Hot compression behaviors and microstructure evolutions of a cast dual-phase NiCoFeCrAl0.7 high-entropy alloy

Hot compression behaviors and microstructure evolutions of a cast dual-phase NiCoFeCrAl0.7 high-entropy alloy (HEA) consisting of 79.2 vol% face-centered-cubic (FCC) plus 20.8 vol% body-centered-cubic (BCC) phases were investigated under various parameters. Dynamic recrystallization (DRX) dominated the flow softening behavior, strongly depending on the hot compression parameters. The constitutive equation describing the correlations between the flow stress and hot compression parameters was constructed, and the activation energy of the dual-phase HEA was significantly improved up to approximately 379.81 kJ/mol. The curves of X-drx (volume fraction of DRX grains) against the strain exhibits a "C" shape. Continuous dynamic recrystallization (CDRX) governed the flow softening, which was preferred in the FCC phase. With the proceeding of hot compression, the substructure within the deformed microstructure evolved in a sequence from the disordered dislocations, cellular structure, subgrain to DRX grains.