Materials Science and Engineering: A最新文献

Mechanisms of recrystallization and microstructure evolution during hot deformation of 550 MPa grade HSLA steel 550mpa级HSLA钢热变形再结晶机理及组织演变

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-08 DOI: 10.1016/j.msea.2025.149579

Shu-gang Cui , Pan-dong Lin , Wen-hua Xu , Guo-chao Gu , Chang-xin Shi , Yu-peng Lu

Understanding the hot deformation behavior of HSLA steel is essential for optimizing thermo-mechanical processing and controlling final microstructures. In this study, the dynamic recrystallization and microstructure evolution behaviors of 550 MPa grade high-strength low-alloy steel (HSLA) during thermal deformation were investigated using hot compression experiments and microstructure analysis. Tests were conducted at 900–1150 °C, with the strain rates of 0.01, 0.1, and 1 s⁻¹. The critical conditions for recrystallization were determined, and a corresponding kinetic model was established. The results show that the microstructure is dominated by martensite after hot deformation. When the deformation temperature was below 950 °C, a significant fraction of deformed austenite grains remained in the microstructure. Fine Nb (C, N) precipitates, with sizes of several nanometers, and Fe₃C carbides exhibiting a Bagaryatskii orientation relationship with the matrix were also observed. Based on the friction-corrected flow stress curve, the ratio of the recrystallization critical strain to the peak strain was found to be about 0.419. Meanwhile, the softening mechanism during hot deformation consists of the combined effect of mainly Discontinuous dynamic recrystallization and dynamic recovery.

了解高强度钢的热变形行为对优化热机械加工和控制最终组织具有重要意义。通过热压缩实验和显微组织分析，研究了550 MPa级高强度低合金钢（HSLA）在热变形过程中的动态再结晶和显微组织演变行为。试验在900-1150°C下进行，应变速率为0.01、0.1和1 s−1。确定了再结晶的临界条件，并建立了相应的动力学模型。结果表明：热变形后的组织以马氏体为主；当变形温度低于950℃时，组织中仍有大量形变的奥氏体晶粒残留。此外，还观察到细小的Nb （C， N）析出物（尺寸为几纳米）和Fe3C碳化物（与基体呈Bagaryatskii取向关系）。基于摩擦修正流动应力曲线，再结晶临界应变与峰值应变之比约为0.419。热变形过程中的软化机制主要是不连续动态再结晶和动态恢复的共同作用。

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引用次数: 0

Multi-scale insights into Ti(C,N)-reinforced CoCr0.5FeNiTi0.2high-entropy alloys via in-situ synthesis microstructural evolution and strengthening mechanisms 原位合成Ti（C，N）增强cocr0.5 feniti0.2高熵合金显微组织演化及强化机制的多尺度研究

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-08 DOI: 10.1016/j.msea.2025.149587

Jidong Zhang, Yifan Guo, Haiwei Zhao, Hui-zhong Ma, Lan Zhang

A novel in-situ synthesis strategy employing graphitic carbon nitride (g-C₃N₄) as a dual C–N precursor was developed to fabricate Ti(C,N)/CoCr_0.5FeNiTi_0.2 composites. The controlled decomposition of g-C₃N₄ at 1050 °C enabled uniform Ti(C,N) precipitation with semi-coherent interfaces, leading to refined grains (∼2.1 μm), elevated dislocation density, and enhanced interfacial load transfer. At the optimum reinforcement level (1.0 wt% g-C₃N₄), the composite exhibited 99.3 % relative density, 857 HV hardness, and 1297 MPa ultimate tensile strength. Multi-scale characterization combined with molecular dynamics simulations revealed that Ti(C,N) particles enhance mechanical properties through grain refinement, dislocation hindrance, thermal-mismatch-induced residual stresses, and effective load transfer. At the atomic scale, Ti(C,N) acted simultaneously as dislocation sources and obstacles, markedly increasing dislocation density, while stacking-fault networks at subgrain boundaries further contributed to yield-strength increments. A quantitative strengthening model accurately predicted the experimental results with deviations below 5 %. The MD simulations reproduced the dynamic interfacial failure process, including atomic rearrangement, bond rupture, critical yielding, and ultimate fracture. The study delivers a high-performance HEA composite while elucidating processing–microstructure–property correlations, thereby advancing the understanding of strengthening mechanisms and providing the design of nanoparticle-reinforced metallic materials.

