Solid-solution strengthening of Ti-Zr-Hf-Nb-Ta-Fe refractory high-entropy alloy

Ti-Zr-Hf-Nb-Ta system refractory high-entropy alloys (RHEAs) exhibits outstanding tensile ductility in room temperature. However, the moderate yield strength of them is insufficient. In this work, the Fe element with small atomic radius was added into a non-equiatomic Ti-Zr-Hf-Nb-Ta RHEA for furtherly improving the yield strength. As a result, the yield strength of modified RHEA is as high as ∼970 MPa, while retains a considerable fracture train of ∼17.5%. However, the Hf2Fe brittle precipitates were formed at grain boundary after aging treatment, leading to a further increment of yield strength but severe deterioration of ductility.