A Comprehensive Investigation Of Phase Evolution Of Al-Si Coating During The Prolonged Aging At 650 Degrees C

Microstructural evolution of silicon-modified aluminide coating during 10,000 h aging at 650 degrees C was systematically investigated. Upon aging, the coating was gradually transformed from a multilayered structure to a double-layer structure, with the matrixes of Al-Fe-Si compounds and beta-(Fe, Ni)Al in the two layers, respectively. An internal oxide layer formed below the coating, while the thickness of interdiffusion zone (IDZ) increased as the inward diffusion of Al. Precipitate evolutions in both the coating and the IDZ were discussed, which clarifies the microstructural origin of long-term stability of the coating. The phase evolution of Al-Si coating in prolonged aging was further discussed.