical alloying of various additives and spark plasma sintering. The additives were 1 wt.% process control agent (stearic acid) + 1 wt.% graphene nanofiber (GNF) (PG) or 1 [...] Read more.

We studied the microstructural evolution and mechanical properties of ultrafine-grained CrMnFeCoNi high-entropy alloys fabricated by mechanical alloying of various additives and spark plasma sintering. The additives were 1 wt.% process control agent (stearic acid) + 1 wt.% graphene nanofiber (GNF) (PG) or 1 wt.% Y₂O₃ + 1 wt.% GNF (YG) to modify the constituting phase of the sintered alloy. The PG and YG powders exhibited a single FCC phase. The YG powders had a larger powder size and a smaller crystallite size than the PG powders. Ultrafine-grained FCC matrices with average particle sizes of 0.57 μm and 0.71 μm, respectively, were formed through the SPS process of PG and YG powders. The absence of PCA in YG alloys resulted in a bimodal distribution of fine and coarse grains (due to incomplete mechanical alloying) and formation of a lesser and finer Cr₇C₃ phase (due to reduced C content). The sintered PG alloy contained coarse (~60 nm) spinel Mn₃O₄ oxides along grain boundaries, whereas the YG alloy exhibited coarse Mn₃O₄ and fine (~17 nm) Y₂O₃ oxide particles along grain boundaries. Additionally, the YG alloy contained tiny (~5 nm) Y₂O₃ oxide particles with a cube-on-cube orientation relationship within the FCC matrix. YG alloy exhibited higher hardness and compressive yield strength than PG alloy, mainly due to the oxide dispersion strengthening of finely dispersed Y₂O₃ particles. The addition of Y₂O₃ reinforcing particles had a minimal effect on the ultimate compressive strength and fracture strain of the sintered alloy. Full article

(This article belongs to the Special Issue Feature Papers in Entropic Alloys and Meta-Metals)

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34 pages, 10560 KB

Open AccessEditor’s ChoiceReview

Large Language Models for High-Entropy Alloys: Literature Mining, Design Orchestration, and Evaluation Standards

by Yutong Guo and Chao Yang

Metals 2026, 16(2), 162; https://doi.org/10.3390/met16020162 - 29 Jan 2026

Cited by 2 | Viewed by 1905

Abstract

High-entropy alloys (HEAs) present a fundamental design paradox: their exceptional properties arise from complex, high-dimensional composition–process–microstructure–property (CPMP) relationships, yet the knowledge needed to navigate this space is fragmented across a vast and unstructured literature. Large language models (LLMs) offer a transformative interface to [...] Read more.

High-entropy alloys (HEAs) present a fundamental design paradox: their exceptional properties arise from complex, high-dimensional composition–process–microstructure–property (CPMP) relationships, yet the knowledge needed to navigate this space is fragmented across a vast and unstructured literature. Large language models (LLMs) offer a transformative interface to this complexity. By extracting structured facts from text, they can convert dispersed and heterogeneous evidence (i.e., findings scattered across many studies and reported with inconsistent test protocols or characterization standards) into queryable knowledge graphs. Through code generation and tool composition, they can automate simulation pipelines, surrogate model construction, and inverse design workflows. This review analyzes how LLMs can augment key stages of HEA research—from intelligent literature mining and multimodal data integration (using LLMs to automatically extract and structure data from texts and to combine information across text, images, and other data sources) to model-driven design and closed-loop experimentation—illustrated by emerging case studies. We propose concrete evaluation protocols that measure direct scientific utility, including knowledge-graph completeness, workflow setup efficiency, and experimental validation hit rates. We also confront practical limitations: data sparsity and noise, model hallucination, domain bias (where models may exhibit superior predictive performance for specific, well-represented alloy systems over others due to imbalances in training data), and the imperative for reproducible infrastructure. We argue that domain-specialized LLMs, embedded within grounded, verifiable research systems, can not only accelerate HEA discovery but also standardize the representation, sharing, and reuse of community knowledge. Full article

(This article belongs to the Special Issue Advances in High-Entropy Alloys’ Microstructure, Properties and Preparation)

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16 pages, 7668 KB

Open AccessEditor’s ChoiceArticle

Heterogeneity of Microstructure and Mechanical Response in Steel–Titanium Multilayer Wires Subjected to Severe Plastic Deformation

by Bartłomiej Pabich, Paulina Lisiecka-Graca, Marcin Kwiecień and Janusz Majta

Metals 2026, 16(1), 106; https://doi.org/10.3390/met16010106 - 17 Jan 2026

Cited by 1 | Viewed by 1054

Abstract

This study addresses the fundamental problem of representing the rheological properties of heterostructured materials composed of metals that differ significantly in their crystal structure, stacking fault energy, and related characteristics. The necessity of accounting for essential strengthening mechanisms is highlighted. The study is [...] Read more.

This study addresses the fundamental problem of representing the rheological properties of heterostructured materials composed of metals that differ significantly in their crystal structure, stacking fault energy, and related characteristics. The necessity of accounting for essential strengthening mechanisms is highlighted. The study is based on experimental results related to the fabrication of a multilayer, heterogeneous system via multistage wire drawing, supported by microstructural analysis, microhardness measurements, and numerical simulations employing various flow-stress models. A discussion is presented regarding the effectiveness of these models in representing the deformation behavior of the investigated materials. The primary materials examined were a multilayer system composed of microalloyed steel and titanium. The obtained results indicate that, in addition to incorporating strengthening mechanisms, it is necessary to consider significant microstructural changes affecting microstructure evolution—particularly grain refinement induced by continuous recrystallization and the effects of strain hardening. Moreover, the findings point to the potential intensification of strengthening associated with pile-up mechanisms, linked to the development of dislocation substructures and the possible fragmentation of the hard phase in the vicinity of the more ductile microalloyed steel phase. In conclusion, the discussion integrates measurements of rheological properties obtained through tensile tests, supported by microstructural analysis, digital image correlation (DIC), and microhardness measurements, which collectively demonstrate the effectiveness of the adopted analytical approach. Full article

(This article belongs to the Special Issue Advances in the Forming and Processing of Metallic Materials)

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20 pages, 7671 KB

Open AccessEditor’s ChoiceArticle

Impact of Aggressive Environments and Processing Orientation on the Mechanical Performance of L-PBF 316L Stainless Steel

by Najib Abu-warda, Javier Bedmar, Sonia García-Rodríguez, Belén Torres and Joaquin Rams

Metals 2026, 16(1), 86; https://doi.org/10.3390/met16010086 - 13 Jan 2026

Cited by 1 | Viewed by 697

Abstract

This study addresses the limited understanding of how build orientation and aggressive environments jointly affect the mechanical reliability of L-PBF 316L stainless steel. Specimens were fabricated in vertical, edge, and flat orientations and exposed for 360 h to 1 M H₂SO [...] Read more.

This study addresses the limited understanding of how build orientation and aggressive environments jointly affect the mechanical reliability of L-PBF 316L stainless steel. Specimens were fabricated in vertical, edge, and flat orientations and exposed for 360 h to 1 M H₂SO₄, 3.5 wt.% NaCl, and dry air oxidation at 800 °C. Tensile tests and microstructural analyses revealed strong anisotropy: edge and flat builds showed higher tensile and yield strength, while vertical builds exhibited greater ductility. Aqueous environments caused surface degradation and moderate strength loss, most severe in vertical samples. High-temperature oxidation induced σ-phase precipitation, increasing tensile strength (~20%) but reducing ductility and yield strength. These findings highlight the critical role of building orientation and service conditions in ensuring long-term performance of L-PBF 316L stainless steel. Full article

(This article belongs to the Special Issue Recent Advances in Powder-Based Additive Manufacturing of Metals)

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20 pages, 6158 KB

Open AccessEditor’s ChoiceArticle

Improving Surface Roughness and Printability of LPBF Ti6246 Components Without Affecting Their Structure, Mechanical Properties and Building Rate

by Thibault Mouret, Aurore Leclercq, Patrick K. Dubois and Vladimir Brailovski

Metals 2026, 16(1), 32; https://doi.org/10.3390/met16010032 - 27 Dec 2025

Cited by 3 | Viewed by 1297

Abstract

Laser powder bed fusion (LPBF) is the best suited technology to manufacture temperature-resistant Ti-6Al-2Sn-4Zr-6Mo parts with complex geometrical features for high-end applications. Improving printing accuracy by reducing the layer thickness (t) generally requires repeating a tedious and time-consuming process optimization routine. [...] Read more.

