Microstructure and high temperature oxidation resistance property of packing Al cementation on Ti-Al-Zr alloy

The aluminide coating was prepared on Ti-6Al-2Zr-1Mo-1 V titanium alloy by pack cementation to enhance the high temperature oxidation resistance for aircraft and aerospace applications. High temperature oxidation behaviors of packing cementation coated and uncoated titanium alloy samples were comparatively investigated by isothermal oxidation at 800 °C and 900 °C in air. The results show that the compact coating with about 60 μm thick was composed of TiAl₃. With isothermal oxidation for 100 h at 800 and 900 °C, the weight gains of the coated samples are 1.29 mg·cm⁻² and 4.06 mg·cm⁻² respectively, which are about 2/5 and 1/5 of that of titanium alloy substrates (3.20 mg·cm⁻² and 20.33 mg·cm⁻²). The excellent oxidation resistance performance is attributed to the formation of a continuous and dense Al₂O₃ layer on the TiAl₃ coating surface, which was effective to prevent the O element diffusing into the coating and then reduce the oxidation rate.