Rare earth cobalt-based permanent magnet
AssigneesKyushu Institute of Technology, Tokin Corporation
InventorsMasaaki Takezawa, Teruhiko Fujiwara, Hiroaki Machida, Hideyuki Yoshikawa
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Abstract
A rare-earth cobalt permanent magnet with good magnetic properties is provided. A rare-earth cobalt permanent magnet contains 23 to 27 mass % R, 3.5 to 5.0 mass % Cu, 18 to 25 mass % Fe, 1.5 to 3.0 mass % Zr in mass and a remainder Co with inevitable impurities, where an element R is a rare earth element at least containing Sm. The rare-earth cobalt permanent magnet has a metal structure including a plurality of crystal grains and a continuously extending grain boundary. A content of Cu in the grain boundary is higher than a content of Cu in the crystal grains, and a content of Zr in the grain boundary is higher than a content of Zr in the crystal grains.
Claims16
A rare earth-cobalt permanent magnet containing 23 to 27 mass % R, 3.5 to 5.0 mass % Cu, 18 to 25 mass % Fe, 1.5 to 3.0 mass % Zr, and a remainder Co with inevitable impurities, where R is Sm and optionally additional rare earth elements, wherein the rare earth-cobalt permanent magnet has a metal structure including a plurality of crystal grains and a grain boundary, the grain boundary has a continuously extending shape, a content of Cu in the grain boundary is higher than a content of Cu in the crystal grains, a content of Zr in the grain boundary is higher than a content of Zr in the crystal grains, the grain boundary contains 6 to 20 mass % Zr;
- and wherein in a magnetic field, a reverse magnetic domain occurs only from one side of a cross section of the grain boundary and propagates into the crystal grains.
Dependencies are inferred from the claim text.