Change in the primary solidification phase from fcc to bcc-based B2 in high entropy or complex concentrated alloys
Résumé
An examination of a compositionally graded AlxCuCrFeNi2 high entropy alloy (HEA) or complex concentrated alloy (CCA), revealed that marginally increasing Al content from x = 0.8 to x = 1.0 (+ 6 at.%) changes the primary solidification phase from a simple disordered-fcc to a bcc-based ordered-B2 phase. Subsequently, a second solidification product forms, a disordered-bcc in case of x = 0.8 and a disordered-fcc in case of x = 1.0. Solid-state decomposition within these phases results in fcc + L12 and bcc + B2 products, accompanied by compositional partitioning. These results provide new insights into the influence of Al on the primary solidification product, and have been rationalized using a computational thermodynamic approach.