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金属学报, 2023, 59(6): 727-743 DOI: 10.11900/0412.1961.2022.00598

综述

高熵合金的低温塑性变形机制及强韧化研究进展

刘俊鹏,1, 陈浩1, 张弛1, 杨志刚1, 张勇2,3, 戴兰宏4

1清华大学 材料学院 教育部先进材料重点实验室 北京 100084

2北京科技大学 新金属材料国家重点实验室 北京 100083

3北京材料基因工程高精尖创新中心 北京 100083

4中国科学院力学研究所 非线性力学国家重点实验室 北京 100190

Progress of Cryogenic Deformation and Strengthening-Toughening Mechanisms of High-Entropy Alloys

LIU Junpeng,1, CHEN Hao1, ZHANG Chi1, YANG Zhigang1, ZHANG Yong2,3, DAI Lanhong4

1Key Laboratory of Advanced Materials of Ministry of Education, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China

2State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China

3Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing 100083, China

4State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China

通讯作者: 刘俊鹏，liujunpeng@mail.tsinghua.edu.cn，主要从事高熵合金的基础研究

责任编辑: 毕淑娟

收稿日期: 2022-11-21   修回日期: 2023-03-20  

基金资助: 国家重点研发计划项目(2022YFE0110800)
国家重点研发计划项目(2021YFB3702300)
国家自然科学基金项目(52101169)
国家自然科学基金项目(52273280)

Corresponding authors: LIU Junpeng, Tel:(010)62781646, E-mail:liujunpeng@mail.tsinghua.edu.cn

Received: 2022-11-21   Revised: 2023-03-20  

Fund supported: National Key Research and Development Program of China(2022YFE0110800)
National Key Research and Development Program of China(2021YFB3702300)
National Natural Science Foundation of China(52101169)
National Natural Science Foundation of China(52273280)

作者简介 About authors

刘俊鹏，男，1988年生，博士

摘要

高熵合金是由多种主要元素组成的新型金属材料，固有的多主元和构型熵高等特点，使其具备诸多优异的力学及物理化学性能，从而引起了研究人员的广泛关注。在低温工程应用方面，高熵合金优异的强塑性、良好的韧性和抗冲击能力、较高的相稳定性等特点使其在深空探测、低温超导、气体工业等领域极具应用前景。本文综述了高熵合金的低温研究进展，详细总结了高熵合金在低温环境的变形机制及强韧化机理，并结合传统低温工程材料的性能对比，展望了高熵合金未来低温工程应用的主要方向。

关键词： 高熵合金; 低温性能; 变形机理; 强韧化策略

Abstract

Owing to the multi-principal element and higher intrinsic configurational entropy, high-entropy alloys exhibit excellent mechanical and physicochemical performance, which has garnered extensive attention from researchers. By virtue of the excellent performances in terms of superior strength, ductility, toughness, impact resistance property, and adjustable phase stability, especially in cryogenic environments, high-entropy alloys have broad application prospects in fields such as deep-space exploration, low temperature superconducting, and the gas industry. In this paper, the deformation and strengthening-toughening mechanisms of high-entropy alloys are summarized by reviewing the cryogenic progress. Furthermore, the promising research directions of high-entropy alloys in cryogenic engineering application combined with the performance of traditional cryogenic materials are also presented.

Keywords： high-entropy alloy; cryogenic property; deformation mechanism; strengthening-toughening strategy

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本文引用格式

刘俊鹏, 陈浩, 张弛, 杨志刚, 张勇, 戴兰宏. 高熵合金的低温塑性变形机制及强韧化研究进展[J]. 金属学报, 2023, 59(6): 727-743 DOI:10.11900/0412.1961.2022.00598

LIU Junpeng, CHEN Hao, ZHANG Chi, YANG Zhigang, ZHANG Yong, DAI Lanhong. Progress of Cryogenic Deformation and Strengthening-Toughening Mechanisms of High-Entropy Alloys[J]. Acta Metallurgica Sinica, 2023, 59(6): 727-743 DOI:10.11900/0412.1961.2022.00598

高熵合金自被发现以来，由于其多主元合金的独特设计理念、新奇的结构和优异的性能，引起了研究人员的广泛关注[1~3]。关于高熵合金的研究进展和工程应用，已有较多报道，本文重点总结了近年来高熵合金的低温研究进展。早期对高熵合金变形机理的研究[4~6]发现，其在低温环境下位错运动受阻，而较低的层错能使高熵合金呈现出孪晶变形的特点，位错运动和孪晶机制的协同作用使高熵合金展现出“越低温、越强韧”的特征。然而与传统低温结构材料(如奥氏体不锈钢、镍基合金、钛合金等)相比，单相高熵合金的低温强度并不具备显著优势。为了拓展高熵合金的低温应用领域，推进其工程化应用，首要目标是进一步改善高熵合金的低温性能。为此，过去10余年研究人员[4,7~13]开展了广泛的强韧化研究，并取得了显著进展，同时也加深了人们对高熵合金基础结构和低温塑性变形的认识。此外，由于析出强化、相变增韧等传统材料的强韧化方法和多机制耦合等理念被成功应用于强化高熵合金，实现了低温性能的大幅度提升，从而使高熵合金展现出广阔的低温工程应用前景。本文简要综述了近年来高熵合金低温性能的实验进展，归纳了高熵合金在低温环境的变形机理和强韧化策略，同时对尚未解决的重要问题进行了梳理和展望。

1 高熵合金的提出和结构特征

1.1 高熵合金的提出

高熵合金最早是在2004年由Cantor等[1]和Yeh等[2]提出的新型金属材料，主要由多种元素以等原子比或近似等原子比构成的固溶体合金。与以往传统金属材料由1种或2种主要元素构成不同，多种主要元素的添加易使组织中产生金属间化合物，从而恶化材料性能。因此，以往关于金属材料的研究主要集中于边际固溶体，而极少涉及相图的中心区域。而多主元单相固溶体的发现，打破了人们对金属材料相形成规律的传统认识，极大拓宽了金属材料的成分设计范围。

多主元的合金设计理念一经提出便引起研究人员的广泛关注，近年来的研究[14~24]发现，高熵合金具有高强度、高塑性、高韧性、良好的耐磨和疲劳性能，以及优异的低温、耐蚀、抗辐照、抗氢脆能力和出色的催化效果。这些优于传统材料的力学及物理化学性能，加深了人们对高熵合金的认识，也拓展了其工程化应用前景。

1.2 高熵合金的化学无序结构

高熵合金由多种主要元素组成，导致混合熵较高。依照Gibbs自由能公式[3] (ΔGmix = ΔHmix - TΔSmix，其中，ΔGmix为合金体系的Gibbs自由能；ΔHmix为混合焓；ΔSmix为混合熵；T为体系的热力学温度)可知，高的混合熵降低了体系的自由能，从而有利于保持固溶体结构而抑制金属间化合物的形成，因此高温环境高熵合金通常具有稳定的固溶体结构，而在成分上呈现出化学无序的特点[3]，典型结构如图1[3]所示。另外，Luan等[25]研究发现，随着元素数量的增加，合金体系中可能生成的金属间化合物数量会有所增加，而低温环境混合焓的影响随之提高，金属间化合物的形成会导致体系的自由能下降，因此多数高熵合金更倾向于形成多相组织。多种因素的共同作用使高熵合金的相形成规律极为复杂，同时也为调控其微结构特征提供了广阔空间。

图1

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图1   具有严重晶格畸变特征的高熵合金化学无序原子结构示意图[3]

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Fig.1   Schematic of crystal structure in high-entropy alloy (HEA) with severe distortion[3]


与传统金属材料相比，这种多组元新奇结构使高熵合金具有较大的晶格畸变[26~31]、迟滞扩散[32,33]等特点，也因此对材料的变形机制产生了显著影响，并为其强韧化设计提供了广阔空间。

近年来的一些研究结果证明，具有非等原子比的合金也能保持稳定的固溶体结构[34]，并且某一成分的波动可以对性能产生显著影响[14,35]。这种性能的“鸡尾酒效应”[36]不仅使高熵合金可以在较宽的成分范围保持相结构稳定，也拓宽了其在复杂严苛环境的工程应用潜力。因此高熵合金被认为有潜力突破传统材料的性能极限，成为国内外金属材料领域的研究热点。

除此之外，研究[37]发现高熵合金的结构具有元素偏聚的特点，如TiZrNbHf合金中的有序氧复合体等合金中的有序相，这种纳米尺度的有序结构打破了人们对高熵合金化学无序的传统认识，也革新了固体材料的变形机理，为强韧化合金提供了新的广阔空间，具有重要的科学价值。

2 高熵合金的低温塑性流动

2.1 高熵合金低温环境的塑性流动特点

金属材料在外力作用下，会呈现出塑性流动的特点，其塑性流动规律与材料内部的微观变形机制密切相关。室温环境下大多数金属材料都依赖微观的位错运动来实现宏观的塑性流动，从而使材料呈现出特定的力学性能。然而随着温度降低，位错运动的激活能随之提高，从而使位错滑移变得困难，因此大多数金属材料在低温环境都会出现脆化的趋势，从而严重影响服役稳定性和可靠性。

