Strengthening of an Al0.45CoCrFeNi high-entropy alloy via in situ fabricated duplex-structured composites.

Phase precipitation and recrystallization process of Al_0.45CoCrFeNi high-entropy alloys (HEAs) were investigated by calculation of phase diagram and electron backscattered diffraction. To reveal the influences of microstructures on the response of mechanical behaviors, the tensile properties, hardness, elastic modulus, and fracture characteristics were thoroughly studied here. The as-processed duplex microstructures demonstrate that intercritical annealing treatments in the dual-phase filed could greatly slow down the recrystallization kinetics, attributing to the in situ precipitation of Ni, Al-rich phase formed initiatively along grain boundary. A series of fine-grained dual-phase HEAs, accompanying with yield strength widely ranging from 558 to 1223 MPa, were well fabricated via annealing the cold-rolled HEAs. Surprisingly, present HEAs exhibit excellent resistance to anneal softening, together with a relatively high recrystallization temperature of 900 °C (~ 0.63 T_m). Additionally, the coupled effect of fine-grain strengthening and precipitation strengthening is successful in manipulating the properties of face-centered-cubic HEA system. [ABSTRACT FROM AUTHOR]