Transmission electron microscopic observations of amorphous NiZr alloy formation by solid-state reaction

The interdiffusion of nickel and zirconium by a solid-state reaction to form an amorphous NiZr alloy has been followed by transmission electron microscopy. Cross-sectional examination of NiZr bilayers annealed at 300°C has shown the formation of amorphous NiZr and the development of large voids in the nickel neighboring the Ni/NiZr interface. Our results indicate that nickel is the dominant diffusing species in the amorphous alloy and that the diffusion requires a defect mechanism. Prolonged annealing at 300°C results in the formation of a crystalline NiZr phase, which co-exists with the amorphous alloy.