由于成分的复杂和变形机制的多样性，高熵合金的低温塑性流动比传统材料更为复杂。近年来，针对多种变形机制的深入科学认识和有效调控，兼具高强度、大塑性和良好的加工硬化能力等特点的低温高强韧高熵合金得以成功研发，这不仅推进了高熵合金的基础研究和工程应用进展，同时也加深了人们对高熵合金塑性流动特点的认识。然而多机制耦合作用给准确解析高熵合金的低温塑性流动规律带来了诸多挑战。以高熵合金在超低温环境变形时的锯齿流变行为为例，本文作者[10,38]研究了CoCrFeNi高熵合金在超低温环境的塑性变形特点，发现在20 K及以下的超低温环境变形时，高熵合金呈现出锯齿流变的特点。高分辨透射电镜(HRTEM)结果证实，变形后的组织中存在大量的纳米孪晶(包括交叉孪晶和协同孪晶)和少量的fcc-hcp相转变行为，孪晶主导的变形机制和相变行为的共同作用导致了高熵合金在超低温环境优异的综合性能。Pu等[39]在研究CoCrFeNiMn高熵合金的超低温力学行为时发现，极低温环境变形会导致组织中产生大量的压杆位错(Lomer-Cottrell位错，即L-C锁)，而低温高应力激励下的位错惯性运动与L-C锁强烈的交互作用使高熵合金在4.2 K的超低温度下涌现出非热主控的锯齿不稳定流动现象。Naeem等[12]利用原位中子衍射技术观察了高熵合金在极低温环境变形时的结构演变情况。研究发现，CoCrFeNi合金在极低温变形时的位错密度可高达9.2 × 1015 m-2，他们认为虽然在极低温环境位错运动仍为主要的硬化机制，但在25 K时明显增多的孪晶变形可能是锯齿流变的重要诱因。而后续研究[40]表明，具有较高层错能的CoNiV合金在超低温变形时的锯齿流变则主要由位错运动引起。

针对高熵合金超低温变形过程中的锯齿流变行为，受制于中子衍射技术时空分辨率有限的现状，目前还无法准确解析具体的锯齿流变过程。而现已证实的多种机制无疑都可能对其塑性流动产生影响，如何科学认识低温锯齿流变行为和准确揭示对应的微观变形机理，仍然是当前制约人们对高熵合金的科学认识走向深入的难题。

2.2 典型高熵合金的低温力学性能

近年来的研究证明，高熵合金在低温环境具有优异的强塑性[4,11,15,41,42]、韧性[7,13]和良好的室温耐蚀[18,20,21]及抗辐照[19,43,44]等优势，从而成为低温工程关键部件的新型候选材料。关于高熵合金低温性能的研究，Qiao等[15]于2011年率先研究了具有单相bcc结构AlCoCrFeNi高熵合金的低温性能，发现该合金在低温环境下具有极高的压缩性能(屈服强度达1.88 GPa)和锯齿流变的特点，展示了高熵合金作为新型高强韧低温工程材料的应用前景。

与单相bcc结构高熵合金相比，单相fcc结构高熵合金因易于制备成形、综合性能优异等特点，其低温研究发展较为成熟。2013年，Gali和George[45]研究了CoCrFeNiMn (后被称为Cantor合金)和CoCrFeNi高熵合金在不同温度的拉伸性能。研究发现，随着温度的降低，该合金的强度和塑性同时得到了大幅度改善。在77 K时，CoCrFeNi高熵合金的拉伸强度超过1 GPa，且延伸率超过60%。随后，Otto等[4]在此基础上深入研究了晶粒尺寸对高熵合金低温力学性能的影响及其变形机理。研究发现，fcc高熵合金在低温变形后期会出现纳米孪晶，而孪生机制产生的大量低能界面导致晶粒显著细化。另外这些低能界面可有效阻碍位错运动，提高高熵合金在低温环境的加工硬化率，进而推迟了颈缩行为的发生。在位错滑移和孪晶机制的共同作用下，Cantor合金在77 K时的强度和塑性都得到了明显提高。此外，2014年，Gludovatz等[16]详细评估了单相fcc高熵合金的室温及低温断裂韧性，发现该合金具有优异的低温韧性，其裂纹萌生初期的断裂韧性超过200 MPa·m1/2，并且在77 K裂纹扩展阶段的断裂韧性超过300 MPa·m1/2，如此优异的综合性能可以与低温性能最好的奥氏体不锈钢和高镍钢相媲美。

3 高熵合金的低温强韧化

针对单相fcc结构高熵合金屈服强度较低的特点，研究人员[46~49]开展了广泛的强韧化研究，近年来取得了长足发展。强韧化的方法主要依赖于缺陷策略，即通过在组织中引入点、线、面、体缺陷的方式来提升高熵合金的性能。点缺陷，即添加C、N等间隙原子或Al等置换原子；线缺陷，即增加位错密度；面缺陷，即调控层错、孪晶等形成低能界面；体缺陷，即引入第二相或相变诱导塑性等机制。经过近20年的发展，传统材料的这些强韧化方法在高熵合金中得到了广泛应用，显著提高了高熵合金的低温性能。具体的变形机理和强韧化策略总结如下。

3.1 固溶强化

固溶强化是经典的强化方法，研究人员通过将间隙或置换原子加入高熵合金，可以增大晶格畸变，提高位错滑移抗力，从而提高材料强度。Tian等[50]通过在Cantor合金中加入1% (原子分数，下同)的C，得到了具有亚微米尺寸的超细完全再结晶组织。依赖于C的强化、细晶强化和低温变形过程中的位错和孪晶机制的共同作用，该合金在77 K的屈服强度可达1 GPa，断裂强度可达1.46 GPa，同时还保持42.6%的延伸率。

Shim等[51]通过电弧熔炼氮化铬铁(Cr60Fe35N5)的方式在CoCrFeNiMn合金中引入2.1%的间隙N元素，研究发现引入N元素可抑制σ相的析出，促进Cr2N析出相的产生。析出相的存在明显抑制了晶粒长大而使含N高熵合金的晶粒尺寸更小；细晶组织和析出相的作用可明显改善高熵合金的屈服强度，且Cr2N析出相的强化效果更好。另外N的加入在组织中可产生短程缺陷来阻碍位错滑移，低温环境的纳米孪晶和二次孪晶界显著细化了晶粒，并降低了位错的平均自由程，从而阻碍了位错运动，提高了该合金的加工硬化能力。低温环境下，在位错的平面滑移、层错和变形孪晶的共同作用下，含N高熵合金的低温屈服强度可高达1 GPa，断裂强度超过1.6 GPa，同时还保持70%的延伸率。然而，间隙原子强化后的高熵合金普遍出现了塑性的明显下降，且随着间隙原子含量的增加，易发生碳化物的析出和间隙原子在晶界或其他缺陷处的偏聚[52]，从而导致材料过早断裂，而低温环境会加剧这种脆化。因此，适当的间隙原子含量对高熵合金低温性能的改善至关重要。

除此之外，研究人员还详细研究了置换原子对高熵合金的低温性能影响。2016年，Li等[53]通过磁悬浮熔炼设备制备了2种不同Al含量的高熵合金，分别是Al0.1CoCrFeNi和Al0.3CoCrFeNi高熵合金。研究发现，随着Al元素含量的增加，高熵合金的低温屈服强度可由410 MPa提高至510 MPa。另外他们发现该合金具有优异的低温冲击韧性，在77 K的Charpy冲击功可高达328 J。

3.2 形变强化

早期关于高熵合金的形变强化主要通过冷轧工艺实现。2012年，Zhang和Peng[54]详细研究了冷轧工艺对CoCrFeNiCu高熵合金力学性能的影响，发现冷轧工艺(50%的压下量)可将铸态高熵合金的屈服强度由350 MPa提高至900 MPa，展现了冷轧工艺显著的强化效果。2015年，Stepanov等[55]探索了低温轧制工艺对Cantor合金力学性能的影响，研究发现，在低温轧制过程中，Cantor合金会发生位错密度的急剧增加和大量的变形孪晶，且孪晶片层间距会逐渐变薄；在低温轧制后期，会发生孪晶片层的旋转和剪切带的萌生和扩展，而没有观察到新晶粒和亚晶的出现。受益于低温轧制后组织中的极高密度位错和极细孪晶片层，低温轧制后Cantor合金的拉伸强度可达1500 MPa。

随后，本文作者[9]深入研究了轧制工艺对fcc高熵合金低温性能的影响，研究发现，轧制工艺可以显著提高高熵合金的强度，其中低温轧制后的Cantor合金在77 K时的拉伸强度可达2 GPa，且断裂应变超过7%，如图2[9]所示，如此优异的低温性能突破了传统低温材料的性能极限。进一步研究发现，当温度降低至4.2 K时，低温轧制后的高熵合金强度可达2.25 GPa。但由于样品初始状态的位错密度极高，而超低温环境又极大限制了位错的滑移，导致孪晶变形也被明显抑制，从而使该合金在超低温环境下的断裂应变下降至6%。极低温环境下2 GPa超高强度高熵合金的开发，加深了人们对高熵合金低温极限性能的认识，展现了高熵合金在低温环境潜在的工程应用前景。

图2

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图2   低温轧制后CoCrFeNiMn高熵合金的室温及低温拉伸性能[9]

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Fig.2   Tensile properties of CoCrFeNiMn HEA at room temperature and cryogenic condition after cryogenic rolling process[9] (σb—ultimate tensile strength)


高压扭转工艺(high-pressure torsion，HPT)也是利用形变强化机制显著提高材料强度或硬度的有效方式。Tang等[56]和Yu等[57]研究了高压扭转工艺对单相高熵合金组织与性能的影响，发现高压扭转工艺可以显著细化Al0.1CoCrFeNi高熵合金的组织，且在室温环境能够激发大量的纳米孪晶和二次孪晶。由于高压扭转工艺导致的位错机制和变形孪晶强化，高熵合金的硬度可由150 HV提高至482 HV。随后Moon等[58]研究发现，低温扭转工艺可以使Co20Cr26Fe20Mn20Ni14高熵合金发生无扩散型的fcc-hcp相转变行为。虽然形变强化及高压扭转工艺显著提高了高熵合金的屈服强度，但这种方法会导致塑性的显著下降，如高压扭转后的强度可达2 GPa，但延伸率降低至5%[47]，并且高压扭转工艺无法制备厚板和样品组织不均匀等缺点制约了HPT高熵合金在低温结构材料领域的广泛应用。

