Phase transition and heterogeneous strengthening mechanism in CoCrFeNiMn high-entropy alloy fabricated by laser-engineered net shaping via annealing at intermediate-temperature

Yunjian Bai ¹Heng Jiang ¹Kuo Yan ²Maohui Li ³Yanpeng Wei ⁴Kun Zhang ¹Bingchen Wei⁵

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作者信息

1. Key Laboratory of Microgravity(National Microgravity Laboratory),Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China;School of Engineering Science,University of Chinese Academy of Sciences,Beijing 100049,China
2. Key Laboratory of Microgravity(National Microgravity Laboratory),Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China
3. Institute of Quartermaster Engineering&Technology,Academy of System Engineering,Academy of Military Sciences,Beijing 100010,China
4. Key Laboratory for Mechanics in Fluid Solid Coupling Systems,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China;School of Engineering Science,University of Chinese Academy of Sciences,Beijing 100049,China
5. Key Laboratory of Microgravity(National Microgravity Laboratory),Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China;School of Engineering Science,University of Chinese Academy of Sciences,Beijing 100049,China;Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China
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Abstract

High-entropy alloys(HEAs)have attracted tremendous attention owing to their controllable mechanical properties,whereas additive manufacturing(AM)is an efficient and flexible processing route for novel materials design.However,a profound appraisal of the fundamental material physics behind the strength-ening of AM-printed HEAs upon low/intermediate-temperature annealing is essential.In this work,CoCr-FeNiMn HEAs have been prepared using laser-engineered net shaping(LENS)and subsequently annealed at different temperatures.The CoCrFeNiMn HEA annealed at intermediate-temperature(873 K)exhibits a strong strain hardening capability,resulting in ultimate strength of 725 MPa and plasticity of 22％.A ternary heterogeneous strengthening mechanism is proposed to explain this phenomenon,in which equiaxed grains,columnar grains,and σ precipitates play different roles during tensile deformation.The resultant excellent strength and ductility can be ascribed to the heterostructure-induced mismatch.The equiaxed grains provide adequate grain boundaries(GBs),which induce dislocation plugging-up and en-tanglement;the columnar grains induce the onset and arrest of the dislocations for plastic deformation;and the σ precipitates hinder the movement of slip dislocations.The results provide new insights into overcoming the strength-ductility trade-off of LENS-printed HEAs with complex geometries.

Key words

High-entropy alloys/Phase transition/Heterogeneous strengthening/Intermediate-temperature

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基金项目

National Natural Science Foundation of China(51401028)

National Natural Science Foundation of China(51271193)

National Natural Science Foundation of China(11402277)

National Natural Science Foundation of China(11790292)

Strategic Priority Research Program of the Chinese Academy of Sciences(XDB22040303)

Innovation program(237099000000170004)

出版年

2021

材料科学技术(英文版)

中国金属学会中国材料研究学会中国科学院金属研究所

材料科学技术(英文版)

CSTPCDCSCDSCI

影响因子：0.657

ISSN：1005-0302

参考文献量49

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