Abstract
Zinc was electrodeposited on pure silver plates 1mm in thickness, which were then annealed at 473K in an argon atmosphere in order to obtain a corrosion resistant Ag-Zn alloy layer.
Observasion after annealing revealed a η phase (the solid solution of Ag in Zn), and three intermediate phases, ε, γ and ζ. After prolonged annealing the η solid solution layer supplied zinc atoms to the inner intermediate phase layers, thereby becoming porous.
When the electrodeposited zinc layer was 10μm in thickness, difficulty of the supply of zinc atoms from the porous layer lying on the specimen surface resulted in disapperance of the ε phase layer after 83ks annealing, and of the γ phase layer after 115ks annealing.
The porous surface layer was easily removed by buff polishing. The silver plates with zinc deposited layers 200μm in thickness were clamped to prevent void formation and used as a diffusion couple. The interdiffusion coefficient obtained were: 7.9×10-15-3.7×10-16m2/s at 13-30 at% Ag in the ε phase, 6.0×10-15-4.0×10-15m2/s at 34.9-37.9 at% Ag in the γ phase and 1.7×10-14-6.8×10-16 m2/s at 46.9-59.0 at% Ag in the ζ phase.