为了改善高压扭转工艺导致的塑性损失，后续的热处理工艺优化被用于改善高强度材料的均匀延伸率。Sathiyamoorthi等[59]研究发现，将高压扭转后的CoCrNi中熵合金样品在600℃退火1 h，即可获得超细晶组织(平均晶粒尺寸为650 nm)，且组织中有大量的纳米孪晶；此外透射电镜(TEM)观察证实初始组织中还有部分亚晶和少量位错。超细晶组织和退火孪晶、适量的位错密度以及高的晶格摩擦力，使该合金具有极高的低温屈服强度；另外，该合金在低温变形时会产生更高密度的变形孪晶/层错和高密度位错。在多种变形机制的共同作用下，高压扭转后的CoCrNi中熵合金在77 K时的屈服强度可高达1.97 GPa，且延伸率达到27%。

3.3 孪晶强化

Deng等[60]于2015年将孪晶诱导塑性(twinning induced plasticity，TWIP)理念引入高熵合金，制备了具有室温变形孪晶的Fe40Mn40Co10Cr10亚稳高熵合金，该合金在室温变形时会产生大量孪晶，导致了优异的塑性和加工硬化能力。Fe40Mn40Co10Cr10高熵合金的开发拓展了fcc高熵合金室温变形机制的可操控范围，给高熵合金的韧化提供了更多空间。但由于该合金的强度低于500 MPa，限制了其工业应用。

2017年，Jo等[61]通过冷轧和不完全退火工艺在VCoCrFeNiMn高熵合金中实现了孪晶组织的室温存在，研究发现该合金在冷轧后组织中会产生变形孪晶，且变形孪晶在后续的短时不完全再结晶退火过程中可以保留下来。最终形成的组织由完全再结晶的细晶区(平均晶粒尺寸为1.5 μm)和未完全再结晶的粗晶区(平均晶粒尺寸为32 μm)构成，且粗晶晶粒中存在大量的变形孪晶。室温未再结晶组织的存在极大改善了高熵合金的屈服强度，而受益于变形时的高应力状态，细晶区和粗晶区在后续的低温拉伸过程中，能产生新的纳米孪晶和二次孪晶，从而使该合金具有优异的综合力学性能。在77 K的低温环境，该合金的屈服强度将近1 GPa，断裂强度达1.3 GPa，延伸率为46%。

3.4 相变强韧化

2016年，Li等[62]将传统高锰钢变形过程中的相变行为引入高熵合金，制备出了具有非等原子比的Fe50Mn30Co10Cr10高熵合金，该合金在室温塑性变形过程中会发生fcc→hcp相变行为，从而大幅度改善了高熵合金的强度和塑性，其室温断裂强度可达900 MPa，且延伸率超过70%。该合金的成功研发，使人们普遍关注到高熵合金的相变行为。

随后，Li等[63]在此基础上深入研究了Fe50Mn30Co10-Cr10高熵合金的低温性能。发现当温度降低时，该合金的力学性得到持续强化，且随着晶粒尺寸由200 μm细化至4 μm，fcc相的稳定性也得到了提高，初始组织由“fcc + hcp”双相结构转变为单相的fcc结构；而在77 K低温变形时，近80% (体积分数)的fcc相会转变成hcp新相。依赖于低温环境相变行为的大量进行，亚稳双相高熵合金的低温强度超过1300 MPa，同时延伸率超过50%。

相较于fcc高熵合金，具有单相bcc结构难熔高熵合金的低温性能鲜有报道。主要原因是难熔高熵合金熔点较高且在室温环境通常较脆，难以加工和制备。2020年，Wang等[41]制备了具有优异低温性能的TiZrHfNbTa等原子比难熔高熵合金，该合金具有单相的bcc结构。研究发现，与以往难熔高熵合金的变形单纯依赖位错滑移机制不同，该合金在低温变形时会发生纳米孪生和bcc→ω的相转变行为。受益于多种变形机制的共同作用，即便温度降低至77 K，该难熔合金也没有发生脆化，强塑性反而得到了明显改善，其低温屈服强度达到1.5 GPa，且延伸率超过20%。进一步研究发现，在低温环境变形时的螺位错滑移、机械孪晶和bcc→ω相变行为的协同作用导致了TiZrHfNbTa难熔高熵合金优异的综合性能。

3.5 析出强化

高熵合金属于强固溶体合金，元素种类较多且含量较高，因此将传统的析出强化应用于高熵合金来提高强度会面临很大挑战。2016年，He等[64]通过在CoCrFeNi合金中加入适量的Al、Ti元素，成功在单相的fcc基体中制备出弥散分布的Ni3(Al/Ti)型有序析出相，极大改善了高熵合金的强度。在经过适当的热处理工艺后，(FeCoNiCr)94Ti2Al4高熵合金的室温强度可由固溶态的500 MPa提升至时效态的1300 MPa。

随后，Yang等[65]通过成分优化，制备了具有高体积分数的(FeCoNi)86Al7Ti7 (以下简称Al7Ti7合金)析出强化型高熵合金。研究发现，多组元共格L12有序析出相的大量存在，显著提高了该合金的屈服强度和加工硬化能力，其室温强塑积达到72 GPa·%。后续研究[11]发现Ni30Co30Fe13Cr15Al6Ti6高熵合金(以下简称Al6Ti6合金)在低温环境的力学性能更为优异，其断裂强度可达1.7 GPa，且保持51%的延伸率。但与单相高熵合金在低温环境发生大量纳米孪晶不同，Al6Ti6合金虽然在低温环境也会发生孪生，但其孪晶变形明显被抑制。这主要是因为L12型高熵有序析出相的层错能较高，可达200~250 mJ/m2，与fcc基体的低层错能特征差异明显。TEM的结果也证实，该合金低温环境主要依靠高密度的层错(图3a[11])进行变形，并且大量层错的相互作用使组织中出现了纳米尺度的菱形层错网，如图3b[11]所示。这种菱形结构不仅显著细化了晶粒，而且大幅度降低了位错运动的平均自由程，从而阻碍位错运动，提高了材料的加工硬化能力。与此同时，由于晶体内部大量分位错的形成，(111)面上扩展位错极易演变为压杆位错，这种固定位错可作为很强的障碍物将(111)面上的其他位错牢牢锁住，因此也被称为面交位错，如图4[66]所示。低温环境下，L-C锁的大量存在有效提高了材料在高应力状态的持续硬化和变形能力。

图3

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图3   Ni30Co30Fe13Cr15Al6Ti6高熵合金低温变形后的位错组态[11]

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(a) TEM image of the dislocation structure of the deformed alloy at 77 K

(b) nano-spaced stacking fault (SF) network in the deformed alloy

Fig.3   Dislocation configurations of Ni30Co30Fe13Cr15Al6Ti6 HEA after cryogenic deformation[11]


图4

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图4   高熵合金中由位错反应生成的Lomer-Cottrell (L-C)锁[66]

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Fig.4   Typical Lomer-Cottrell (L-C) lock in HEA during dislocation motion[66]


与此同时，Tong等[67]研究发现，CoCrFeNiTi0.2高熵合金(Ti0.2高熵合金)中由于晶界附近的非均匀性形核和晶内的均匀形核，组织中会出现2种不同形貌的析出相，即晶界附近的片层状析出相和晶内的球形析出相。深入研究发现2种析出相的成分一致，均富集Ni和Ti元素，且片层状析出相呈连续的纳米层状分布，但片层状析出相具有化学无序的长周期堆垛有序结构，而球形析出相为有序的L12型结构。与Al6Ti6高熵合金类似，球形的L12析出相由于层错能较高，抑制了孪晶变形的发生，使得变形主要依赖于层错进行。然而化学无序的片层状析出相在低温加载过程中会发生明显变形，且变形区域中发现了微孪晶的存在。这证明球形析出相的化学有序结构会显著提高孪晶的形核势垒，抑制孪晶变形的发生。得益于析出相对位错运动的有效阻碍，Ti0.2高熵合金的强塑性均较单相的CoCrFeNi高熵合金有大幅度提升，77 K时的屈服强度和断裂强度分别高达860 MPa和1.58 GPa，同时还保持46%的延伸率。

随后Liu等[68]详细研究了Al3.6Co27.3Cr18.2Fe18.2Ni27.3Ti5.4高熵合金低温变形过程中L12析出相的演化规律。研究发现，该合金中的L12析出相在低温变形时与基体的共格界面会被破坏，并发生溶解现象，即L12有序相的无序化转变。由于L12无序化转变降低了析出相的层错能，从而降低了孪晶形核的能垒，因此在变形后期L12析出相可以发生孪晶变形，如图5[68]所示，从而提高了该合金的低温塑性。析出相变形过程中的多组态层错和孪晶机制进一步提高了该合金在低温环境的强度和塑性，使析出强化型高熵合金的性能得到了进一步提升。

图5

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图5   Al3.6Co27.3Cr18.2Fe18.2Ni27.3Ti5.4高熵合金中L12析出相低温变形后的孪晶特征[68]

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(a) HRTEM image (b) enlarged image of the yellow rectangle in Fig.5a (c) SAED pattern of the twinning feature

