文献类型：期刊文献

英文题名：The influence of L12 ordered precipitates on hydrogen embrittlement behavior in CoCrNi-based medium entropy alloys

作者：Cheng, Huijie[1];Lu, Xu[2];Zhou, Jingjing[1];Lu, Tiwen[1];Sun, Binhan[1];Zhang, Xian-Cheng[1];Tu, Shan -Tung[1]

机构：[1]East China Univ Sci & Technol, Sch Mech & Power Engn, Key Lab Pressure Syst & Safety, Minist Educ, Shanghai 200237, Peoples R China;[2]Norwegian Univ Sci & Technol, Dept Mech & Ind Engn, Richard Birkelands Vei 2B, N-7491 Trondheim, Norway

年份：2023

卷号：260

外文期刊名：ACTA MATERIALIA

收录：;EI(收录号：20233714716472);WOS:【SCI-EXPANDED(收录号:WOS:001080024300001)】；

基金：This work was financially supported by the National Key Research and Development Project (No. 2022YFB4600019) , National Natural Science Foundation of China (No. 52275147, No. 52205152) , and the Science Center for Gas Turbine Project from China (Project No. P2022-C- III-002-001).

语种：英文

外文关键词：Hydrogen embrittlement; Medium-entropy alloy; Coherent precipitates; Intergranular cracking; H-enhanced decohesion

摘要：The recently emerged multicomponent (or medium/high entropy) alloys have generated considerable excitement globally in the last 10 years because of their excellent mechanical and functional properties, particularly in terms of strength-ductility combinations that can surpass most other metallic materials. However, the achieved high strength level (above 1 GPa in many cases) fuels strong concerns about hydrogen embrittlement (HE). Detailed investigation in this field is still scarce, especially pertaining to the face-centered cubic medium entropy alloys (MEA) that are typically strengthened by ordered precipitates. Here, we unravel the effect of gamma' (L1(2)) ordered precipitates on H-induced damage behavior and the associated HE resistance in CoCrNi-based MEAs. Compared with the equi-molar CoCrNi MEA, the precipitation-hardened (CoCrNi)(94)Al3Ti3 MEA shows an enhanced HE resistance even at a higher strength level. Both alloys are fractured due to H-assisted intergranular cracking at the initial failure stage when loaded in the presence of H. The formation of intergranular cracks is primarily attributed to the H-induced decohesion at grain boundaries, where a high stress/strain concentration accompanied by a more intensive dislocation planar slip (or stacking fault formation) caused by H was observed. The presence of gamma' precipitates serves to slow down the internal diffusion/migration of H due to the trapping effects. The precipitates with a relatively larger size (similar to 50 nm) also hinder dislocation planar slip thus decreasing the number of pile-up dislocations at grain boundaries. Both effects collectively reduce the tendency of H-induced intergranular cracking, leading to the improved HE resistance. The work reveals the positive role of ordered precipitates in H tolerance and thus provides some insights in further microstructure design of medium/high entropy alloys for applications in H-abundant environment.