Ultrafine-grained dual phase Al0.45CoCrFeNi high-entropy alloys

A duplex microstructure consisting of body-centered-cubic (BCC/B2) and face-centered-cubic (FCC) phases was observed after homogenization and recrystallization treatments in Al0.45CoCrFeNi high-entropy alloys (HEAs). The precipitates of BCC phase effectively suppressed the grain growth during recrystallization and annealing, resulting in an ultrafine-grained microstructure. Analysis based on the modified Zener-Smith model and growth kinetics for grain size of the matrix indicate the phase boundaries act as strong obstacle for grain coarsening. This dual phase HEAs exhibit yield strength values varying widely from 300 MPa to 1200 MPa, depending on the heat treatment conditions and corresponding microstructures. An excellent combination of yield strength (similar to 980 MPa), ultimate tensile strength (similar to 1160 MPa), and tensile elongation (similar to 15%) was achieved by optimizing and coupling both phase precipitation and recrystallization kinetics. The current work describes a strategy in developing high-performance ultrafine-grained HEAs for future industrial applications. (C) 2019 The Authors. Published by Elsevier Ltd.