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Keywords = high Nb-containing TiAl

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14 pages, 4901 KB  
Article
Irradiation-Induced Phase Stability in Ti- and Nb-Containing Nickel-Based High-Entropy Alloys at 500 °C
by Yan Li, Xintian Liang, Huilong Yang, Dongyue Chen, Zhengcao Li and Guma Yeli
Nanomaterials 2026, 16(5), 287; https://doi.org/10.3390/nano16050287 - 25 Feb 2026
Viewed by 345
Abstract
This study investigates the irradiation response of two L12-strengthened HEAs, (Ni2Co2FeCr)92Ti4Al4 (TiHEA) and (Ni2Co2FeCr)92Nb4Al4 (NbHEA), subjected to 6.4 MeV Fe3+ irradiation at [...] Read more.
This study investigates the irradiation response of two L12-strengthened HEAs, (Ni2Co2FeCr)92Ti4Al4 (TiHEA) and (Ni2Co2FeCr)92Nb4Al4 (NbHEA), subjected to 6.4 MeV Fe3+ irradiation at 500 °C up to 30 dpa. Transmission electron microscopy (TEM) and atom probe tomography (APT) consistently showed that the Ti-containing HEA maintains L12-ordered structure and compositional stability better than Nb-containing alloys under irradiation. This difference is attributed to the distinct solute–defect interactions. Ti imposes a weaker hindering effect on vacancy mobility, allowing vacancies to remain mobile and participate in thermal reordering processes that counteract ballistic mixing, whereas Nb acts as a strong vacancy trap, suppressing the diffusion required for structural recovery. Irradiation-induced dislocation loops in the two alloys further exhibited different characteristics. TiHEA showed larger loops at lower number density, and NbHEA exhibited a higher density of smaller loops, consistent with their respective stacking fault energies and loop mobility. Nanoindentation results indicated that TiHEA exhibited a slightly higher irradiation hardening rate (27%) than NbHEA (23%), likely associated with a stronger order-strengthening contribution, given the better preservation of precipitate order in TiHEA under irradiation. These findings show the critical role of solute addition in designing radiation-tolerant high-entropy alloys. Full article
(This article belongs to the Special Issue Fabrication and Properties of Alloys at Nanoscale)
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30 pages, 7342 KB  
Article
Petrogenesis of the Monzonite in the Jiashan Area, Northern Jiangsu, China: Constraints from Whole-Rock Geochemistry and Zircon U–Pb Ages and Lu–Hf Isotopes
by Tao Kang, Duolikun Hainaer, Peng Zhu, Wei-Guo Zhang, Bostan Damla, Zhe-Ming Cao and Xiao-Qiang Liu
Minerals 2026, 16(2), 137; https://doi.org/10.3390/min16020137 - 27 Jan 2026
Viewed by 443
Abstract
Recent discoveries of fluorite–barite deposits in the Donghai–Linshu area in northern Jiangsu Province, China, underscore the region’s mineral potential, yet detailed geological investigations remain limited. In this study, we examined monzonite and quartz monzonite from drill cores in the Jiashan mining area using [...] Read more.
Recent discoveries of fluorite–barite deposits in the Donghai–Linshu area in northern Jiangsu Province, China, underscore the region’s mineral potential, yet detailed geological investigations remain limited. In this study, we examined monzonite and quartz monzonite from drill cores in the Jiashan mining area using petrography, U–Pb zircon dating, zircon trace element geochemistry, whole-rock geochemistry, and zircon Lu–Hf isotopes. Laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) zircon U–Pb analyses were conducted to constrain the crystallization ages of the monzonite (127.06 ± 0.54 Ma and 126.83 ± 0.75 Ma) and quartz monzonite (127.2 ± 0.5 Ma and 128.59 ± 0.62 Ma) to the Early Cretaceous, marking a significant magmatic event. Many of the zircons contain inherited Neoproterozoic cores (718–760 Ma and 800–860 Ma), indicating the assimilation of deep crustal materials of this age. The monzonite is metaluminous, with moderate SiO2 (61.61–62.41 wt.%), high alkalis (Na2O + K2O = 7.48–7.92 wt.%), and A/CNK = 0.72–0.91. The quartz monzonite has higher SiO2 (66.26–68.18 wt.%) and alkalis (8.32–9.33 wt.%). Both rock types exhibit similar trace and rare earth element patterns: enrichment in large-ion lithophile and light rare earth elements, depletions in Nb, Ta, and Ti, no significant Zr-Hf depletion, and weak negative Eu anomalies (δEu ≈ 0.84–1.00). Their low Zr + Nb + Ce + Y contents, Ga/Al ratios, and TFeO/MgO ratios indicate that they have an I-type granite affinity. The Early Cretaceous zircons have highly negative εHf(t) values (−33.7 to −23.5) and ancient two-stage model ages (2622–3247 Ma), which are consistent with derivation from Archean crust. The inherited Neoproterozoic zircons have younger Paleo–Mesoproterozoic TDM2 ages. The evidence suggests that both intrusions were mainly generated by partial melting of ancient Archean basement, with minor mantle input. The magma generation was likely triggered by crustal anatexis induced by the underplating of mantle-derived magmas in an extensional tectonic regime, coeval with Early Cretaceous magmatism in the Sulu orogen. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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18 pages, 5668 KB  
Article
Chronology and Geochemistry of Intrusive Magmatic Rocks in the Shiquanhe Ophiolitic Mélange, Tibet: Constraints on the Tectonic Evolution of the Meso-Tethys Ocean
by Kegang Dai, Xu Zhang, Ru-Xin Ding, Harald Furnes, Wei-Liang Liu, Xiaobo Kang, Hongfei Zhao, Jing Li, Qin Wang, Yun Bai, Chi Yan and Yutong Shi
Minerals 2026, 16(2), 123; https://doi.org/10.3390/min16020123 - 23 Jan 2026
Viewed by 418
Abstract
Magmatic activity is crucial for identification of the tectonic framework of the ancient oceanic crust. In this study, systematic investigation, including a field survey, zircon LA-ICP-MS U-Pb dating, and whole-rock geochemical analysis, has been carried out on the intrusive quartz- and granodiorites within [...] Read more.
