Abstract
The gas jet flow type electromagnetic levitation process is one of the containerless processes. The levitated sample under gas jet flow in quartz holder is cooled and solidified instantly, when electromagnetic power is shut down. The sample can not be affected by electromagnetic convection. In this work, Nd-Fe and Pr-Fe alloys were solidified at various cooling rates by using the gas jet levitation, a drop tube process and a splat quenching process. In the gas jet levitation process, undercooling of LRE90Fe10 samples increased with cooling rate. Undercooling, ΔT of Nd90Fe10 samples was 35 K when solidified at 268 K/s, the coercivity was about 4.5 kOe at room temperature. Coercivity of Nd60Fe40 samples produced by splat quenching process was about 4.1 kOe. Both samples showed the same Curie temperature. The coercivity of Nd60Fe40 samples solidified by the drop tube process depended on diameter of the samples. When the sample diameter was 212～300 μm range, the coercivity showed the maximum value, 2.6 kOe. The coercivity of the LRE-Fe samples was caused by fine microstructure of metastable phase.
