Tdk Corporation

Mariko Fujiwara

Makoto Iwasaki

Masashi Miwa

The object of the present invention is to provide an R-T-B based permanent magnet having a wide temperature range suitable for sintering. The R-T-B based permanent magnet in which R is one or more rare earth elements, T is a combination of Fe and Co, and B is boron. The R-T-B based permanent magnet comprises M, O, C, and N. M is three or more selected from Cu, Ga, Mn, Zr, and Al; and at least comprises Cu, Ga, and Zr. A content of each component is within a predetermined range. The R-T-B based permanent magnet includes main phase grains made of RTB compound and grain boundaries existing between main phase grains. The grain boundaries include a two-grain boundary which is a grain boundary formed between two adjacent main phase grains, and a Zr&#x2014;B compound is included in the two-grain boundary.

R-T-B based permanent magnet

An R-T-B-based sintered magnetcontains a rare earth element R, a transition metal element T, B, Ga, and O, the sintered magnetincludes a magnet bodyand an oxidized layercovering the magnet body, the magnet bodyincludes main phase grainscontaining a crystal of RTB and a grain boundary phasepositioned between the main phase grainsand containing R, the oxidized layerincludes a plurality of oxide phasesA containing R, T, Ga, and O, the oxide phaseA satisfies the following Formulas (1) and (2) regarding the content (unit: atom %) of each element, and the oxide phaseA in the oxidized layercovers the grain boundary phasein the magnet body0.3&#x2264;[R]/[T]&#x2264;0.5&#x2003;&#x2003;(1)0.2&#x2264;[O]/([R]+[T]+[Ga]+[O])&#x2264;0.7&#x2003;&#x2003;(2)

R-T-B-based sintered magnet

The present invention provides an R-T-B based permanent magnet capable of improving a coercive force HcJ while maintaining a residual magnetic flux density Br. The R-T-B based permanent magnet includes Ga. R is one or more selected from rare earth elements, T is Fe or a combination of Fe and Co, and B is boron. The R-T-B based permanent magnet has main phase grains including a crystal grain having an RTB crystal structure and grain boundaries formed between adjacent two or more main phase grains, and 0.030&#x2264;[Ga]/[R]&#x2264;0.100 is satisfied in which [Ga] represents an atomic concentration of Ga and [R] represents an atomic concentration of R in the main phase grains.

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Tokyo, Japan

Mariko Fujiwara