Magmatic activity is crucial for identification of the tectonic framework of the ancient oceanic crust. In this study, systematic investigation, including a field survey, zircon LA-ICP-MS U-Pb dating, and whole-rock geochemical analysis, has been carried out on the intrusive quartz- and granodiorites within the Meso-Tethyan Shiquanhe Ophiolitic Mélange (SQM), Tibet. Zircon U-Pb dating yields the weighted mean ages of 174.7 ± 1.4 Ma (quartz diorite) and 178.9 ± 1.2 Ma (granodiorite), respectively, demonstrating the Early Jurassic formation age. The quartz diorite samples are metaluminous (A/NKC = 0.77–0.95) (molar/Al2O3/(CaO + Na2O + K2O)), while the granodiorite samples are weakly peraluminous (A/NKC = 0.95–1.21), and both of them exhibit tholeiitic to calc-alkaline geochemical characteristics and can be classified as I-type granites. The right-dipping rare-earth element (REE) patterns, enrichment in large ion lithophile elements (LILEs: Rb, Ba, Th), and depletion in high-field-strength elements (HFSEs: Nb, Ta, Ti), as well as relatively high (La/Yb)N ratios, are features compatible with an island arc setting. Combined with previous works, we suggest that the Shiquanhe ophiolitic mélange not only preserves records of mid-late Jurassic island arc magmatic activity but also contains evidence of island arc magmatism from the late Early Jurassic. Full article
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17 pages, 3465 KB  
Article
Designing TiZrNbTa-Al Medium-Entropy Alloy for Next-Generation Hydrogen Storage
by Jakub Kubaško, Miloš Matvija, Katarína Nigutová, Lenka Oroszová, Zuzana Molčanová, Beáta Ballóková, Róbert Džunda, Gabriel Sučik, Ľuboš Popovič, Róbert Kočiško, Jens Möllmer, Marcus Lange and Karel Saksl
Materials 2026, 19(2), 379; https://doi.org/10.3390/ma19020379 - 17 Jan 2026
Viewed by 501
Abstract
Medium-entropy alloys (MEAs) represent a promising class of materials for solid-state hydrogen storage due to their high hydrogen affinity, structural stability, and tunable properties. In this work, a compositional series of (TiZrNbTa){100−x}Alx (x = 0–10 at. %) MEAs were prepared [...] Read more.
Medium-entropy alloys (MEAs) represent a promising class of materials for solid-state hydrogen storage due to their high hydrogen affinity, structural stability, and tunable properties. In this work, a compositional series of (TiZrNbTa){100−x}Alx (x = 0–10 at. %) MEAs were prepared and systematically investigated to clarify the influence of aluminum addition on microstructure, mechanical response, and hydrogen sorption behavior. The alloys were synthesized by arc melting, homogenized by annealing, and characterized using microscopy, X-ray diffraction, density measurements, microhardness testing, nanoindentation, and hydrogen absorption/desorption experiments. Hydrogen sorption was evaluated by isobaric absorption measurements at 2 MPa H2 over two consecutive cycles, complemented by thermogravimetric desorption analysis of hydrogenated samples. The results show that aluminum addition significantly affects activation behavior, hydrogen uptake, and residual hydrogen retention, while simultaneously increasing hardness and elastic modulus in a non-linear manner. The alloy containing 5 at. % Al exhibits the most balanced performance, combining reduced activation temperature in the second absorption cycle, relatively high hydrogen capacity, and moderate mechanical stiffness. These findings demonstrate that controlled aluminum alloying is an effective strategy for tailoring hydrogen–metal interactions and optimizing the performance of TiZrNbTa-based MEAs for solid-state hydrogen storage applications. Full article
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20 pages, 11502 KB  
Article
Laser Remelting of Biocompatible Ti-Based Glass-Forming Alloys: Microstructure, Mechanical Properties, and Cytotoxicity
by Aleksandra Małachowska, Wiktoria Drej, Agnieszka Rusak, Tomasz Kozieł, Denis Pikulski and Wojciech Stopyra
Materials 2025, 18(24), 5687; https://doi.org/10.3390/ma18245687 - 18 Dec 2025
Cited by 1 | Viewed by 622
Abstract
Titanium-based bulk metallic glasses (BMGs) offer high strength, lower stiffness than Ti-6Al-4V, and superior corrosion resistance, but conventional Ti glass-forming systems often contain toxic Ni, Be, or Cu. This work investigates five novel Ti-based alloys free of these elements—Ti42Zr35Si [...] Read more.
