Oxidation behavior of the Ti₃₈V₁₅Nb₂₃Hf₂₄ refractory high-entropy alloy at elevated temperatures

Abstract

The oxidation behavior of the Ti38V15Nb23Hf24 refractory high-entropy alloy (RHEA) in air was systematically studied in this work. Two distinct types of oxidation behavior were observed. Below 1000 ℃, a dense composite oxide scale with highly consistent lattice constant and crystallographic orientation was formed on the surface, while above 1000 ℃, internal oxidation with the formation of needle-like HfO2 occurred in the alloy matrix below the alloy-scale interface. The internal oxidation is caused by the sufficient inward-diffusing oxygen after the decomposition of dense outer oxide layer with sluggish oxygen diffusivity. This research provides new understanding for the development of new antioxidation RHEAs.