Microstructure and Magnetic Properties of Rapidly Quenched Pr9Fe91-zBz (z=4-12) Nanocomposite Magnets
The microstructure and magnetic properties of rapidly quenched nanocomposites Pr9Fe91-xBx(x=4, 5, 6, 7, 8, 8.5, 9, 10.5 and 12) have been studied in this work. The results showed that the phases present in the Pr9Fe91-xBx nanocomposites were strongly dependent on the B content. The samples consist of Pr2Fe14B and α-Fe phases when the B content was low (4-8 at％), and Pr2Fe14B, α-Fe and Fe3B when the B content was sufficiently high (>11 at％). The metastable Pr2Fe23B3 phase appears in the intermediate B content (8-10.5 at％) and is associated with poor magnetic performance. It was further found that this metastable phase can be transformed into Pr2Fe14B, α-Fe and Fe3B by annealing the sample at temperatures above 750℃, leading to a more square demagnetization curve. However, the Br of such nanocomposites decreases slightly due to the excessive grain growth during high-temperature annealing. A comparison of microstructure and magnetic properties between Pr2Fe14B/α-Fe and Pr2Fe14B/Fe3B was also made in this work. It was found that the Pr2Fe14B/α-Fe exhibited a finer and more uniform microstructure with an average grain size of -10 nm, whereas a relatively coarse microstructure (grain size up to 100 nm) was observed in the Pr2Fe14B/Fe3B. It was also found that the Pr2Fe14B/α-Fe yielded higher Br, (BH)max and a more square demagnetization loop, although the Hci was slightly lower. The superior magnetic properties observed in the Pr2Fe14B/α-Fe can be attributed to the more favorable intrinsic magnetic properties of a-Fe (higher Ms and lower K) and the much finer microstructure which produces stronger inter-grain exchange coupling between the Pr2Fe14B and α-Fe phases. The results indicate that RE2Fe14B/α-Fe nanocomposites are more desirable than RE2Fe14B/Fe3B for future development of RE-Fe-B nanocomposite magnets.
RE-Fe-B nanocomposite magnet rapid solidification
CHEN Zhong-min David N.Brown WU Ya-qiao Matthew J.Kramer
Magnequench Technology Center, 61 Science Park Rd, ＃01-17The Galen, Singapore 117525, Singapore Ames Lab, Iowa State University, Ames, IA 50011, USA
国际会议
北京
英文
177-182
2006-08-29（万方平台首次上网日期，不代表论文的发表时间）