Role of Chemical Short‐Range Order in Point‐Defect Formation Energetics of CrCoNi Medium‐Entropy Alloy

Abstract

The formation energy of point defects is a key parameter governing their concentration, stability, and evolution under both equilibrium and nonequilibrium conditions. In medium‐ and high‐entropy alloys (M/HEAs), intrinsic chemical complexity produces a broad distribution of defect‐formation energies, in contrast to the comparatively well‐defined values typical of pure metals and dilute alloys. However, how chemical short‐range order (CSRO) modifies these energetics remains incompletely understood. Here, we employ first‐principles calculations to systematically investigate the formation energies of vacancies and interstitials in random solid‐solution (RSS) and CSRO‐containing CrCoNi alloys. The results show that local compositional fluctuations and chemical ordering generate pronounced site‐to‐site variations in the formation energies of both defect types. More importantly, CSRO shifts the energy distributions toward higher values, making the formation of vacancies and interstitials thermodynamically less favorable. These findings provide quantitative atomic‐scale insight into the influence of CSRO on point‐defect energetics and establish a thermodynamic basis for understanding defect stability and evolution in irradiated CrCoNi alloys.