Martensite formation in a ductile Cu47.5Zr47.5Al5 bulk metallic glass composite

The evolution of the microstructure and the mechanical properties of differently solidified Cu47.5Zr47.5Al5 alloys with different thickness, was investigated. The alloy was obtained by arc-melting a mixture of 47.5 at. % Cu, 47.5 at.% Zr and 5 at. % Al in Ti gettered Argon atmosphere. The prealloy was remelted several times to achieve chemical homogeneity. X-ray diffraction was performed in transmission geometry using a STOE STADI P diffractometer equipped with Mo-Ka1 radiation. A Pekin-Elmer Diamond differential scanning calorimetry (DSC) was also operated at a heating rate of 40 K/min. The microstructures and fracture surfaces were investigated with a Zeiss DSM 962 scanning electron microscope (SEM) at voltage of 25 kV coupled with energy-dispersive x-ray spectroscopy (EDX). Results show that the volume fraction increases with increasing casting thickness, while the Poisson's ratio along with ductility decreases.