Search Results (4,818)

In this study, AA7068 aluminum matrix composites reinforced with TiB₂/TiC were fabricated via mechanical alloying and microwave sintering to investigate the influence of reinforcement content and sintering temperature on microstructure, mechanical properties, and dry sliding wear. Mechanical alloying refined powders, reducing D₅₀ from 51.5 µm (AA) to 22.5 µm (AC9) and enhancing dispersion and retention of TiB₂/TiC particles. XRD confirmed α-Al as the dominant matrix phase, preserved TiB₂ and TiC phases, and limited MgAl₂O₄/ZnAl₂O₄ spinel formation. Crystallite refinement and increased lattice microstrain were observed with the addition of reinforcement. Microhardness increased with reinforcement content and sintering temperature, reaching 122.2 HV_0.05 in AC9-2. At the same time, the highest compressive strength was observed in AC6-2 (431.05 MPa), indicating that optimal load-bearing depends on densification and interfacial integrity rather than hardness alone. AC9-2 exhibited the best wear resistance, with a cumulative specific wear rate of 2.723 × 10⁻⁴ mm³/Nm over 1000 m. SEM-EDS analysis revealed oxide-rich tribolayers, mechanically mixed layers, TiB₂/TiC fragments, and Fe-rich third-body debris, indicating wear is predominantly hardness-controlled but strongly influenced by microstructural factors. Overall, TiB₂/TiC hybrid reinforcement improves AA7068 wear resistance through combined hard-particle load-bearing, reduced penetration, tribolayer stability, and third-body effects, offering insight for high-performance hybrid aluminum composites. Full article

Aluminum alloys are widely used in the automotive and aerospace industries due to their low density and very high specific strength, and high-pressure die casting (HPDC) allows us to mass-produce complex components despite porosity and microstructural heterogeneity. In this study, we examine the individual and combined effect of grain refinement (AlTi5B1), chemical modification (AlSr15), and T6 heat treatment on the microstructure, mechanical properties, and corrosion of ENAC 46000 alloy produced in cold-chamber HPDC. The material characteristics were assessed through hardness, tensile, fatigue, and corrosion testing as well as optical microscopy, SEM, and EDS measurements. The microstructural characteristics were found to be fine α-Al grains, and Sr modification transformed eutectic Si into a fibrous structure. T6 treatment dissolved coarse Al₂Cu phases into fine coherent precipitates. T6 heat treatment was the primary strengthening process and produced an increase in hardness of 59% (to 143 HB) compared to non-T6 conditions, while the fatigue resistance was still excellent in the as-cast state (1.16 × 10⁶ cycles). Moreover, the modified and T6-treated condition exhibited the lowest corrosion rate (15.3 × 10⁻³ mm/year). Therefore, because no single processing route is the best way to maximize all performance characteristics (as well as process efficiency), a multi-property evaluation should be performed to tailor treatment to the engineering service requirements. Full article

High-speed machining of complex freeform geometries faces fundamental challenges in balancing computational efficiency, kinematic constraints, and precision, particularly in high-curvature regions where traditional interpolation methods suffer from geometric errors and jerk-induced vibrations. This study presents a Galerkin-NURBS interpolation framework that integrates Galerkin projection to optimize NURBS parameterization, minimizing geometric approximation error, and couples it with a jerk-limited S-curve trajectory planning algorithm that enforces $C^3$ continuity while respecting feedrate, acceleration, and jerk constraints. Numerical simulations and machining experiments were conducted on butterfly-shaped and horse-shaped curves using a five-axis CNC machine equipped with rotary/linear encoders and validated via profilometer-based surface roughness measurements. The proposed method achieved a 32.9% reduction in processing time (3.091 s) compared to the CQSF method (4.61 s) and a 35.1% reduction in interpolation steps relative to FSRC. Surface roughness ($R_a$) values ranged from 0.1271 μm to 0.2009 μm, with most measurements compliant with ISO 21920-1:2021; the maximum value (0.2009 μm) represents the upper bound of the standard’s high-precision threshold for aluminum alloy 6061. These findings demonstrate that the proposed framework significantly improves machining efficiency and surface quality while maintaining geometric fidelity, making it suitable for precision manufacturing applications where sensor-guided process optimization is critical. Full article

