Intermetallic phases formed by ruthenium–nickel alloy interdiffusion

Diffusion couples were formed between elemental ruthenium and a low refractory-content nickel-base superalloy. The couples were heat treated at various temperatures to evaluate diffusion paths and phase equilibria between the constituent materials. The interfacial layers formed by interdiffusion have been evaluated by electron microprobe analysis and transmission electron microscopy. An intermetallic Heusler phase, based on Ru2AlTa, formed at the interface of the couples during heat treatment. Two buttons of similar composition to the interface layer were arc-melted and analyzed by X-ray diffraction and transmission electron microscopy. The results of these analyses and their implications for nickel-based systems and their coatings will be discussed.