Titanium-based bulk metallic glasses (BMGs) offer high strength, lower stiffness than Ti-6Al-4V, and superior corrosion resistance, but conventional Ti glass-forming systems often contain toxic Ni, Be, or Cu. This work investigates five novel Ti-based alloys free of these elements—Ti42Zr35Si5Co12.5Sn2.5Ta3, Ti42Zr40Ta3Si15, Ti60Nb15Zr10Si15, Ti39Zr32Si29, and Ti65.5Fe22.5Si12—synthesized by arc melting and suction casting. Single-track laser remelting using a selective laser melting (SLM) system was performed to simulate additive manufacturing and examine microstructural evolution, cracking behavior, mechanical properties, and cytocompatibility. All alloys solidified into fully crystalline α/β-Ti matrices with Ti/Zr silicides; no amorphous structures were obtained. Laser remelting refined the microstructure but did not induce glass formation, consistent with the known limited glass-forming ability of Cu/Ni/Be-free Ti systems. Cracking was observed at low laser energies but crack density decreased as laser energy increased. Cracks were eliminated above ~0.4 J/mm for most alloys. Ti42Zr35Si5Co12.5Sn2.5Ta3 exhibited the lowest stiffness (~125 GPa), while Ti60Nb15Zr10Si15 showed the highest due to silicide precipitation. Cytotoxicity tests (ISO 10993-5) confirmed all alloys to be non-toxic, with some extracts even enhancing fibroblast proliferation. This rapid laser-remelting approach enables cost-effective screening of Ti-based glass-forming alloys for additive manufacturing. Ti–Zr–Ta–Si systems demonstrated the most promising properties for further testing using the powder bed method. Full article
(This article belongs to the Section Biomaterials)
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33 pages, 77489 KB  
Article
Chemistry and Fe Isotopes of Magnetites in the Orbicular Bodies in the Tanling Diorite and Implications for the Skarn Iron Mineralization in the North China Craton
by Ruipeng Li, Shangguo Su and Peng Wang
Minerals 2025, 15(10), 1061; https://doi.org/10.3390/min15101061 - 9 Oct 2025
Viewed by 783
Abstract
Skarn-type iron ore is economically significant, and numerous skarn ore deposits have been identified in the North China Craton. The newly discovered orbicular diorite in this region is distinguished from other analogous rocks due to the accumulation of large magnetite particles, which may [...] Read more.
Skarn-type iron ore is economically significant, and numerous skarn ore deposits have been identified in the North China Craton. The newly discovered orbicular diorite in this region is distinguished from other analogous rocks due to the accumulation of large magnetite particles, which may shed new light on the genesis of this ore type. The magnetite in different parts of the orbicular structure exhibits distinct compositional differences. For example, magnetite at the edge has a small particle size (200 μm) and is associated with the minerals plagioclase and hornblende, indicating that it crystallized from normal diorite magma. By contrast, magnetite in the core has a relatively large particle size (>1000 μm), is associated with apatite and actinolite, and contains apatite inclusions as well as numerous pores. The size of magnetite in the mantle falls between that of the edge and the core. The syngenetic minerals of magnetite in the mantle include epidote and plagioclase. The magnetites in the cores of orbicules have a higher content of Ti, Al, Ni, Cr, Sc, Zn, Co, Ga, and Nb than those in the rim. The δ56Fe value of the core magnetite (0.46‰–0.78‰) is much higher than that of the mantle and rim magnetite in orbicules. Moreover, the δ56Fe value of magnetite increases as the V content of magnetite gradually decreases. This large iron isotope fractionation is likely driven by liquid immiscibility that forms iron-rich melts under high oxygen fugacity. The reaction between magma and carbonate xenoliths (Ca, Mg)CO3 during magma migration generates abundant CO2, which significantly increases the oxygen fugacity of the magmatic system. Under the action of CO2 and other volatile components, liquid immiscibility occurs in the magma chamber, and Fe-rich oxide melts are formed by the melting of carbonate xenoliths. Iron oxides (Fe3O4/Fe2O3) will crystallize close to the liquidus due to high oxygen fugacity. These characteristics of magnetite in the Tanling orbicular diorite (Wuan, China) indicate that diorite magma reacts with carbonate xenoliths to form “Fe-rich melts”, and skarn iron deposits are probably formed by the reaction of intermediate-basic magma with carbonate rocks that generate such “Fe-rich melts”. A possible reaction is as follows: diorite magma + carbonate → (magnetite-actinolite-apatite) + garnet + epidote + feldspar + hornblende + CO2↑. Full article
(This article belongs to the Special Issue Using Mineral Chemistry to Characterize Ore-Forming Processes)
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16 pages, 4887 KB  
Article
Composition Design of a Novel High-Temperature Titanium Alloy Based on Data Augmentation Machine Learning
by Xinpeng Fu, Boya Li, Binguo Fu, Tianshun Dong and Jingkun Li
Materials 2025, 18(13), 3099; https://doi.org/10.3390/ma18133099 - 30 Jun 2025
Cited by 3 | Viewed by 1993
Abstract
The application fields of high-temperature titanium alloys are mainly concentrated in the aerospace, defense and military industries, such as the high-temperature parts of rocket and aircraft engines, missile cases, tail rudders, etc., which can greatly reduce the weight of aircraft while resisting high [...] Read more.
