Microstructural features and tensile behaviors of the Al0.5CrCuFeNi2 high-entropy alloys by cold rolling and subsequent annealing

Abstract

The Al0.5CrCuFeNi2 HEAs with three different statuses (as-cast, -rolled, and -annealed) are prepared to investigate their microstructure evolutions and tensile behaviors. The as-cast sample exhibits simple solid-solution dendrite structure, imperfect lattice configurations (dislocation lines and stacking faults), and moderate tensile properties. Relying on the significantly-enhanced dislocation density, the as-rolled alloy demonstrates a rapidly-increased tensile strength, but that has come at the expense of the tensile elongation. Annealing treatments reveal that the temperature effect evidently influences the tensile strength of the annealed samples, indicating the recovery of the dislocations with the temperature. Annealing twinning crystals and subgrains induced by the aforementioned lattice defects are embedded on the recrystallized grains, suggesting that multiple deformation mechanisms are possible upon sample loading. The annealed alloys mainly exhibit intergranular-dominated fracture features, which yields a limited modification of the tensile plasticity as compared with the as-rolled alloy.