The release of aluminum (Al) and vanadium (V) ions represents a critical concern limiting the long-term performance and biocompatibility of Ti6Al4V-based permanent orthopedic implants. This study focuses on improving the corrosion resistance of Ti6Al4V alloys through the application of a novel organic–inorganic ZnO nanocoating. In addition, the present study investigated the influence of substrate roughness on surface morphology, microhardness, and wettability characteristics. Xanthan gum (XG) and celite (CE) were utilized as a biopolymeric–ceramic matrix for the ceramic–biopolymer-assisted synthesis of ZnO nanoparticles (ZnO NPs) through ultrasonication, which was subsequently followed by deposition onto Ti6Al4V substrates with varying surface roughness (Ra) achieved through controlled turning. The synthesized XG/CE-ZnO NPs exhibited a uniform spherical morphology with an average particle size of nearly 50 nm and a hexagonal wurtzite crystalline structure, as confirmed by TEM, XRD, and FTIR analyses. Contact angle (CA) measurements indicated that wettability increased with higher Ra, while SEM with energy-dispersive X-ray spectroscopy characterization revealed morphology transitions from smooth, homogeneous coatings to agglomerate, star-like nanostructures as Ra increased. Electrochemical testing in Ringer’s solution demonstrated a significant improvement in corrosion resistance after coating, with protection efficiencies ranging from 95.18% to 98.48%, particularly for smoother substrates. Although increased Ra may enhance coating adhesion through mechanical interlocking, smoother substrates promote the formation of more homogeneous coatings, resulting in superior corrosion protection. These results demonstrate the significant influence of substrate topography in enhancing the functional performance of biocompatible ZnO nanocoatings, providing valuable insights for the surface engineering of metallic implants. Full article

Aluminum alloys based on the Al-Ce-Mg system, with microstructure and properties weakly sensitive to elevated temperatures, are developed for applications such as thermal engine blocks and supersonic aircraft fuselage components. Cast Al-10Ce-4Mg (wt%) was produced by slab casting and further processed by rolling. Rolling with an area reduction of 54% results in a 97% increase in strength (tensile strength of 269 MPa at room temperature) and a more than a factor of two increase in strain at failure relative to the as-cast (AC) state. We show that Al-10Ce-4Mg is highly stable upon exposure to elevated temperature: 83% strength retention after exposure to 300 °C for 100 h, without reduction in the strain at failure. The yield stress (YS) follows the same trend, increasing by ~40% upon rolling and retaining 92% of its value after exposure to 300 °C for 100 h. The ratio of the strength at 300 °C to the strength at room temperature is 0.45, which is larger than the respective ratio of most commercial Al alloys. Rolling increases the dislocation density and introduces texture, while not modifying the grain size significantly and fragmenting only the largest intermetallics. Exposure to elevated temperatures up to 100 h has no measurable effect on grain size and intermetallic distribution, while slightly changing texture. This microstructural evolution is used to rationalize the observed changes in mechanical properties. Full article

To accurately characterize the warm deformation behavior and workability of the 5A06 aluminum alloy, this study presents an innovative workflow that develops and systematically validates machine learning-assisted Johnson–Cook (ML-JC) frameworks based on artificial neural network (ANN) surrogate models. Two predictive frameworks—the parallel-decoupled PD-ANN-JC and the multi-objective integrated MOI-ANN-JC—were constructed. Quantitatively, both developed ML-JC frameworks achieve significantly higher stress prediction accuracy and superior generalization capability compared with the conventional JC model. Specifically, on the testing set, the MOI-ANN-JC framework yields an average absolute relative error (AARE) of 1.424% and an R² of 0.997, outperforming the PD-ANN-JC framework (AARE of 3.246%, R² of 0.988). On the validation set, the MOI-ANN-JC framework also demonstrates exceptional generalization, with an AARE of 3.302% and an R² of 0.987. Scientifically, the superior performance of the MOI-ANN-JC framework stems from its ANN-mnδ surrogate model, which simultaneously predicts the strain hardening exponent n, thermal softening exponent m, and relative error δ directly from deformation parameters. This mutual coupling establishes an intrinsic correlation between m and n, successfully aligning with the physical reality wherein strain hardening and thermal softening are inherently linked during deformation. Qualitatively and practically, by integrating the MOI-ANN-JC framework into finite element (FE) simulation software, dynamic tracking and visualization of the thermal softening exponent m during warm deformation were achieved. Combined with FE simulations, Vickers hardness testing and EBSD observations, this study successfully establishes a direct qualitative spatial correspondence between low-m regions and macroscopic defects, which was further verified through the warm forging of a thin-walled dual-cavity component. Crucially, this approach for evaluating deformation stability bridges the gap caused by the inapplicability of conventional processing maps within this temperature regime, offering a robust and broadly applicable workflow for complex forming optimization. Full article

