2020/03/15 by Spencer L. Thomas, Thomas, Spencer L., Srikanth Patala +1 · 1 citation
Engineering · #FOS: Physical sciences #High Entropy Alloys Studies #High Temperature Alloys and Creep #High-Temperature Coating Behaviors #Materials Science (cond-mat.mtrl-sci)
paper · pdf · doi:10.48550/arxiv.2003.06900
openalex publication_date 2020/03/15 · openalex created_date 2022/07/26 · openalex updated_date 2026/07/28
Many of the purported virtues of Multi-Principal Element Alloys (MPEAs), such\nas corrosion, high-temperature oxidation and irradiation resistance, are highly\nsensitive to vacancy diffusivity. Similarly, solute interdiffusion is governed\nby vacancy diffusion -- it is often unclear whether MPEAs are truly stable, or\neffectively stabilized by slow interdiffusion. The considerable composition\nspace afforded to these alloys makes optimizing for desired properties a\ndaunting task; theoretical and computational tools are necessary to guide alloy\ndevelopment. For diffusion, such tools depend on both a knowledge of the\nvacancy migration barriers within a given alloy and an understanding of how\nthese barriers influence vacancy diffusivity. We present a generalized theory\nof vacancy diffusion in rugged energy landscapes, paired with Kinetic Monte\nCarlo simulations of MPEA vacancy diffusion. The barrier energy statistics are\ninformed by nudged elastic band calculations in the equiatomic CoNiCrFeMn\nalloy. Theory and simulations show that vacancy diffusion in solid-solution\nMPEAs is not necessarily sluggish, but can potentially be tuned, and that trap\nmodels are an insufficient explanation for sluggish diffusion in the CoNiCrFeMn\nHEA. These results also show that any model that endeavors to faithfully\nrepresent diffusion-related phenomena must account for the full nature of the\nenergy landscape, not just the migration barriers.\n