采用石墨化碳氮（g-C3N4）作为双碳氮前驱体制备Ti(C，N)/CoCr0.5FeNiTi0.2复合材料。在1050℃下g-C3N4的控制分解使Ti（C，N）在半共格界面均匀析出，导致晶粒细化（~ 2.1 μm），位错密度升高，界面载荷传递增强。在最佳增强水平（1.0 wt% g-C3N4）下，复合材料的相对密度为99.3%，硬度为857 HV，极限抗拉强度为1297 MPa。多尺度表征结合分子动力学模拟表明，Ti（C，N）颗粒通过晶粒细化、位错阻挡、热失配引起的残余应力和有效的载荷传递来提高力学性能。在原子尺度上，Ti（C，N）同时作为位错源和障碍，显著增加了位错密度，而亚晶界的堆积-断层网络进一步促进了屈服强度的增加。定量强化模型准确预测实验结果，误差小于5%。MD模拟再现了动态界面破坏过程，包括原子重排、键断裂、临界屈服和最终断裂。该研究提供了高性能HEA复合材料，同时阐明了加工-微观结构-性能的相关性，从而促进了对强化机制的理解，并为纳米颗粒增强金属材料的设计提供了依据。

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引用次数: 0

Stretch flangeability of hot-rolled Ti-Nb microalloyed steels containing tramp Cu, Sn and Sb 含Cu、Sn、Sb的热轧Ti-Nb微合金钢的拉伸翻边性

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-06 DOI: 10.1016/j.msea.2025.149580

Ho Hyeong Lee , Chang Jae Yu , Jeongseok Kim , Sung-Il Kim , Dae Geon Lee , Heung Nam Han , Dong-Woo Suh

This study investigates the impact of tramp elements on the stretch flangeability of hot-rolled high-strength steels microalloyed with Ti and Nb. Two alloy systems - Ti-rich and Nb-rich - were designed to achieve similar tensile properties by varying Ti/Nb ratios, while systematically introducing tramp elements. Microstructural characterization revealed that Ti-rich alloys exhibited a higher population of coarse TiN precipitates. The Ti-rich alloys demonstrated lower hole expansion ratios (HER) than Nb-rich counterparts when holes were fabricated via mechanical punching, whereas this difference disappeared when wire-EDM was used, indicating that coarse TiN contributes significantly to damage generation during punching. The presence of tramp Sn and Sb further reduced HER, even in wire-EDM specimens, suggesting a detrimental effect on the intrinsic hole expansion property, which was led by surface segregation of the Sn and Sb. In addition, the tramp Sn and Sb have a propensity to segregate to TiN/matrix interface, ending up with exacerbation of the detrimental effect of TiN on the stretch flangeability of hole punched specimen. In contrast, Cu showed marginal segregation and negligible influence on HER.

本文研究了不稳定元素对Ti、Nb微合金化热轧高强钢拉伸可翻性的影响。两种合金体系——富钛和富铌——通过不同的Ti/Nb比率来获得相似的拉伸性能，同时系统地引入了不稳定元素。显微组织表征表明，富钛合金中有大量粗TiN析出。当采用机械冲孔时，富钛合金的孔膨胀率（HER）低于富铌合金，而当采用电火花加工时，这种差异消失，这表明粗TiN对冲孔过程中的损伤产生有重要影响。不均匀Sn和Sb的存在进一步降低了HER，即使在线切割样品中也是如此，这表明Sn和Sb的表面偏析导致了对固有孔扩展性能的不利影响。此外，不均匀Sn和Sb倾向于偏析到TiN/基体界面，最终加剧了TiN对穿孔样品拉伸可折性的不利影响。相比之下，Cu表现出边际偏析，对HER的影响可以忽略不计。

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引用次数: 0

Ultrafine-grained heterogeneous nugget zone enables enhanced mechanical properties of friction stir welded CrMnFeCoNi high-entropy alloy 超细晶非均质熔核区提高了搅拌摩擦焊接crmnnfeconi高熵合金的力学性能

