The magnetic properties and amorphous formation ability of Pr-based alloys have been reported and discussed. In this paper, Pr 90 Fe 10 alloys were studied to reveal the solidification behavior associated with undercooling, magnetic properties of the metastable phase, and relation between undercooling and metastable phase formation by using the gas flow levitation method. The samples were solidified at various cooling rates from approximately 50 K/s to approximately 270 K/s. Undercooling increased with the cooling rate. According to the results of the SEM-EDS analysis, the Pr 90 Fe 10 samples that solidified at high undercooling conditions in eutectic reactions consist of the primary -Pr, eutectic -Pr, and metastable phases whereas the samples that solidified at low undercooling conditions in eutectic reactions consist of the primary -Pr, eutectic -Pr, and Pr 2 Fe 17 phases. Additionally, the magnetic properties changed due to the undercooling.

In the last decades, Nd Fe amorphous alloys have been studied by many methods because of high coercivity at room temperature and relation to Nd Fe B permanent magnets. In this study, we examined the effect of the containerless process for high undercooling and the metastable phase formation in detail.In the gas levitating process, undercooling of Nd 90 Fe 10 samples increased with cooling rate. Undercooling of Nd 90 Fe 10 sample solidified at 268 K/s is DT＝35 K. The primary a Nd phases were surrounded by fine metastable phases. And the intergranular eutectic like areas were comprised of a Nd phase and metastable phase. In contrast, the sample with low undercooling was comprised of a Nd phases and rod like Nd 2 Fe 17 phases among primary a Nd phases. In Nd 90 Fe 10 samples with undercooling of DT＝ 35 K, coercivity of Nd 90 Fe 10 samples is about 4.5 kOe at room temperature. This high coercivity is caused by fine crystallization of matastable phases.