The application fields of high-temperature titanium alloys are mainly concentrated in the aerospace, defense and military industries, such as the high-temperature parts of rocket and aircraft engines, missile cases, tail rudders, etc., which can greatly reduce the weight of aircraft while resisting high temperatures. However, traditional high-temperature titanium alloys containing multiple types of elements (more than six) have a complex impact on the solidification, deformation, and phase transformation processes of the alloys, which greatly increases the difficulty of casting and deformation manufacturing of aerospace and military components. Therefore, developing low-component high-temperature titanium alloys suitable for hot processing and forming is urgent. This study used data augmentation (Gaussian noise) to expedite the development of a novel quinary high-temperature titanium alloy. Utilizing data augmentation, the generalization abilities of four machine learning models (XGBoost, RF, AdaBoost, Lasso) were effectively improved, with the XGBoost model demonstrating superior prediction accuracy (with an R2 value of 0.94, an RMSE of 53.31, and an MAE of 42.93 in the test set). Based on this model, a novel Ti-7.2Al-1.8Mo-2.0Nb-0.4Si (wt.%) alloy was designed and experimentally validated. The UTS of the alloy at 600 °C was 629 MPa, closely aligning with the value (649 MPa) predicted by the model, with an error of 3.2%. Compared to as-cast Ti1100 and Ti6242S alloy (both containing six elements), the novel quinary alloy has considerable high-temperature (600 °C) mechanical properties and fewer components. The microstructure analysis revealed that the designed alloy was an α+β type alloy, featuring a typical Widmanstätten structure. The fracture form of the alloy was a mixture of brittle and ductile fracture at both room and high temperatures. Full article
(This article belongs to the Section Metals and Alloys)
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20 pages, 8782 KB  
Article
Laser Powder Bed Fusion of a Ti-16Nb-Based Alloy: Processability, Microstructure, and Mechanical Properties
by Azim Gökçe, Vamsi Krishna Balla, Subrata Deb Nath, Arulselvan Arumugham Akilan and Sundar V. Atre
Metals 2025, 15(7), 728; https://doi.org/10.3390/met15070728 - 29 Jun 2025
Cited by 2 | Viewed by 1095
Abstract
Titanium alloys, especially Ti6Al4V, are widely used in biomedical implants due to their biocompatibility and mechanical strength. However, their high elastic modulus (>100 GPa), compared to that of human bone (10–30 GPa), often causes stress shielding, reducing implant lifespan. To address this, titanium [...] Read more.
Titanium alloys, especially Ti6Al4V, are widely used in biomedical implants due to their biocompatibility and mechanical strength. However, their high elastic modulus (>100 GPa), compared to that of human bone (10–30 GPa), often causes stress shielding, reducing implant lifespan. To address this, titanium alloys with lower elastic modulus are under development. In this study, Ti-based multi-element alloy with 16 wt.% Nb samples were fabricated using laser powder bed fusion (L-PBF) from a premixed powder blend of Ti6Al4V and Nb-Hf-Ti. Processing high-melting Nb-based alloys via L-PBF poses challenges, which were mitigated through optimized parameters, including a maximum laser power of 100 W. Eleven parameter sets were employed to evaluate printability, microstructure, and mechanical properties. Microstructural analysis revealed Widmanstätten structures composed of α and β phases, along with isolated spherical pores. Reduced hatch spacing and slower laser speed led to increased hardness. The highest hardness (~43 HRC) was observed at the highest energy density (266 J/mm3), while the lowest (~28 HRC) corresponded to 44 J/mm3. Elastic modulus values ranged from 30 to 35 GPa, closely matching that of bone. These results demonstrate the potential of the developed Ti-based alloy containing 16 wt.% Nb as a promising candidate for load-bearing biomedical implants. Full article
(This article belongs to the Section Additive Manufacturing)
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9 pages, 3787 KB  
Proceeding Paper
Powder-Mixed Micro Electrical Discharge Machining-Assisted Surface Modification of Ti-35Nb-7Zr-5Ta Alloy in Biomedical Applications
by Altair Kossymbayev, Shahid Ali, Didier Talamona and Asma Perveen
Eng. Proc. 2025, 92(1), 71; https://doi.org/10.3390/engproc2025092071 - 16 May 2025
Cited by 2 | Viewed by 863
Abstract
One of the most popular alloys for biomedical applications is TiAl6V4. Even though TiAl6V4 is widely used, it faces several challenges. Firstly, TiAl6V4 is prone to stress shielding caused by the difference in Young’s moduli of the alloy (110 GPa) and human bones [...] Read more.
