Phase equilibria of an Al0.5CrFeCoNiCu High Entropy Alloy

The phase equilibria of an Al0.5CrFeCoNiCu High Entropy Alloy has been studied following 1000 h exposures at 700, 850 and 1000 °C. Above 1000 °C, the material comprised of two fcc solid solutions, one a multi-element phase and the other a Cu rich phase. Below 1000 °C, the fcc phases persisted, but were accompanied by the formation of two intermetallic compounds. In contrast to previous reports, the L12 phase was also found to precipitate through a solvus at~850 °C. The results indicated that a solid state single phase field does not exist in this material at any temperature and all of the observed phases could be rationalised with reference to existing phase diagrams. This suggests that configurational entropy does not overcome the enthalpic contribution to the Gibbs energy, which governs phase equilibria of this alloy.