Study of the Pressure−Time−Temperature Transformation of Amorphous La6Ni5Al89 by the Energy Dispersive Method for Phase Transition

Abstract

An energy dispersive X-ray diffraction method to observe phase transitions is applied to follow the crystallization of an amorphous alloy (La6Ni5Al89) in isothermal conditions. In this way, the diffraction-based configurational entropy (DCE) of the system undergoing the phase transformations was measured and the curves describing the transitions, qualitatively equivalent to a differential scanning calorimetry (DSC) thermogram, could be drawn. Finally, the analysis of such curves allowed calculation of some points of the alloy pressure−time−temperature transformation (PTTT) diagram. More importantly, the present work shows that the DCE method can be successfully applied even when DSC can no longer be used. As a consequence, regions of the phase diagram that could not be reached up to now become accessible, opening the way to the study of transition phenomena under extreme conditions.