Abstract:Cylindrical ingots of bulk amorphous Nd₇₀Fe₂₀Al₁₀ with a diameter of 8  mm were prepared by a copper mold casting method. It was proved that as-prepared samples are mainly consisted of amorphous phase by measurement of  X-ray diffraction, observation of scanning electronic microscopy and analysis of differential scanning calorie. The onset crystallization temperature (T_x) and the melting temperature (T_m) of the samples were measured to be 743 K and 823 K, respectively. The temperature interval between T_xand T_m(ΔT_m) is as small as 80 K and the resulting reduced ratio of T_x/T_m is as high as 0.90. The extremely high T_x/T_m and the small ΔT_m values are assumed to be the reason for the achievement of the large glass-forming ability. The Curie temperature (T_c) of these samples was determined to be 525 K by magnto-thermal gravity analysis, which is higher than the highest T_c of binary Nd-Fe amorphous alloys. Dual phase alloys of different nano-crystalline volume fraction were obtained by means of various annealing treatments to the as-prepared samples. The magnetic measurement indicated that the hard magnetic behaviour of the dual phase samples deteriorates most at the volume fraction about 40%, which has predicted in our previous theoretical computation.

Key words: solidification; rare-earth; amorphous/nano-crystalline alloy; magnetism