During aviation operations, low temperatures can cause fuel freezing and icing on 6061 aluminum fuel lines, threatening flight safety. To mitigate this, a surface treatment combining FeCl₃ etching and an ORMOSIL sol–gel coating was proposed to construct a superhydrophobic functional layer. FeCl₃ etching generated a hierarchical micro/nanostructure on the aluminum surface, while the ORMOSIL layer, formed by the co-hydrolysis and condensation of PFOTES and HDTMS, built Si-O-Si networks and introduced C-F groups to reduce surface energy and enhance stability. The modified surface showed a high water contact angle of 161.44°, confirming excellent superhydrophobicity. AFM analysis revealed a significant increase in surface roughness (Sa = 0.844 μm), confirming the formation of a hierarchical micro/nanostructure. Electrochemical measurements showed a positive shift in corrosion potential from −0.723 V to −0.652 V, demonstrating enhanced corrosion resistance. More importantly, after 120 h of immersion in aviation fuel, the coating maintained a high contact angle of 156.73° and preserved its Si-O-Si network and fluorinated functional groups, confirming outstanding fuel resistance and long-term stability. These results demonstrate that the proposed ORMOSIL coating is a promising protective strategy for aviation fuel systems operating under low-temperature and corrosive conditions. Full article

Aluminum volatilization during laser deposition manufacturing severely deteriorates the microstructure and service performance of TiAl alloys, causing aggravated brittleness, elevated crack sensitivity and structural degradation. To tackle this issue, this work proposes an aluminum composition compensation strategy based on Ti-48Al-2Cr-2Nb pre-alloyed powder, with three mass fractions of elemental Al (15 wt.%, 20 wt.% and 25 wt.%) added to systematically investigate their influences on the macroscopic cracking behavior, microstructure evolution, phase constitution and mechanical properties of the deposited alloys. The results demonstrate that 15 wt.% Al addition achieves crack-free laser deposition, yielding a uniform microstructure dominated by γ-TiAl phase with dispersedly distributed TiAl₂ and minor B2 phases as well as low residual internal stress. No α₂-Ti₃Al phase is detected in all samples, as the Al-rich composition shift thermodynamically suppresses the stability of Ti-rich α₂ phase. Excessive Al addition induces the massive formation of brittle Al-rich intermetallics (TiAl₂ and TiAl₃), which gradually evolve from isolated particles to a continuous network structure, leading to a sharp increase in crack susceptibility. Al addition continuously improves the microhardness of the alloys, and the 25 wt.% Al sample attains the maximum hardness of 522.3 HV, benefiting from the synergistic effects of grain refinement strengthening and second-phase strengthening. The 15 wt.% Al sample delivers the optimal comprehensive mechanical performance, with an ultimate tensile strength of 550.2 Mpa and a fracture elongation of 0.76%, where the finely dispersed TiAl₂ precipitates exert a remarkable dispersion strengthening effect without causing severe embrittlement. This work provides a feasible experimental basis and technical reference for crack control and property optimization of laser deposition-manufactured TiAl alloys. Full article

Heat accumulation during wire-laser directed energy deposition (WL-DED) may cause the thermal softening of thin aluminum alloy substrates. In this study, a liquid nitrogen-assisted cooling platform was introduced to regulate the substrate temperature during WL-DED of a 6061 aluminum alloy substrate with 5356 aluminum alloy wire. The results show that substrate cooling can mitigate substrate softening, and −100 °C provides improved substrate-bottom hardness while maintaining acceptable bonding quality. The hardness variation is discussed in relation to reduced thermal exposure, grain-size variation, recrystallization behavior, and the possible retention of strengthening phases. This work establishes a preliminary basis for tailoring the local properties of thin aluminum alloy substrates in WL-DED. Since the substrate is not removed, but forms an integrated component of the final assembly along with the deposited material, its properties are critical to component performance. This integrated approach also enhances material utilization and streamlines production by eliminating substrate separation steps. Full article

