文献类型：期刊文献

英文题名：Nanotwining induced by tensile fatigue and dynamic impact of laser powder b e d fusion additively manufactured CoCrFeNi high-entropy alloy

作者：Huang, Guoqing[1,2];Li, Bo[1,2,3];Chen, Yinan[2,3];Xuan, Fuzhen[1,3]

机构：[1]East China Univ Sci & Technol, Sch Mech & Power Engn, Shanghai 200237, Peoples R China;[2]East China Univ Sci & Technol, Addit Mfg & Intelligent Equipment Res Inst, Shanghai 200237, Peoples R China;[3]Shanghai Collaborat Innovat Ctr High End Equipment, Shanghai 200237, Peoples R China

年份：2024

卷号：183

起止页码：241

外文期刊名：JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY

收录：;EI(收录号：20234915187716);WOS:【SCI-EXPANDED(收录号:WOS:001134487800001)】；

基金：This research work is sponsored by the National Natural Sci- ence Foundation of China (Grant No. 52175140) , National Key R&D Program of China (Grant No. 2022YFB4602102) , Fundamental Re- search Funds for the Central Universities in China (Grant No. JKG01231610) , Pre research project of Civil Aerospace Technology (Grant No. D020301) , and Equipment Pre -research Sharing Technol- ogy Key Project (Grant No. JZX7Y20210422004601) .

语种：英文

外文关键词：High-entropy alloy; Nanotwins; Fatigue; Impact behavior; Additive manufacturing

摘要：The laser powder bed fusion (L-PBF) additively manufactured CoCrFeNi high-entropy alloy (HEA), with face-centered cubic (FCC) crystal structure, demonstrates better comprehensive mechanical properties in the building direction (BD). Loading quasi-static, dynamic fatigue, and dynamic separated Hopkinson press bar (SHPB) impact stress conditions along the BD of the L -PBF processed HEA exhibit intriguing microstructural evolution characteristics. The L -PBF generates hierarchical dislocation grids containing numerous cell substructures within the HEA FCC grains, impeding dislocation motion during deformation and improving the strength. When subjected to dynamic fatigue loading, the dislocation grids restrict the mean free path of dislocations and thus trigger the activation of abundant stacking faults. Hence, numerous nanotwins form near the end of the fatigue life. Multiple twinning systems can also be activated under dynamic high-speed impact loading. Especially at a low temperature of 77 K, the stacking fault energy of the CoCrFeNi HEA decreases, resulting in increased activation of nanotwins, exhibiting exceptional toughness and resistance to dynamic loads. Additional twin boundaries also impede dislocation movement for the strain hardening. These findings hold valuable implications for the study of additively manufactured HEA parts working in extreme environments. (c) 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.