Laser powder bed fusion (LPBF) is the best suited technology to manufacture temperature-resistant Ti-6Al-2Sn-4Zr-6Mo parts with complex geometrical features for high-end applications. Improving printing accuracy by reducing the layer thickness (t) generally requires repeating a tedious and time-consuming process optimization routine. To simplify this endeavour, the present work proposes three process equivalence criteria allowing to transfer optimized process conditions from one printing parameter set to another. This approach recommends keeping the volumetric laser energy density (VED) and hatching space-to-layer thickness ratio (h/t) constant, while adjusting the scanning speed (v) and hatching space (h) accordingly. To validate this approach, Ti6246 parts were printed with 50 µm and 25 µm layer thicknesses, while keeping VED = 100 J/mm³ and h/t = 3 constant for both cases. The printed samples were analyzed in terms of their density, microstructure and mechanical properties, as well as the geometric compliance of wall-, gap- and channel-containing artefacts. Highly dense samples exhibiting comparable microstructures and mechanical properties were obtained with both parameters sets investigated. However, they induced markedly differing geometric characteristics. Notably, using 25 µm layers allowed printing walls as thin as 0.2 mm as compared to 1.0 mm for 50 µm layers. Full article

(This article belongs to the Special Issue Recent Advances in Powder-Based Additive Manufacturing of Metals)

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20 pages, 6996 KB

Open AccessEditor’s ChoiceArticle

Influence of Surface Finishing on the Corrosion and Wear Behaviour of AISI 304 and AISI 436 Stainless Steels

by Silvia Gómez, Ismael Lamas, Alejandro Pereira and M. Consuelo Pérez

Metals 2025, 15(12), 1390; https://doi.org/10.3390/met15121390 - 18 Dec 2025

Viewed by 852

Abstract

The pitting corrosion resistance and the tribological behaviour of a ferritic stainless steel with high Mo content (AISI 436) and a commonly employed austenitic stainless steel (AISI 304) are compared. Special attention was paid to the role of Mo in improving corrosion resistance [...] Read more.

The pitting corrosion resistance and the tribological behaviour of a ferritic stainless steel with high Mo content (AISI 436) and a commonly employed austenitic stainless steel (AISI 304) are compared. Special attention was paid to the role of Mo in improving corrosion resistance of ferritic stainless steels. Since the surface condition is an important parameter related to the onset of pitting corrosion in the presence of chlorides, three different surface finishes were tested for both steels. Two commercial finishing grades and laboratory polishing down to 1 µm were compared. Moreover, the influence of surface condition on the tribological properties for both steels was also evaluated. The study demonstrates that surface finishing plays a decisive role in both the electrochemical and mechanical response of stainless steels. A comprehensive microstructural and tribological analysis reveals not only how commercial finishing treatments modify passive film behaviour, but also how they affect friction stability and wear mechanisms. Special emphasis is placed on the synergistic effect between molybdenum content, passive film integrity and manufacturing processes. The obtained results provide valuable insight for industrial applications where durability against chloride exposure and abrasion is critical. Full article

(This article belongs to the Special Issue Corrosion Behavior of Carbon Steels in Natural and Industrial Environments—3rd Edition)

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29 pages, 12009 KB

Open AccessFeature PaperEditor’s ChoiceReview

Anode Protection Strategies for Next-Generation Lithium–Oxygen Batteries: Toward Dendrite-Free Lithium Metal at Practical Current Densities

by Myeong-Chang Sung, Minhe Kim, Jiyoon Yu and Changhoon Choi

Metals 2025, 15(12), 1373; https://doi.org/10.3390/met15121373 - 15 Dec 2025

Cited by 1 | Viewed by 1486

Abstract

The promise of lithium–oxygen batteries lie not merely in their record-breaking theoretical energy density, but in the challenge of making such energy truly reversible. Rising as the key obstacle is the lithium metal anode, whose remarkable capacity and low potential come at the [...] Read more.

The promise of lithium–oxygen batteries lie not merely in their record-breaking theoretical energy density, but in the challenge of making such energy truly reversible. Rising as the key obstacle is the lithium metal anode, whose remarkable capacity and low potential come at the cost of dendritic growth, unstable solid electrolyte interphases, and relentless reactions with oxygen species. These instabilities, once overshadowed by cathode-related limitations, now define the frontier of research as current densities and energy demands approach practical levels. This review highlights recent progress in two complementary directions for anode protection: physical approaches, such as artificial protective layers, solid or functional separators, and oxygen-blocking interlayers that isolate and stabilize the surface; and chemical strategies, including electrolyte and additive design that enable in situ formation of LiF- and Li₃N-rich interfaces with high ionic conductivity and chemical robustness. Together, these approaches establish a unified framework for achieving dendrite-free and oxygen-resistant lithium interfaces. Mastering solid electrolyte interfacial stability rather than only cathode catalysis will ultimately determine whether lithium oxygen battery can evolve from laboratory prototypes to truly viable high-energy systems. Full article

(This article belongs to the Special Issue Surface Treatments and Coating of Metallic Materials)

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15 pages, 6689 KB

Open AccessEditor’s ChoiceArticle

Study of Selective Recovery of Lead- and Zinc-Based Products from Leachate After Alkaline Leaching of Copper Shaft Furnace Dust

by Michaela Ružičková, Martina Laubertová and Michal Marcin

Metals 2025, 15(12), 1362; https://doi.org/10.3390/met15121362 - 11 Dec 2025

Viewed by 916

Abstract

A leachate from alkaline leaching of copper shaft furnace (CSF) dust as a hazardous waste was used in this study for performing a chemical precipitation experiment of lead, zinc, and copper. The precipitation processes for lead, zinc, and copper were theoretically optimized based [...] Read more.

A leachate from alkaline leaching of copper shaft furnace (CSF) dust as a hazardous waste was used in this study for performing a chemical precipitation experiment of lead, zinc, and copper. The precipitation processes for lead, zinc, and copper were theoretically optimized based on a thermodynamic study. To determine suitable operating conditions, metal phase stability, reaction mechanisms, and precipitation order were analyzed using the Hydra/Medusa and HSC Chemistry v.10 software packages. In the first experimental stage, treatment of the alkaline leachate resulted in the formation of insoluble lead sulfate (PbSO₄), while zinc remained dissolved for subsequent recovery. In the second stage, the zinc-bearing solution was treated with Na₂CO₃, producing a mixed zinc precipitate consisting of Zn₅(OH)₆(CO₃)_2(s). This study determined that the optimal conditions for chemically precipitating lead as PbSO₄ from alkaline leachate (pH 13.5) are the use of 1 mol/L H₂SO₄ at pH 3.09 and Eh 0.22 V at 25 °C, while optimal zinc precipitation from this solution (pH 3.02) is achieved with 2 mol/L Na₂CO₃ at pH 9.39 and Eh –0.14 V at 25 °C. A small amount of copper present in the solution co-precipitated and was identified as an impurity in the zinc product. The chemical composition of the resulting precipitates was confirmed by SEM–EDX analysis. Full article

(This article belongs to the Special Issue Studies on Metal Leaching, Extraction and Recovery)

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30 pages, 10331 KB

Open AccessEditor’s ChoiceArticle

A Statistical-Based Model of Roll Force During Commercial Hot Rolling of Steel

by Edikan Udofia, Luke Messer, Gus Greivel, Alexandra Newman and Brian G. Thomas

Metals 2025, 15(12), 1346; https://doi.org/10.3390/met15121346 - 8 Dec 2025

Cited by 2 | Viewed by 1401

Abstract

This research introduces a new model to predict the roll force during hot rolling of steel, based on a statistical analysis of approximately 38,980 sets of measurements in a commercial mill with five finishing stands. The study includes ten different steel grades and [...] Read more.

This research introduces a new model to predict the roll force during hot rolling of steel, based on a statistical analysis of approximately 38,980 sets of measurements in a commercial mill with five finishing stands. The study includes ten different steel grades and features models of both single grades and the entire dataset. Three models are developed and compared: a temperature-dependent strain rate model (M1), a strain rate model (M2), and a simplified strain rate model (M3). The decrease in temperature with roll stand has a strong cross-correlation with compensating decreases in strain and contact length by roll stand, such that both the temperature and strain terms are statistically insignificant. The final model (M3)—

F [N] = 113.1 \cdot \dot{ϵ} {[s^{- 1}]}^{0.3141} \cdot w [mm] \cdot ℓ [mm]

—relates force (F) to strain rate (

\dot{ϵ}

), width (w), and contact length (ℓ) and achieves an

R^{2}

fit of 0.946 over all 10 steel grades. Although the single-grade models show slightly higher accuracy, the final model retains robust predictive capability with only two fitting parameters. This model enables fast and easy estimation of roll force for commercial hot rolling of low-carbon, medium-carbon, and high-strength–low-alloy steels. Full article

(This article belongs to the Special Issue Advanced Rolling Technologies of Steels and Alloys)

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18 pages, 9799 KB

Open AccessEditor’s ChoiceArticle

Influence of Experimental Parameters on the Determination of Copper Dissolution in Corrosion Processes Using Gold Microelectrodes

by Javier Izquierdo, Adrián Méndez-Guerra, Raquel Rodríguez-Raposo and Ricardo M. Souto

Metals 2025, 15(12), 1278; https://doi.org/10.3390/met15121278 - 21 Nov 2025

Cited by 1 | Viewed by 775

Abstract

In situ electrochemical imaging of corrosion reactions is performed directly by scanning electrochemical microscopy (SECM) in generation-collection mode. This method involves redox conversion of soluble metal ions at the amperometric tip for quantification. Unfortunately, many metals, such as copper, do not undergo redox [...] Read more.

