Element Diffusion and Interface Characteristics between NiCrAlY Coating and Ni-Base Single Crystal S

A NiCrAlY coating was deposited on a Ni-base superalloy substrate by magnetron sputtering. The elemental diffusion and the microstructural change in the interface zone between the NiCrAlY coating and the substrate were investigated. It was shown that the elemental distribution in the as-sputtered NiCrAlY coating was homogeneous and had an abrupt change at the interface between the substrate and coating. During vacuum heat treatment, microstructure changed and a phase transformation took place in the coating because of interdiffusion between the substrate and coating. An interdiffusion layer (outer and inner diffusion layer) appeared and two new phases, g-Ni3Al and a-Cr, emerged from local Cr-rich regions in the coating. After 200h oxidation at 1 000℃, the interdiffusion layer thickened, beneath which diffusion influence layer emerged because of the further diffusion of elements. Ta replaced some of the Al in the g-Ni3Al phase, resulting in an increase of the lattice parameter a0 of g phase.