On the superior hot hardness and softening resistance of AlCoCrxFeMo0.5Ni high-entropy alloys

► Increasing Cr content increases the volume fraction of σ phase. ► Cr-2.0 alloy has the highest hot hardness Hv 450 at 1273 K. ► Cr-2.0 alloy possesses the lowest softening coefficient which is related to the multi-principal-element effect. ► Schematic phase diagram of AlCoCrxFeMo0.5Ni providing valuable information for alloy design and prediction.