Fig.5   Nano-twins in L12 precipitate in Al3.6Co27.3Cr18.2Fe18.2Ni27.3Ti5.4 HEA after deformation at 77 K[68]


3.6 多机制耦合强韧化

随着传统材料的强韧化方法在高熵合金中的应用，结合位错、层错、孪晶和相变等多种耦合机制的强韧化方案也被研究人员广泛关注，成为推动高熵合金低温研究发展的重要方向[12,69~85]。以亚稳双相高熵合金为例，前期研究[62,63]虽然证实该合金具有优异的低温综合性能，但由于屈服强度普遍低于1 GPa，限制了该合金作为高强度结构材料的应用领域。因此，结合固溶强化和相变机制的强韧化方法成为提升亚稳双相型高熵合金屈服强度的有效手段[86~91]。

Wang等[92]研究了间隙C原子对亚稳双相高熵合金低温性能的影响，发现Fe49.5Mn30Co10Cr10C0.5高熵合金室温组织为单相的fcc结构，且C的加入提高了fcc基体的相稳定性。但低温变形后，会有近70% (体积分数)的fcc相转变成hcp相，如此大比例的相变行为以及低应变时的位错运动和层错的共同作用，极大改善了该合金的低温性能，使得77 K时该合金的强度为1.3 GPa，且延伸率达到50%。

Seol等[93]详细研究了B元素对Fe40Mn40Co10Cr10亚稳双相高熵合金低温性能的影响，研究发现，B元素不仅在晶界处富集，提高了界面结合强度，并且低温变形时晶内固溶的B还有利于形成短程有序结构(SRO)，如图6[93]所示。这种低温变形导致的SRO会使晶内产生严重的晶格畸变，从而可以提高低温屈服强度。经B掺杂的FeMnCoCr高熵合金的低温拉伸屈服强度可达1.1 GPa，并兼具优异的加工硬化能力，断裂强度可达1.4 GPa。这些结果展现了B强化高熵合金低温性能的巨大潜力。

图6

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图6   B掺杂Fe40Mn40Co10Cr10高熵合金低温变形组织中的短程有序结构[93]

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(a) TEM image

(b) SAED pattern of the SRO feature (The SRO-generated reflections are seen only under [112] zone axis marked by yellow arrows)

Fig.6   Structure of short-range-order (SRO) in B-doped Fe40Mn40Co10Cr10 HEA after cryogenic deformation[93]


除此之外，He等[94]利用MnN冶炼的方法将N元素引入FeMnCoCr高熵合金，研究发现经过1%N添加后，该合金的屈服强度、断裂强度和延伸率可分别高达1.08 GPa、1.63 GPa和33.5%。N的加入不仅提高了奥氏体的稳定性，使相变行为发生在更小范围内，从而导致新相的尺寸更小，且以片层状的形貌为主。较高的位错滑移抗力和孪晶及相变行为的共同作用使含N高熵合金的强度得到了大幅度提高。由于合金的氮化在工业生产中容易实现且成本低廉，因此氮强化策略有望广泛应用于不同结构高熵合金的强韧化设计中。

此外，以往研究[10,49,86]证明，结合孪晶变形和相变增韧特征的复合强韧化机理是提高高熵合金低温性能的有效方法。2019年，本文作者[10]研究发现，CoCrFeNi高熵合金在极低温环境(4.2 K)会发生大量的孪晶变形，TWIP机制显著提高了高熵合金在极低温环境的加工硬化能力，推迟了颈缩行为的产生，从而明显改善了低温塑性。另外，在极低温环境准静态加载过程中，高熵合金组织中还会发生明显的fcc-hcp相变诱发塑性(transformation induced plasticity，TRIP)行为，如图7[10]所示。源于“TWIP + TRIP”复合强韧化机制，高熵合金在极低温环境(4.2 K)的断裂强度可达1.26 GPa，同时保持高达61%的延伸率，其综合性能优于传统的低温工程材料，如图8[10]所示。

图7

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图7   CoCrFeNi高熵合金极低温变形时的孪晶及相变特征[10]

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(a) TEM image and SAED pattern (inset), showing the twins and fcc-hcp phase transition occur in the sample

(b) HRTEM image (T—twins)

(c) atomic image of the enlarged red rectangle in Fig.7b, witness the hcp SF appears in the sample

Fig.7   Feature of twins and phase transition in CoCrFeNi HEA after deformation at 4.2 K[10]


图8

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图8   高熵合金和其他低温金属材料的超低温性能对比[10]

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Fig.8   Ashby map of tensile properties at 4.2 K among HEA with other cryogenic metallic materials[10]


由于fcc高熵合金在低温环境复杂的变形机制和微结构可调控的特点，关于高熵合金低温强韧化原理的探索也逐步涉及传统钢铁材料的相变行为[63]。

2018年，Bae等[95]将传统钢铁材料的马氏体相变行为引入高熵合金，研发了具有优异低温性能的低成本Fe60Co15Ni15Cr10中熵合金。在低温环境变形时，该合金内部的多步硬化机制被激活，如图9[95]所示，使得其低温强度可达1.5 GPa，同时延伸率达到87%。深入研究发现，该合金的初始状态为fcc结构，随着低温变形的进行，无扩散型fcc-bcc的相转变行为大量发生，且最终转变量超过90%。与此同时，大量变形导致的剪切带、层错和分位错滑移产生的hcp片层等多种机制的共同作用，导致该合金的加工硬化能力明显提高。原位中子衍射的结果也证实，马氏体相变和fcc与bcc相间的应力配分导致了强度的显著提升。由于Fe含量的提高，Co和Ni等贵重元素的含量大大减少，显著降低了该合金的成本。

图9

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图9   铁基中熵合金的低温硬化机制示意图[95]

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Fig.9   Schematic diagram of cryogenic work-hardening mechanisms in Fe-based medium-entropy alloy (GB—grain boundary, SB—shear band)[95]


Jo等[96]提出利用硬而脆的σ相来强化高熵合金，他们设计了具有双相组织的Ni45Fe20Cr15V20高熵合金，该合金的冷轧态样品在900℃时效10 min后，会在晶界处析出大量直径为110 nm的析出相。这些纳米析出相为富V-Cr的四方结构σ相，研究结果证实晶界处大量的纳米析出相对提高高熵合金的强度和加工硬化能力都是有益的。另外，由于σ相对晶界的钉扎，该合金的晶粒得到了进一步细化。与传统等原子比高熵合金添加脆性σ相会导致塑性恶化不同，控制适当比例的σ相不仅可以显著提高合金强度，且不会明显降低塑性。该合金在900℃退火后σ相的体积分数为4%，其低温强度可达1.37 GPa，同时延伸率超过40%，且断裂韧性达到244 MPa·m1/2。以上结果证明，脆性的σ相可以作为高强韧高熵合金的有效强化手段，且该方案工艺简单，易于工业化生产。

此外，传统钢铁材料中广泛应用的碳化物强化机制也被引入高熵合金[88,91]。2020年，Kwon等[91]设计制备了具有优异低温性能的Fe55Co17.5Cr12.5Ni10Mo3C2高熵合金，该合金的室温组织由fcc基体和大量弥散分布的M6C和M23C6型析出相组成，如图10a[91]。除了Mo和C的加入导致的固溶强化，依赖于晶内和晶界处碳化物的析出强化效应，该合金的低温屈服强度可达1 GPa；另外，低温环境下被大量激发的TRIP效应(图10c[91])进一步提升了该合金变形时的加工硬化能力，最终将高熵合金的低温强度提升至2 GPa超高强度水平，同时还保持53%的优异延伸率，如图10b[91]所示。

图10

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图10   Fe55Co17.5Cr12.5Ni10Mo3C2高熵合金的微观形貌、力学性能及低温组织演变特征[91]

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(a) TEM image and SAED patterns of the M6C (inset A) and M23C6 (inset B) precipitates in the original sample

(b) tensile properties at room and cryogenic temperatures

(c) EBSD images of HEA alloy during the tensile test at 77 K (εT—true strain)

Fig.10   Morphology, mechanical properties, and microstructure evolutions of Fe55Co17.5Cr12.5Ni10Mo3C2 HEA[91]


另外，结合析出强化和相转变行为的耦合强韧化机制也被应用于提升高熵合金的性能。2020年，Du等[97]通过Calphad相图计算设计了具有析出强化和相变行为的Co35Cr32Ni27Al3Ti3高熵合金，经过锻造和完全再结晶退火后，该合金的初始组织由fcc基体、少量hcp相和弥散分布的L12析出相构成。由于多相组织的强化和变形时明显的fcc-hcp相转变行为，该合金在低温环境具有优异的力学性能和加工硬化能力，其屈服强度可达1.3 GPa，断裂强度达1.8 GPa，同时保持53%的延伸率。

随着研究的深入，面向工业应用的共晶高熵合金和高强韧高熵合金丝材也被成功研发[8,98]。2014年，Lu等[98]最早提出了共晶高熵合金的概念。研究发现AlCoCrFeNi2.1高熵合金冷却过程会发生共晶反应(液相L→fcc + B2)，生成由B2相和fcc相组成的共晶组织，如图11[98]所示，该组织中富Al的B2相与fcc基体呈片层状分布。后续研究[99]发现，依赖于极细的片层状组织，该共晶合金呈现出优异的低温性能。铸态样品在77 K的屈服强度可达700 MPa，断裂强度超过1 GPa，延伸率达到9%，胜过目前所有铸态合金的性能。另外，Li等[100]深入研究了Al19Co20Fe20Ni41共晶高熵合金的低温变形机制。该共晶组织由L12相和富Al的bcc相组成，且两相界面满足Kurdjumov-Sachs (K-S)位向关系。研究发现，低温变形时该共晶组织中的fcc相会发生位错的多系滑移，并且毗邻bcc相也会发生相应的协同变形，如图12[100]所示。大量的几何必需位错在两相界面处的累积赋予了该合金极强的非均匀变形硬化能力。另外，随着变形的持续，由于低温环境突出的林位错硬化效应和非均匀变形硬化的协同作用，该合金的低温性能较AlCoCrFeNi2.1高熵合金有明显提升，其低温强度可达1.2 GPa，且均匀延伸率超过11%。

