Effect of cooling rate on fluidity and glass-forming ability of Zr-based amorphous alloys using different molds

Abstract

Herein, the effect of cooling rate on fluidity and glass-forming ability (GFA) of the Zr41.2Ti13.8Cu12.5Ni10Be22.5 amorphous alloy is systematically studied by using a self-designed fluidity testing system and gravity casting. The molds are made of refractory steel, purity graphite and copper with spiral cavities. Moreover, the fluidity model of amorphous alloy is established and flow length is calculated based on the heat balance theory. Furthermore, the fluidity of amorphous alloy melt is quantitatively and qualitatively analyzed by comparing the calculated and experimentally measured flow lengths. The results reveal that the cooling capacity of mold mainly influences the flow length of amorphous alloy melt. Moreover, the discrepancy between experimentally measured and theoretically calculated flow lengths can be ascribed to the difference between actual and theoretical thermophysical parameters. X-ray diffraction (XRD), differential scanning calorimetry (DSC) and high-resolution transmission electron microscopy (HRTEM) reveal the traces of crystalline phase in samples prepared using steel and graphite molds, however, the crystalline phase is not observed in the case of copper mold. The results demonstrate that the mold material renders a certain influence on GFA of Zr41.2Ti13.8Cu12.5Ni10Be22.5 amorphous alloy.