Thermal stability and glass-forming ability of amorphous Nd-Al-TM (TM = Fe, Co, Ni or Cu) alloys

Abstract

Bulk amorphous alloys were prepared for Nd 70Al 10TM 20 and Nd 60Al 10TM 30 (TM = Fe or Co) alloys by copper mold casting. The maximum sample thickness for glass formation reaches 15 mm for the Nd-Al-Fe alloys and 5 mm for the Nd-Al-Co alloys, A significant difference in the phase transition upon heating is recognized between the Fe- and Co-containing alloys. No glass transition before crystallization is observed for the Nd-Al-Fe alloys, but the Nd-Al-Co alloys exhibit the glass transition. The ΔT x(= T x − T g) and T g/T m are 40–55 K and 0.65–0.67, respectively, for the latter alloys. The absence of supercooled liquid for the former alloys is different from those for all bulk amorphous alloys reported up to date. The T x/T m and ΔT m(= T m − T x) are 0.85–0.89 and 88–137 K, respectively, for the Nd-Al-Fe alloys and, hence, the large glass-forming ability is presumably due to the high T x/T m and small ΔT m values.