In situ electrochemical imaging of corrosion reactions is performed directly by scanning electrochemical microscopy (SECM) in generation-collection mode. This method involves redox conversion of soluble metal ions at the amperometric tip for quantification. Unfortunately, many metals, such as copper, do not undergo redox conversion to a soluble state and are deposited on the SECM tip. They therefore modify the electrochemical behavior of the tip and require consideration of metal stripping processes. In addition, the miniaturization of the electrode to operate as a microelectrode tip can be accompanied by variations in the potential range and distribution of the redox processes related to copper deposition and redissolution, thus complicating the adequate choice of electrochemical conditions applied to the tip for the unambiguous operation of SECM in the generation-collection mode to study the corrosion of copper-based materials. Therefore, in this work, a study of different parameters for the amperometric determination of Cu²⁺ ions was conducted using gold disk electrodes of 500 and 10 μm diameter to represent the typical sizes employed in conventional and scanning microelectrochemical measurements. The investigation was performed to analyze the effect of underpotential deposition (UPD) and overpotential deposition (ODP) on the voltammetric characteristics of copper deposition and redissolution resulting from variations in the solution composition, i.e., the nature of anions and pH. The dependence and limits of the reduction and reoxidation waves were analyzed as functions of the Cu²⁺ ion concentration, the ionic strength of the electrolyte, and the pH of the solution. The results were interpreted as UPD and OPD. Under conditions close to the marine environment, the release of Cu²⁺ ions can be unambiguously detected and quantified from potentials above −0.1 V vs. Ag/AgCl. Full article

(This article belongs to the Section Corrosion and Protection)

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14 pages, 2656 KB

Open AccessEditor’s ChoiceArticle

Evaluation of Filter Cake Washing Processes in Hydrometallurgical Battery Recycling of Lithium-Ion Batteries to Optimize Recoveries

by Dominic Dittmer, Maya Andary, Fabian Diaz and Bernd Friedrich

Metals 2025, 15(11), 1262; https://doi.org/10.3390/met15111262 - 19 Nov 2025

Cited by 2 | Viewed by 1750

Abstract

Due to climate change, electromobility and thus lithium-ion batteries are attracting increased interest. With a simultaneous increase in demand for raw materials like Li, Ni, Co, and Mn, their hydrometallurgical recycling is also gaining attention. The associated recoveries must be improved due to [...] Read more.

Due to climate change, electromobility and thus lithium-ion batteries are attracting increased interest. With a simultaneous increase in demand for raw materials like Li, Ni, Co, and Mn, their hydrometallurgical recycling is also gaining attention. The associated recoveries must be improved due to EU regulations. In a lab scale, metals are lost to the wrong filter cakes after leaching, cementation, and precipitations. Therefore, this work investigates the question of how many wash steps are suitable after each process step to optimize the recoveries and purity of filter cakes by comparing a reference process and a process with extended washing. The comparison showed that it is possible to recover up to 3.5% of Ni, Co, and Mn by extended washing at each step and in total nearly 100% of Li if wash water is recirculated. An investigation of the substeps of washing demonstrated that single wash steps are able to recover from 0.5% to 3.5% of Ni, Co, and Mn and from 1.6% to 8.7% of Li. The impact of extended washing on purity is shown by the analysis of filter cakes, where the purity of Fe and Al could be improved by 43.0% and for Ni, Co, and Mn by 48.0%. The paper closes with recommendations on how many wash steps are suitable after each process step. Full article

(This article belongs to the Special Issue New Science-Based Concepts for Enhancing Efficiency in Battery Recycling)

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28 pages, 33891 KB

Open AccessEditor’s ChoiceArticle

Influence of Substrate Preheating on Processing Dynamics and Microstructure of Alloy 718 Produced by Directed Energy Deposition Using a Laser Beam and Wire

by Atieh Sahraeidolatkhaneh, Achmad Ariaseta, Gökçe Aydin, Morgan Nilsen and Fredrik Sikström

Metals 2025, 15(11), 1184; https://doi.org/10.3390/met15111184 - 25 Oct 2025

Cited by 5 | Viewed by 1615

Abstract

Effective thermal management is essential in metal additive manufacturing to ensure process stability and desirable material properties. Directed energy deposition using a laser beam and wire (DED-LB/w) enables the production of large, high-performance components but remains sensitive to adverse thermal effects during multi-layer [...] Read more.

Effective thermal management is essential in metal additive manufacturing to ensure process stability and desirable material properties. Directed energy deposition using a laser beam and wire (DED-LB/w) enables the production of large, high-performance components but remains sensitive to adverse thermal effects during multi-layer deposition due to heat accumulation. While prior studies have investigated interlayer temperature control and substrate preheating in DED modalities, including laser-powder and arc-based systems, the influence of substrate preheating in DED-LB/w has not been thoroughly examined. This study employs substrate preheating to simulate heat accumulation and assess its effects on melt pool geometry, wire–melt pool interaction, and the microstructural evolution of Alloy 718. Experimental results demonstrate that increased substrate temperatures lead to a gradual expansion of the melt pool, with a notable transition occurring beyond 400 °C. Microstructural analysis reveals that elevated preheat temperatures promote coarser secondary dendrite arm spacing and the development of wider columnar grains. Moreover, Nb-rich secondary phases, including the Laves phase, exhibit increased size but relatively unchanged area fractions. Observations from electrical conductance measurements and coaxial visual imaging show that preheat temperature significantly affects the process dynamics and microstructural evolution, providing a basis for advanced process control strategies. Full article

(This article belongs to the Special Issue Advanced Manufacturing Technologies: Friction Stir Welding and Additive Manufacturing of Metals)

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14 pages, 21454 KB

Open AccessEditor’s ChoiceArticle

Microstructure and Mechanical Properties of Y-Doped AlCoCrFeNi_2.1 Eutectic High-Entropy Alloy Fabricated by PBF-LB/M

by Gang Wang, Xiangyu Xu, Runbo Zhang, Ren Yuan and Xuteng Lv

Metals 2025, 15(10), 1130; https://doi.org/10.3390/met15101130 - 11 Oct 2025

Viewed by 1176

Abstract

A Y-doped AlCoCrFeNi_2.1 eutectic high-entropy alloy was fabricated via powder bed fusion-laser melting/metal (PBF-LB/M), and the effects of the rare-earth element Y on its microstructure and mechanical properties were investigated. The results indicate that Y addition preserves the fine eutectic microstructure inherent [...] Read more.

A Y-doped AlCoCrFeNi_2.1 eutectic high-entropy alloy was fabricated via powder bed fusion-laser melting/metal (PBF-LB/M), and the effects of the rare-earth element Y on its microstructure and mechanical properties were investigated. The results indicate that Y addition preserves the fine eutectic microstructure inherent to the PBF-LB/M process, while inducing lattice distortion within the face-centered cubic (FCC) matrix and promoting grain refinement. During solidification, Y facilitates heterogeneous nucleation and, due to its strong affinity with Al, increases both the volume fraction of the body-centered cubic (BCC) phase and the proportion of high-angle grain boundaries. X-ray diffraction (XRD) analysis further confirms that Y suppresses the formation of the ordered B2 phase. Tensile testing reveals that Y doping improves the tensile strength from 1383 MPa to 1475 MPa and enhances the elongation from 13.0% to 16.3%. Fractography shows a transition from quasi-cleavage to ductile fracture mode, indicating that Y significantly enhances the strength–ductility synergy of the alloy. Full article

(This article belongs to the Section Additive Manufacturing)

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27 pages, 3885 KB

Open AccessEditor’s ChoiceArticle

Experimental and Machine Learning-Based Assessment of Fatigue Crack Growth in API X60 Steel Under Hydrogen–Natural Gas Blending Conditions

by Nayem Ahmed, Ramadan Ahmed, Samin Rhythm, Andres Felipe Baena Velasquez and Catalin Teodoriu

Metals 2025, 15(10), 1125; https://doi.org/10.3390/met15101125 - 10 Oct 2025

Cited by 5 | Viewed by 2294

Abstract

Hydrogen-assisted fatigue cracking presents a critical challenge to the structural integrity of legacy carbon steel natural gas pipelines being repurposed for hydrogen transport, posing a major barrier to the deployment of hydrogen infrastructure. This study systematically evaluates the fatigue crack growth (FCG) behavior [...] Read more.

