Achieving superior cryogenic tensile properties in a Ti-doped (Fe₄₀Mn₄₀Co₁₀Cr₁₀)_96.7C_3.3 high-entropy alloy by recovering deformation twinning

K. Tang^a, Y.K. Wu^a, R. Wei^b, L.B. Chen^a, S. Lu^c, Y.L. Qi^a, F. Jiang^a*, J. Sun^a

^aState Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiao tong University, Xi'an 710049, China

^bSchool of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001, China

^cApplied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, Stockholm SE-10044, Sweden

Abstract

A minor Ti-doped (Fe₄₀Mn₄₀Co₁₀Cr₁₀)_96.7C_3.3 high-entropy alloy presents a higher yield strength and a littler lower elongation than the un-doped one at room temperature. And more interestingly, superior cryogenic temperature (77 K) tensile properties: yield strength of ~1 GPa, ultimate tensile strength of ~1.5 GPa, and elongation of ~52 % are achieved in this alloy. The high yield strength is attributed to the improved strengthening effect by the grain boundary and nano-sized TiC precipitation and the better ductility at cryogenic temperature is ascribed to the recovery of deformation twinning by titanium addition. It is proposed that the critical twinning stress of C-contained alloy is temperature dependent, which is related with the unbalanced pinning effect assisted twinning mechanism due to carbon diffusion.

该合金在液氮温度表现出良好的强度和塑性配合，采用了卢松博士的碳原子钉扎辅助孪晶机制来解释了实验现象，论文提出含碳高熵合金的孪晶形成应力是与环境温度密切相关，而不是常认为的 roughly temperature-independent。 

感谢审稿人、编辑、合作者（郑大的魏然博士、信阳师范的陈良斌博士、瑞典皇家理工学院的卢松博士）还有我们自己。