图11

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图11   AlCoCrFeNi2.1高熵合金的共晶组织[98]

Fig.11   Eutectic structure of AlCoCrFeNi2.1 HEA[98]


图12

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图12   Al19Co20Fe20Ni41共晶高熵合金两相组织的低温变形特点[100]

Fig.12   Deformation feature of dual-phases in Al19Co20-Fe20Ni41 eutectic high-entropy alloy (EHEA) at cryogenic environment[100]

(a, b) structure features of L12 and B2 phase after tensile test (strain ε ≈ 12%) at 77 K, which forest-dislocation hardening occurs in the L12 phase (c) structure feature of L12 and B2 phase after tensile test (ε ≈ 16%) at 293 K (Inset shows cooperative deformation of the adjacent B2 phase)


2017年，Li等[8]通过悬锻拉拔的方法制备了具有优异力学性能的Al0.3CoCrFeNi高熵合金丝材，其室温组织由单相的fcc和少量B2相组成。受益于拉拔时的剧烈塑性变形，该丝材的晶粒尺寸被细化至2 μm以下，极高的初始位错密度和超细晶组织使高熵合金丝材的屈服强度超过1.2 GPa，并且随着温度降低，孪晶机制被激活。低温环境纳米孪晶机制的加入进一步提高了高熵合金丝材的加工硬化能力，使该合金的强塑性得到明显改善。77 K时该丝材的屈服强度可达1.3 GPa，断裂强度高达1.6 GPa，同时保持17.5%的延伸率。之后Huo等[101]通过冷拔工艺制备了具有优异低温性能的CoCrFeNi高熵合金丝材，研究发现，该丝材在低温环境会发生二次孪晶变形，相关结果证实，结合孪晶机制和高密度位错能够有效提升高熵合金丝材在低温环境的加工硬化能力和强度。然而，随着强度的提升，高熵合金丝材的加工硬化能力较铸态明显降低，冷拔CoCrFeNi高熵合金丝材甚至在室温环境已表现出加工软化现象。为进一步提升高强度高熵合金丝材的加工硬化能力，耦合多种变形机制的复合强韧化研究成为解决该问题的有效手段。2020年，本文作者[49]通过热拉拔工艺制备了CoCrNi合金丝材，研究发现，除了低温变形时的孪晶机制，该丝材在变形过程中会产生大量层错。高密度的层错和孪晶片层显著细化了晶粒，使该丝材具有优异的加工硬化能力。另外，在低温变形后的组织中还观察到了明显的fcc-hcp相变行为，且组织中极细的hcp片层不仅显著细化了组织，还可以有效阻碍位错运动，从而进一步提高丝材的加工硬化能力，推迟颈缩行为的发生。经过位错运动、层错、孪晶和相变等多种变形机制的耦合作用，CoCrNi丝材的低温屈服强度可达1.5 GPa，断裂强度超过1.8 GPa，并且延伸率超过37%，如图13[49]所示，其综合性能优于目前报道的所有金属丝材，展现了高强韧高熵合金丝材在替代传统高性能丝材方面的显著优势。随后，通过多道次拉拔和后续热处理工艺改进，具有更高强度的共晶高熵合金丝材被成功开发[102]。研究发现，多道次拉拔形成的径向非均匀梯度片层结构和低温环境B2相因高密度交滑移导致的动态微结构细化的共同作用，导致了该丝材极优异的低温性能(图14[102])，其低温强度可达2.5 GPa，同时保持14%的均匀延伸率。高强韧共晶高熵合金丝材的成功制备不仅为新型金属丝材的开发提供了新思路，也为极端环境用金属丝材的安全服役提供了新方案。

图13

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图13   热拉拔CoCrNi丝材的室温及低温力学性能[49]

Fig.13   Tensile properties of hot-drawing CoCrNi wire at room and cryogenic temperatures[49] (σy—yield strength, εu—uniform elongation, εf—fracture strain)


图14

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图14   AlCoCrFeNi2.1共晶高熵合金丝材低温拉伸时的组织特征[102]

(a) deformation twins (DT) and dislocation cells (DC) in fcc matrix and microstructure refinement deriving from dense dislocation cross-slip in B2 phase of EHEA wire during cryogenic tension

(b) SAED pattern of B2 phase (green circle) in Fig.14a

Fig.14   Microstructures of AlCoCrFeNi2.1 EHEA wire during tensile test at 77 K[102]


4 高熵合金的低温应用前景总结及研究展望

高熵合金作为新型金属材料，在近20年的发展历程中，获得了研究人员的广泛关注。近年来针对其无主元、成分可调、机制多变等组织及变形特点，研究人员[4,7~11,16,40~42,45,48~51,53,59,61,63,67~73,75,77,79~82,84,86,88~97,99,100,102]取得了一系列重要成果(图15)，突破了传统材料的性能极限，并且还具备进一步优化的空间。而基于低温环境对高强韧材料的迫切需求，高熵合金在低温超导、深空探测、气体工业等极端环境领域均具有重要的工程应用潜力。

图15

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图15   不同类型高熵合金的低温强度-延伸率Ashby图

Fig.15   Ashby maps showing the yield strength (a) and ultimate tensile strength (b) vs elongation to failure for different HEAs at 77 K (CoCr-FeNiMn alloy[4,9,16,50,51,77,81,82]; PS—precipitate-strengthening[11,48,67,68,80,91,97]; TRIP—phase transformation induced plasticity[42,63,69,70,86,88-90,92-95]; eutectic HEA[99,100]; TiZrHfNbTa HEA[41]; HEA-wire[8,49,102]; CoCrNi medium-entropy alloy (MEA)[7,10,40,45,53,59]; SP— single-phase[61,71,72,75,79]; DP—dual-phase[73,84,96])


与此同时，如何精确调控组织和优化变形机制，以求低温性能提升的最大化，仍然是当前高熵合金前沿研究的重要课题。另外，作为相图中间区域的成分复杂合金，高熵合金的成分优化任务艰巨、充满挑战。而结合高通量实验、多尺度计算和集成计算模型的新一代高通量计算平台(涉及成分筛选、制备与表征、服役性能评价及优化等技术)将显著加速高强韧高熵合金的开发与应用。

此外，新型制备工艺的探索，如增材制造、快速加热等极端制造方法也将有效提升高强韧高熵合金的研发效率和服役性能，并加速高熵合金在抗辐照、强冲击和宽温域等超常环境的工程应用示范。由于其独特结构和性能优势，高熵合金未来有望在航空航天领域的低温燃料储罐和火箭发动机低温管道、阀门/泵等关键易耗部件、聚变反应堆的低温超导铠甲材料、液氢/液氧等低温介质的储藏和运输等领域替代传统的奥氏体不锈钢或镍基合金，实现典型应用示范。

当前针对高熵合金变形机理和强韧化原理的基础研究，加深了人们对多主元合金的认识，也为新型超高强韧材料的开发提供了广阔空间，但仍存在一些尚未解决的问题，需要重点关注。

4.1 多种变形机制对低温性能的具体影响

目前已有大量研究将传统材料的强韧化机制引入高熵合金，并显著改善了其服役性能。通过耦合多种变形机制提升高熵合金性能的理念也深入人心，但如何厘清多种变形机制对服役性能的具体影响，尤其是低温环境下如何量化各机制对力学性能的贡献，是指导更高强韧高熵合金设计的基础。除此之外，析出强化被证明是提高低温强度的有效方法，但由于时效过程会导致初始位错密度的显著下降，高熵合金的屈服强度也会明显降低。如何在保证析出强化效果的同时，尽可能提升基体的位错密度，是进一步强化高熵合金的重大挑战。随着实验和计算技术的发展，人们对低温变形过程中位错与多组元析出相的交互作用、孪生行为的精确设计、晶界及相界面的元素扩散与配分的认识将更加深入。

4.2 低温超高强度高熵合金的韧塑化机理

目前虽有少量2 GPa高熵合金的研究报道[42,48,91,103~106]，但大多数合金的低温屈服强度在1.5 GPa以下，没有展现出超高强韧高熵合金在替代传统低温工程材料(如钛合金、316LN不锈钢等)方面的显著优势。未来需要进一步加强对高熵合金基础结构和变形机理的研究，深入挖掘其低温性能潜力，提高人们对2 GPa超高强韧fcc及bcc结构高熵合金低温变形机理和韧塑化原理的认识，以便开发出具有显著性能优势的新型低温超高强度高熵合金。

4.3 低成本铁基中熵合金的研发与应用

与传统材料相比，高熵合金等原子比的设计方案使其成本高昂，限制了其大规模工业应用。近年来低成本铁基中熵合金的成功研发显著降低了合金成本，有力推动了高熵合金的工程应用向前发展。但由于合金多组元的特点，铁基中熵合金中的相变行为比钢铁材料中的马氏体相变更为复杂，也更难准确调控。虽然耦合多组元碳化物、基体相稳定性控制和孪晶变形等多种机制的材料设计给铁基中熵合金的性能提升提供了广阔空间，但也增加了更多挑战。随着人们对高熵合金相变行为认识的深入，未来面向工程应用的低成本铁基中熵合金的开发仍是研究的重点和难点。

