Development of High Performance Magnets by Crystallization of Amorphous RE-Fe-B Ribbons

1987 Fiscal Year Final Research Report Summary

• Project/Area Number: 61850052
• Research Category: Grant-in-Aid for Developmental Scientific Research
• Allocation Type: Single-year Grants
• Research Field: 電子材料工学
• Research Institution: CHUBU UNIVERSITY and NAGASAKI UNIVERSITY
• Principal Investigator: NARITA Kenji Professor, Faculty of Engineering, CHUBU UNIVERSITY, 工学部, 教授 (90037664)
• Co-Investigator(Kenkyū-buntansha): 清水 泰式 長崎大学, 工学部, 助手 (60039667) ; FUKUNAGA Hirotoshi Associate Professor, Faculty of Engineering, NAGASAKI UNIVERSITY, 工学部, 助教授 (10136533) ; TERADA Hiroshi Lecturer, Faculty of Engineering, CHUBU UNIVERSITY, 工学部, 講師 ; KATO Akira Associate Professor, Faculty of Engineering, CHUBU UNIVERSITY, 工学部, 助教授 (00113085) ; SHIMIZU Yasukazu Research Assistant, Faculty of Engineering, NAGASAKI UNIVERSITY
• Project Period (FY): 1986 – 1987
• Keywords: Amorphous / Crystallization / RE-Fe-B / Nd-Fe-B

Research Abstract

Amorphous ND_x Fe 100-(x+y)B_y (13.5(less than or equal)X(less than or equal)10) ribbons were prepared by the single roller quenching method and crystallized into magnets with sub-(micrn)m micro-structures by flash annealing at 700-750゜C. The coercivity measured under an applied field of 20KOe is not affected remarkably by B content, but devreases abruptly with decreasing Nd content. The coercivities in excess of 15KOe are achieved in magnets with x(greater than or equal)15. The maximum (BH)_<max> can be obtained in Nd_<15> Fe_<75> B_<10> magnet. However, the dependence of the coercivity on the maximum lower B content if applied fields larger than 20KOe are applied.
All the magnets magnetize rapldly at low fields, indicating the existence of domain walls shich are initially free to move. This would be due to the fact that the grain size is large compared with taht of rapidly solidified magnets.
In all the magnets crystallized under the best condition, only two magnetic phases, Nd_2 Fe_<14> B and <alpha>-Fe, are detected by the thermo-magnetic analysis. X-ray diffraction analysis indicates that the lack of the Nd-rich phase results in devrease in the coercivity similarly to shintered magnets.
The above results suggest that crystallized magnets have magnetic and structural properties which differ from tghose reported on the rapidly solidified magnets, and seem to be hardened by the same mechanism as sintered magnets.