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-05 DOI: 10.1016/j.msea.2025.149581

G.Q. Huang , B. Cheng , J.P. Hu , X.Y. Han , Z.H. Wang , J. Xu , T.H. Chou , T. Yang , F.Q. Meng , Z.K. Shen , X.M. Feng , Y.F. Shen

In this study, we employed water-cooling-assisted friction stir welding (FSW) to join CrMnFeCoNi high-entropy alloy (HEA), achieving an ultrafine-grained heterogeneous structure in the nugget zone (NZ) with excellent strength–ductility synergy. Microstructural analysis indicates that grain refinement during FSW is governed by both continuous and discontinuous dynamic recrystallization (CDRX and DDRX), with water cooling promoting DDRX and inhibiting grain growth. The transition zone between the base material (BM) and NZ exhibits partial recrystallization, leading to local strengthening by grain refinement and elevated dislocation density. This heterogeneous structure enables the joint to accommodate higher local strain in the BM during tensile loading, surpassing its yield strength while retaining significant ductility due to its superior strain-hardening capacity. The water-cooling-assisted FSW joint exhibits a yield strength of ∼317 MPa, an ultimate tensile strength of ∼606 MPa, and a uniform elongation of ∼53 %, achieving over 100 % joint efficiency. This simple yet effective approach offers a promising method for high-quality welding of CrMnFeCoNi HEA and potentially other FCC-based HEAs, advancing alloy joining technologies.

在本研究中，我们采用水冷辅助搅拌摩擦焊（FSW）连接crmnnfeconi高熵合金（HEA），在熔核区（NZ）获得了具有优异强度-塑性协同作用的超细晶非均质组织。显微组织分析表明，FSW过程中晶粒细化受连续和不连续动态再结晶（CDRX和DDRX）控制，水冷却促进了DDRX，抑制了晶粒长大。基材（BM）和NZ之间的过渡区表现出部分再结晶，导致晶粒细化和位错密度的局部强化。这种非均质结构使接头能够在拉伸加载期间适应BM中较高的局部应变，超过其屈服强度，同时由于其优越的应变硬化能力而保持显著的延性。水冷辅助FSW接头的屈服强度为~ 317 MPa，极限抗拉强度为~ 606 MPa，均匀伸长率为~ 53%，接头效率超过100%。这种简单而有效的方法为高质量焊接CrMnFeCoNi HEA和潜在的其他基于fcc的HEA提供了一种有前途的方法，推动了合金连接技术的发展。

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引用次数: 0

Tailoring the microstructure and mechanical properties of laser-directed-energy-deposited IN738LC alloy via heat treatment 激光定向能沉积IN738LC合金热处理的微观组织和力学性能

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-04 DOI: 10.1016/j.msea.2025.149573

Ho Seoung Kang , Ye Chan Sung , Seong-Moon Seo , Hyungsoo Lee , Hyoung Seop Kim , Jung Gi Kim

The additive manufacturing (AM) of IN738LC, a high-strength Ni-based superalloy, is limited by its inherent crack susceptibility because of its high Al and Ti contents. In this study, crack-suppressed IN738LC components were fabricated via laser-directed energy deposition (DED) using a reduced laser power (300–600 W) and a small beam diameter (0.8 mm), thereby minimizing heat-affected zones. Post-heat treatments were systematically applied, including direct aging (DA), partial (2STEP), and full (3STEP) solution treatments, to investigate their impact on the microstructural evolution and mechanical performance. Electron-backscatter diffraction, transmission electron microscopy, and energy dispersive X-ray spectroscopy analyses revealed that the γ′ precipitate size and M₂₃C₆ carbide distribution were highly sensitive to the degree of homogenization. The use of DA formed ultrafine γ′ precipitates and the highest M₂₃C₆ fraction, resulting in a high yield strength (1322.68 MPa at 25 °C) and creep resistance (1109 h at 850 °C) but limited ductility. In contrast, the 3STEP treatment promoted an equiaxed grain morphology and coarsened γ′ precipitates, yielding improved ductility (5.3 %) with moderate strength. These findings demonstrate that precise thermal management during and after DED processing enables both microstructural control and crack suppression in IN738LC alloy, optimizing both tensile and creep properties for high-temperature structural applications.

