Dynamic tensile deformation of Al0.1Ti0.1CoCrFeNi high entropy alloy with heterogeneous grain structure

Abstract

The single-phase Al0.1Ti0.1CoCrFeNi high-entropy alloy (HEA) with heterogeneous grain structure was processed through cold rolling followed by annealing at 1073 K. The mechanical behaviors of this HEA under quasi-static (10−3 ∼ 10−1 s−1) and dynamic (1200 ∼ 3000 s−1) uniaxial tension were investigated. A combination of high tensile strength and large fracture strain was achieved. Specifically, the yield strength and ultimate tensile strength were increased from 381 MPa and 1000 MPa at 10−3 s−1 to 590 MPa and over 1200 MPa at a strain rate of 3000 s−1, respectively. Meanwhile, the engineering fracture strain of the HEA increased from 43 % to 62 % with increasing strain rate. Under dynamic tension, a high density of dislocations, together with numerous deformation twins and stacking faults, inside the fine grains contributed to the simultaneous improvement of the tensile strength and ductility.