FORMATION OF SILICONIZED LAYER ON TiAl-BASED ALLOY AND THE OXIDATION RESISTANCE

The Ti-48Al alloy was pack siliconized with 15%Si+85%Al2 O3. The microstructure of the siliconized coating on the TiAl-based alloy was analyzed and its effect on oxidation resistance was investigated. The specimens before and after cycle oxidation were examined by XRD and SEM equipped with XEDS. The results showed that the coating is composed of a thin Al2 O3 outer layer and a composite inner layer of Ti5Si3 with an appropriate amount of Al2 O3 dispersed in. Cycle oxidation tests showed that the high temperature oxidation resistance of TiAl-based alloy was greatly improved by forming such composite coating. No spallation and crack happened and the weight gain was very small after cycle oxidation at 900℃ for 314h.