Oxidation resistance of Ti₈Zr₆Nb₄V₅Cr₄lightweight high-entropy alloys by different trace addition of Al

A series of Ti₈Zr₆Nb₄V₅Cr₄ lightweight high-entropy alloys with different trace addition of Al were prepared, and high temperature oxidation resistance tests for the alloys were tested at 800°C/100 h. Results show that oxidation weight gain of the alloys with trace addition of Al from 0.1at.% to 0.4at.% is decreased from 546.0 mg/cm² to 175.3 mg/cm². Moreover, thickness of oxide film for different alloys decreases significantly from 995 µm to 645 µm. Oxides formed on oxidation surface are greatly affected by Al content, and cracks on oxidation surface of the alloy with higher Al content are obviously reduced. Increase of dense TiO₂, Ti₄Cr₃Nb₃O₂, CrVNbO₆, and Al₂O₃ oxides within the oxide film can effectively prevent further diffusion of oxygen, and therefore significantly improve oxidation resistance of the alloys.