One of the most popular alloys for biomedical applications is TiAl6V4. Even though TiAl6V4 is widely used, it faces several challenges. Firstly, TiAl6V4 is prone to stress shielding caused by the difference in Young’s moduli of the alloy (110 GPa) and human bones (20–30 GPa). Secondly, there is the presence of cytotoxic elements, aluminum and vanadium. Researchers have proposed Ti-35Nb-7Zr-5Ta (TNZT) alloy to overcome these disadvantages, an excellent substitute for natural human bones. This alloy offers a lower elastic modulus (up to 81 GPa), much closer to human bones than TiAl6V4 alloy. Also, TNZT alloy contains no cytotoxic elements and has excellent biocompatibility and high corrosion resistance. Given the positive outcomes on powder-mixed micro electro-discharge machining (PM-μ-EDM) of Ti alloy using hydroxyapatite (HA) powder, we studied the machinability of TNZT alloy using HA powder mixed-μ-EDM by changing the HA powder concentration (0, 5, and 10 g/L), gap voltage (90, 100, and 110 V), and capacitance (10, 100, and 400 nF) according to the Taguchi L9 method. Machining performance metrics such as material removal rate (MRR), overcut, and circularity were examined using a tungsten carbide tool of 237 µm diameter. The results showed an overcut of 10.33 µm, circularity of 8.47 µm, and MRR of 6030.89 µm3/s for the lowest energy setup. Full article
(This article belongs to the Proceedings of 2024 IEEE 6th Eurasia Conference on IoT, Communication and Engineering)
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21 pages, 8306 KB  
Article
Magmatic–Hydrothermal Processes of the Pulang Giant Porphyry Cu (–Mo–Au) Deposit, Western Yunnan: A Perspective from Different Generations of Titanite
by Mengmeng Li, Xue Gao, Guohui Gu and Sheng Guan
Minerals 2025, 15(3), 263; https://doi.org/10.3390/min15030263 - 3 Mar 2025
Cited by 2 | Viewed by 1821
Abstract
The Yidun island arc was formed in response to the Late Triassic westward subduction of the Ganzi–Litang oceanic plate, a branch of the Paleo-Tethys Ocean. The Zhongdian arc, located in the south of the Yidun island arc, has relatively large number of porphyry [...] Read more.
The Yidun island arc was formed in response to the Late Triassic westward subduction of the Ganzi–Litang oceanic plate, a branch of the Paleo-Tethys Ocean. The Zhongdian arc, located in the south of the Yidun island arc, has relatively large number of porphyry (skarn) type Cu–Mo ± Au polymetallic deposits, the largest of which is the Pulang Cu (–Mo–Au) deposit with proven Cu reserves of 5.11 Mt, Au reserves of 113 t, and 0.17 Mt of molybdenum. However, the relationship between mineralization and the potassic alteration zone, phyllic zone, and propylitic zone of the Pulang porphyry deposit is still controversial and needs further study. Titanite (CaTiSiO5) is a common accessory mineral in acidic, intermediate, and alkaline igneous rocks. It is widely developed in various types of metamorphic rocks, hydrothermally altered rocks, and a few sedimentary rocks. It is a dominant Mo-bearing phase in igneous rocks and contains abundant rare earth elements and high-field-strength elements. As an effective geochronometer, thermobarometer, oxybarometer, and metallogenic potential indicator mineral, titanite is ideal to reveal the magmatic–hydrothermal evolution and the mechanism of metal enrichment and precipitation. In this paper, major and trace element contents of the titanite grains from different alteration zones were obtained using electron probe microanalysis (EPMA) and laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to define the changes in physicochemical conditions and the behavior of these elements during the process of hydrothermal alteration at Pulang. Titanite in the potassic alteration zone is usually shaped like an envelope. It occurs discretely or is enclosed by feldspar, with lower contents of CaO, Al, Sr, Zr and Hf; a low Nb/Ta ratio; high ∑REE + Y, U, Th, Ta, Nb, and Ga content; and high FeO/Al2O3 and LREE/HREE ratios. This is consistent with the characteristics of magmatic titanite from fresh quartz monzonite porphyry in Pulang and other porphyry Cu deposits. Titanite in the potassium