Hydrogen-assisted fatigue cracking presents a critical challenge to the structural integrity of legacy carbon steel natural gas pipelines being repurposed for hydrogen transport, posing a major barrier to the deployment of hydrogen infrastructure. This study systematically evaluates the fatigue crack growth (FCG) behavior of API 5L X60 pipeline steel under varying hydrogen–natural gas (H₂–NG) blending conditions to assess its suitability for long-term hydrogen service. Experiments are conducted using a custom-designed autoclave to replicate field-relevant environmental conditions. Gas mixtures range from 0% to 100% hydrogen by volume, with tests performed at a constant pressure of 6.9 MPa and a temperature of 25 °C. A fixed loading frequency of 8.8 Hz and load ratio (R) of 0.60 ± 0.1 are applied to simulate operational fatigue loading. The test matrix is designed to capture FCG behavior across a broad range of stress intensity factor values (ΔK), spanning from near-threshold to moderate levels consistent with real-world pipeline pressure fluctuations. The results demonstrate a clear correlation between increasing hydrogen concentration and elevated FCG rates. Notably, at 100% hydrogen, API X60 specimens exhibit crack propagation rates up to two orders of magnitude higher than those in 0% hydrogen (natural gas) conditions, particularly within the Paris regime. In the lower threshold region (ΔK ≈ 10 MPa·√m), the FCG rate (da/dN) increased nonlinearly with hydrogen concentration, indicating early crack activation and reduced crack initiation resistance. In the upper Paris regime (ΔK ≈ 20 MPa·√m), da/dNs remained significantly elevated but exhibited signs of saturation, suggesting a potential limiting effect of hydrogen concentration on crack propagation kinetics. Fatigue life declined substantially with hydrogen addition, decreasing by ~33% at 50% H₂ and more than 55% in pure hydrogen. To complement the experimental investigation and enable predictive capability, a modular machine learning (ML) framework was developed and validated. The framework integrates sequential models for predicting hydrogen-induced reduction of area (RA), fracture toughness (FT), and FCG rate (da/dN), using CatBoost regression algorithms. This approach allows upstream degradation effects to be propagated through nested model layers, enhancing predictive accuracy. The ML models accurately captured nonlinear trends in fatigue behavior across varying hydrogen concentrations and environmental conditions, offering a transferable tool for integrity assessment of hydrogen-compatible pipeline steels. These findings confirm that even low-to-moderate hydrogen blends significantly reduce fatigue resistance, underscoring the importance of data-driven approaches in guiding material selection and infrastructure retrofitting for future hydrogen energy systems. Full article

(This article belongs to the Special Issue Failure Analysis and Evaluation of Metallic Materials)

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22 pages, 16895 KB

Open AccessEditor’s ChoiceArticle

Surface Characterization of Hot-Rolled AISI 440C Round Wire at the Different Steps of the Typical Production Process

by Alessio Malandruccolo, Stefano Rossi and Cinzia Menapace

Metals 2025, 15(10), 1102; https://doi.org/10.3390/met15101102 - 2 Oct 2025

Viewed by 1040

Abstract

This study investigates the surface characteristics and corrosion behavior of a high-C martensitic stainless steel (AISI 440C) at different stages of its manufacturing process. As a class, these steels prioritize high mechanical properties and wear resistance over superior corrosion resistance. Hot working operations, [...] Read more.

This study investigates the surface characteristics and corrosion behavior of a high-C martensitic stainless steel (AISI 440C) at different stages of its manufacturing process. As a class, these steels prioritize high mechanical properties and wear resistance over superior corrosion resistance. Hot working operations, such as rolling, create a surface oxide scale that must be removed via pickling to restore the material’s inherent corrosion resistance. This process also eliminates the underlying Cr-depleted layer, allowing for the re-establishment of a protective passive film. Using potentiodynamic polarization curves and micrographic analysis, the material’s behavior in different conditions, as-rolled, with a post-heat treatment oxide scale, and in a bare, oxide-free state, has been assessed. The results showed that the material lacks stable passive behavior under all conditions. The as-rolled and heat-treated conditions both exhibited active behavior and formed thick, non-adherent corrosion products. The oxide layer formed after heat treatment performed the worst, showing a significant increase in corrosion current density. These findings confirm the material’s susceptibility to corrosion in Cl⁻ ion-rich environments, highlighting the need for limited storage in such conditions and rapid pickling after thermal processing to mitigate surface damage. Full article

(This article belongs to the Section Corrosion and Protection)

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29 pages, 4438 KB

Open AccessEditor’s ChoiceReview

AI Design for High Entropy Alloys: Progress, Challenges and Future Prospects

by Enzhi Xie and Chao Yang

Metals 2025, 15(9), 1012; https://doi.org/10.3390/met15091012 - 11 Sep 2025

Cited by 10 | Viewed by 6713

Abstract

High-entropy alloys have demonstrated significant application potential in many industrial fields due to their outstanding comprehensive properties. However, the complex multi-component compositions pose challenges for traditional design approaches. In recent years, artificial intelligence (AI) technology, with its powerful capabilities in data analysis, prediction, [...] Read more.

High-entropy alloys have demonstrated significant application potential in many industrial fields due to their outstanding comprehensive properties. However, the complex multi-component compositions pose challenges for traditional design approaches. In recent years, artificial intelligence (AI) technology, with its powerful capabilities in data analysis, prediction, and optimization, has provided new pathways for rapid discovery and performance modulation of high-entropy alloys. This paper systematically reviews the latest advancements in AI applications for high-entropy alloy design, covering key technologies such as machine learning models (e.g., active learning, generative models, transfer learning), high-throughput computing and experimental data processing, phase structure and property prediction. It also presents typical application cases, including compositional optimization, phase structure prediction, performance synergistic regulation, and novel material discovery. Although AI has significantly improved design efficiency and accuracy, challenges remain, such as the scarcity of high-quality data, insufficient model interpretability, and interdisciplinary integration. Future efforts should focus on building a more robust data ecosystem, enhancing model transparency, and strengthening closed-loop validation between AI and experimental science to advance intelligent design and engineering applications of high-entropy alloys. Full article

(This article belongs to the Special Issue Advances in High-Entropy Alloys’ Microstructure, Properties and Preparation)

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15 pages, 8787 KB

Open AccessEditor’s ChoiceArticle

Point Defects in MoNbTi-Based Refractory Multi-Principal-Element Alloys

by Thai hang Chung, Maciej Oskar Liedke, Saikumaran Ayyappan, Maik Butterling, Riley Craig Ferguson, Adric C. L. Jones, Andreas Wagner, Khalid Hattar, Djamel Kaoumi and Farida A. Selim

Metals 2025, 15(9), 989; https://doi.org/10.3390/met15090989 - 6 Sep 2025

Cited by 1 | Viewed by 1370

Abstract

As emergent material candidates for extreme environments, refractory high-entropy alloys (HEAs) or refractory multi-principal-element alloys (RMPEAs) comprising refractory metals feature qualities such as high radiation tolerance, corrosion resistance, and mechanical strength. A set of MoNbTi-based RMPEA samples with Al, Cr, V, and Zr [...] Read more.

As emergent material candidates for extreme environments, refractory high-entropy alloys (HEAs) or refractory multi-principal-element alloys (RMPEAs) comprising refractory metals feature qualities such as high radiation tolerance, corrosion resistance, and mechanical strength. A set of MoNbTi-based RMPEA samples with Al, Cr, V, and Zr additions are prepared by spark plasma sintering and investigated for their response to irradiation using 10 MeV Si⁺ ions with a dose of

1.43 \times 10^{15}

ions/cm². Positron annihilation spectroscopy and transmission electron microscopy are employed as atomic- and meso- scale techniques to reveal how chemical complexity, nanotwinning, and phase fractions play an important role in radiation-induced defect accumulation and damage tolerance. The study provides experimental evidence of nanotwinning acting as an effective sink for radiation-induced point defects. Full article

(This article belongs to the Special Issue Advances in High-Entropy Alloys’ Microstructure, Properties and Preparation)

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24 pages, 6760 KB

Open AccessEditor’s ChoiceArticle

Influence of Microstructure and Heat Treatment on the Corrosion Resistance of Mg-1Zn Alloy Produced by Laser Powder Bed Fusion

by Raúl Reyes-Riverol, Ángel Triviño-Peláez, Federico García-Galván, Marcela Lieblich, José Antonio Jiménez and Santiago Fajardo

Metals 2025, 15(8), 853; https://doi.org/10.3390/met15080853 - 30 Jul 2025

Cited by 2 | Viewed by 2066

Abstract

The corrosion behavior of an additively manufactured Mg-1Zn alloy was investigated in both the transverse and longitudinal directions relative to the build direction, in the as-built condition and after annealing at 350 °C for 24 h under high vacuum. Microstructural characterization using XRD [...] Read more.

The corrosion behavior of an additively manufactured Mg-1Zn alloy was investigated in both the transverse and longitudinal directions relative to the build direction, in the as-built condition and after annealing at 350 °C for 24 h under high vacuum. Microstructural characterization using XRD and SEM revealed the presence of magnesium oxide (MgO) and the absence of intermetallic second-phase particles. Optical microscopy (OM) images and Electron Backscatter Diffraction (EBSD) maps showed a highly complex grain morphology with anomalous, anisotropic shapes and a heterogeneous grain size distribution. The microstructure includes grains with a pronounced columnar morphology aligned along the build direction and is therefore characterized by a strong crystallographic texture. Electrochemical techniques, including PDP and EIS, along with gravimetric H₂ collection, concluded that the transverse plane exhibited greater corrosion resistance compared to the longitudinal plane. Additionally, an increase in cathodic kinetics was observed when comparing as-built with heat-treated samples. Full article

(This article belongs to the Section Corrosion and Protection)

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19 pages, 3512 KB

Open AccessEditor’s ChoiceReview

Data Science in Order and Disorder of High-Entropy Materials

by Jiasheng Wang, Jianzhong Jiang, Peter K. Liaw, Guihong Geng and Yong Zhang

Metals 2025, 15(6), 632; https://doi.org/10.3390/met15060632 - 3 Jun 2025

Cited by 5 | Viewed by 3423

Abstract

In recent years, high-entropy materials (HEMs) have garnered significant attention due to their unique multi-principal element compositions, which endow them with remarkable properties distinct from traditional materials. The order and disorder in HEMs are particularly complex, influenced by factors such as temperature, pressure, [...] Read more.

