|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Materials Science for High-Performance Permanent Magnets
||Microstructure and Coercivity in Ultra-fine Grained Nd-Fe-B Sintered Magnets
||Taisuke Sasaki, Tadakatsu Ohkubo, Yasuhiro Une, Hirokazu Kubo, Masato Sagawa
|On-Site Speaker (Planned)
Grain size refinement of Nd-Fe-B magnets is one effective way to increase the coercivity, and high coercivity (μoHc) of 2.0 T was reported by refining the grain size to about 1μm using He jet milling and pressless sintering. Further grain size refinement was recently achieved by using the powder prepared by hydrogen- disproportionation-desorption-recombination (HDDR) process; however, the coercivity of the ultrafine grained magnets processed by sintering the HDDR powder remained only 1.3 T. This work presents the microstructure of fine-grained sintered magnets fabricated from HDDR powders and He-jet milled powders to discuss the possible origin of the low coercivity of the sintered magnets fabricated from the HDDR process. The Nd2Fe14B grains in the sintered magnets fabricated from HDDR powders have sharp angular corner, and the Nd-rich grain boundary phase was thinner compared to that fabricated from jet-milled powders. This explains the low coercivity in the sample fabricated from HDDR powders.