Phase prediction in high entropy alloys*

The term “High entropy” alloys (HEA) refers to a relatively new class of multicomponent—usually five or more—metallic alloys in equal or near equal atomic concentrations. The complex compositions of these alloys, and their derivatives, lead to unique properties. 

Phase prediction in multicomponent alloys remains one of the most fundamental challenges.  We propose a Multi-Cell Monte Carlo algorithm, or (MC)^2, for predicting stable phases in chemically complex crystalline systems. This algorithm takes advantage of multiple cells to represent possible phases while eliminating the size and concentration restrictions in their previous counterparts. Free atomic transfer among cells is achieved via the application of the lever rule, where an assigned molar ratio virtually controls the percentage of each cell in the overall simulation, making (MC)^2 the first successful algorithm for simulating phase coexistence in crystalline solids. We test the method by successfully predicting the stable phases of known binary systems. We then apply the method to several families of “high-entropy” alloys. This method is particularly powerful when applied to multicomponent systems for which phase diagrams do not exist.