The Formation of the Structure of the Alloys of the Tin–Zinc System upon High-Speed Solidification

Abstract

The results of the study of the parameters of the structure of the fast-solidificated foil of hypoeutectic, eutectic, and hypereutectic alloys of the Sn-Zn system containing 4.4, 8.8, and 15 wt % Zn are presented. The fast-solidificated foil consists of equiaxial zinc particles and a supersaturated solid solution of tin. The zinc particles are uniformly distributed in the foil, which is induced by the formation of a supercooled and supersaturated liquid solution and its subsequent spinodal decomposition. The tin-and zinc-enriched regions of the liquid solution transform to crystalline phase nuclei. The volume fraction of zinc particles, the mean chord of the random secants on the sections of the zinc particles, and the specific surface of the inter-phase boundary formed by zinc and tin increase with the increase in the concentration of zinc in the alloys under study. The foil of the Sn-Zn alloys has a microcrystalline structure, in which crystallographic texture of the grains is observed. The formation of the (100) texture of tin and (0001) texture of zinc is observed. The fastsolidificated foils of the alloys are in an unstable state, which leads to the decomposition of the supersaturated solid solution, dissolution of small particles, and growth of large particles. Annealing at 180C for 22 h induces an increase in the mean chord of the sections of the zinc particles and volume of the zinc particles and a decrease in the specific surface of the interphase boundary.