In recent years, high-entropy materials (HEMs) have garnered significant attention due to their unique multi-principal element compositions, which endow them with remarkable properties distinct from traditional materials. The order and disorder in HEMs are particularly complex, influenced by factors such as temperature, pressure, and composition, and are closely related to their mechanical and physical properties. This review systematically summarizes the progress in understanding the order and disorder in HEMs, with a focus on the role of data science in this field. We introduce the basic concepts of order and disorder and the related research in HEMs, discuss the nonlinear behaviors of HEMs, and elaborate on the relevant applications of data science, including analysis by machine learning, molecular dynamics simulations, and Monte Carlo simulations. Challenges and future directions are also explored, aiming to provide comprehensive insights into materials science. Full article

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18 pages, 8811 KB

Open AccessEditor’s ChoiceArticle

Lightweight Ti₃VNbAl_0.5Zr_x (x = 0, 0.1, 0.5, and 1) Refractory High-Entropy Alloys with an Optimized Balance of Strength and Ductility

by Haoyu Fang, Xuejiao Wang, Aidong Lan, Xi Jin and Junwei Qiao

Metals 2025, 15(5), 503; https://doi.org/10.3390/met15050503 - 30 Apr 2025

Cited by 2 | Viewed by 1908

Abstract

Achieving a balance between strength and room-temperature ductility remains an urgent need and a significant challenge for body-centered cubic (BCC) structure materials. In this paper, a good combination of strength and ductility in single-phase BCC-structured Ti₃VNbAl_0.5Zr_x (x = [...] Read more.

Achieving a balance between strength and room-temperature ductility remains an urgent need and a significant challenge for body-centered cubic (BCC) structure materials. In this paper, a good combination of strength and ductility in single-phase BCC-structured Ti₃VNbAl_0.5Zr_x (x = 0, 0.1, 0.5, and 1) lightweight high-entropy alloys (LHEAs) was designed by reducing the valence-electron concentration in combination with the d-electron theory. The influences of Zr on the microstructures and mechanical properties of the alloys were systematically studied. The yield strengths of Zr0, Zr0.1, Zr0.5, and Zr1 alloys were 644 MPa, 703 MPa, 827 MPa, and 904 Mpa, respectively. The tensile strains of Zr0, Zr0.1, Zr0.5, and Zr1 alloys were 29%, 30%, 20%, and 16%, respectively. The deformation mechanism was studied using transmission electron microscopy (TEM). The results demonstrate that the alloys could still maintain single-phase BCC structure after deformation, and neither phase transformation nor twinning was detected during the deformation process. The main deformation mechanism of the Zr1 alloy is dislocation slip. The current work has great significance for developing high-strength, ductile, and low-density structural materials. Full article

(This article belongs to the Special Issue Feature Papers in Entropic Alloys and Meta-Metals)

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16 pages, 4063 KB

Open AccessEditor’s ChoiceArticle

Kinetics of Oxidation of Binary Ti-Cu Alloys in the 600–800 °C Temperature Range

by Fatemah Alqattan, Fei Yang and Leandro Bolzoni

Metals 2025, 15(2), 222; https://doi.org/10.3390/met15020222 - 18 Feb 2025

Cited by 4 | Viewed by 2875

Abstract

The oxidation behaviour of Ti alloys is a crucial aspect for structural components operating at high service temperature. The aim of this study is to identify the oxidation kinetics and mechanism of binary Ti-Cu alloys with a progressively higher amount of Cu with [...] Read more.

The oxidation behaviour of Ti alloys is a crucial aspect for structural components operating at high service temperature. The aim of this study is to identify the oxidation kinetics and mechanism of binary Ti-Cu alloys with a progressively higher amount of Cu with the alloys having a α + β lamellar structure. It is found that all the alloys followed a non-ideal (i.e., n ≠ 2) parabolic relationship, as controlled by anionic oxygen diffusion, with a distinct effect from both oxidation temperature and alloy chemistry. Specifically, faster oxidation kinetics are found both at higher temperatures and for higher Cu contents, resulting in the formation of thicker oxide scale layers. The oxidation mechanism primarily entails the formation of the stable TiO₂ rutile polymorph. However, transitions through metastable phases (e.g., anatase) and texturing of rutile are also revealed as dictated by the composition of the alloy at specific oxidation temperature/time pairs. Full article

(This article belongs to the Special Issue Powder Metallurgy of Metals and Alloys)

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14 pages, 5744 KB

Open AccessEditor’s ChoiceArticle

Effect of Multi-Phase Composite Structure on the Mechanical Properties of Al_xFe_1.5CoNiC_0.12 High Entropy Alloys

by Yiteng Jiang, Aoxiang Li, Kaiwen Kang, Jinshan Zhang, Di Huang, Chunning Che, Saike Liu, Mingkun Xu, Yaqing Li, Borui Zhang and Gong Li

Metals 2025, 15(2), 203; https://doi.org/10.3390/met15020203 - 14 Feb 2025

Cited by 5 | Viewed by 1829

Abstract

Single-phase high entropy alloys (HEAs) exhibit limited mechanical properties while dual-phase and multi-phase HEAs offer better strength, toughness, and stability. In this paper, the as-cast Al_xFe_1.5CoNiC_0.12 HEAs with triple-phase dendritic composite structure is studied, and the influence of [...] Read more.

Single-phase high entropy alloys (HEAs) exhibit limited mechanical properties while dual-phase and multi-phase HEAs offer better strength, toughness, and stability. In this paper, the as-cast Al_xFe_1.5CoNiC_0.12 HEAs with triple-phase dendritic composite structure is studied, and the influence of the composite structure on the mechanical properties is discussed. The interdendrite (ID) of this structure is composed of a uniformly distributed high-density ordered face-centered cubic structure (L1₂) precipitate phase and face-centered cubic (FCC) matrix, while the dendrite (DR) consists of an ordered body-centered cubic (B2) single-phase. The high density L1₂ precipitate phase leads to a higher hardness in the FCC+L1₂ dual-phase region compared to the B2 single-phase region. The decrease in Al content can greatly improve mechanical performance. The improvement was attributed to the higher volume fraction of the ID and the smaller particle size of the precipitates. The L1₂ phase nano-precipitates exhibit minimal lattice mismatch with the FCC matrix, thereby significantly enhancing the stability of the alloy at the nanoscale. This stability is reflected in the fracture morphology. Modulating the triple-phase dendritic composite structure effectively improves the mechanical properties of the alloy. Full article

(This article belongs to the Special Issue Advances in High-Entropy Alloys’ Microstructure, Properties and Preparation)

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22 pages, 6744 KB

Open AccessEditor’s ChoiceArticle

Magnetic Pulse Powder Compaction

by Viktors Mironovs, Jekaterina Nikitina, Matthias Kolbe, Irina Boiko and Yulia Usherenko

Metals 2025, 15(2), 155; https://doi.org/10.3390/met15020155 - 4 Feb 2025

Cited by 1 | Viewed by 4157

Abstract

Powder metallurgy (PM) offers several advantages over conventional melt metallurgy, including improved homogeneity, fine grain size, and pseudo-alloying capabilities. Transitioning from conventional methods to PM can result in significant enhancements in material properties and production efficiency by eliminating unnecessary process steps. Dynamic compaction [...] Read more.

Powder metallurgy (PM) offers several advantages over conventional melt metallurgy, including improved homogeneity, fine grain size, and pseudo-alloying capabilities. Transitioning from conventional methods to PM can result in significant enhancements in material properties and production efficiency by eliminating unnecessary process steps. Dynamic compaction techniques, such as impulse and explosive compaction, aim to achieve higher powder density without requiring sintering, further improving PM efficiency. Among these techniques, magnetic pulse compaction (MPC) has gained notable interest due to its unique process mechanics and distinct advantages. MPC utilizes the rapid discharge of energy stored in capacitors to generate a pulsed electromagnetic field, which accelerates a tool to compress the powder. This high-speed process is particularly well-suited for compacting complex geometries and finds extensive application in industries such as powder metallurgy, welding, die forging, and advanced material manufacturing. This paper provides an overview of recent advancements and applications of MPC technology, highlighting its capabilities and potential for broader integration into modern manufacturing processes. Full article

(This article belongs to the Special Issue Powder Metallurgy of Metallic Materials)

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15 pages, 3642 KB

Open AccessEditor’s ChoiceArticle

Effect of Annealing after Casting and Cold Rolling on Microstructure and Electrochemical Behavior of High-Entropy Alloy, Cantor

by Jinsurang Lim, Byung-Hyun Shin, Doo-In Kim, Jong-Seong Bae, Jung-Woo Ok, Seongjun Kim, Jinyong Park, Je In Lee and Jang-Hee Yoon

Metals 2024, 14(8), 846; https://doi.org/10.3390/met14080846 - 24 Jul 2024

Cited by 7 | Viewed by 3605

Abstract

High-entropy alloys (HEAs), a relatively new class of materials, have attracted significant attention in materials science owing to their unique properties and potential applications. High entropy stabilizes the phase of a solid solution over a wide range of chemical compositions, yielding unique properties [...] Read more.