silicate alteration zone has more negative Eu anomaly and a higher U content and Th/U ratio, indicating that the oxygen fugacity decreased during the transformation to phyllic alteration and propylitic alteration in Pulang. High oxygen fugacity is favorable for the enrichment of copper, gold, and other metallogenic elements. Therefore, the enrichment of copper is more closely related to the potassium silicate alteration. The molybdenum content of titanite in the potassium silicate alteration zone is 102–104 times that of the phyllic alteration zone and propylitic alteration zone, while the copper content is indistinctive, indicating that molybdenum was dissolved into the fluid or deposited in the form of sulfide before the medium- to low-temperature hydrothermal alteration, which may lead to the further separation and deposition of copper and molybdenum. Full article
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13 pages, 6626 KB  
Article
High Strength–Ductility Synergy of As-Cast B2-Containing AlNbTaTiZr Refractory High-Entropy Alloy Under Intermediate and Dynamic Strain Rates
by Hashim Naseer, Yangwei Wang, Muhammad Abubaker Khan, Jamieson Brechtl and Mohamed A. Afifi
Metals 2025, 15(3), 249; https://doi.org/10.3390/met15030249 - 26 Feb 2025
Cited by 4 | Viewed by 2181
Abstract
Understanding the mechanical behavior of materials under various strain-rate regimes is critical for many scientific and engineering applications. Accordingly, this study investigates the strain-rate-dependent compressive mechanical behavior of B2-containing (TiZrNb)79.5(TaAl)20.5 refractory high-entropy alloy (RHEA) at room temperature. The RHEA is [...] Read more.
Understanding the mechanical behavior of materials under various strain-rate regimes is critical for many scientific and engineering applications. Accordingly, this study investigates the strain-rate-dependent compressive mechanical behavior of B2-containing (TiZrNb)79.5(TaAl)20.5 refractory high-entropy alloy (RHEA) at room temperature. The RHEA is prepared by vacuum arc melting and is tested over intermediate (1.0 × 10−1 s−1, 1.0 s−1) and dynamic (1.0 × 103 s−1, 2.0 × 103 s−1, 2.8 × 103 s−1, 3.2 × 103 s−1, and 3.5 × 103 s−1) strain rates. The alloy characterized as hybrid body-centered-cubic (BCC)/B2 nanostructure reveals an exceptional yield strength (YS) of ~1437 MPa and a fracture strain exceeding 90% at an intermediate (1.0 s−1) strain rate. The YS increases to ~1797 MPa under dynamic strain-rate (3.2 × 103 s−1) loadings, which is a ~25 % improvement in strength compared with the deformation at the intermediate strain rate. Microstructural analysis of the deformed specimens reveals the severity of dislocation activity with strain and strain rate that evolves from fine dislocation bands to the formation of localized adiabatic shear bands (ASBs) at the strain rate 3.5 × 103 s−1. Consequently, the RHEA fracture features mixed ductile–brittle morphology. Overall, the RHEA exhibits excellent strength–ductility synergy over a wide strain-rate domain. The study enhances understanding of the strain-rate-dependent mechanical behavior of B2-containing RHEA, which is significant for alloy processes and impact resistance applications. Full article
(This article belongs to the Special Issue Structure and Properties of Refractory Medium/High-Entropy Alloys)
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26 pages, 14835 KB  
Article
Mechanical and Tribological Properties of (AlCrNbSiTiMo)N High-Entropy Alloy Films Prepared Using Single Multiple-Element Powder Hot-Pressed Sintered Target and Their Practical Application in Nickel-Based Alloy Milling
by Jeng-Haur Horng, Wen-Hsien Kao, Wei-Chen Lin and Ren-Hao Chang
Lubricants 2024, 12(11), 391; https://doi.org/10.3390/lubricants12110391 - 14 Nov 2024
Cited by 1 | Viewed by 1838
Abstract
(AlCrNbSiTiMo)N high-entropy alloy films with different nitrogen contents were deposited on tungsten carbide substrates using a radio-frequency magnetron sputtering system. Two different types of targets were used in the sputtering process: a hot-pressing sintered AlCrNbSiTi target fabricated using a single powder containing multiple [...] Read more.