Aerospace die forgings are safety-critical structural products whose service performance is governed by coupled microstructural evolution across multiple length scales rather than by any single descriptor. This review critically synthesizes recent progress in multiscale characterization and process–structure–property analysis of aerospace die forgings, with emphasis on forged titanium alloys, wrought nickel-based superalloys, and high-strength aluminum alloys. A practical framework is first established by linking macroscale metal-flow integrity and defect control with mesoscale gradients, microscale grain-boundary and texture evolution, and nanoscale precipitation, segregation, and interface states. The principal characterization routes are then discussed, including X-ray diffraction, EBSD/3D-EBSD, TEM/STEM, atom probe tomography, tomography-based defect evaluation, and correlative workflows. The alloy-specific sections are organized around mechanisms and property consequences rather than isolated micrographs. Finally, the review discusses how multiscale descriptors can support crystal-plasticity, phase-field, cellular-automata, and ICME-oriented modeling, and identifies future priorities in three-dimensional characterization, quantitative descriptor extraction, uncertainty-aware modeling, environmental degradation assessment, and closed-loop process optimization. Overall, the performance of aerospace die forgings is shown to depend on coordinated control of phase stability, grain-boundary network evolution, precipitation state, defect population, and location-dependent heterogeneity across the full manufacturing route. Full article

ZIF-8-modified micro-arc oxidation (MAO) coatings have attracted considerable attention for improving the corrosion resistance of aluminum alloys, owing to their combined barrier and chemical protection effects. In this work, ZIF-8/MAO composite coatings were fabricated via in situ solvothermal growth, and the effects of solvothermal temperature and time on coating evolution and corrosion performance were systematically investigated. The coatings were characterized by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR). The results show that increasing the solvothermal temperature promotes ZIF-8 formation, which may be related to enhanced coordination reactions and particle growth. Prolonging the solvothermal time induces a transition from ZnO-dominated coatings at 8 h to ZIF-8-dominated structures at 16–24 h, whereas unconverted ZnO is still detected after prolonged growth. The in situ-grown ZIF-8 particles cover the MAO surface and contribute to the sealing of surface micropores and cracks, forming a more compact composite barrier structure. The reduced coating performance at 220 °C or after 32 h may be associated with excessive particle refinement, local structural imperfections, or reduced coating integrity under prolonged or high-temperature solvothermal conditions. Electrochemical impedance spectroscopy (EIS) results reveal that the composite coating exhibits a charge transfer resistance more than one order of magnitude higher than that of the bare MAO coating, indicating significantly enhanced barrier protection. These findings demonstrate that in situ-grown ZIF-8 is an effective strategy for improving the corrosion resistance of MAO coatings on aluminum alloys. Full article

This study investigates the effect of Gas Metal Arc Welding (GMAW) parameters on solidification cracking and mechanical behavior of AA6061 and AA7075 aluminum alloys, which are widely used in automotive, aerospace, and battery-related applications due to their low density, corrosion resistance, and high specific strength. The influence of filler metals, ER4043 and ER5356, welding speed, wire feed speed, and calculated heat input was evaluated using the Circular Patch Test (CPT). Surface and internal cracking were examined by X-ray inspection, while microstructural evolution, phase formation, hardness, tensile behavior, and local strain distribution were analyzed using optical microscopy, SEM/EDS, XRD, microhardness testing, micro-tensile testing, and Digital Image Correlation (DIC). The results show that cracking susceptibility depends on the combined effects of welding speed, heat input, filler-metal chemistry, and dilution. The observed cracking behavior is associated with local compositional variations, weld defects, and the formation of low-melting/eutectic or secondary constituents within the fusion zone, rather than being attributed to a single factor. ER5356 showed favorable cracking resistance for AA7075 under the selected conditions, while ER4043 generally improved cracking resistance for AA6061. The mechanical response and fracture behavior were also influenced by filler composition and local weld microstructure. These findings provide useful guidance for selecting welding parameters and filler metals to improve weld quality and reduce solidification cracking in AA6061 and AA7075 aluminum alloys. Full article

