Metastable Phase Formation and High Coercivity of Nd90Fe10 by Gas Flow Type Levitating Process

Abstract

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.