Easy glass formation in La- and Pd-based alloys by Bridgman solidification

Critical cooling rates for easy glass formation in La-based La₅₅Al₂₅Ni₁₀Cu₅Co₅ and Pd-based Pd₄₀Ni₁₀Cu₃₀P₂₀ alloys, which exhibit a wide supercooled liquid region, are directly measured using Bridgman solidification technique. The formation of the amorphous state of the resulting samples was confirmed by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and optical microscopy (OM). The critical cooling rates (R_c) for glass formation in La₅₅Al₂₅Ni₁₀Cu₅Co₅ and Pd₄₀Ni₁₀Cu₃₀P₂₀ were determined to be 18.8 and 1.9 K/s respectively. The glass forming ability of the La₅₅Al₂₅Ni₁₀Cu₅Co₅ alloy using the avoidance of crystallization approach has been evaluated from the time-temperature-transformation (TTT) curve using Volger-Fulcer-type viscosity-temperature expression.