Формирование структуры сплавов системы олово—цинк при высокоскоростном затвердевании

Abstract

The results of a study of the structure parameters of rapidly solidified foil of a hypoeutectic, eutectic, hypereutectic Sn—Zn system alloys containing 4.4; 8.8 and 15 mas. % Zn are presented Rapidly solidified foil consists of equiaxed zinc particles and a supersaturated tin solid solution. Zinc particles are distributed uniformly in the foil, that is caused by the formation of a supercooled and supersaturated liquid solution and its subsequent spinodal decomposition. The areas of the liquid solution enriched with tin and zinc are transformed into nuclei of crystalline phases. With an increase in the zinc concentration in the studied alloys, the volume fraction of zinc particles, the average chord of random secant sections at the sections of zinc particles, and the specific surface of the interphase formed by zinc and tin increase. The foil of Sn—Zn alloys has a microcrystalline structure in which the predominant grain orientation is observed. The formation of the texture of (100) tin and (0001) zinc occurs. Rapidly solidified alloy foils are in an unstable state, that results in the decomposition of a tin solid solution, the dissolution of small particles and the growth of large particles. Annealing at 180 °C for 22 hours causes an increase in the average chord of sections of zinc particles, volume of zinc particles and a decrease in the specific surface of the interface.