4.4 多相高强韧金属丝材的研发

高强韧金属丝材是交通、航空航天、国防等领域的重点战略性材料，其综合性能与基础设施的长寿命安全服役和重点装备的可靠运行密切相关。当前，已有少量报道证实高熵合金丝材在低温、强冲击等超常环境具有独特优势，但这些材料大多是单相的fcc合金，其综合性能还有待进一步提高。本文中也提到多相组织调控可以有效提升高熵合金的低温性能，但多相组织对高强韧金属丝材的成形工艺，尤其是热加工工艺提出了诸多挑战。未来，针对多相高强韧金属丝材的研发仍是该领域亟待突破的重要问题。

4.5 极端环境用高强韧高熵合金管材等工业产品的研发及应用

航空航天、低温超导等领域对装备轻量化有迫切需求，高熵合金由于其高强塑性、优异的韧性、出色的抗冲击和抗辐照性能等使其在低温及超低温领域具有广阔的轻量化设计优势。未来针对极端环境用的高强韧高熵合金管材等工业产品的成功研发，对推动高熵合金从基础研究走向工程应用具有重要意义。高强韧金属管材是航空航天低温燃料储运的关键通道，要求其具有良好的宽温域服役性能、优异的耐蚀性能、优良的尺寸稳定性和简捷的连接工艺，以往工程上常采用奥氏体不锈钢或镍基合金，但这些传统合金目前的性能已优化至极限，很难再有大幅度的提升。因此，针对低温超高强度高熵合金管材及部件的研发具有重要的战略意义，不仅能显著提升我国在相关领域的技术优势和自主保障能力，而且对行业的绿色低碳发展有重要助力。另外，低温高强韧金属导管、泵、阀门等航空航天、低温超导领域的关键部件往往还需要兼具优异的疲劳性能、抗辐照、抗冲击等多重特性，而高熵合金在结构功能一体化设计方面具有明显优势，因此新型低温超高强度高熵合金工业产品的研发、应用以及连接工艺的优化等是未来高熵合金低温应用研究的重点方向。

4.6 高熵合金的低温动态力学行为研究及应用

近年来的研究[107~110]证明，高熵合金在强冲击环境具有优异的服役表现，如自锐性、高吸能特性等，从而在交通、能源及高技术等领域展现出广阔的应用潜力。深入研究[111~118]发现，室温环境高熵合金由于其本征的固溶强化、林位错硬化、变形孪晶及相变等多种机制的耦合作用，抑制了高速加载过程中局部绝热剪切带的形成，使得高熵合金具有优异的动态力学性能。另有研究[119,120]证实随着温度的降低，高熵合金的动态性能会明显改善。而针对低温强冲击耦合环境下，复杂组织高熵合金的动态变形机理揭示、组织优化及性能提升，仍然是目前高熵合金动态力学行为研究的重要方向。

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A FeCoNiCrTi0.2 high-entropy alloy strengthened by two types of coherent nano-precipitates but with the same composition was fabricated, and its tensile properties at room (293 K) and cryogenic temperatures (77 K) and the corresponding defect-structure evolution were investigated. Compared with the single-phase FeCoNiCr parent alloy, the precipitation-strengthened FeCoNiCrTi0.2 high-entropy alloy exhibits a significant increase in yield strength and ultimate tensile strength but with little sacrifice in ductility. Similar to the single-phase FeCoNiCr high-entropy alloy, the deformation behavior of this precipitation-strengthened FeCoNiCrTi0.2 high-entropy alloy shows strong temperature dependence. When the temperature decreases from 293 K to 77 K, its yield strength and ultimate tensile strength are increased from 700 MPa to 860 MPa and from 1.24 GPa to 1.58 GPa, respectively, associated with a ductility improvement from 36% to 46%. However, different from the single-phase FeCoNiCr high-entropy alloy with a twinning-dominant deformation mode at 77 K. multiple-layered stacking faults with a hierarchical substructure prevail in the precipitation-strengthened FeCoNiCrTi0.2 high-entropy alloy when deformed at 77 K. The mechanism of twinning inhibition in this precipitation-strengthened high-entropy alloy is the high energy barrier for twin nucleation in the ordered gamma' nano-particles. Our results may provide a guide for the design of tough high-entropy alloys for applications at cryogenic temperatures through combining precipitation strengthening and twinning/stacking faults. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd.

Liu H C, Kuo C M, Shen P K, et al.

Disordering of L12 phase in high-entropy alloy deformed at cryogenic temperature

[J]. Adv. Eng. Mater., 2021, 23: 2100564

DOI      URL     [本文引用: 5]

Jo Y H, Yang J H, Doh K Y, et al.

Analysis of damage-tolerance of TRIP-assisted V10Cr10Fe45Co30Ni5 high-entropy alloy at room and cryogenic temperatures

[J]. J. Alloys Compd., 2020, 844: 156090

DOI      URL     [本文引用: 2]

Zhang K S, Zhang X H, Zhang E G, et al.

Strengthening of ferrous medium entropy alloys by promoting phase transformation

[J]. Intermetallics, 2021, 136: 107265

DOI      URL     [本文引用: 1]

Wei C B, Lu Y P, Du X H, et al.

Remarkable strength of a non-equiatomic Co29Cr29Fe29Ni12.5W0.5 high-entropy alloy at cryogenic temperatures

[J]. Mater. Sci. Eng., 2021, A818: 141446

[本文引用: 1]

Liu D, Jin X, Guo N, et al.

Non-equiatomic FeMnCrNiAl high-entropy alloys with heterogeneous structures for strength and ductility combination

[J]. Mater. Sci. Eng., 2021, A818: 141386

[本文引用: 1]

Dong Y, Duan S G, Huang X, et al.

Excellent strength-ductility synergy in as-cast Al0.6CoCrFeNi2Mo0.08V0.04 high-entropy alloy at room and cryogenic temperatures

[J]. Mater. Lett., 2021, 294: 129778

DOI      URL     [本文引用: 2]

Fiocchi J, Mostaed A, Coduri M, et al.

Enhanced cryogenic and ambient temperature mechanical properties of CoCuFeMnNi high entropy alloy through controlled heat treatment

[J]. J. Alloys Compd., 2022, 910: 164810

DOI      URL    

Pei B, Fan J P, Wang Z, et al.

Excellent combination of strength and ductility in CoNiCr-based MP159 alloys at cryogenic temperature

[J]. J. Alloys Compd., 2022, 907: 164144

DOI      URL     [本文引用: 2]

Giwa A M, Aitken Z H, Liaw P K, et al.

Effect of temperature on small-scale deformation of individual face-centered-cubic and body-centered-cubic phases of an Al0.7CoCrFeNi high-entropy alloy

[J]. Mater. Des., 2020, 191: 108611

DOI      URL    

Sun S J, Tian Y Z, Lin H R, et al.

Temperature dependence of the Hall-Petch relationship in CoCrFeMnNi high-entropy alloy

[J]. J. Alloys Compd., 2019, 806: 992

DOI      URL     [本文引用: 2]

Ding Q Q, Fu X Q, Chen D K, et al.

Real-time nanoscale observation of deformation mechanisms in CrCoNi-based medium- to high-entropy alloys at cryogenic temperatures

[J]. Mater. Today, 2019, 25: 21

DOI      URL    

Jang M J, Kwak H, Lee Y W, et al.

Plastic deformation behavior of 40Fe-25Ni-15Cr-10Co-10V high-entropy alloy for cryogenic applications

[J]. Met. Mater. Int., 2019, 25: 277

DOI      [本文引用: 2]

A single FCC phase 40Fe-25Ni-15Cr-10Co-10V high-entropy alloy was designed, fabricated, and evaluated for potential cryogenic applications. The alloy forms a single FCC phase and exhibits higher yield strength, tensile strength, and elongation at cryogenic temperature (77K) than at room temperature (298K). The superior tensile properties at cryogenic temperature are discussed based on the formation of deformation twins during the tensile test at cryogenic temperature. In addition, a constitutive model reflecting the cryogenic deformation mechanism (i.e., twinning-induced plasticity) was implemented into the finite element method to analyze this behavior. Experimental results and the finite element analysis suggest that the increase in plastic deformation capacity at cryogenic temperature contributes to the formation of deformation twins.

Górecki K, Bała P, Bednarczyk W, et al.

Cryogenic behaviour of the Al5Ti5Co35Ni35Fe20 multi-principal component alloy

[J]. Mater. Sci. Eng., 2019, A745: 346

[本文引用: 1]

Sun S J, Tian Y Z, Lin H R, et al.

Achieving high ductility in the 1.7  GPa grade CoCrFeMnNi high-entropy alloy at 77 K

[J]. Mater. Sci. Eng., 2019, A740-741: 336

[本文引用: 1]

Sun S J, Tian Y Z, An X H, et al.

Ultrahigh cryogenic strength and exceptional ductility in ultrafine-grained CoCrFeMnNi high-entropy alloy with fully recrystallized structure

[J]. Mater. Today Nano., 2018, 4: 46

[本文引用: 2]

Bönisch M, Wu Y, Sehitoglu H.

