Easy glass formation in Mg₆₄Ni₂₁Nd₁₅ by Bridgman solidification

Easy glass-forming Mg₆₄Ni₂₁Nd₁₅ alloy was subjected to Bridgman steady state directional solidification at growth velocities between 0.5 and 2.4 mm s^-1 through a temperature gradient of about 15 K mm^-1. X-ray diffraction (XRD) indicated crystalline solidification structure at 0.5 and 1.0 mm s^-1, amorphous with some residual crystallinity at 1.7 mm s^-1 and fully amorphous at 2.4 mm s^-1. The strongest XRD peaks at 0.5 and 1.0 mm s^-1 correspond to Mg₃Nd, the other phases present being, as yet, unidentified. Values of T_g and T_x of 467 K and 507 K respectively, determined by differential scanning calorimetry for the amorphous condition, match well our previous determinations from chill-cast or melt-spun ribbon of similar alloy composition. The significance of these results for an improved understanding of glass formation in this and related easy glass-forming systems is discussed.