Nanostructure-property relation of Σ5 grain boundary in HfNbZrTi high-entropy alloy under shear

Recently, the HfNbZrTi high-entropy alloy (HEA) has received extensive attention due to its exceptional mechanical properties, which is ascribed to the significant lattice distortion and complex structural evolution induced by inherent chemical short-range order (CSRO). In this study, we employ molecular dynamics (MD) technique to study nanoscale CSRO phenomenon and its influence on the mechanical response of Σ5(210) and Σ5(310) grain boundaries (GBs) in HEA under shear loadings. Results reveal an apparent CSRO manifested by clustering of Hf-Nb and Zr-Ti pairs consistent with experimental observations. Further analyses on some representative Σ5 GB models unveil that the presence of CSRO can induce transformation of GB structure, which not only causes a transition in deformation behavior from migration-dominated to sliding but also raises the yield strengths. Moreover, after probing into the stress–strain curves and the relative sliding energy curves of massive GB models, we discover that the transition in GB behavior is ascribed to the CSRO impeded dislocation motion. The findings of this work promote atomistic understanding on the CSRO modulated shear response of GBs in HfNbZrTi HEA.