Twinning-induced strain hardening in dual-phase FeCoCrNiAl0.5 at room and cryogenic temperature

[J]. Sci. Rep., 2018, 8: 10663

DOI      PMID     

A face-centered-cubic (fcc) oriented FeCoCrNiAl0.5 dual-phase high entropy alloy (HEA) was plastically strained in uniaxial compression at 77K and 293K and the underlying deformation mechanisms were studied. The undeformed microstructure consists of a body-centered-cubic (bcc)/B2 interdendritic network and precipitates embedded in < 001 >-oriented fcc dendrites. In contrast to other dual-phase HEAs, at both deformation temperatures a steep rise in the stress-strain curves occurs above 23% total axial strain. As a result, the hardening rate associated saturates at the unusual high value of similar to 6 GPa. Analysis of the strain partitioning between fcc and bcc/B2 by digital image correlation shows that the fcc component carries the larger part of the plastic strain. Further, electron backscatter diffraction and transmission electron microscopy evidence ample fcc deformation twinning both at 77K and 293K, while slip activity only is found in the bcc/B2. These results may guide future advancements in the design of novel alloys with superior toughening characteristics.

Jo Y H, Choi W M, Sohn S S, et al.

Role of brittle sigma phase in cryogenic-temperature-strength improvement of non-equi-atomic Fe-rich VCrMnFeCoNi high entropy alloys

[J]. Mater. Sci. Eng., 2018, A724: 403

[本文引用: 2]

Lu Z P, Lei Z F, Huang H L, et al.

Deformation behavior and toughening of high-entropy alloys

[J]. Acta Metall. Sin., 2018, 54: 1553

DOI      [本文引用: 1]

A new alloy design concept, high-entropy alloys (HEAs), has attracted increasing attentions and becomes a new research highlight recently. Different from traditional alloy design strategy which usually blends with one or two elements as the principal constituent and other minor elements for the further optimization of properties, HEAs are multicomponent alloys containing several principle elements (usually ≥5) in equiatomic or near equiatomic ratio. Due to their unique atomic structure, HEAs possess a lot of distinguished properties. Since the discovery of HEAs, a variety of HEA systems have been developed and shown unique physical, chemical and thermodynamic properties, especially the promising mechanical properties such as high strength and hardness, abrasion resistance, corrosion resistance and softening resistance. Here in this short review manuscript, starting from the research challenges for understanding the deformation mechanism of HEAs, this work briefly summarized the mechanical properties and deformation behavior of HEAs, reviewed the proposed strengthening-toughening strategies and their corresponding deformation mechanism in HEAs. A brief perspective on the research directions of mechanical behavior of HEAs was also proposed.

吕昭平, 雷智锋, 黄海龙 等.

高熵合金的变形行为及强韧化

[J]. 金属学报, 2018, 54: 1553

DOI      [本文引用: 1]

高熵合金是近年来涌现出的一种新型金属材料。不同于传统合金设计以1种或2种元素为主添加其它合金元素为辅的方案,高熵合金由多种元素以等原子比或近等原子比的成分组成,具有独特的原子结构特征,因而呈现出诸多不同于传统合金的独特性能。自高熵合金被首次报道以来,目前已经研发出了一系列的高熵合金体系,在物理、化学、热力学性能方面显示出独有的优势,尤其在力学行为方面显示出高强、高硬、耐磨、耐蚀、抗高温软化等优异的性能,在国际学术界引起了广泛的关注和研究兴趣,已经成为新的研究热点。本文从高熵合金变形机理研究存在的挑战出发,主要综述了高熵合金的力学性能和变形行为特点,已经提出的强韧化方案及相关机理,并对未来高熵合金变形行为的研究进行了简单展望。

Abuzaid W, Egilmez M, Chumlyakov Y I.

TWIP-TRIP effect in single crystalline VFeCoCrNi multi-principle element alloy

[J]. Scr. Mater., 2021, 194: 113637

DOI      URL     [本文引用: 4]

Wu P F, Gan K F, Yan D S, et al.

The temperature dependence of deformation behaviors in high-entropy alloys: A review

[J]. Metals, 2021, 11: 2005

DOI      URL    

Over the past seventeen years, deformation behaviors of various types of high-entropy alloys (HEAs) have been investigated within a wide temperature range, from cryogenic to high temperatures, to demonstrate the excellent performance of HEAs under extreme conditions. It has been suggested that the dominated deformation mechanisms in HEAs would be varied with respect to the environmental temperatures, which significantly alters the mechanical properties. In this article, we systematically review the temperature-dependent mechanical behaviors, as well as the corresponding mechanisms of various types of HEAs, aiming to provide a comprehensive and up-to-date understanding of the recent progress achieved on this subject. More specifically, we summarize the deformation behaviors and microscale mechanisms of single-phase HEAs, metastable HEAs, precipitates-hardened HEAs and multiphase HEAs, at cryogenic, room and elevated temperatures. The possible strategies for strengthening and toughening HEAs at different temperatures are also discussed to provide new insights for further alloy development.

Rizi M S, Minouei H, Lee B J, et al.

Effects of carbon and molybdenum on the nanostructural evolution and strength/ductility trade-off in Fe40Mn40Co10Cr10 high-entropy alloys

[J]. J. Alloys Compd., 2022, 911: 165108

DOI      URL     [本文引用: 3]

Park H D, Won J W, Moon J, et al.

Fe55Co17.5Ni10Cr12.5Mo5 high-entropy alloy with outstanding cryogenic mechanical properties driven by deformation-induced phase transformation behavior

[J]. Met. Mater. Int., 2023, 29: 95

DOI     

Jo Y H, Choi W M, Kim D G, et al.

FCC to BCC transformation-induced plasticity based on thermodynamic phase stability in novel V10Cr10Fe45Co x Ni35- x medium-entropy alloys

[J]. Sci. Rep., 2019, 9: 2948

DOI      PMID      [本文引用: 1]

We introduce a novel transformation-induced plasticity mechanism, i.e., a martensitic transformation from fcc phase to bcc phase, in medium-entropy alloys (MEAs). A VCrFeCoNi MEA system is designed by thermodynamic calculations in consideration of phase stability between bcc and fcc phases. The resultantly formed bcc martensite favorably contributes to the transformation-induced plasticity, thereby leading to a significant enhancement in both strength and ductility as well as strain hardening. We reveal the microstructural evolutions according to the Co-Ni balance and their contributions to a mechanical response. The Co-Ni balance plays a leading role in phase stability and consequently tunes the cryogenic-temperature strength-ductility balance. The main difference from recently-reported metastable high-entropy dual-phase alloys is the formation of bcc martensite as a daughter phase, which shows significant effects on strain hardening. The hcp phase in the present MEA mostly acts as a nucleation site for the bcc martensite. Our findings demonstrate that the fcc to bcc transformation can be an attractive route to a new MEA design strategy for improving cryogenic strength-ductility.

Kwon H, Moon J, Bae J W, et al.

Precipitation-driven metastability engineering of carbon-doped CoCrFeNiMo medium-entropy alloys at cryogenic temperature

[J]. Scr. Mater., 2020, 188: 140

DOI      URL     [本文引用: 10]

Wang Z W, Lu W J, Raabe D, et al.

On the mechanism of extraordinary strain hardening in an interstitial high-entropy alloy under cryogenic conditions

[J]. J. Alloys Compd., 2019, 781: 734

DOI      URL     [本文引用: 2]

Seol J B, Bae J W, Kim J G, et al.

Short-range order strengthening in boron-doped high-entropy alloys for cryogenic applications

[J]. Acta Mater., 2020, 194: 366

DOI      URL     [本文引用: 4]

He Z F, Jia N, Wang H W, et al.

Synergy effect of multi-strengthening mechanisms in FeMnCoCrN HEA at cryogenic temperature

[J]. J. Mater. Sci. Technol., 2021, 86: 158

DOI      URL     [本文引用: 1]

Bae J W, Seol J B, Moon J, et al.

Exceptional phase-transformation strengthening of ferrous medium-entropy alloys at cryogenic temperatures

[J]. Acta Mater., 2018, 161: 388

DOI      URL     [本文引用: 5]

Jo Y H, Choi W M, Kim D G, et al.

Utilization of brittle σ phase for strengthening and strain hardening in ductile VCrFeNi high-entropy alloy

[J]. Mater. Sci. Eng., 2019, A743: 665

[本文引用: 2]

Du X H, Huo X F, Chang H T, et al.

Superior strength-ductility combination of a Co-rich CoCrNiAlTi high-entropy alloy at room and cryogenic temperatures

[J]. Mater. Res. Express, 2020, 7: 034001

[本文引用: 3]

Lu Y P, Dong Y, Guo S, et al.

A promising new class of high-temperature alloys: Eutectic high-entropy alloys

[J]. Sci. Rep., 2014, 4: 6200

DOI      PMID      [本文引用: 5]

High-entropy alloys (HEAs) can have either high strength or high ductility, and a simultaneous achievement of both still constitutes a tough challenge. The inferior castability and compositional segregation of HEAs are also obstacles for their technological applications. To tackle these problems, here we proposed a novel strategy to design HEAs using the eutectic alloy concept, i.e. to achieve a microstructure composed of alternating soft fcc and hard bcc phases. As a manifestation of this concept, an AlCoCrFeNi2.1 (atomic portion) eutectic high-entropy alloy (EHEA) was designed. The as-cast EHEA possessed a fine lamellar fcc/B2 microstructure, and showed an unprecedented combination of high tensile ductility and high fracture strength at room temperature. The excellent mechanical properties could be kept up to 700 degrees C. This new alloy design strategy can be readily adapted to large-scale industrial production of HEAs with simultaneous high fracture strength and high ductility.

Lu Y P, Gao X Z, Jiang L, et al.

Directly cast bulk eutectic and near-eutectic high entropy alloys with balanced strength and ductility in a wide temperature range

[J]. Acta Mater., 2017, 124: 143

DOI      URL     [本文引用: 3]

Li Y, Shi P J, Wang M Y, et al.

