Kinetics and Mechanism of the C49 to C54 Titanium Disilicide Polymorphic Transformation

Abstract

ABSTRACTThe kinetics and mechanism of the C49 to C54 TiSi2 polymorphic transformation have been investigated in a temperature range from 660 to 720°C using in situ sheet resistance measurement and transmission electron microscopy. The kinetics results were correlated with the microstructural changes during the phase transformation. The main structural characteristics demonstrating the mechanism of the transformation were established by examining the nucleation and growth of the C54-TiSi2 in the polycrystalline C49-TiSi2 thin films. It was found that the C54 nuclei predominantly formed at grain edges (three-grain junctions) of the C49 phase and grew very fast by moving its incoherent interphase boundaries. Preliminary results have not revealed rigorous orientation relationships between the two phases. It is suggested that the C49 to C54 structural transition is massive in nature.