IN738LC是一种高强度镍基高温合金，由于其高Al和Ti含量，其固有的裂纹敏感性限制了增材制造技术的发展。在本研究中，采用激光定向能量沉积（DED）技术，使用较低的激光功率（300-600 W）和较小的光束直径（0.8 mm）制备了裂纹抑制IN738LC组件，从而最大限度地减少了热影响区。采用直接时效（DA）、部分固溶（2STEP）和完全固溶（3STEP）三种热处理方法，研究其对合金显微组织演变和力学性能的影响。电子后向散射衍射、透射电镜和能量色散x射线能谱分析表明，γ′析出物尺寸和M23C6碳化物分布对均匀化程度高度敏感。使用DA形成了超细γ′相和最高的M23C6分数，导致高屈服强度（25°C时为1322.68 MPa）和抗蠕变（850°C时为1109 h），但塑性有限。相比之下，3STEP处理促进了等轴晶粒形貌和粗化的γ′析出，提高了韧性（5.3%），强度中等。这些发现表明，在DED过程中和之后进行精确的热管理，可以实现IN738LC合金的微观组织控制和裂纹抑制，从而优化高温结构应用的拉伸和蠕变性能。

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引用次数: 0

The development of the novel Al-Mg-Sc-Zr-Ag alloy: Achieving corrosion resistance-strength synergy via optimized processing routes 新型Al-Mg-Sc-Zr-Ag合金的开发：通过优化工艺路线实现耐蚀-强度协同

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-03 DOI: 10.1016/j.msea.2025.149563

Xinru Shao , Cheng Guo , Haoshang Liu , Jianxin Hu , Haitao Zhang , Zibin Wu , Hiromi Nagaumi

This study elucidates the mechanisms underlying the simultaneous enhancement of corrosion resistance and mechanical properties in an Al-5.02Mg-0.21Sc-0.11Zr-0.67Ag (wt%) alloy achieved through optimized thermomechanical processing. In comparison with the conventional T6 process (solution treatment at 500 °C/2 h + artificial aging at 180 °C/36 h), the P-T8 process (solution treatment at 500 °C/2 h + pre-aging + pre-deformation + artificial aging at 150 °C/36 h) enhances both strength and corrosion resistance through synergistic interactions between dislocations and nanoscale precipitates. Remarkably, the non-recrystallization annealing (350 °C/4 h NRA) process implemented after cold rolling not only strengthens the alloy via uniform precipitation of nanoscale Al₃(Sc, Zr) particles, but also improves corrosion resistance by completely suppressing grain boundary precipitation while generating high-density dislocation cells and low-angle grain boundaries (LAGBs). Compared to the corrosion depths of the P-T8 alloy (23.45 μm) and the T6 alloy (44.63 μm), the corrosion depth of the NRA-treated alloy was significantly reduced, at only 5.51 μm. The NRA-processed alloy maintains competitive mechanical properties, with yield strength, ultimate tensile strength, and elongation reaching 251.2 MPa, 368.86 MPa, and 9.22 %, respectively. This work provides a novel method and theoretical basis for achieving corrosion resistance–strength synergy in aluminum alloys.

本研究阐明了Al-5.02Mg-0.21Sc-0.11Zr-0.67Ag （wt%）合金通过优化的热处理工艺同时提高耐蚀性和力学性能的机制。与传统的T6工艺（500°C/2 h固溶处理+ 180°C/36 h人工时效）相比，P-T8工艺（500°C/2 h固溶处理+预时效+预变形+ 150°C/36 h人工时效）通过位错和纳米级析出物之间的协同相互作用提高了强度和耐腐蚀性。值得注意的是，冷轧后进行的非再结晶退火（350℃/4 h NRA）工艺不仅通过均匀析出纳米级Al3（Sc, Zr）颗粒来强化合金，而且通过完全抑制晶界析出而产生高密度位错胞和低角度晶界（lagb）来提高合金的耐蚀性。与P-T8合金（23.45 μm）和T6合金（44.63 μm）的腐蚀深度相比，经nra处理的合金的腐蚀深度明显减小，仅为5.51 μm。经nra处理后，合金的屈服强度、极限抗拉强度和伸长率分别达到251.2 MPa、368.86 MPa和9.22%，具有较好的力学性能。本研究为实现铝合金耐蚀-强度协同提供了新的方法和理论依据。

