Microstructure of Rapidly Solidified Alloys of the Sn–Zn–Bi–In System

Abstract

The results of a study of the phase composition and microstructure of foils of Sn–8.0 Zn–3.0 Bi–X In (X = 1.5, 2.5, 4.5, 9.0) (wt %) alloys formed by rapidly quenching from the melt at a cooling rate of up to 5 × 10⁵ K/s have been presented. The dependence of the phase composition of the rapidly quenched foils on the concentration of In has been determined. It has been shown that, in rapidly quenched foils, crystallization occurs with the formation of supersaturated solid solutions based on β-Sn and γ phase (Sn₄In). The mechanisms and rates of decomposition of the supersaturated solid solutions at room temperature have been established. The specific features of the formation of the microstructure of the foils have been discussed. The grain structure has been studied by the electron back-scatter diffraction (EBSD) method; the formation of an elongated shape of grains and the high specific surface area of small-angle boundaries has been explained.