Dilatational strain biplots against enthalpy of mixing for predicting high-entropy alloys and complex concentrated alloys phase stability

Multiple principal component alloy systems are a new class of alloys that can provide interesting combinations of functional and mechanical properties. Due to the multiple principal components, their interactions are complex, and their structural stabilities are often not easily predicted. Prediction parameter biplots offer a good way to distinguish between structural stabilities of different compositions. The enthalpy of mixing is one parameter that is often used in such biplots. Although it does not accurately follow quantum principles, it is nevertheless this deviation that gives it its predictive power when combined with other parameters in a biplot. This deviation can be in part attributed to the mechanical strain energy (from large atomic size difference) that may be present in alloy systems. Such a biplot can leverage on their expected deviations to provide a prediction scheme. Here, we investigate the predictive efficacy of enthalpy-of-mixing/strain-energy biplots using cluster analysis. The results are validated against enthalpy-of-mixing/valence electron concentration biplots. The investigated biplot not only maintains the ability to distinguish between the intermetallic and solid solutions phases but offers enhanced ability to distinguish between individual intermetallic phases (Sigma, Laves, Mu, and B2).