Effect of crystalline phases on deformation and warm formability of a bulk metallic glass composite within supercooled liquid region

The thermal and mechanical properties of a Zr66.4Nb6.4Cu10.5Ni8.7Al8.0 bulk metallic glass composite (BMGC) have been investigated. The thermal properties were determined by using a differential scanning calorimeter (DSC), while the phase and composition analysis of crystalline precipitates within glassy matrix were carried out by X-ray diffraction (XRD). The deformation behavior has also been investigated through a series of compression tests performed under several strain rates between 10(-4) s(-1) and 10(-2) s(-1) at various temperatures within supercooled liquid region (SLR). This BMG composite was found to have improved high temperature strength compared to other Zr-based monolithic BMGs. The in situ formed crystalline phases are believed to hinder the viscous flow of glassy matrix to raise the high temperature strength, compensating more the minor softening of crystalline phases at higher temperatures within the SLR. The warm formability of the composite was also estimated by applying the dynamic materials model (DMM) and the results were verified by subsequent laboratory-scale extrusion tests. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.