Recent progress in the development of high-performance bonded magnets using rare earth-Fe compounds

• Published in: Science and technology of advanced materials Vol. 22; no. 1; pp. 729 - 747
• Main Authors: Horikawa, Takashi, Yamazaki, Masao, Matsuura, Masashi, Sugimoto ‎, Satoshi
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 31.12.2021; Taylor & Francis Group
• Subjects: 203 Magnetics / Spintronics / Superconductors; 40 Optical, magnetic and electronic device materials; anisotropy; coercivity; Focus on Science and Technology of Element-Strategic Permanent Magnets; Hydrogenation disproportionation desorption recombination (HDDR); nanoparticle; oxygen; Review
• ISSN: 1468-6996; 1878-5514
• DOI: 10.1080/14686996.2021.1944780

Permanent magnets, and particularly rare earth magnets such as Nd-Fe-B, have attracted much attention because of their magnetic properties. There are two well-established techniques for obtaining sintered magnets and bonded Nd-Fe-B magnets. Powder metallurgy is used to obtain high-performance anisotropic sintered magnets. To produce bonded magnets, either melt-spinning or the hydrogenation, disproportionation, desorption, and recombination process is used to produce magnet powders, which are then mixed with binders. Since the development of Nd-Fe-B magnets, several kinds of intermetallic compounds have been reported, such as Sm 2 Fe 17 N x and Sm(Fe,M) 12 (M: Ti, V, etc.). However, it is difficult to apply a liquid-phase sintering process similar to the one used for Nd-Fe-B sintered magnets in order to produce high-performance Sm-Fe-based sintered magnets because of the low decomposition temperature of the compound and the lack of a liquid grain boundary phase like that in the Nd-Fe-B system. Therefore, bonded magnets are useful in the production of bulk magnets using these Sm-Fe-based compounds. This article reviews recent progress in our work on the development of high-performance bonded magnets using Nd 2 Fe 14 B and Sm 2 Fe 17 N x compounds.