Simultaneous enhancement of strength and ductility via microband formation and nanotwinning in an L12-strengthened alloy

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外文摘要：Metallic alloys with high strength and large ductility are required for extreme structural applications.However,the achievement of ultrahigh strength often results in a substantially decreased ductility.Here,we report a strat-egy to achieve the strength-ductility synergy by tailoring the alloy composition to control the local stacking fault energy(SFE)of the face-centered-cubic(fcc)matrix in an L1 2-strengthened superlattice alloy.As a proof of con-cept,based on the thermodynamic calculations,we developed a non-equiatomic CoCrNi2(Al0.2Nb0 2)alloy using phase separation to create a near-equiatomic low SFE disordered CoCrNi medium-entropy alloy matrix with in situ formed high-content coherent Ni3(Al,Nb)-type ordered nanoprecipitates(～12 nm).The alloy achieves a high tensile strength up to 1.6 GPa and a uniform ductility of 33％.The low SFE of the fcc matrix promotes the formation of nanotwins and parallel microbands during plastic deformation which could remarkably enhance the strain hardening capacity.This work provides a strategy for developing ultrahigh-strength alloys with large uniform ductility.

外文关键词：

L12-strengthened superlattice alloyStacking fault energyNanotwinsMicrobandsStrain hardening

作者：

Lu Yang、Dingshan Liang、Zhuo Cheng、Ranxi Duan、Chuanxin Zhong、Junhua Luan、Zengbao Jiao、Fuzeng Ren

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作者单位：

Department of Materials Science and Engineering,Southern University of Science and Technology,Shenzhen 518055,China

Department of Materials Science and Engineering,City University of Hong Kong,Hong Kong 999077,China

Department of Mechanical Engineering,The Hong Kong Polytechnic University,Hong Kong 999077,China

基金：

Microscope and Imaging Center at Southern University of Science and Technology,China国家自然科学基金Guangdong Innovative & Entrepreneurial Research Team ProgramInter-University 3D APT Unit of City University of Hong Kong(CityU)CityU grant

项目编号：

521221022016ZT06C2799360161

出版年：

2024

DOI：

10.1016/j.fmre.2022.05.024

自然科学基础研究(英文)

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ISSN：

年,卷(期)：2024.(1)

参考文献量56