Superb cryogenic strength of equiatomic CrCoNi derived from gradient hierarchical microstructure

作     者：Bin Gan Jeffrey M. Wheeler Zhongnan Bi Lin Liu Jun Zhang Hengzhi Fu 

作者机构：School of Materials Science and Engineering Northwestern Polytechnical University Xi'an 710072 China Laboratory for Nanometallurgy Department of Materials Science ETH Zurich Vladimir-Prelog-Weg 5 Zurich CH-8093 Switzerland Central Iron and Steel Research Institute No. 76 Xueyuannan Road Beijing 100081 China 

出 版 物：《Journal of Materials Science & Technology》 (材料科学技术（英文版）)

年 卷 期：2019年第35卷第6期

页      面：957-961页

核心收录：

学科分类：0806[工学-冶金工程] 0817[工学-化学工程与技术] 08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0703[理学-化学] 0802[工学-机械工程] 0702[理学-物理学] 0801[工学-力学（可授工学、理学学位）] 

基　　金：the financial support of the project from the National Natural Science Foundation of China(No.51601147) the Natural Science Foundation of Shaanxi Province(No.2017JQ5010) “the Fundamental Research Funds for the Central Universities”(No.3102016OQD048,3102017JC11001,3102017JC01003) 

主　　题：Medium entropy alloy CrCoNi Torsion Hierarchical microstructure Strengthening 

摘      要：This work demonstrates the effectiveness of a cryogenic torsional pre-straining for significantly improving the cryogenic strength of an equiatomic CrCoNi alloy. The origin of this phenomenon is elucidated by various microstructural characterization tools, which shows that the sequential torsion and tension tests lead to the observed hierarchical microstructure through the activation of different twinning systems and stacking faults. This gives rise to the significant increase in the yield strength from 600 MPa to 1215 MPa,while the fracture strain changes from 68% to 48%. The current study reveals that the incorporation of nanotwins architecture by shear deformation may constitute a viable strategy to tune the mechanical performance and, in particular, to dramatically increase the strength while keeping a good ductility.