Phase evolution in an Al0.5CrFeCoNiCu High Entropy Alloy

The phase evolution of an Al_0.5CrFeCoNiCu High Entropy Alloy has been characterised following isothermal exposures between 0.1 and 1000 h at temperatures of 700, 800 and 900 °C. The NiAl based B2 phase formed extremely quickly, within 0.1 h at the higher exposure temperatures, whilst the Cr-rich σ phase formed more slowly. The solvus temperatures of these two phases were found to be ∼975 and ∼875 °C respectively. Compilation of the data presented here with results previously reported in the literature enabled the production of a time-temperature-transformation diagram, which clearly indicates that the diffusion kinetics of this material cannot be considered sluggish.