Microstructures evolution of directionally solidified Sn-16%Sb hyperperitectic alloy

Directional solidified microstructures of Sn-16% Sb hyperperitectic alloy have been investigated at various solidification rates using a high-thermal gradient directional solidification apparatus. The results indicate that the solidification microstructures consist of hard primary intermetallic SnSb phase embedded in a matrix of soft peritectic β-Sn phase. The primary SnSb phase exhibits the faceted growth with the tetragonal or trigonal shapes. At the same time, the primary SnSb phase is refined with the increase of the solidification rate and dispersed more uniformly in the matrix of β-Sn phase. The volume fraction of SnSb phase firstly decrease and then increase, when the solidification rate increases in directional solidification of Sn-16% Sb hyperperitectic alloy.