Unraveling the Origin of the Excellent High-Temperature Oxidation Resistance of an Alcrfeniti High-Entropy Alloy

Abstract

The oxidation behavior of Al8Cr13.3Fe63.5Ni11.2Ti4 high-entropy alloy was studied in the air at 800 °C. Results show that the oxidation kinetics does not obey a parabola relationship. The oxidation process was divided into two distinct stages, transforming from an approximately parabolic law to a quasi-linear law at 10 h. This alloy exhibits excellent oxidation resistance with only 0.41 mg/cm2 of specific mass gain after 100 h oxidation, ascribed to the compact outer CrTi2O5+TiO2 and inner Cr2O3+nano-scale CrTi2O5 oxide layers. However, this oxide scale does not prevent the N from diffusion inward, forming the TiN and AlN in internal oxidation zone.

Keywords: High-entropy alloy, High-temperature oxidation, Oxide scale, TEM, On-axis TKD