This study investigates the nanomechanical response of aluminum substrates coated with crystalline or amorphous equiatomic FeNiCrCo compositionally complex alloy (CCA) layers using molecular dynamics nanoindentation. We evaluated the influence of coating microstructure and pre-relaxation via Monte Carlo/molecular dynamics (MC/MD) on deformation behavior at shallow (35 Å) and deep (65 Å) indentation depths. The relaxation process is critical for equilibrating internal stresses and homogenizing the initial stress field in amorphous phases, while preventing chaotic defect multiplication in crystalline lattices, yet it simultaneously promotes Fe and Cr surface segregation consistent with the equilibrium chemical short-range ordering of the alloy. The results reveal distinct deformation mechanisms: crystalline coatings exhibit higher peak indentation forces of about 300 ± 16 eV/Å characterized by discrete force fluctuations indicative of localized plastic events, while amorphous coatings show lower peak loads (~170–220 ± 12 eV/Å), corresponding to a reduction in load-bearing capacity of roughly 25%–40%, and smooth, continuous deformation governed by shear transformation zones. Notably, in amorphous systems, pressure-induced local crystallization occurs under load, with ordered FCC/HCP regions persisting after unloading, indicating partial irreversibility of the phase transition. Upon deep indentation into the substrate, the amorphous system exhibits a sharp increase in stiffness due to substrate compaction, whereas the crystalline system maintains high load-bearing capacity with reduced defect density in the relaxed state compared to the non-relaxed counterpart. Relaxation significantly reduces force-curve fluctuations in both systems, enhancing the stability of the mechanical response. Compared with uncoated aluminum, which exhibits extensive twin propagation and deep defect penetration, the FeNiCrCo-coated systems approximately halve the defect penetration depth and reduce the defective-atom volume fraction in the substrate by about a factor of two, thereby more effectively confining plastic deformation and preserving substrate integrity under the simulated conditions. These findings demonstrate that the synergy between coating crystallinity and rigorous relaxation protocols governs stress distribution patterns—localized hotspots in amorphous phases versus extended networks in crystalline ones—providing key insights for designing advanced protective coating–substrate systems with optimized mechanical performance. Full article

The objective of this study is to recover the transient out-of-plane displacement field of clamped circular plates subjected to blast loading using a single high-speed camera, as a low-cost alternative to stereo Digital Image Correlation (DIC) for the specific class of axisymmetrical structural responses of circular plates. The dynamic response of thin metal plates to blast loading is a fundamental problem in protective structural design, traditionally investigated through DIC. Although it provides full-field displacement measurements with high spatial resolution, it requires stereo camera arrangements, controlled illumination, speckle pattern preparation, and elaborate calibration procedures that significantly increase experimental cost and complexity. This study introduces a monocular optical method applicable to axisymmetrically defined material testing applications, such as the response of circularly supported isotropic plates under a uniform impulsive load, to recover the transient out-of-plane displacement field without using DIC. Clamped circular aluminum plates are subjected to blast loading generated by PG-3 charges of variable mass detonated at the closed end of a shock tube, with the exposed face matching the tube cross-section so as to enforce axisymmetric pressure load. A diametral reference line marked on the rear face of each specimen was recorded by a single high-speed camera, and a perspective correction derived from the axisymmetric deformed geometry was then applied to reconstruct the time-resolved displacement profile along the diameter. The permanent post-test deformed shape of each plate was subsequently digitized through 3D scanning and used as ground truth to validate the optical reconstruction. The reconstructed profiles closely matched the scans: for the conventional responses the root-mean-square error was 1.251 mm with a normalized mean residual of 6.57% (Case A) and 1.793 mm (9.20%, Case B), while for the anomalous counterintuitive response it was 1.043 mm (14.93%, Case C). Symmetry can thus be exploited as an active measurement principle to obtain quantitative blast-response data with substantially reduced experimental burden and without specialized stereo-optical instrumentation. Full article

Friction stir welding (FSW) is a solid-state joining process capable of producing high-quality joints in materials that are difficult to weld, particularly lightweight alloys. It is especially suitable for high-strength aluminum alloys like AW7075-T651, which are prone to hot cracking and mechanical degradation during conventional fusion welding. The AW7075-T651 alloy is one of the strongest commercially available aluminum alloys, whose high strength is primarily provided by MgZn₂ precipitates. The influence of welding parameters, especially welding speed, on heat input was studied using thermocouples positioned beneath the tool shoulder and in the weld root region. Tool lifetime was evaluated using WC-Co probes with different Co content, while tool wear was analyzed by 3D scanning. Microstructural characterization was performed using EBSD and TEM analyses. The maximum tool lifetime reached 2.7 km. Welding speed significantly affected the temperature in the weld root region, and a minimum temperature of 0.58T_M was required to produce a sound weld. Weld efficiency of 90% was reached; microhardness profiles showed a typical W-shape. TEM and SAED analyses confirmed the presence of an α-Al matrix and strengthening MgZn₂ precipitates and showed a more uniform distribution and refinement of precipitates in the stir zone. Full article