Bulk Amorphous Formation and Magnetic Properties of Nd-Fe-Co-Al Alloys by the New Gas Jet Flow Type Levitating Process

Abstract

The amorphous formation ability and the magnetic properties of Nd 60 Fe 30-x Co x Al 10 (x = 10, 15, 20 or 30) alloys in the containerless process were studied by the new gas jet flow type levitating process. The gas jet flow type 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 of samples exhibits high values (AT = 60-150 K). From X-ray diffraction measurements, the Nd 60 Fe 30-x Co x Al 10 samples exhibit a typical broad diffraction pattern for an amorphous structure. The DTA curves of x = 10, 15 and 20 showed an exothermic peak due to the crystallization. That is, it was revealed that the Nd 60 Fe 30-x Co x Al 10 samples formed bulk amorphous. Also, the coercivity is 1.6, 3.3 and 3.6kOe for the Nd 60 Fe 20 Co 10 Al 10 , Nd 60 Fe 15 Co 15 Al 10 and Nd 60 Fe 10 Co 20 Al 10 , respectively. From the thermomagnetic curves, the Curie temperature is determined to be 463, 482 and 482 K for the Nd 60 Fe 20 Co 10 Al 10 , Nd 60 Fe 15 Co 15 Al 10 and Nd 60 Fe 10 Co 20 Al 10 , respectively. In the M-H loops and the thermomagnetic curves, this difference between x = 10 and x = 15, 20 may depend on the microstructure.