High-entropy alloys (HEAs), a relatively new class of materials, have attracted significant attention in materials science owing to their unique properties and potential applications. High entropy stabilizes the phase of a solid solution over a wide range of chemical compositions, yielding unique properties superior to those of conventional alloys. Therefore, this study analyzed the microstructure and electrochemical behavior of HEAs (Cantor) to evaluate their corrosion resistance, according to their manufacturing process (casting, cold rolling, and annealing). The microstructural morphologies and sizes were analyzed using electron backscatter diffraction. The electrochemical behavior was examined using open circuit potential measurements, electrochemical impedance spectroscopy, potentiodynamic polarization tests, and critical pitting temperature measurements using a potentiostat. The casting process formed a nonuniform microstructure (average grain size = 19 μm). The cold rolling process caused the formation of fine grains (size = 4 μm). A uniform microstructure (grain size > 151 μm) was formed after heat treatment. The corrosion resistance of the HEAs was determined from the passivation layer formed by Cr oxidation. These microstructural differences resulted in variations in the electrochemical behavior. Microstructural and electrochemical analyses are crucial because HEAs have diverse potential applications. Therefore, this study contributes to future improvements in HEA manufacturing processes. Full article

(This article belongs to the Special Issue Casting Alloy Design and Characterization—2nd Edition)

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19 pages, 13655 KB

Open AccessFeature PaperEditor’s ChoiceArticle

High-Entropy Alloy Al_0.2Co_1.5CrFeNi_1.5Ti_0.5 Prepared from High-Entropy Oxide (Al_0.2Co_1.5CrFeNi_1.5Ti_0.5)₃O₄ by a Deoxidation Process via a CaH₂-Assisted Molten Salt Method

by Yasukazu Kobayashi, Shota Yokoyama and Ryo Shoji

Metals 2024, 14(4), 443; https://doi.org/10.3390/met14040443 - 10 Apr 2024

Cited by 5 | Viewed by 4031

Abstract

High-entropy alloys (HEAs) have attracted a great deal of research interest these days because of their attractive properties. Low-temperature chemical synthesis methods are being developed to obtain nanoscale HEAs with low energy consumption. In this study, we prepared HEA Al_0.2Co_1.5 [...] Read more.

High-entropy alloys (HEAs) have attracted a great deal of research interest these days because of their attractive properties. Low-temperature chemical synthesis methods are being developed to obtain nanoscale HEAs with low energy consumption. In this study, we prepared HEA Al_0.2Co_1.5CrFeNi_1.5Ti_0.5 nanoparticles from high-entropy oxide (HEO) (Al_0.2Co_1.5CrFeNi_1.5Ti_0.5)₃O₄ by a deoxidation process via a CaH₂-assisted molten salt method at 600 °C. X-ray diffraction measurements demonstrated that the oxide precursor and the reduced product have single-phases of spinel structure and face-centered cubic structures, indicating the formation of HEO and HEA, respectively. The HEA nanoparticles exhibited superior catalytic performance in the liquid-phase hydrogenation of p-nitrophenol at room temperature with little leaching of the component elements. Scanning electron microscopy (SEM) with energy-dispersive X-ray spectrometry (EDX) exhibited a good distribution of constituent elements over the HEA nanoparticles in a micro-sized range. However, transmission electron microscopy (TEM) with EDX revealed a slight deviation of elemental distributions of Al and Ti from those of Co, Cr, Fe, and Ni in a nano-sized range, probably due to the incomplete reduction of aluminum and titanium oxides. The elemental homogeneity in the HEA nanoparticles could be improved by taking advantage of the HEO precursor with homogeneous elemental distributions, but the experimental results suggested the importance of the total reduction of oxide precursors to prepare homogeneous HEAs from HEOs. Full article

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13 pages, 9623 KB

Open AccessEditor’s ChoiceArticle

Effect of Tropical Marine Atmospheric Environment on Corrosion Behaviour of the 7B04-T74 Aluminium Alloy

by Ning Li, Weifang Zhang, Xiaojun Yan, Meng Zhang, Lu Han and Yikun Cai

Metals 2023, 13(5), 995; https://doi.org/10.3390/met13050995 - 21 May 2023

Cited by 12 | Viewed by 4583

Abstract

In this work, the effects of the tropical marine atmospheric environment on the corrosion behaviour of the 7B04-T74 aluminium alloy were systematically investigated by using accelerated testing, together with corrosion kinetic analysis, microstructure observation, product composition analysis, and potentiodynamic polarization curve tests. The [...] Read more.

In this work, the effects of the tropical marine atmospheric environment on the corrosion behaviour of the 7B04-T74 aluminium alloy were systematically investigated by using accelerated testing, together with corrosion kinetic analysis, microstructure observation, product composition analysis, and potentiodynamic polarization curve tests. The weight loss method was used for the corrosion kinetics analysis. The surface morphology and corrosion products transformation law were investigated by OM, SEM, EDS, and XPS. The electrochemical characteristics were studied using potentiodynamic polarization curves. The research indicated that the 7B04-T74 aluminium alloy has eminent corrosion resistance in the tropical marine atmospheric environment. Localized pitting corrosion occurred rapidly in the tropical marine atmosphere. In the later stage of corrosion, the corrosion of aluminium alloy did not become serious. Specifically, no obvious intergranular corrosion was found, which is related to the thermal treatment method. Corrosion products included Al(OH)₃, Al₂O₃, and AlCl₃, of which Al(OH)₃ is the most notable. Full article

(This article belongs to the Special Issue Corrosion Prediction in Different Environment)

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11 pages, 1840 KB

Open AccessEditor’s ChoiceArticle

Corrosion of Copper in a Tropical Marine Atmosphere Rich in H₂S Resulting from the Decomposition of Sargassum Algae

by Mahado Said Ahmed, Mounim Lebrini, Benoit Lescop, Julien Pellé, Stéphane Rioual, Olivia Amintas, Carole Boullanger and Christophe Roos

Metals 2023, 13(5), 982; https://doi.org/10.3390/met13050982 - 19 May 2023

Cited by 14 | Viewed by 4725

Abstract

The atmospheric corrosion of copper exposed in Martinique (Caribbean Sea) for 1 year was reported. This island suffered the stranding of sargassum algae, which decompose and release toxic gases such as hydrogen sulfide (H₂S) or ammonia (NH₃). Four sites [...] Read more.

The atmospheric corrosion of copper exposed in Martinique (Caribbean Sea) for 1 year was reported. This island suffered the stranding of sargassum algae, which decompose and release toxic gases such as hydrogen sulfide (H₂S) or ammonia (NH₃). Four sites in Martinique (France) more or less impacted by sargassum algae strandings were selected. The corrosion rate was studied via mass loss determination. The morphology and properties of the corrosion products were determined using Scanning Electron Microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The samples were exposed for up to 12 months. The mass loss results after 1-year exposure were from 4.8 µm for the least impacted site to 325 µm for the site most affected by sargassum algae. This very high value proves that the presence of sargassum algae caused a significant degradation of copper. The morphological structures and properties of the corrosion products obtained at the impacted and non-impacted sites differed significantly. In the absence of sargassum algae, classical corrosion products of copper were reported such as Cu₂O and Cu₂Cl(OH)₃. In the sites near the stranding of the sargassum algae, the CuS product is the main corrosion product obtained, but copper hydroxylsulfate is created. Full article

(This article belongs to the Section Corrosion and Protection)

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13 pages, 80879 KB

Open AccessEditor’s ChoiceArticle

Corrosion Behavior of the AZ31 Mg Alloy in Neutral Aqueous Solutions Containing Various Anions

by Duyoung Kwon, Hien Van Pham, Pungkeun Song and Sungmo Moon

Metals 2023, 13(5), 962; https://doi.org/10.3390/met13050962 - 16 May 2023

Cited by 11 | Viewed by 4052

Abstract

This work demonstrates the corrosion behavior of the AZ31 Mg alloy as a function of an immersion time of 48 h in 0.1 M HCl, H₂SO₄, H₃PO₄ and HF solutions, in which pH was adjusted to [...] Read more.

This work demonstrates the corrosion behavior of the AZ31 Mg alloy as a function of an immersion time of 48 h in 0.1 M HCl, H₂SO₄, H₃PO₄ and HF solutions, in which pH was adjusted to 6 to exclude the contribution of hydrogen ions (H⁺) and hydroxide ions (OH⁻). In situ observations, open circuit potential (OCP), weight changes and AC impedance measurements were performed with an immersion time of 48 h and the morphologies and chemical compositions of the surface products after 48 h of immersion were analyzed by SEM, EDS and XPS. In the chloride ion (Cl⁻)-containing solution, the corrosion of the AZ31 Mg alloy initiated locally and propagated discontinuously over the surface with immersion time. The OCP value of the AZ31 Mg alloy showed an initial increase from −1.51 V_Ag/AgCl to −1.47 V_Ag/AgCl after about 5 h of immersion and then a decrease to −1.51 V_Ag/AgCl due to corrosion initiation. In the F⁻-containing solution, after 48 h of immersion, the OCP showed an extremely large value of −0.6 V_Ag/AgCl, while the relatively lower values of −1.52 V_Ag/AgCl, −1.59 V_Ag/AgCl were seen in the solutions containing SO₄²⁻ and PO₄³, respectively. In the sulfate ion (SO₄²⁻)-containing neutral aqueous solution, needle-like surface films were formed and there were no changes in the weight of the AZ31 Mg alloy with immersion time. In the phosphate ion (PO₄³⁻)-containing neutral aqueous solution, a vigorous gas evolution occurred, together with the formation of black surface films with cracks, and a high corrosion rate of −13.8018 × 10⁻³ g·cm⁻²·day⁻¹ was obtained. In the fluoride ion (F⁻)-containing neutral aqueous solution, a surface film with crystalline grains of MgF₂ was formed and the weight of the AZ31 Mg alloy increased continuously with immersion time. In conclusion, the corrosion of the AZ31 Mg alloy occurred uniformly in neutral phosphate solution but locally in chloride solution. No corrosion was observed in either the neutral sulfate or fluoride solutions. Full article

(This article belongs to the Special Issue Corrosion and Protection of Lightweight Engineering Materials: Mg Alloys, Al Alloys, Ti Alloys and Other Related Metals)

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14 pages, 4704 KB

Open AccessEditor’s ChoiceArticle

Electrochemical Corrosion Behavior of 310S Stainless Steel in Hot Concentrated Tap Water

by Wen Xian, Zhong Yin, Lele Liu and Moucheng Li

Metals 2023, 13(4), 713; https://doi.org/10.3390/met13040713 - 5 Apr 2023

Cited by 8 | Viewed by 4138

Abstract

The corrosion behavior of 310S stainless steel was investigated in synthetic tap water and Ca²⁺ and Mg²⁺-free solutions with different concentration ratios at 80 °C using electrochemical measurement techniques and surface analysis methods. The main purpose was to obtain the [...] Read more.

