High-temperature polymorphism of tin

Abstract

Using the methods of low-frequency internal friction, microhardness, differential thermal analysis, and x-ray diffraction analysis, the authors investigate the specifics of the high-temperature β-γ polymorphic transformation in high-purity tin. The multistep nature of this transition, which is unusual for pure metals, is demonstrated. This transition is represented by a series of specific mixed phase transitions. The hypothesis is advanced that β tin is transformed into its high-temperature modification through the formation of intermediate metastable phases, and a new scheme is proposed for this transformation. The lattice constants and melting temperature of one of the metastable phases are determined.