Surface microstructure of aluminized CoCrAlY coating irradiated by high current pulsed electron beam

A thermally sprayed CoCrAlY coating was prepared by air plasma spray on Ni-based superalloy GH4169, then a nano-scale Al film was deposited by electric beam evaporation. The coating was subjected to a high current pulsed electron beam. After HCPEB treatment, the Al film was remelted. The XRD result showed that Al phase was formed in the irradiated coatings, and the original Co-based oxide disappeared, but the content of β-CoAl was increased with the increase of irradiated pulses. Microstuctural observations revealed that the original coating with porosity, cavities and inclusions was significantly changed to a compact appearance with interconnected bulged nodules after HCPEB treatment. Moreover, the grains on the irradiated coating were very refined and homogeneously dispersed on the surface, which could effectively inhibit the infiltration of corrosive gases and improve the oxidation resistance of coating.