The oxidation-resistance mechanism of WTaNbTiAl refractory high entropy alloy

The WTaNbTiAl alloy demonstrated excellent oxidation resistance with a 31.83 mg/cm2 of specific mass gain after 48 h oxidation at 1000 °C in the air environment. Based on the multi-scale microstructural characterizations, a diffusion-controlled three-layers oxide scale model was proposed to explain the oxidation kinetics of this RHEA. In addition, thermodynamic calculation results shed light on the formation mechanism of the oxides based on the standard free energy of formation. The present work uncovered the oxidation-resistance mechanism of WTaNbTiAl RHEA via delicate microstructural analysis of oxides, which assists to guide the design of oxidation-resistant high entropy alloys. [Display omitted] •Uncover the oxidation-resistant mechanism WTaNbTiAl alloy via mult-scale electron microscopy characterizations.•A novel diffusion-control three-layers oxide scale model is proposed for WTaNbTiAl alloy.•The formation mechanism of the oxides is identified via the thermodynamic calculations.