Solid solubility extension of copper-tin immiscible system during mechanical alloying

In this paper, copper-5wt.%-tin (Cu-5wt%Sn) powder mixture was mechanically alloyed in order to study the solid solubility extension during the alloying process. Nanocrystalline supersaturated solid solution has been prepared in this system by high energy ball milling. Based on the thermodynamic model, the Gibbs free energy change in this alloy system during the formation of solid solution is calculated to be positive, which means that there is no driving force to form solid solution in copper-tin (Cu-Sn) immiscible system. It has been found that a large fraction of grain boundaries and a high density of dislocations play a significant role in the solid solubility extension of immiscible copper and tin.