|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Materials Science for High-Performance Permanent Magnets
||Microstructure Formation of Strip-cast R-Fe-B Alloys for Magnets
||Kazuhiko Yamamoto, Masashi Matsuura, Satoshi Sugimoto
|On-Site Speaker (Planned)
The purpose of this study is to clarify the microstructure formation in R-Fe-B strip-cast alloys, from nucleation to dendrite growth. Microstructure was observed using optical microscopy and field emission electron probe micro-analyzer. The nucleation area called the “disc” by Biloni et al., and pre-dendrites were observed in the vicinity of dimples distributed on the chilled surface in contact with the cooling roll. The discs was consisted of rare-earth elements (R) and Fe in the atomic ratio = 1:2, implying a Laves phase RFe2 composition. The pre-dendrites consisted of dendrites growing outward in all directions from the disc containing the fine R2Fe14B particles. The dendrites seemed to grow from the pre-dendrite, preferentially along the direction of thermal flow. Since these discs observed in the super-cooled area influence magnet fabrication adversely, it is important to avoid excessive super-cooling to obtain the preferred magnetic properties.