Sluggish diffusion in random equimolar FCC alloys

Compositionally complex alloys, also known as high entropy or multiple principle component alloys, can exhibit greatly improved mechanical properties. Researchers often ascribe this to sluggish diffusion that is thought to result from having multiple constituents. Here, the authors present a systematic investigation of diffusion in multielement alloys with molecular dynamics simulations. Only a small minority of the studied alloys show sluggish diffusion, whereas the large majority show diffusion that is faster or even vigorous. The authors find that diffusivities do not correlate with the number of constituents, but instead strongly correlate with the mismatch in lattice constants among the elements.