Thermal and mechanical characterizations of a Zr-based bulk metallic glass composite toughened by in-situ precipitated Ta-rich particles

The Zr₅₃Cu_30-xNi₉Al₈Ta_x (x = 2, 4, 6, 8) bulk metallic glass composites (BMGCs) rods with a diameter of 2-4 mm have been successfully fabricated by suction casting method in this study. The thermal and the mechanical properties of these Zr-based BMGCs were systematically investigated by the combination of DSC, XRD, SEM, TEM, and compression test. The results show that a superior mechanical performance with up to 30% compressive plastic strain, 1750 MPa yield strength and 2100 MPa fracture strength at room temperature can be obtained for the 2 mm diameter rod of the Zr₅₃Cu₂₂Ni₉Al₈Ta₈ BMGC. There are two kinds of in-situ dispersed Ta-rich particles, micro-sized (10-30 μm), and nano-sized (20-80 nm) were found homogeneously distributed in the amorphous matrix. These Ta-rich particles act as discrete obstacles in the amorphous matrix, which separates and restricts the highly localized shear-banding, avoiding shear-through of the whole sample. This results in the formation of multiple shear bands around the Ta-rich particles and decreases the stress concentration for further propagation of shear band, and so as to enhance plasticity dramatically. In addition, the Ta-added BMG also exhibits similar GFA in comparison with the base BMG.