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引用次数: 0

Achieving exceptional ductility in an ultra-high strength heterostructured lightweight steel through regulated microstructural engineering 通过规范的微结构工程实现超高强度异质轻钢的卓越延展性

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-03 DOI: 10.1016/j.msea.2025.149572

Qian Cheng , Chao Zhang , Bo Yang , Zihao Feng , Xianghui Zheng , Qingyuan Wang , Wenquan Cao , Chongxiang Huang

Achieving ultra-high strength (>1.5 GPa) within lightweight steels necessitates the introduction of structures with high dislocation density, while how to tailor these structures to maintain an exceptional ductility? In this study, a dual-phase regulated heterostructured lightweight steel with dispersed deformed substructures (with the sizes of several hundred nanometers and an average spacing less than 1 μm) is prepared through critical annealing followed by pre-straining (ε = 18 %), contrasting it with the rolling-rested, and banded partially recrystallized counterpart fabricated solely by the truncated annealing. The regulated microstructure achieves an ultra-high strength (∼1.67 GPa), coupled with a substantially improved ductility of 18.6 %, twice that of the banded partially recrystallized counterpart. Deformation analysis reveals notable strain partitioning, where austenite grains undertake primary applied strains, evidenced by intense slip bands, dislocation pile-ups, and minor stacking faults, suppressing crack initiation and propagation. Ultra-high strength stems from heterogeneous-deformation induced (HDI) strengthening, dislocation strengthening, and intrinsic strengthening of austenite and B2 phases. Pronounced dual-synergistic deformation, operating at intergranular and intragranular scales, promotes the exceptional ductility. Fracture resistance is notably enhanced via restructuring failure pathways, enabled by stable interfacial cohesion and effective constraints from ductile constituents. This work provides insights into microstructural design of ultra-high-strength lightweight steel possessing exceptional ductility.

在轻钢中实现超高强度（>1.5 GPa）需要引入具有高位错密度的结构，而如何定制这些结构以保持卓越的延展性？本研究通过临界退火和预应变（ε = 18%）制备了具有分散变形子结构（尺寸为几百纳米，平均间距小于1 μm）的双相调节异质轻钢，并与仅通过截断退火制备的滚动休息带状部分再结晶的异质轻钢进行了对比。调节后的微观结构实现了超高强度（约1.67 GPa），同时延展性大幅提高，达到18.6%，是带状部分再结晶合金的两倍。变形分析揭示了显著的应变分配，其中奥氏体晶粒承担主要的施加应变，表现为强烈的滑移带、位错堆积和较小的层错，抑制了裂纹的萌生和扩展。超高强度源于非均质变形诱导（HDI）强化、位错强化以及奥氏体和B2相的本征强化。明显的双协同变形，作用于晶间和晶内，促进了特殊的延展性。通过重构断裂路径，通过稳定的界面内聚和延性成分的有效约束，显著增强了抗断裂能力。这项工作为具有特殊延展性的超高强度轻钢的微观结构设计提供了见解。

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引用次数: 0

Improving the hydrogen embrittlement resistance of high-strength fastener steels 提高高强度紧固件钢的抗氢脆性能

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-03 DOI: 10.1016/j.msea.2025.149560

Marjolein Weyns , Vsevolod Razumovskiy , Matthew Galler , Kim Verbeken , Tom Depover

High-strength fasteners play a crucial role in maintaining the structural integrity in various applications. Unfortunately, they are highly sensitive to hydrogen embrittlement (HE). This research aims to improve the HE resistance of steel grade 32CrB4 by adding the carbide-forming elements titanium and vanadium. Three alloys are considered: alloy A (32CrB4), B (alloy A + Ti), and C (alloy B + V). The hydrogen-assisted mechanical degradation is evaluated by performing slow strain rate tensile (SSRT) tests with both ex- and in-situ hydrogen charging. The influence of hydrogen on the mechanical properties is typically quantified by using a hydrogen embrittlement index (HEI). When using the relative reduction of area (RRA), a clear discrepancy was observed between the results obtained for ex- and in-situ testing. For the former, alloys B and C showed a clear improvement in behaviour, whereas no improvement was observed for the latter. More appropriate HEI's were defined directly related to the impact of the charging method on the fracture mechanism, indicating a higher HE resistance for alloys B and C in both cases. For ex-situ testing, the improved behaviour is linked to a preserved fracture pattern called radial cracking, also observed in air reference testing for all materials, yet only present in H conditions for alloys B and C. For in-situ testing, by combining SSRT and thermal desorption spectroscopy (TDS), it was demonstrated that additional hydrogen trapping occurs in alloys B and C during tensile testing, as compared to charging without mechanical loading, explaining their improved behaviour.

