Effect of solidification process on magnetic properties of Nd-based bulk amorphous forming alloy

The magnetic behavior and structure of Nd60Al10Fe20Co10 bulk amorphous forming alloy prepared under a wide cooling rate, from 1 K/s to 105 K/s, by means of fluxing method, drop tube, suction casting and melt-spinning were studied. The samples achieved by suction casting, melt-spinning and drop tube undergo a cooling rate larger than 30 K/s, and comprise a large fraction of amorphous phase. Samples produced by fluxing method with the cooling rate in the magnitude of 1 K/s are fully crystallized. The room temperature hysteresis loops of the samples with high cooling rate show one ferromagnetic phase, which decomposes upon crystallization of the amorphous phase at about 750 K. The drop tube and fluxing samples exhibit two-phase hysteresis loops at room temperature, and the hard magnetic phase is found stable upon heating to 773 K. The crystalline hard magnetic phase in the slowly cooled sample shows comparable coercivity and Curie temperature with that of the metastable ferromagnetic phase in the amorphous alloys. These trends suggest that all phases have a similar local structure and chemical composition