Development of Refractory High Entropy Alloys with Tensile Ductility at Room Temperature

In this study, a low-cost refractory high-entropy alloy (RHEA) with obvious macroscopic tensile ductility was designed. The evolution of the microstructures and fundamental mechanical properties with the TiZr concentration in arc-melted (TiZr)x(NbTaV)1−x (x = 0.4, 0.6, and 0.8) high-entropy alloys (HEAs) were investigated. The alloys (TiZr)0.4(NbTaV)0.6 and (TiZr)0.6(NbTaV)0.4 had a single body-centered cubic solid solution phase. Two phases were confirmed in the as-cast (TiZr)0.8(NbTaV)0.2 alloy using X-ray diffraction and scanning electron microscopy. All three alloys had dendritic structures with severe element segregation. (TiZr)0.4(NbTaV)0.6 had a high yield strength of 1300 MPa with a compressive fracture strain of 16%. (TiZr)0.8(NbTaV)0.2 showed exceptional compressive plasticity but a low yield strength. (TiZr)0.6(NbTaV)0.4 had a relatively uniform yield strength and compressive fracture plasticity (950 MPa and 35%). In addition, (TiZr)0.8(NbTaV)0.2 also had a tensile ductility of 7% at room temperature.