文献类型：期刊文献

英文题名：Hydrogen segregation by local chemical ordering structure in CrCoNi medium-entropy alloys: A first principle study

作者：Yin, Xunlu[1];Liu, Xingxing[1];Chen, Hao[1];Chen, Shaohua[2,3]

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]Beijing Inst Technol, Inst Adv Struct Technol, Beijing 100081, Peoples R China;[3]Beijing Inst Technol, Beijing Key Lab Lightweight Multifunct Composite M, Beijing 100081, Peoples R China

年份：2023

卷号：34

外文期刊名：MATERIALS TODAY COMMUNICATIONS

收录：;EI(收录号：20230213361549);WOS:【SCI-EXPANDED(收录号:WOS:000991795500001)】；

基金：Acknowledgments This work was supported financially by the National Natural Science Foundation of China (No. 52005186) . HC acknowledges supports by Shanghai Sailing Program, China (20YF1409400) .

语种：英文

外文关键词：First-principle calculation; Monte Carlo method; Diffusion barrier; Local chemical ordering; Medium-entropy alloys

摘要：The solution energy (Es) of the hydrogen (H) atom in the octahedral interstitials (OIs) of the CrCoNi medium entropy alloys (MEAs) is investigated based on the random solid solution (RSS) and local chemical ordering (LCO) models. Results show that the distribution of Es can be well represented by a Gaussian distribution with an average energy of 0.033 eV in the RSS model with a maximum value of E-s = 0.14 eV. In comparison, the distribution of Es is separated into three parts in the LCO model. The first part is the value of E-s higher than 0.5 eV, where Co-Cr ordering around these OIs. The second part is the lower part in which the Es value is lower than 0.17 eV. The atomic environment around these OIs are occupied by H atoms exhibit local Ni bias. The third part is E-s between 0.17 eV and 0.5 eV, which hardly exists and accounts for only 4%. The separation of the Es comes from the effect of the LCO structure, in which two heterogeneous chemical environments appear (localized Ni bias and Co-Cr ordering). When H atoms lie in the OIs with E-s in the first part of the LCO model, the diffusion energy barrier disappears and the H atoms spontaneously move to lower energy sites, leading to the segregation of H atoms in the LCO model. However, when H atoms lie in the OIs of the lower second part, the migration barriers of the H atom between energetically stable OIs in the LCO model (0.3 eV to 1.38 eV) are higher than those in the RSS model (0.4 eV to 0.6 eV). Our study discloses the atomic-scale mechanisms of good resistance to hydrogen embrittlement (HE) of CrCoNi MEAs to some extent.