Thermodynamic analysis of nanocrystalline solid solutions formation in copper‐lead‐tin ternary immiscible system during mechanical alloying

In this paper, copper‐15 wt.%‐lead‐1 wt.%‐tin (Cu‐15wt %Pb‐1wt %Sn), copper‐15 wt.%‐lead‐2 wt.%‐tin (Cu‐15wt %Pb‐2wt %Sn) and copper‐15 wt.%‐lead‐3 wt.%‐tin (Cu‐15wt %Pb‐3wt %Sn) powder mixtures were mechanically alloyed in order to study the solid solubility extension during the alloying process. Nanocrystalline supersaturated solid solutions have been prepared in copper‐lead‐tin (Cu−Pb−Sn) ternary immiscible system by mechanical alloying (MA). Based on the thermodynamic model, the Gibbs free energy changes in these alloys during the formation of solid solutions are calculated to be positive, which means that there are no driving force to form solid solutions in copper‐lead‐tin ternary immiscible system. It was found that a large fraction of grain boundaries and a high density of dislocations play a significant role in the solid solubility extension in copper‐lead‐tin ternary immiscible system.