Recrystallization of a novel two-phase FeNiMnAlCr high entropy alloy

Abstract

Cold rolling followed by annealing was performed on the as-cast, two-phase (f.c.c. + B2), lamellar-structured high entropy alloy Fe28.2Ni18.8Mn32.9Al14.1Cr6. The cold-rolled Fe28.2Ni18.8Mn32.9Al14.1Cr6 showed a very high yield strength of 1422 MPa due to the high dislocation density (>1 × 1015 m−2), but only 2.3% elongation to failure. Annealing produced recrystallization, which caused the as-cast lamellar microstructure to be replaced by an equi-axed, duplex grain structure consisting of discrete B2 and f.c.c. grains with both different compositions and volume fractions. The recrystallized alloy showed a yield strength of ∼600 MPa and an elongation of ∼20%, which was only slightly different from the as-cast mechanical properties, a feature ascribed to the similarity in the scale (0.5 μm) of the microstructure in the two states. It was found that although initial plastic deformation takes place in the f.c.c. phase, specimens either cold-rolled or strained to failure showed that both phases plastically deformed.