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.