Structure-property relations in Pb-supersaturated metastable Sn-rich Pb-Sn alloys

Abstract We have performed a theoretical study of three different allotropes of Pb-supersaturated Sn-rich Pb-Sn alloys with the α-Sn, β-Sn and a simple hexagonal γ-Sn structure employing quantum-mechanical calculations. Structure-property relations were analyzed in the case of the lattice parameters, thermodynamic stability, elastic properties and mechanical stability as well as electronic-structure density of states. Compositional trends in structural, thermodynamic and electronic-structure properties were found nearly linear. Our theoretical study sheds new light on a decades-long controversy related to the γ-phase of supersaturated Sn-rich Pb-Sn alloys. We suggest that the experimental difficulties to synthesized the γ-phase solid solutions are due to the high formation energy of this phase.