Structure and properties of detonation coatings based on gamma-TiAl

Investigations of a coating - substrate composite before and after oxidatio n in air at 900 degreesC revealed that the main structural features were: f ormation of an Al2O3 Scale on the surface of the TiAlCrSc(gamma) coating (a s a result of oxidation) and of inner layer at its interface with a 90% tit anium substrate (as a result of diffusion in the composite). The observed p henomenon was caused by a Kirkendall effect resulting in the formation of t itanium-enriched phases, apparently Ti3Al and alpha -Ti, which have a broad homogeneity range. The formation of a diffusion zone in the system with di splacement of the Kirkendall plane in the direction of the substrate has a positive effect on the adherence of the coating. Furthermore, the filling o f vacancies and pores in the coating with additional material supplied by t he diffusion of titanium should have a favorable effect on the strength and durability of the coating, particularly its fatigue resistance.