(AlCrNbSiTiMo)N high-entropy alloy films with different nitrogen contents were deposited on tungsten carbide substrates using a radio-frequency magnetron sputtering system. Two different types of targets were used in the sputtering process: a hot-pressing sintered AlCrNbSiTi target fabricated using a single powder containing multiple elements and a vacuum arc melting Mo target. The deposited films were denoted as RN0, RN33, RN43, RN50, and RN56, where RN indicates the nitrogen flow ratio relative to the total nitrogen and argon flow rate (RN = (N2/(N2 + Ar)) × 100%). The as-sputtered films were vacuum annealed, with the resulting films denoted as HRN0, HRN33, HRN43, HRN50, and HRN56, respectively. The effects of the nitrogen content on the composition, microstructure, mechanical properties, and tribological properties of the films, in both as-sputtered and annealed states, underwent thorough analysis. The RN0 and RN33 films displayed non-crystalline structures. However, with an increase in nitrogen content, the RN43, RN50, and RN56 films transitioned to FCC structures. Among the as-deposited films, the RN43 film exhibited the best mechanical and tribological properties. All of the annealed films, except for the HRN0 film, displayed an FCC structure. In addition, they all formed an MoO3 solid lubricating phase, which reduced the coefficient of friction and improved the anti-wear performance. The heat treatment HRN43 film displayed the supreme hardness, H/E ratio, and adhesion strength. It also demonstrated excellent thermal stability and the best wear resistance. As a result, in milling tests on Inconel 718, the RN43-coated tool demonstrated a significantly lower flank wear and notch wear, indicating an improved machining performance and extended tool life. Thus, the application of the RN43 film in aerospace manufacturing can effectively reduce the tool replacement cost. Full article
(This article belongs to the Special Issue Recent Advances in Tribological Properties of Machine Tools)
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21 pages, 9535 KB  
Article
Petrogenesis of Eocene A-Type Granite Associated with the Yingpanshan–Damanbie Regolith-Hosted Ion-Adsorption Rare Earth Element Deposit in the Tengchong Block, Southwest China
by Zhong Tang, Zewei Pan, Tianxue Ming, Rong Li, Xiaohu He, Hanjie Wen and Wenxiu Yu
Minerals 2024, 14(9), 933; https://doi.org/10.3390/min14090933 - 12 Sep 2024
Cited by 2 | Viewed by 1589
Abstract
The ion-adsorption-type rare earth element (iREE) deposits dominantly supply global resources of the heavy rare earth elements (HREEs), which have a critical role in a variety of advanced technological applications. The initial enrichment of REEs in the parent granites controls the formation of [...] Read more.
The ion-adsorption-type rare earth element (iREE) deposits dominantly supply global resources of the heavy rare earth elements (HREEs), which have a critical role in a variety of advanced technological applications. The initial enrichment of REEs in the parent granites controls the formation of iREE deposits. Many Mesozoic and Cenozoic granites are associated with iREE mineralization in the Tengchong block, Southwest China. However, it is unclear how vital the mineralogical and geochemical characteristics of these granites are to the formation of iREE mineralization. We conducted geochronology, geochemistry, and Hf isotope analyses of the Yingpanshan–Damanbie granitoids associated with the iREE deposit in the Tengchong block with the aims to discuss their petrogenesis and illustrate the process of the initial REE enrichment in the granites. The results showed that the Yingpanshan–Damanbie pluton consists of syenogranite and monzogranite, containing REE-bearing accessory minerals such as monazite, xenotime, apatite, zircon, allanite, and titanite, with a high REE concentration (210–626 ppm, mean value is 402 ppm). The parent granites have Zr + Nb + Ce + Y (333–747 ppm) contents and a high FeOT/MgO ratio (5.89–11.4), and are enriched in Th (mean value of 43.6 ppm), U (mean value of 4.57 ppm), Zr (mean value of 305 ppm), Hf (mean value of 7.94 ppm), Rb (mean value of 198 ppm), K (mean value of 48,902 ppm), and have depletions of Sr (mean value of 188 ppm), Ba (mean value of 699 ppm), P (mean value of 586 ppm), Ti (mean value of 2757 ppm). The granites plot in the A-type area in FeOT/MgO vs. Zr + Nb + Ce + Y and Zr vs. 10,000 Ga/Al diagrams, suggesting that they are A2-type granites. These granites are believed to have formed through the partial melting of amphibolites at a post-collisional extension setting when the Tethys Ocean closed. REE-bearing minerals (e.g., apatite, titanite, allanite, and fluorite) and rock-forming minerals (e.g., potassium feldspar, plagioclase, biotite, muscovite) supply rare earth elements in weathering regolith for the Yingpanshan–Damanbie iREE deposit. Full article
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21 pages, 3193 KB  
Article
Plagioclase Megacrysts in Mesoproterozoic Amphibolites from the New Jersey Highlands, USA: Indicators of Mixed-Source Magma and Fractionation Interruption in Anorthosite-Dominated Terrains
by Matthew L. Gorring, Richard A. Volkert and William H. Peck
Minerals 2024, 14(8), 768; https://doi.org/10.3390/min14080768 - 28 Jul 2024
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Abstract
Rare amphibolite in the New Jersey Highlands containing plagioclase megacrysts ≤13 cm long forms bodies 0.5 to 2 m thick that preserve a penetrative metamorphic fabric and have sharp, conformable contacts against Mesoproterozoic country rocks. The megacrystic amphibolites were emplaced as thin dikes [...] Read more.
