Study of the Diagram of Cu-Si-Zn Alloy, On the Range Near η Phase

Abstract

The range near η solid solution of the Cu-Si-Zn system has been investigated by means of thermal analysis, measurement of electrical resistance and microscopic examination. The η solid solution, which is a Cu₃Si solid solution, has two transformations of η\ ightleftharpoonsη′ and η′\ ightleftharpoonsη″. That is, the peritectoids of γ+η\ ightleftharpoonsη′ and γ+η′\ ightleftharpoonsη″ are at 620°C and 570°C and the eutectoids of η\ ightleftharpoonsη′+Si and η′\ ightleftharpoonsη″+Si are at 558°C and 467°C respectively, in Cu-Si binary system. And in the ternary system, the non-variants to ε′+η\ ightleftharpoonsγ+η′, η\ ightleftharpoonsγ+η′+Si, ε′+η′\ ightleftharpoonsγ+η″, and γ+η′\ ightleftharpoonsη″+Si are found at 600°, 530°, 500° and 480°C, respectively. The twin of the solid solution found in the cast or annealed alloys is the annealing twin attributed to the transformations.