Rate-dependent mechanical behavior of single-,bi-,twinned-,and poly-crystals of CoCrFeNi high-entropy alloy  

作　　者：Siyuan Wei Yakai Zhao Jae-il Jang Upadrasta Ramamurty 

机构地区：[1]School of Mechanical and Aerospace Engineering,Nanyang Technological University,639798,Republic of Singapore [2]Division of Materials Science and Engineering,Hanyang University,Seoul 04763,Republic of Korea [3]Technology and Research,Institute of Materials Research and Engineering,Agency for Science,138634,Republic of Singapore

出　　处：《Journal of Materials Science & Technology》2022年第25期253-264,共12页材料科学技术（英文版）

基　　金：supported by Agency for Science,Technology and Research(A*STAR)of Singapore via the Structural Metal Alloys Programme(No.A18B1b0061);Hanyang University was supported by the NRF grants(Nos.2020R1A2B5B01001446 and 2020R1A5A6017701)。

摘　　要：While considerable effort is made to understand the solid solution strengthening on the deformation behavior of high-entropy alloys(HEAs),relatively little attention is paid to the role of microstructural interfaces,especially twin boundaries(TBs),on the strain-rate sensitivity(SRS)of them.To address this,we have conducted micropillar compression experiments on single-,bi-,and twinned-crystals of Co CrFe Ni HEA and compared the results with those obtained with uniaxial tensile and compression tests on polycrystalline bulk samples.Results show that SRS,as well as the yield strength and plastic flow behavior,in single crystals are orientation dependent due to the differences in the maximum Schmid factors.While the high-angle grain boundaries arrest dislocation motion,TBs allow for dislocation transmission through them,which result in distinct mechanical responses.While the bi-crystal’s deformation behavior is controlled by the‘hard’grain,twinned crystals exhibit an‘averaged’response.The large diversity of the reported SRS values in face centered cubic HEAs could be due to the varying fractions and thus contributions of annealing twins in the tested samples.

关 键 词：High-entropy alloy Strain-rate sensitivity Micropillar compression ORIENTATION NANOINDENTATION 

分 类 号：TG139[一般工业技术—材料科学与工程]