在各种应用中，高强度紧固件在保持结构完整性方面起着至关重要的作用。不幸的是，它们对氢脆（HE）非常敏感。本研究旨在通过添加碳化物形成元素钛和钒来提高钢级32CrB4的抗HE性能。考虑三种合金：合金A (32CrB4)，合金B（合金A + Ti）和合金C（合金B + V）。氢气辅助的机械降解是通过进行慢应变速率拉伸（SSRT）试验来评估的，同时进行了前充氢和原位充氢。氢对力学性能的影响通常用氢脆指数（HEI）来量化。当使用相对面积收缩率（RRA）时，在现场测试和现场测试中得到的结果有明显的差异。对于前者，合金B和C表现出明显的性能改善，而对于后者则没有观察到任何改善。更合适的HEI被定义为直接与充注方式对断裂机制的影响相关，表明合金B和C在两种情况下都具有更高的HE电阻。对于非原位测试，性能的改善与被称为径向开裂的断裂模式有关，这在所有材料的空气参考测试中也观察到，但只存在于H条件下的合金B和C。对于原位测试，通过结合SSRT和热解吸光谱（TDS），证明了在拉伸测试期间，与没有机械载荷的加载相比，合金B和C中出现了额外的氢捕获，解释了它们性能的改善。

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引用次数: 0

Outstanding mechanical and electrical properties of CoCrFeMnNi high entropy alloy with partial substitution of Mn by Si Si部分取代Mn的CoCrFeMnNi高熵合金具有优异的力学和电学性能

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-02 DOI: 10.1016/j.msea.2025.149571

Jiaqi Tang , Hui Yang , Yalin Xue , Wenjuan Jia , Yang Wang , Yunjia Shi , Hai Huang , Guopeng Zhang

Face-centered cubic (FCC)-structured high entropy alloys (HEAs) with high plasticity and resistivity are promising candidates for the integration and miniaturization of electrothermal devices. Further improving their mechanical and electrical properties remains a key challenge. Here, partial substitution of Mn by Si is employed to modify the CoCrFeMnNi HEA (Cantor alloy), a representative FCC-structured HEA. A Co₂₀Cr₂₀Fe₂₀Ni₂₀Mn₁₀Si₁₀ (Si10) HEA with a high negative mixing enthalpy was fabricated by hot-pressing sintering of gas-atomized powder. The microstructure and the mechanical and electrical properties were investigated. The as-sintered Si10 alloy consisted of an equiaxed FCC major phase and a monoclinic minor phase. After solutionization at 1250 °C for 12 h, the minor phase dissolved, and the mechanical properties were significantly improved. The yield strength, ultimate strength, and elongation of the as-solutionized Si10 reached 289.6 MPa, 791.1 MPa, and 79.5 %, respectively. This strong strength–ductility combination was likely related to the extremely fine deformation-twin thickness, which produced a dynamic Hall–Petch effect and stable strain-hardening rate. Moreover, the as-solutionized Si10 alloy exhibited a high electrical resistivity of 153.0 μΩ cm and a low temperature coefficient of resistivity of 5.2 × 10⁻⁴ °C⁻¹, both significantly improved relative to the Cantor alloy. Si substitution enhanced the mechanical and electrical properties simultaneously, providing useful guidance for developing high-performance electrical resistance HEAs.

