Significant plasticity enhancement of ZrCu-based bulk metallic glass composite dispersed by in situ and ex situ Ta particles

Using two-step arc melting process and suction casting, the Zr_47.3Cu₃₂Al₈Ag₈Ta₄Si_0.7-based bulk metallic glass composites (BMGCs) rods with ex situ added micro-sized Ta particles have been successfully fabricated. The structure and thermal properties of these BMGCs samples were examined by differential scanning calorimeter (DSC) and X-ray diffraction (XRD). It was found that these BMGCs with ex situ added Ta exhibit similar thermal properties in comparison with their base alloy counterpart, with relatively high glass forming ability (GFA). For the mechanical study, the results of compression test show that more than 25% compressive plastic strain and 1800MPa fracture strength at room temperature can be obtained for the 2mm diameter rod of the ZrCu-based BMGC ex situ added 6 and 9vol.% Ta particles, respectively. Images from SEM on the fractured surfaces show that the homogeneously distributed Ta particles (20±8μm) would form semi-uniform confinement zones to restrict the shear band propagation. In other words, the inter-particle free space and the size of confinement zone (mean free path of shear bands) is apparently the controlling factor in affecting the plasticity of BMGCs.