Mechanism of solute hardening and dislocation debris-me diate d ductilization in Nb-Si alloy  

作　　者：Bo-Qing Li Irene J.Beyerlein Shuhei Shinzato Shigenobu Ogata Wei-Zhong Han 

机构地区：[1]Center for Advancing Materials Performance from the Nanoscale,State Key Laboratory for Mechanical Behavior of Materials,Xi’an Jiaotong University,Xi’an 710049,China [2]Materials Department,University of California,Santa Barbara,CA 93106-5070,USA [3]Department of Mechanical Engineering,University of California,Santa Barbara,CA 93106-5070,USA [4]Department of Mechanical Science and Bioengineering,Osaka University,Osaka 560-8531,Japan

出　　处：《Journal of Materials Science & Technology》2024年第36期167-179,共13页材料科学技术(英文版)

基　　金：supported by the National Natu-ral Science Foundation of China(Nos.51971170 and 51922082);the Shaanxi Science&Technology Innovation Project(No.2022QFY10-03);the assistance of Dr.Ping-Jiong Yang during the earlier stage of this project.S.O.and S.S.were supported by the Ministry of Education,Culture,Sport,Sci-ence and Technology of Japan programs(Nos.JPMXP1122684766,JPMXP1020230325,and JPMXP1020230327);JSPS KAKENHI(No.JP23H00161).S.S.was supported by JSPS KAKENHI(Nos.21K14042 and 22H05283).S.S.and S.O.wish to thank Dr.Tomo-hito Tsuru for discussions regarding NNP creation.

摘　　要：Niobium(Nb)is sensitive to even minute quantities of silicon(Si)solutes,which are known to induce pronounced hardening.However,the underlying mechanism for hardening remains elusive since the ef-fect of Si solutes on dislocation behavior is unclear.Here,using tensile testing,in-situ microscopy and nanomechanical testing,the behavior of dislocations in dilute Nb-Si alloys,containing from 0 at.%to 0.8 at.%Si,is investigated.We show that the hardness,strength and strain hardening rate increase from two to four times,while the uniform elongation in tension only reduces 50%as the Si content increases.Dislocations evolve from complex entangled patterns in Nb to parallel long-straight screw dislocation-dominated structures in Nb-Si alloys.In-situ indentation reveals that the origins of the marked harden-ing in Nb-Si alloy are the reduction of dislocation mobility and cross-slip propensity.Large densities of dislocation debris-superjogs and loops introduced throughout the sample during warm rolling and an-nealing are found to provide active internal dislocation sources,which explain the minimal ductility loss seen in these Nb-Si alloys.These findings can help guide the alloy design of high-performance refractory materials for extreme temperature applications.

关 键 词：NIOBIUM Si solute HARDENING Ductilization DISLOCATION 

分 类 号：TG1[金属学及工艺—金属学]