The corrosion behavior of 310S stainless steel was investigated in synthetic tap water and Ca²⁺ and Mg²⁺-free solutions with different concentration ratios at 80 °C using electrochemical measurement techniques and surface analysis methods. The main purpose was to obtain the electrochemical corrosion characteristics under carbonate scale conditions. The specimens displayed a spontaneous passivation state in the solutions with or without Ca²⁺ and Mg²⁺ ions. With the enlargement of the concentration ratio of synthetic tap water from 1 to 10 times, the polarization resistance under free corrosion conditions and the pitting potential decreased by about 48% and 327 mV, respectively. The pitting tendency increased with increasing concentration ratio of tap water. The carbonate scales deposited from the synthetic tap water solutions were mainly composed of CaCO₃, which led to a slight increase in the polarization resistance and the pitting potential and decrease in the passive current density. Full article

(This article belongs to the Special Issue Applications of Electrochemistry in Corrosion Science and in Practice)

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38 pages, 7189 KB

Open AccessEditor’s ChoiceReview

High-Entropy Alloy Coatings Deposited by Thermal Spraying: A Review of Strengthening Mechanisms, Performance Assessments and Perspectives on Future Applications

by Rakesh Bhaskaran Nair, Raunak Supekar, Seyyed Morteza Javid, Wandong Wang, Yu Zou, André McDonald, Javad Mostaghimi and Pantcho Stoyanov

Metals 2023, 13(3), 579; https://doi.org/10.3390/met13030579 - 13 Mar 2023

Cited by 68 | Viewed by 14039

Abstract

Thermal spray deposition techniques have been well-established, owing to their flexibility in addressing degradation due to wear and corrosion issues faced due to extreme environmental conditions. With the adoption of these techniques, a broad spectrum of industries is experiencing continuous improvement in resolving [...] Read more.

Thermal spray deposition techniques have been well-established, owing to their flexibility in addressing degradation due to wear and corrosion issues faced due to extreme environmental conditions. With the adoption of these techniques, a broad spectrum of industries is experiencing continuous improvement in resolving these issues. To increase industrial-level implementation, state-of-the-art advanced materials are required. High-entropy alloys (HEAs) have recently gained considerable attention within the scientific community as advanced materials, mainly due to their exceptional properties and desirable microstructural features. Unlike traditional material systems, high-entropy alloys are composed of multi-component elements (at least five elements) with equimolar or nearly equimolar concentrations. This allows for a stable microstructure that is associated with high configurational entropy. This review article provides a critical assessment of different strengthening mechanisms observed in various high-entropy alloys developed by means of deposition techniques. The wear, corrosion, and oxidation responses of these alloys are reviewed in detail and correlated to microstructural and mechanical properties and behavior. In addition, the review focused on material design principles for developing next-generation HEAs that can significantly benefit the aerospace, marine, oil and gas, nuclear sector, etc. Despite having shown exceptional mechanical properties, the article describes the need to further evaluate the tribological behavior of these HEAs in order to show proof-of-concept perspectives for several industrial applications in extreme environments. Full article

(This article belongs to the Special Issue Wear and Corrosion Behavior of High-Entropy Alloy)

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17 pages, 5148 KB

Open AccessEditor’s ChoiceArticle

Stress Corrosion Cracking Mechanisms of UNS S32205 Duplex Stainless Steel in Carbonated Solution Induced by Chlorides

by Ulises Martin and David M. Bastidas

Metals 2023, 13(3), 567; https://doi.org/10.3390/met13030567 - 11 Mar 2023

Cited by 9 | Viewed by 7405

Abstract

Herein, the chloride-induced stress corrosion cracking (SCC) mechanisms of UNS S32205 duplex stainless steel (DSS) reinforcing bars in alkaline and carbonated solutions are studied. Electrochemical monitoring and mechanical properties were tested using linear polarization resistance and electrochemical impedance spectroscopy, coupled with the slow [...] Read more.

Herein, the chloride-induced stress corrosion cracking (SCC) mechanisms of UNS S32205 duplex stainless steel (DSS) reinforcing bars in alkaline and carbonated solutions are studied. Electrochemical monitoring and mechanical properties were tested using linear polarization resistance and electrochemical impedance spectroscopy, coupled with the slow strain rate tensile test (SSRT) to evaluate the SCC behavior and unravel the pit-to-crack mechanisms. Pit initiation and crack morphology were identified by fractographic analysis, which revealed the transgranular (TG) SCC mechanism. HCO₃⁻ acidification enhanced the anodic dissolution kinetics, thus promoting a premature pit-to-crack transition, seen by the decrease in the maximum phase angle in the Bode plot at low frequencies (≈ 1 Hz) for the carbonated solution. The crack propagation rate for the carbonated solution increased by over 100% compared to the alkaline solution, coinciding with the lower phase angle from the Bode plots, as well as with the lower charge transfer resistance. Pit initiation was found at the TiN nonmetallic inclusion inside the ferrite phase cleavage facet, which developed TG-SCC. Full article

(This article belongs to the Special Issue Corrosion and Protection of Stainless Steels)

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21 pages, 14270 KB

Open AccessEditor’s ChoiceArticle

Effect of Laser Shock Peening on the Stress Corrosion Cracking of 304L Stainless Steel

by Young-Ran Yoo, Seung-Heon Choi and Young-Sik Kim

Metals 2023, 13(3), 516; https://doi.org/10.3390/met13030516 - 3 Mar 2023

Cited by 25 | Viewed by 5745

Abstract

Storage canisters used in nuclear power plants operating in seaside areas—where the salt content in the atmosphere is high—may be susceptible to chloride-induced stress corrosion cracking (CISCC). Chloride-induced stress corrosion cracking is one of the ways in which dry storage canisters made of [...] Read more.

Storage canisters used in nuclear power plants operating in seaside areas—where the salt content in the atmosphere is high—may be susceptible to chloride-induced stress corrosion cracking (CISCC). Chloride-induced stress corrosion cracking is one of the ways in which dry storage canisters made of stainless steel can degrade. Stress corrosion cracking depends on the microstructure and residual stress, and it is therefore very important to improve the surface properties of materials. Laser shock peening both greatly deforms the material surface and refines grains, and it generates compressive residual stress in the deep part from the surface of the material. This study focused on the effect of laser shock peening on the stress corrosion cracking of 304L stainless steel. The laser shock peening was found to induce compressive residual stress from the surface to a 1 mm depth, and the SCC properties were evaluated by a U-bend test. The results showed that the SCC resistance of laser-peened 304L stainless steel in a chloride environment was enhanced, and that it was closely related to grain size, the pitting potential of the cross section, and residual stress. Full article

(This article belongs to the Special Issue Feature Paper Collection of “Current Challenges in Corrosion Research”)

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29 pages, 15823 KB

Open AccessEditor’s ChoiceReview

Corrosion Behavior of High Entropy Alloys and Their Application in the Nuclear Industry—An Overview

by Tianrun Li, Debin Wang, Suode Zhang and Jianqiang Wang

Metals 2023, 13(2), 363; https://doi.org/10.3390/met13020363 - 10 Feb 2023

Cited by 49 | Viewed by 11764

Abstract

With multiple principal components, high entropy alloys (HEAs) have aroused great interest due to their unique microstructures and outstanding properties. Recently, the corrosion behavior of HEAs has become a scientific hotspot in the area of material science and engineering, and HEAs can exhibit [...] Read more.

