Specific Heat and Solidification of Undercooled Bi-Sb Alloy Melts

Abstract

Phase selection and metastable phase formation during solidification of undercooled alloy melts have been studied using Bi-Sb alloys. Undercoolings larger than 0.2T 1 were obtained for bulk Bi 95 Sb 5 alloy melts. The factors which influence the undercooling behavior are discussed. Microstructures of the samples obtained at different undercoolings reveal that undercooling can play an important role on the formation of the final phase structure. The specific heat of the undercooled Bi 95 Sb 5 alloy melt is measured by DSC. Results of X-ray diffraction on the samples show that a metastable phase with tetragonal structure, which is similar to that existing stable under high pressure, can form if the undercooling of Bi 95 Sb 5 is 121K.