Abstract: Microstructure and composition distribution of diffusion layer of four binary equal atomic alloys, Cu₅₀Ni₅₀, Cu₅₀Co₅₀, Fe₅₀Ni₅₀ and Fe₅₀Cr₅₀, after copper plating and diffusion at 850 ℃ for 10 h, were studied. The results show that after diffusion treatment at 850 ℃ for 10 h, there is obvious mutual diffusion between Ni atom and Cu atom due to the existence of suitable vacancies in Cu₅₀Ni₅₀ alloy, and the mutual diffusion between Cu atom and Fe atom often occurs at grain boundary. In the diffusion couple of Cu-Fe₅₀Ni₅₀, there is mutual diffusion between Cu atom and Fe atom. In Cu-Fe₅₀Cr₅₀ and Cu-Cu₅₀Co₅₀ diffusion couple, no atoms diffuse.

Key words: binary equal atomic alloy, mutual diffusion, suitable vacancies