Electron microscopy of microstructural transformation in electrodeposited Ni-rich, Ag–Ni film

• Amorphous Ag–Ni film with a fibrous microstructure was electrodeposited.
• Isothermal annealing led to amorphous-to-crystalline transition.
• Initial crystallization produced solid solution Ni–Ag phase.
• Nano-sized particles evolved gradually with time during annealing.
• The kinetics of decomposition of the solid solution phase was extremely slow.

Ag–Ni films were electrodeposited over a Cu substrate. Structural characterization revealed a fibrous microstructure with an amorphous structure for the as-deposited film. Isothermal annealing at 400 °C of the film inside transmission electron microscope led to amorphous-to-crystalline transition along with the evolution of nano-sized particles in the microstructure. The crystalline phase was Ni–Ag solid solution. The relative volume fraction of the nano-sized particles increased gradually with time. There was however no detectable decomposition of solid solution phase till about 4 h of annealing. Beyond 4 h phase separation initiated and pure Ag and Ni phases formed in the film. This study provides a methodology by which microstructural engineering of as-electrodeposited amorphous Ag–Ni films can be conducted to isolate a particular microstructure in order to tap specific potentially usable functionalities.