To improve the high temperature wear resistance of Ti-46?5Al-1Cr-1?5V, an Al/Al 2 O 3 composite ceramic coating was prepared on it by radio frequency sputtering. In this paper, microstructure, elements distribution, phase identification of the Al/Al 2 O 3 composite coating were investigated. Also, its nanohardness and elastic modulus were examined. High temperature dry sliding wear behaviour at 300uC was analysed in details. The results indicated that the homogeneous and dense composite coating was about 20 mm thick. Additionally, the composite coating possessed higher H/E and H 3 /E 2 ratios than those of substrate. Compared to the substrate, the Al/Al 2 O 3 composite coating recorded a lower friction coefficient and the volume loss of Al/Al 2 O 3 coating was only 1/3 of the bare substrate under dry sliding conditions at 300uC. All the results demonstrated that the Al/Al 2 O 3 coating has effectively improved the wear resistance of Ti-46?5Al-1Cr-1?5V at 300uC.

A TiAl 3 -rich coating was developed by hot-dip aluminizing method and subsequent interdiffusion treatment on Ti-6.5Al-1Mo-1V-2Zr (mass %) alloy for high temperature resistance. Interrupted oxidation at temperatures from 973 to 1173 K and isothermal oxidation at temperatures from 923 to 1073 K of the TiAl 3 -rich coating were conducted. The coating markedly decreased the oxidation rate in comparison with the substrate alloy at 1073 K and lower during the interrupted oxidation, and a layered structure of Al 2 O 3 /TiAl 3 /TiAl 2 /TiAl/alloy from the outside to the inside formed after oxidation at 973 K without changing the main body of the TiAl 3 -rich coating. The oxidation kinetics followed parabolic relations during the stable state stage of the isothermal oxidation; the activation energy for oxidation of the coating was calculated as 323 kJ mol 1 . The hot-dip aluminizing coating provided high protectiveness for the Ti-6.5Al-1Mo-1V-2Zr alloy at 973 K and lower. The oxidation performance of the TiAl 3 -rich coating was discussed in detail.Keywords. Ti-6.5Al-1Mo-1V-2Zr, high temperature oxidation, hot-dip aluminizing, activation energy.