The solid state reaction between Cu3P and silicon or germanium

The phase relations in low-phosphorus parts of the ternary systems Cu-Si-P and Cu-Ge-P have been determined for alloys annealed in evacuated capsules at 500°C. The reaction of Cu3P with silicon in diffusion couples that have been annealed in vacuum, is never faster than the reaction between copper and silicon. Cu3Si and phosphorus vapour are formed during the reaction. A peculiar morphology, that of isolated Cu3Si columns separated by large gaps, develops when the reaction is hindered. When a diffusion couple is annealed in a closed capsule, Cu3Si and presumably SiP are formed. The reaction between Cu3P and germanium takes place at a rate comparable with that of the copper-germanium reaction and leads to the formation of Cu3Ge and phosphorus vapour. Because of plastic deformation of Cu3Ge no peculiar morphology of the reaction layer was observed.