In situ HEXRD study of a Ca61Al39 metallic glass

Abstract

High energy X-ray diffraction (HEXRD) was used to characterize the amorphous structure of the as-prepared binary Ca61Al39 (at.%) metallic glass and its evolution during thermal loading. The investigation was performed in both reciprocal and real space by means of the first diffuse peak (FDP) analysis and the reduced atomic pair distribution function (PDF) analysis, respectively. It was found that bond lengths of the atomic CaCa and CaAl pairs of the as-prepared structure were 3.70 Å and 3.24 Å, respectively. The coordination number of the first coordination shell was estimated to be 11.9. The analysis of the FDP behaviour during thermal treatment proposed the existence of the relaxation temperature Tr at 150 °C. Analysis of summations of all absolute differences between two consecutive intensity curves in the region of the FDP as a function of temperature revealed two crystallization temperatures at 280 °C and 305 °C. Products of a devitrification process were identified to be alike a triclinic Ca8Al13 and monoclinic Ca13Al14 phase.