Hardening of an Al0.3CoCrFeNi high entropy alloy via high-pressure torsion and thermal annealing

High-pressure torsion (HPT) and thermal annealing were applied to a face-centered cubic as-cast Al0.3CoCrFeNi high entropy alloy. Processing by HPT produced a nanostructure with a higher incremental hardness than in most HPT single-phase materials and subsequent annealing at appropriate temperatures gave an ordered body-centered cubic secondary phase with an additional increase in hardness. The highest hardness after HPT and annealing was approximately four times higher than for the as-cast alloy. •An Al0.3CoCrFeNi alloy (HEA) was nanostructured by high-pressure torsion (HPT).•The HPT HEA exhibits a higher hardness increment than most single-phase materials.•A combination of HPT and annealing significantly strengthens the HEA hardness.•The highest hardness after HPT and annealing is ~4 times over for the as-cast HEA.