Bulk Amorphous Formation and Magnetic Properties of Nd-Fe-TM-Al Alloys by Containerless Process

The amorphous formation ability and the magnetic properties of Nd65Fe10X15Al10 (X = Co, Ni and Cu) alloys were studied by the gas flow levitating process. The gas flow levitating process enables solidification without any container wall by the inert gas jet. The samples were solidified at the cooling rate of around 100 K/s. Then, the undercooling degree of samples exhibited high values (Delta T = 94-138 K). In X-ray diffraction measurements, Nd65Fe10X15Al10 (X = Co and Ni) samples consist of mainly amorphous phase and the crystalline phase. The DTA curves of Nd65Fe10X15Al10 (X = Co, Ni and Cu) showed two exothermic peaks due to the crystallization. That is, it was revealed that the Nd65Fe10X15Al10 (X = Co and Ni) samples formed bulk amorphous or metastable phase. Also, the coercivity showed 3.6, 3.7 and 3.6 kOe for X = Co, Ni and Cu, respectively. Additionally, the microstructure of samples with high coercivity consists of metastable phase in the shape of sphere and amorphous matrix. The high coercivity depends on the metastable phase and amorphous phase by the isothermal annealing experiments.