Synchrotron X-ray radiation diffraction studies of thermal expansion, free volume change and glass transition phenomenon in Cu-based glassy and nanocomposite alloys on heating

Abstract

Thermal expansion and volume changes due to structural relaxation during heat treatment in glassy alloys were studied in situ using Synchrotron X-ray radiation diffractometry. A glass transition phenomenon was also detected. Synchrotron X-ray radiation diffractometry was successfully used for studying dilatation, glass transition and volume change phenomena detecting excess free volume and in glassy alloys. Good correspondence of the thermal expansion coefficients was obtained independently by thermo-mechanical length change measurements and Synchrotron X-ray radiation diffractometry as well as the glass transition temperature obtained by DSC and Synchrotron X-ray radiation diffractometry. The reduced average free volume change is smaller in the alloy consisting of the glassy matrix containing the nanocrystalline phase compared to the fully glassy alloy.