Pairwise dilatational strain as a parametric model describing potential secondary phase formation and high-angle grain misorientation in as-cast high-entropy alloys

Crystallographic strain in high-entropy alloys (HEAs) can affect not only structure stability, but also their mechanical properties. This is studied by comparing the effects of different alloying additions in CoCrFeNi-Ax (A: Mn, V0.3, Ti0.4, Pd1, and Pd1.5) FCC HEAs on their calculated dilatational strains. Dilatational strain values are found to be proportional to the EBSD population of misoriented microstructures at 53–60°. Larger magnitudes of the dilatational strain are exhibited by FCC-stabilising alloying additions. EBSD and TEM suggest increased twin presence for higher strain compositions. This means that HEAs can be designed to present higher ductility if dilatational strain can be maximised when structural stability can be maintained. These model-property relationships can be incorporated into metaheuristic objective functions as an alloy design strategy.