Chemical short-range order regulates hydrogen energetics and hydrogen-dislocation interactions in CoNiV

Abstract

Chemical short-range order (CSRO) has emerged as a critical structural feature in concentrated alloys, yet its coupling with hydrogen remains an active discussion. Here, we develop a machine-learning interatomic potential for the Co-Ni-V-H system and investigate how CSRO regulates hydrogen energetics and dislocation behavior in CoNiV, an alloy with reported strong resistance to hydrogen embrittlement. We identify strong V-centered ordering that suppresses V–V clustering and remains robust up to 1000 K, with negligible changes upon the addition of 1.0 at.% hydrogen. Compared to a chemically random alloy, the ordered state exhibits higher average hydrogen solution energies and a reduced population of strongly binding sites, suggesting lower bulk hydrogen uptake. At partial dislocations, hydrogen preferentially segregates to tensile core regions, where the dislocation core acts as a shallow, reversible trap, with a much weaker effect compared to chemical trapping states. These results show that robust local chemical order plays a critical role in affecting H uptake, partitioning, and dislocation trapping in concentrated CoNiV alloys.