Oxidation of double-glow plasma chromising coating on TC4 titanium alloys

► A chromising coating was prepared on titanium alloys by plasma alloying technology. ► The isothermal oxidation of the chromising coating was studied at 650-850 °C. ► The Ti-Cr mutual diffusion layer of chromsing coating prevented the intrusion of O. ► A multi-layer structure with Cr2O3, TiO2, and Al2O3 was formed during oxidation. ► Ti, Al, and Cr diffused predominantly outward during oxidation.