Unveiling microstructural origins of the balanced strength-ductility combination in eutectic high-entropy alloys at cryogenic temperatures

[J]. Mater. Res. Lett., 2022, 10: 602

DOI      URL     [本文引用: 6]

Huo W Y, Fang F, Zhou H, et al.

Remarkable strength of CoCrFeNi high-entropy alloy wires at cryogenic and elevated temperatures

[J]. Scr. Mater., 2017, 141: 125

DOI      URL     [本文引用: 1]

Chen J X, Li T, Chen Y, et al.

Ultra-strong heavy-drawn eutectic high entropy alloy wire

[J]. Acta Mater., 2023, 243: 118515

DOI      URL     [本文引用: 6]

Fan L, Yang T, Zhao Y L, et al.

Ultrahigh strength and ductility in newly developed materials with coherent nanolamellar architectures

[J]. Nat. Commun., 2020, 11: 6240

DOI      PMID      [本文引用: 1]

Nano-lamellar materials with ultrahigh strengths and unusual physical properties are of technological importance for structural applications. However, these materials generally suffer from low tensile ductility, which severely limits their practical utility. Here we show that markedly enhanced tensile ductility can be achieved in coherent nano-lamellar alloys, which exhibit an unprecedented combination of over 2 GPa yield strength and 16% uniform tensile ductility. The ultrahigh strength originates mainly from the lamellar boundary strengthening, whereas the large ductility correlates to a progressive work-hardening mechanism regulated by the unique nano-lamellar architecture. The coherent lamellar boundaries facilitate the dislocation transmission, which eliminates the stress concentrations at the boundaries. Meanwhile, deformation-induced hierarchical stacking-fault networks and associated high-density Lomer-Cottrell locks enhance the work hardening response, leading to unusually large tensile ductilities. The coherent nano-lamellar strategy can potentially be applied to many other alloys and open new avenues for designing ultrastrong yet ductile materials for technological applications.

Du X H, Li W P, Chang H T, et al.

Dual heterogeneous structures lead to ultrahigh strength and uniform ductility in a Co-Cr-Ni medium-entropy alloy

[J]. Nat. Commun., 2020, 11: 2390

DOI      PMID     

Alloys with ultra-high strength and sufficient ductility are highly desired for modern engineering applications but difficult to develop. Here we report that, by a careful controlling alloy composition, thermomechanical process, and microstructural feature, a Co-Cr-Ni-based medium-entropy alloy (MEA) with a dual heterogeneous structure of both matrix and precipitates can be designed to provide an ultra-high tensile strength of 2.2 GPa and uniform elongation of 13% at ambient temperature, properties that are much improved over their counterparts without the heterogeneous structure. Electron microscopy characterizations reveal that the dual heterogeneous structures are composed of a heterogeneous matrix with both coarse grains (10∼30 μm) and ultra-fine grains (0.5∼2 μm), together with heterogeneous L1-structured nanoprecipitates ranging from several to hundreds of nanometers. The heterogeneous L1 nanoprecipitates are fully coherent with the matrix, minimizing the elastic misfit strain of interfaces, relieving the stress concentration during deformation, and playing an active role in enhanced ductility.

Wang S D, Wang J H, Yang Y, et al.

Ultrastrong interstitially-strengthened chemically complex martensite via tuning phase stability

[J]. Scr. Mater., 2023, 226: 115257

DOI      URL    

Chung H, Choi W S, Jun H, et al.

Doubled strength and ductility via maraging effect and dynamic precipitate transformation in ultrastrong medium-entropy alloy

[J]. Nat. Commun., 2023, 14: 145

DOI      PMID      [本文引用: 1]

Demands for ultrahigh strength in structural materials have been steadily increasing in response to environmental issues. Maraging alloys offer a high tensile strength and fracture toughness through a reduction of lattice defects and formation of intermetallic precipitates. The semi-coherent precipitates are crucial for exhibiting ultrahigh strength; however, they still result in limited work hardening and uniform ductility. Here, we demonstrate a strategy involving deformable semi-coherent precipitates and their dynamic phase transformation based on a narrow stability gap between two kinds of ordered phases. In a model medium-entropy alloy, the matrix precipitate acts as a dislocation barrier and also dislocation glide media; the grain-boundary precipitate further contributes to a significant work-hardening via dynamic precipitate transformation into the type of matrix precipitate. This combination results in a twofold enhancement of strength and uniform ductility, thus suggesting a promising alloy design concept for enhanced mechanical properties in developing various ultrastrong metallic materials.© 2023. The Author(s).

Liu X F, Tian Z L, Zhang X F, et al.

"Self-sharpening" tungsten high-entropy alloy

[J]. Acta Mater., 2020, 186: 257

DOI      URL     [本文引用: 1]

Li Z, Zhao S, Diao H, et al.

High-velocity deformation of Al0.3CoCrFeNi high-entropy alloy: Remarkable resistance to shear failure

[J]. Sci. Rep., 2017, 7: 42742

DOI      PMID     

The mechanical behavior of a single phase (fcc) AlCoCrFeNi high-entropy alloy (HEA) was studied in the low and high strain-rate regimes. The combination of multiple strengthening mechanisms such as solid solution hardening, forest dislocation hardening, as well as mechanical twinning leads to a high work hardening rate, which is significantly larger than that for Al and is retained in the dynamic regime. The resistance to shear localization was studied by dynamically-loading hat-shaped specimens to induce forced shear localization. However, no adiabatic shear band could be observed. It is therefore proposed that the excellent strain hardening ability gives rise to remarkable resistance to shear localization, which makes this material an excellent candidate for penetration protection applications such as armors.

Jiao Z M, Ma S G, Chu M Y, et al.

Superior mechanical properties of AlCoCrFeNiTi x high-entropy alloys upon dynamic loading

[J]. J. Mater. Eng. Perform., 2016, 25: 451

DOI      URL    

Tang Y, Wang R X, Xiao B, et al.

A review on the dynamic-mechanical behaviors of high-entropy alloys

[J]. Prog. Mater. Sci., 2023, 135: 101090

DOI      URL     [本文引用: 1]

He J Y, Wang Q, Zhang H S, et al.

Dynamic deformation behavior of a face-centered cubic FeCoNiCrMn high-entropy alloy

[J]. Sci. Bull., 2018, 63: 362

DOI      PMID      [本文引用: 1]

In this study, mechanical tests were conducted on a face-centered cubic FeCoNiCrMn high-entropy alloy, both in tension and compression, in a wide range of strain rates (10-10 s) to systematically investigate its dynamic response and underlying deformation mechanism. Materials with different grain sizes were tested to understand the effect of grain size, thus grain boundary volume, on the mechanical properties. Microstructures of various samples both before and after deformation were examined using electron backscatter diffraction and transmission electron microscopy. The dislocation structure as well as deformation-induced twins were analyzed and correlated with the measured mechanical properties. Plastic stability during tension of the current high-entropy alloy (HEA), in particular, at dynamic strain rates, was discussed in lights of strain-rate sensitivity and work hardening rate. It was found that, under dynamic conditions, the strength and uniform ductility increased simultaneously as a result of the massive formation of deformation twins. Specifically, an ultimate tensile strength of 734 MPa and uniform elongation of ∼63% are obtained at 2.3 × 10 s, indicating that the alloy has great potential for energy absorption upon impact loading.Copyright © 2018 Science China Press. Published by Elsevier B.V. All rights reserved.

Li Z Z, Zhao S T, Alotaibi S M, et al.

Adiabatic shear localization in the CrMnFeCoNi high-entropy alloy

[J]. Acta Mater., 2018, 151: 424

DOI      URL    

Wang L, Qiao J W, Ma S G, et al.

Mechanical response and deformation behavior of Al0.6CoCrFeNi high-entropy alloys upon dynamic loading

[J]. Mater. Sci. Eng., 2018, A727: 208

Qiao Y, Chen Y, Cao F H, et al.

Dynamic behavior of CrMnFeCoNi high-entropy alloy in impact tension

[J]. Int. J. Impact Eng., 2021, 158: 104008

DOI      URL    

Zhao S T, Li Z Z, Zhu C Y, et al.

Amorphization in extreme deformation of the CrMnFeCoNi high-entropy alloy

[J]. Sci. Adv., 2021, 7: eabb3108

DOI      URL    

Extreme deformation of high-entropy alloys increases toughness by converting crystalline structures to amorphous zones.

Wang R X, Tang Y, Li S, et al.

Research progress on deformation mechanisms under dynamic loading of high-entropy alloys

[J]. Mater. Rep., 2021, 35: 17001

王睿鑫, 唐 宇, 李 顺 等.

高熵合金动态载荷下变形机制的研究进展

[J]. 材料导报. 2021, 35: 17001

Qin S, Yang M X, Liu Y K, et al.

Superior dynamic shear properties and deformation mechanisms in a high entropy alloy with dual heterogeneous structures

[J]. J. Mater. Res. Technol., 2022, 19: 3287

DOI      URL    

Huang A M, Fensin S J, Meyers M A.

Strain-rate effects and dynamic behavior of high entropy alloys

[J]. J. Mater. Res. Technol., 2023, 22: 307

DOI      URL     [本文引用: 1]

Hu M L, Song W D, Duan D B, et al.

Dynamic behavior and microstructure characterization of TaNbHfZrTi high-entropy alloy at a wide range of strain rates and temperatures

[J]. Int. J. Mech. Sci., 2020, 182: 105738

DOI      URL     [本文引用: 1]

Qiao Y, Cao F H, Chen Y, et al.

Impact tension behavior of heavy-drawn nanocrystalline CoCrNi medium entropy alloy wire

[J]. Mater. Sci. Eng., 2022, A856: 144041

[本文引用: 1]

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