Interface Thermal Stability Diffusion Aluminide and Silicon Aluminide Coatings with Ni-Based Superalloy GTD- 111

Thermal stability of aluminide coatings are affected by chemical and phase changes of the coating and coating/substrate interface. In this paper the coating thickness and structure stabilities within interfaces of both simple and silicon-modified aluminide coatings with GTD-111 superalloy substrate were investigated. The coatings were prepared by high-activity pack aluminizing and slurry aluminizing, respectively. Thermal stability test was conducted in 950? C for 1000 h. Microstructural changes of the coatings during high temperature exposure were characterized by optical and scanning electron microscopes. The results indicated that the substrate/coating interfaces in both coatings comprised of two diffusion layers of PID and SID during 100-1000 h of the high-temperature exposure. However, it was found that Si has a minor effect on the phase morphology and widening of the PID and SID in the aluminide coatings.