Solid plasticity and supercooled-liquid thermoplasticity of Zr-Cu-enriched hypoeutectic Zr-Cu-Ni-Al cast glassy alloys

The plasticity of Zr-Cu enriched hypoeutectic Zr-Cu-Ni-Al cast glassy alloys (CGAs) was investigated to determine their tensile elongation as a solid at room temperature, and their precise thermoplastic moldability in a supercooled liquid state. The viscosity of the supercooled liquids was measured by using a penetration viscometer at a high-speed heating rate of 400K/min. The results obtained show that with an increase in the Zr content, the glass transition temperature (T_g) tends to decrease, whereas the crystallization temperature (T_x) tends to increase. We observed tensile elongation with plural sliding shear bands in the Zr-Cu enriched Zr₆₅Cu₂₀Ni₅Al₁₀ CGAs at room temperature. Furthermore, the hypoeutectic Zr₆₅Cu₁₈Ni₇Al₁₀ CGA exhibits the widest δT_x (=T_x-T_g) of about 170K, with a low viscosity in the order of 10⁵Pas being observed in the supercooled liquid under a heating rate of 400K/min. The potential for printing micro-patterns on the surface of a glassy Zr₆₅Cu₁₈Ni₇Al₁₀ alloy is demonstrated by means of tough nanocrystalline Ni-W electro-plating molds.