Effect of high pressure on phase diagram of Zn-Sn system

Phase relation of the Zn-Sn system at various pressure up to 7 GPa is investigated by means of isobaric measurement of electrical resistance. Pressure vs. temperature phase diagrams of Zn-91 mol%Sn, Zn-49 mol%Zn and Zn-10 mol%Sn alloys as well as an isobaric phase diagram of the Zn-Sn system at 5 GPa are constructed on the basis of the results. A new eutectoid horizontal caused by the appearance of the high pressure gamma phase of tin appears in the phase diagrams. The cross point of the eutectic and eutectoid phase boundaries is 3.9 GPa and 273 degrees C. An intermediate electron phase with simple hexagonal structure known in many binary alloy systems was not stable in the Zn-Sn system within the present conditions of high pressure and temperature. In the heating run of temperature vs. electrical resistance curves on the Zn-Sn alloys, a delay of the ending temperature of the reaction at liquidus is observed under high pressures. It is considered to be caused by insufficient interdiffusion of zinc and tin in the liquid phase.