With multiple principal components, high entropy alloys (HEAs) have aroused great interest due to their unique microstructures and outstanding properties. Recently, the corrosion behavior of HEAs has become a scientific hotspot in the area of material science and engineering, and HEAs can exhibit good protection against corrosive environments. A comprehensive understanding of the corrosion mechanism of HEAs is important for further design of HEAs with better performance. This paper reviews the corrosion properties and mechanisms of HEAs (mainly Cantor alloy and its variants) in various environments. More crucially, this paper is focused on the influences of composition and microstructure on the evolution of the corrosion process, especially passive film stability and localized corrosion resistance. The corrosion behavior of HEAs as structural materials in nuclear industry applications is emphasized. Finally, based on this review, the possible perspectives for scientific research and engineering applications of HEAs are proposed. Full article

(This article belongs to the Special Issue Feature Paper Collection of “Current Challenges in Corrosion Research”)

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13 pages, 13119 KB

Open AccessEditor’s ChoiceArticle

Effect of Superhydrophobic Surface on Corrosion Resistance of Magnesium-Neodymium Alloy in Artificial Hand Sweat

by Changyang Liu, Jiapeng Sun and Guosong Wu

Metals 2023, 13(2), 219; https://doi.org/10.3390/met13020219 - 24 Jan 2023

Cited by 12 | Viewed by 3188

Abstract

A superhydrophobic surface can endow metals with some intriguing characteristics such as self-cleaning behavior. In this study, a simple solution-immersion method based on the concept of predesigned corrosion is developed to enhance the corrosion resistance of a magnesium-neodymium alloy. The Mg alloy is [...] Read more.

A superhydrophobic surface can endow metals with some intriguing characteristics such as self-cleaning behavior. In this study, a simple solution-immersion method based on the concept of predesigned corrosion is developed to enhance the corrosion resistance of a magnesium-neodymium alloy. The Mg alloy is directly soaked in potassium dihydrogen phosphate solution with the addition of ultrasound, and a layer of rough but dense coating is uniformly formed on the Mg-Nd alloy after the immersion process, which is mainly composed of MgHPO₄∙3H₂O. A superhydrophobic surface with an average wetting angle of 150.5° and a sliding angle of about 4.5° can be obtained on the Mg alloy by further chemical surface modification with perfluorodecyltriethoxysilane. This superhydrophobic surface has an interesting self-cleaning effect as well as good corrosion resistance in artificial hand sweat. In brief, this study provides a feasible way to prepare a superhydrophobic surface on the Mg-Nd alloy and reveals the effect of a superhydrophobic surface on the corrosion behavior of the Mg-Nd alloy, offering new technical insights into the corrosion protection of magnesium alloys. Full article

(This article belongs to the Special Issue Corrosion and Protection of Lightweight Engineering Materials: Mg Alloys, Al Alloys, Ti Alloys and Other Related Metals)

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37 pages, 17666 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Effect of σ-Phase on the Strength, Stress Relaxation Behavior, and Corrosion Resistance of an Ultrafine-Grained Austenitic Steel AISI 321

by Vladimir I. Kopylov, Aleksey V. Nokhrin, Natalia A. Kozlova, Mikhail K. Chegurov, Mikhail Yu. Gryaznov, Sergey V. Shotin, Nikolay V. Melekhin, Nataliya Yu. Tabachkova, Ksenia E. Smetanina and Vladimir N. Chuvil’deev

Metals 2023, 13(1), 45; https://doi.org/10.3390/met13010045 - 24 Dec 2022

Cited by 13 | Viewed by 5474

Abstract

This paper reported the results of research into the effect of Equal Channel Angular Pressing (ECAP) temperature and 1-h annealing temperature on mechanical properties, stress-relaxation resistance, and corrosion resistance of austenitic steel AISI 321L with strongly elongated thin δ-ferrite particles in its microstructure. [...] Read more.

This paper reported the results of research into the effect of Equal Channel Angular Pressing (ECAP) temperature and 1-h annealing temperature on mechanical properties, stress-relaxation resistance, and corrosion resistance of austenitic steel AISI 321L with strongly elongated thin δ-ferrite particles in its microstructure. The formation of α′-martensite and fragmentation of austenite grains takes place during ECAP. Ultrafine-grained (UFG) steels demonstrate increased strength. However, we observed a reduced Hall–Petch coefficient as compared with coarse-grained (CG) steels due to the fragmentation of δ-ferrite particles. UFG steel specimens were found to have 2–3 times higher stress-relaxation resistance as compared with CG steels. For the first time, the high stress-relaxation resistance of UFG steels was shown to stem from a internal stress-relaxation mechanism, i.e., the interaction of lattice dislocations with non-equilibrium grain boundaries. Short-time 1-h annealing of UFG steel specimens at 600–800 °C was found to result in the nucleation of σ-phase nanoparticles. These nanoparticles affect the grain boundary migration, raise strength, and stress-relaxation resistance of steel but reduce the corrosion resistance of UFG steel. Lower corrosion resistance of UFG steel was shown to be related to the formation of α′-martensite during ECAP and the nucleation of σ-phase particles during annealing. Full article

(This article belongs to the Special Issue Environmentally-Assisted Degradation of Metals and Alloys)

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15 pages, 5943 KB

Open AccessFeature PaperEditor’s ChoiceArticle

A Survey on the Oxidation Behavior of a Nickel-Based Alloy Used in Natural Gas Engine Exhaust Valve Seats

by José Henrique Alano, Renato Luiz Siqueira, Claudio Beserra Martins Júnior, Rodrigo Silva, Guilherme dos Santos Vacchi and Carlos Alberto Della Rovere

Metals 2023, 13(1), 49; https://doi.org/10.3390/met13010049 - 24 Dec 2022

Cited by 6 | Viewed by 3682

Abstract

This study reports the oxidation behavior of a Ni-based alloy used in the manufacture of valve seats for automotive engine exhaust systems. Isothermal thermogravimetric analyses were carried out at temperatures of 660, 740, 860, and 900 °C under an oxygen atmosphere for up [...] Read more.

This study reports the oxidation behavior of a Ni-based alloy used in the manufacture of valve seats for automotive engine exhaust systems. Isothermal thermogravimetric analyses were carried out at temperatures of 660, 740, 860, and 900 °C under an oxygen atmosphere for up to 1 h. At 660 and 740 °C, only one stage was observed during the whole time studied. At this stage, the oxide layer was formed mainly by NiO + Cr₂O₃, following a linear oxidation law with a rate constant (K_l) on the order of magnitude of 10⁻⁶ kg/m²s and an apparent activation energy (E_a) of ~47 kJ/mol. At 860 and 900 °C, an identical first stage was observed with a transition to a different stage. In the second stage, the oxidation layer was composed of Cr₂O₃, and a parabolic oxidation law was followed with a rate constant (K_p) on the order of 10⁻⁸ kg²/m⁴s and E_a of ~128 kJ/mol. Moreover, the Ni-based alloy formed a dense and compact oxide layer after oxidation, with no apparent cavities, pores, or microcracks. Characterization techniques such as Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR), and Raman Spectroscopy were carried out to characterize the formed oxide layer. Full article

(This article belongs to the Special Issue Composition Design and Damage Mechanism of Crystal Superalloys)

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18 pages, 8364 KB

Open AccessEditor’s ChoiceArticle

Challenges and Latest Developments in Diffusion Bonding of High-Magnesium Aluminium Alloy (Al-5056/Al-5A06) to Stainless Steels

by Amir A. Shirzadi, Chengcong Zhang, Muhammad Zeeshan Mughal and Peiyun Xia

Metals 2022, 12(7), 1193; https://doi.org/10.3390/met12071193 - 13 Jul 2022

Cited by 13 | Viewed by 6621

Abstract

The aim of this work was to investigate the challenges associated with bonding Al-Mg alloys and develop a new method for bonding these alloys to steels. During an extensive R&D project, over 80 attempts, using 11 methods, were made to bond Al-6 wt.% [...] Read more.

The aim of this work was to investigate the challenges associated with bonding Al-Mg alloys and develop a new method for bonding these alloys to steels. During an extensive R&D project, over 80 attempts, using 11 methods, were made to bond Al-6 wt.% Mg alloy (Al-5056/Al-5A06) to two types of stainless steels (heat-resistant 1Cr18Ni9Ti and conventional 316). Wide ranges of temperature (500 °C to 580 °C), pressure (0.5 MPa to 10 MPa) and time (1 min to 2 h) were used when direct diffusion bonding of these alloys. Then, effects of using various interlayers and brazing foils were investigated. The interlayers used in this work were gallium, pure titanium, copper and aluminium foils, aluminium 6061 alloy sheets, aluminium-silicon brazing foils, zinc and zinc alloy foils as well as an active brazing foil (known as Incusil-ABA containing silver, copper, indium and titanium). Several complex and multi-stage processes, using up to 3 different interlayers in the same joint, were also developed and assessed. Examination and assessment of the bonded samples, including failed attempts, paved the way of developing new methods for bonding these dissimilar materials. A number of samples with tensile strengths from 200 MPa to 226 MPa were made by using complex combinations of 2 or 3 interlayers and triple-stage bonding cycles. The highest recorded bond strength was 226 MPa in the as-bonded condition. This value is above the measured yield strength (134 MPa) and about 93% of the measured ultimate strength (243 MPa) of the parent Al-Mg alloy after it was subjected to the same bonding cycle. Since the use of complex processes was not feasible for bonding large components, a simpler and more practical bonding cycle was also developed in the project. Using the simpler process, joints with tensile strengths around 90 MPa could be made. This article also sheds light on the difficulties associated with brazing and soldering aluminium alloys with a high magnesium content. Full article

(This article belongs to the Special Issue Advances in Technology and Applications of Diffusion Bonding)

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