面心立方结构高熵合金（FCC）具有较高的塑性和电阻率，是电热器件集成化和小型化的理想材料。进一步提高其机械和电气性能仍然是一个关键的挑战。本文采用Si部分取代Mn来修饰CoCrFeMnNi HEA （Cantor合金），这是一种典型的fcc结构HEA。采用气体雾化粉末热压烧结法制备了具有高负混合焓的Co20Cr20Fe20Ni20Mn10Si10 (Si10) HEA。对其显微组织和力学性能进行了研究。烧结Si10合金由等轴FCC主相和单斜次相组成。1250℃固溶12 h后，小相溶解，力学性能显著提高。固溶态Si10的屈服强度、极限强度和延伸率分别达到289.6 MPa、791.1 MPa和79.5%。这种强大的强度-塑性组合可能与极细的变形孪晶厚度有关，从而产生了动态的Hall-Petch效应和稳定的应变硬化速率。固溶态Si10合金的电阻率为153.0 μΩ cm，低温电阻率系数为5.2 × 10−4°C−1，均较Cantor合金有显著提高。硅取代同时提高了材料的力学性能和电学性能，为开发高性能电阻HEAs提供了有益的指导。

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引用次数: 0

Mechanisms governing synergistic enhancement of strength-plasticity and α2 thermal stability in TiAl alloys fabricated via selective electron beam melting 选择性电子束熔化制备TiAl合金的强度塑性和α2热稳定性协同增强机制

IF 7 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A

Pub Date : 2025-12-02 DOI: 10.1016/j.msea.2025.149561

Qingchao Li , Shulong Xiao , Zhenquan Liang , Guo Jiang , Yifan Wang , Ye Tian , Xicheng Wang , Fuyang Cao , Yuyong Chen , Lijuan Xu

The incoordination of strength-plasticity and the low thermal stability of α₂ phases seriously restrict the development of TiAl alloys. To overcome these shortcomings, Ti-48Al-2Cr-2Nb (at.%) alloys with superior mechanical performance and high thermal stability of α₂ phases were prepared by reasonably optimizing the printing strategy of selective electron beam melting (SEBM) in this work. The alloys exhibit the room-temperature compressive strength of 2716.08 MPa with 58.71 % fracture strain, and maintain compressive strength of 749.43 MPa at 850 °C. The improvement of strength-toughness and enhanced α₂-phase thermal stability are mainly attributed to the influence of long-period stacking ordered (LPSO) structures introduced via SEBM. High temperature and stress will induce the generation of high density 9R-type LPSO structures, and 9R structures can promote the orientation transformation of γ phases. Abundant 9R structures and deformation twins play a key role in enhancing strength and toughness. Furthermore, this study reveals the transformation mechanism of 9R-type and 6H-type LPSO structures and first proposes three reaction pathways for the transformation from γ to α₂ phases, with 6H phases serving as the intermediate structures. The three reaction processes are γ→6H→α₂, γ→9R→6H→α₂ and γ→γ_T→6H→α₂, in which 9R and twin structures can transform into 6H configurations, promoting the transformation of γ to α₂ phases. Due to γ→α₂ transformation induced by LPSO structures, the conventional decomposition reaction of α₂ phase is effectively inhibited, thus improving the stability of α₂ phases.

α2相的强度塑性不协调和较低的热稳定性严重制约了TiAl合金的发展。为了克服这些缺点，本文通过合理优化选择性电子束熔化（SEBM）的打印策略，制备了具有优异力学性能和α2相热稳定性的Ti-48Al-2Cr-2Nb （at.%）合金。合金的室温抗压强度为2716.08 MPa，断裂应变为58.71%，850℃时抗压强度为749.43 MPa。强韧性的提高和α2相热稳定性的增强主要是由于通过SEBM引入长周期有序堆积（LPSO）结构的影响。高温和应力会诱导生成高密度的9R型LPSO结构，9R结构能促进γ相的取向转变。丰富的9R组织和变形孪晶是提高材料强度和韧性的关键。此外，本研究揭示了9r型和6H型LPSO结构的转化机理，并首次提出了以6H相为中间结构的γ向α2相转化的三种反应途径。三个反应过程分别为γ→6H→α2、γ→9R→6H→α2和γ→γ t→6H→α2，其中9R和孪晶结构转变为6H构型，促进γ向α2相转变。由于LPSO结构诱导γ→α2转变，有效抑制了α2相的常规分解反应，从而提高了α2相的稳定性。

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