Atomistic insights into chemical short-range order and its impact on complex stacking fault energies in a CoNiV medium-entropy alloy

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The remarkable mechanical properties of high- and medium-entropy alloys are closely related to their complex atomic-scale chemical environments. In this study, we systematically investigated the formation and evolution of the chemical short-range order (CSRO) in an equiatomic CoNiV alloy using hybrid Monte Carlo/molecular dynamics simulations, with particular emphasis on the CSRO extending beyond the first and second nearest neighbors. Our results revealed a distinctive transition from D⁢0₂₂-like to L⁢1₂-like structures upon CSRO formation at intermediate temperatures. The development of CSRO significantly increases the stacking fault energy and, concomitantly, reduces the stacking fault width. Quantitatively, a linear relationship between the average degree of CSRO and stacking fault energy is established. Furthermore, repeated dislocation slips progressively disrupt CSRO and influence both the complex stacking fault energies and antiphase boundary energies. Our work provides atomistic insights into the interplay between CSRO and fault energies that govern deformation mechanisms in a model system, CoNiV, thereby offering a theoretical foundation for the process design and optimization of advanced multicomponent alloys.