Commercial alloy compositions through a high-entropy lens

After over 20 years of intense study, there is no compelling high-entropy alloy (HEA) application. To explain this, we hypothesize that a major fraction of HEAs are compositionally similar to many commercial alloys, especially those based on 3d transition metals. We explore this hypothesis by characterizing commercial alloys from a high-entropy perspective–we count the number of concentrated elements and calculate their ideal configurational entropy and lattice distortion. We also calculate the compositional distances between 1496 commercial alloys and HEAs. Five separate analyses all show that 3d transition metal HEAs are compositionally similar to Fe-base, Ni-base, Co-base, and Cr-base commercial alloys, supporting our hypothesis. We also show that three concentrated elements are enough to achieve exceptional properties, with one that typically reaches concentrations as high as 75 at%. To guide future work, we highlight compositional areas as yet untouched by both conventional alloys and the HEA approach.