Microstructural evolution at grain boundary and deformation mechanism of Nb_(0.5)TiZrV_(0.5)refractory high entropy alloy doped with Ce at room temperature  

作　　者：H.L.Yao Y.X.Yu J.B.Sha 

机构地区：[1]School of Materials Science and Engineering,Beijing University of Aeronautics and Astronautics,Key Laboratory of Aerospace Materials and Performance(Ministry of Education),Beijing 100191,China

出　　处：《Journal of Materials Science & Technology》2024年第29期25-39,共15页材料科学技术(英文版)

基　　金：financially supported by the National Natural Science Foundation of China(No.52071007).

摘　　要：Nb_(0.5)TiZrV_(0.5)alloy is one of the lightweight refractory high-entropy alloys(RHEAs)and has a great potential to be structural materials.Here,the microstructural evolution at the grain boundaries(GBs),the tensile properties and the deformation mechanism including dislocation and kink evolution of arc-melting(Nb_(0.5)TiZrV_(0.5))_(100-x)Ce_(x)RHEAs(at.%,x=0,0.005,0.01,referred to as 0Ce,0.005Ce and 0.01Ce alloys)at room temperature(RT)were systematically investigated.Ce was found to segregate at GBs and the most pronounced grain refinement effect in the 0.005Ce sample.With the Ce content increased from 0.005 at.%to 0.01 at.%,the Ce concentration at GBs increased from 0.12 at.%to∼1.17 at.%,subsequently,inducing compositional fluctuation and facilitating transformation of BCC band(V-rich but Zr-poor)toω-like phase with a non-close-packed hexagonal structure(NCPHS,V-and Zr-rich but Ti-poor)at GBs.The 0.005Ce al-loy exhibited the optimized ductility(ε_(f)∼7.15%)and maintained yield strength of approximately 964 MPa at RT.The better balance of strength-ductility in the 0.005Ce alloy was resulted from synergistic deformation of multiple grains,high fraction(55.6%)of movable edge dislocations and abundant kink bands with the most slip systems.However,deteriorating ductility(ε_(f)∼2.29%)of the Nb_(0.5)TiZrV_(0.5)alloy with 0.01 at.%Ce addition was mainly attributed to precipitation of the brittleω-like phase at GBs.These results may provide theoretical and experimental guidance for design of the advanced RHEAs with high specific strength through doping Ce or other rare-earth elements.

关 键 词：Refractory high entropy alloy Cerium addition Microstructure Tensile behaviors Deformation 

分 类 号：TG1[金属学及工艺—金属学]