Rare amphibolite in the New Jersey Highlands containing plagioclase megacrysts ≤13 cm long forms bodies 0.5 to 2 m thick that preserve a penetrative metamorphic fabric and have sharp, conformable contacts against Mesoproterozoic country rocks. The megacrystic amphibolites were emplaced as thin dikes along extensional faults between 1160 and 1130 Ma. Amphibolites contain weakly zoned, subhedral andesine megacrysts (An29–44) in a matrix of plagioclase (An18–38), magnesio-hastingsite, biotite, diopside, Fe-Ti oxides, and apatite. The whole-rock major oxide composition of the megacrystic amphibolite matrix has high TiO2 (2.07 wt.% ± 2.0%), Al2O3 (17.03 wt.% ± 0.87%), and Fe2O3t (12.84 wt.% ± 3.2%) that represents an Al-Fe-rich mafic magma type that is characteristic of anorthosite associations globally. The whole-rock, rare earth element (REE) composition of the megacrystic amphibolite matrix is characterized by enrichments in light rare earth elements (LREEs) (La/YbN = 1.73–10.69) relative to middle (MREEs) and heavy (HREEs) rare earth elements (Gd/YbN = 1.30–1.85), and most samples have small positive Eu anomalies (Eu/Eu* = 0.95–1.25). The megacrystic amphibolite matrix is also enriched in large ion lithophile elements (LILEs) and depleted in high field strength elements (HFSEs) (e.g., Ba/Nb = 24–22). Megacrystic amphibolites formed through partial melting of subduction-modified lithospheric mantle that fractionated olivine and plagioclase, producing a high-Al-Fe mafic magma. Plagioclase megacrysts formed through extraction of a plagioclase-rich crystal-liquid mush from anorthosite that mixed with mafic magma and collected in the upper part of the mid-crustal magma (depth of ~20 km based on Al-in-hornblende geobarometry) chamber through flotation. Periodic tapping of this mixed source by extensional fractures led to emplacement of the amphibolites as dikes and may have interrupted the extensive fractionation and plagioclase separation necessary to form voluminous anorthosite intrusions. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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21 pages, 18628 KB  
Article
TiAl Alloy Fabricated Using Election Beam Selective Melting: Process, Microstructure, and Tensile Performance
by Yu Zhang, Yan Li, Meihui Song, Yanchun Li, Shulin Gong and Bin Zhang
Metals 2024, 14(4), 482; https://doi.org/10.3390/met14040482 - 20 Apr 2024
Cited by 7 | Viewed by 2230
Abstract
TiAl alloy is one of the most attractive candidates for a new generation of high-temperature structural materials and has broad application prospects in the aerospace field. As a typical intermetallic material, TiAl is inevitably difficult to process using conventional methods. Election beam selective [...] Read more.
TiAl alloy is one of the most attractive candidates for a new generation of high-temperature structural materials and has broad application prospects in the aerospace field. As a typical intermetallic material, TiAl is inevitably difficult to process using conventional methods. Election beam selective melting (EBSM) is an effective method of addictive manufacturing to prepare TiAl alloy with a complex structure. However, the microstructure of TiAl alloy formed using EBSM often contains defects such as pores, which seriously reduces the mechanical properties of the material. In this work, the effects of EBSM and post-processing procedures on the microstructure and mechanical properties of Ti-48Al-2Cr-2Nb alloy were studied. The results show that the microstructure of Ti-48Al-2Cr-2Nb alloy formed using the EBSM process was dense and composed of equiaxed γ-phase and double-phase regions. A large number of dislocations that formed due to thermal stress were clearly observed inside the Ti-48Al-2Cr-2Nb alloy. When the EBSM process parameters were 13.5 mA, 4.0 m/s, and 40.50 J/mm3, as the current intensity increased, the Al content decreased, the content of α2 phase increased, and the microstructure of the material was coarse. The results of the tensile test fracture morphology indicate that the Ti-48Al-2Cr-2Nb alloy exhibited brittle fracture during tensile deformation, lacking the typical yield deformation of metal materials. As the energy density of the EBSM process increased, the mechanical properties of the Ti-48Al-2Cr-2Nb alloy first increased and then decreased. The samples prepared with an energy density of 34.50~40.50 J/mm3 had excellent mechanical properties, of which the maximum tensile strength and maximum elongation reached 643 MPa and 2.09%, respectively. The phase composition of the Ti-48Al-2Cr-2Nb alloy after hot isostatic pressing (HIP) treatment remained unchanged from the EBSM samples, but there was a slight difference in content. There was an increase in the amount of γ phase and a decrease in B2 phase, accompanied by the generation of a massive γ phase after HIP treatment. Moreover, the number of dislocations inside the material increased. The Ti-48Al-2Cr-2Nb alloy after HIP treatment exhibited obvious plastic deformation characteristics, with a tensile strength of 679 MPa and elongation of 2.5%. A heat treatment of 900 °C/5 h was performed on the Ti-48Al-2Cr-2Nb alloy after HIP. The dislocation density of the Ti-48Al-2Cr-2Nb alloy decreased, and the B2 phase transformed from massive to lamellar. Full article
(This article belongs to the Special Issue Advances in 3D Printing Technologies of Metals—2nd Edition)
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