Simultaneously enhanced oxidation resistance and mechanical properties in a novel lightweight Ti2VZrNb0.5Al0.5 high-entropy alloy

Abstract

Enhanced oxidation resistance is a primary demand for the application of refractory high-entropy alloys (RHEAs) at elevated temperatures. In this study, Al was added to a Ti2VZrNb RHEA to partially substitute Nb to improve its oxidation resistance and mechanical properties. The alloy was found to have an increased oxidation resistance by forming a continuous Al2O3 + ZrO2 oxide protective surface. At the same time, the room-temperature yield strength was also increased by 66% to 1273 MPa via solid solution strengthening. The low atomic mass of Al also helped to reduce the density of the alloy by 8.2% to 5.44 g cm−3. This resulted in a high specific yield strength of 234 MPa cm3 g−1 for the alloy. Meanwhile, the Ti2VZrNb0.5Al0.5 alloy also exhibited a high compressive plasticity of >50%. These values are among the best reported so far for RHEAs.