Glass Forming Ability and Mechanical Properties of Cu-Zr-Al-Nb Amorphous Alloy

Cu46Zr44Al5Nb5 amorphous alloys were fabricated by suspend melting under an argon atmosphere using water-cooled Cu mould suction casting. Glass forming ability and mechanical properties of the alloys were studied. The analyses of DSC curves, X-ray diffraction (XRD) patterns and electron diffraction taken from the rods of Cu46Zr44Al5Nb5 with different diameters (3, 4, 6 mm) indicate that the critical diameter can be up to 6 mm at least. And the best glass former exhibits an undercooled liquid region Delta T of 52 K, and reduced glass transition temperature T-rg of 0.60. The critical cooling rate (R-c) calculated from TTT (Time-Temperature-Transformation) curves of Cu46Zr44Al5Nb5 forming glassy alloy is 3.985 K/s. The intensity of broad peaks from X-ray diffraction patterns, the crystallization enthalpy and the fracture strength of the amorphous rods with different diameters, exhibit obvious difference, which is related to the variation of the cooling rate of solidification for the rods with different size.