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

Bulk amorphous alloys were prepared for Nd70Al10TM20 and Nd60Al10TM30 (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 ΔTx(= Tx − Tg) and Tg/Tm 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 Tx/Tm and ΔTm(= Tm − Tx) 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 Tx/Tm and small ΔTm values.