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Mo元素强化CoCrNi中熵合金不完全再结晶异质结构设计及变形机理研究

李子垚，苏鸿宏，吴诗昶，侯毅熙，庞大为，汪 鑫，蒋 成，毛圣成*，张 泽，韩晓东
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2025年 第44卷 第2期: 1000-6281（2025）02-182-08     下载地址：

Mo元素强化CoCrNi中熵合金不完全再结晶异质结构设计及变形机理研究

李子垚，苏鸿宏，吴诗昶，侯毅熙，庞大为，汪 鑫，蒋 成，毛圣成*，张 泽，韩晓东

(1. 北京工业大学材料科学与工程学院，北京 100124；2. 浙江大学材料科学与工程学院，浙江 杭州 310027 ；3. 南方科技大学材料科学与工程系，广东 深圳 518055)

摘 要 CoCrNi合金是典型的中熵合金，其具有高的室温拉伸塑性，在能源、航空航天等领域具有广泛的应用前景。但其强度通常不高，限制了作为关键结构部件服役的潜力。本文通过Mo元素添加及冷轧退火工艺制备出具有不完全再结晶异质结构Co30Ni30Cr33Mo7中熵合金，并结合扫描电镜与透射电镜在微纳米层次研究其塑性变形机理。结果表明，异质结构Co30Ni30Cr33Mo7中熵合金具有优良的强塑性，其屈服强度与抗拉强度分别为656 MPa与1123 MPa，延伸率达到了38 %。Mo元素添加提供析出相强化作用，同时降低合金层错能，使内部产生高比例的退火孪晶。在塑性变形阶段，异质结构导致合金内部产生非均匀变形，激发大量层错和变形孪晶，引发异变诱导硬化，提高了合金的加工硬化能力和强韧性。因此，通过Mo元素添加及冷轧退火工艺向CoCrNi中熵合金中引入不完全再结晶异质结构的方式为提高其强度提供了可行办法。

关键词 CoCrNi中熵合金；异质结构；异变诱导强化

中图分类号：TG335.12；TG156.2；TG139；TG115.21+5.3 文献标识码：A Doi:10.3969/j.issn.1000-6281.2025.02.005

 

Design of partially-recrystallized heterogeneous structure and deformation mechanism of CoCrNi medium-entropy alloy strengthened by Mo element

LI Ziyao，SU Honghong，WU Shichang，HOU Yixi，PANG Dawei，WANG Xin，JIANG Cheng，MAO Shengcheng*，ZHANG Ze，HAN Xiaodong

(1. Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124； 2. School of Materials Science and Engineering, Zhejiang University, Hangzhou Zhejiang 310027； 3. Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen Guangdong 518055, China)

Abstract CoCrNi alloys are typical medium-entropy alloys with high room-temperature tensile plasticity, making them suitable for wide applications in energy, aerospace and other fields. However, their low strength leads to strength-toughness trade-off, limiting their potential as a key structural component. This paper presents a partially recrystallized heterogeneous structure Co30Ni30Cr33Mo7 medium-entropy alloy, prepared by adding Mo element and using a cold rolling-annealing process. The plastic deformation mechanism was investigated at both the micro and nano levels using scanning electron microscopy and transmission electron microscopy. The results showed that the heterogeneous structure Co30Ni30Cr33Mo7 medium-entropy alloy exhibited excellent strong plasticity, with a yield strength of 656 MPa, tensile strength of 1123 MPa, and elongation of 38 %. The addition of Mo element enhanced precipitation strengthening and lowered the alloy’s stacking fault energy, promoting to the formation of a high proportion of annealed twins in the interior. During plastic deformation, the heterogeneous structure induced non-uniform deformation within the alloy, stimulating the formation of stacking faults and deformation twins. This heterogeneous deformation improved the work-hardening capacity and toughness. Thus, the introduction of a partially recrystallized heterogeneous structure into CoCrNi medium-entropy alloy through Mo addition and cold rolling-annealing process offers a solution to the strength-toughness trade-off, enhancing their potential for structural applications.

Keywords CoCrNi medium-entropy alloy; heterogeneous structure; heterogeneous deformation induced hardenging