Rare earth permanent magnet
AssigneeTDK Corporation
InventorsMakoto Nakane, Eiji Kato, Chikara Ishizaka, Akira Fukuno
Life of this patent
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Abstract
A rare earth permanent magnet consists of 20-40 wt % of at least one rare earth element R, 0.5-4.5 wt % of boron B, 0.03-0.5 wt % of M (at least one of Al, Cu, Sn and Ga), 0.01-0.2 wt % of Bi, and the balance being at least one transition metal element T.
Claims17
A rare earth permanent magnet essentially consisting of from 20 wt % to 40 wt % of at least one rare earth element R, from 0.5 wt % to 4.5 wt % of boron B, from 0.03 wt % to 0.5 wt % of M that is at least one element selected from the group of Al, Cu, Sn and Ga, from 0.01 wt % to 0.2 wt % of Bi, and the balance being at least one transition metal element T.
A rare earth permanent magnet essentially consisting of from 20 wt % to 40 wt % of at least one rare earth element R, from 0.5 wt % to 4.5 wt % of boron B, from 0.01 wt % to 0.2 wt % of Bi, and the balance being at least one transition metal element T.
A rare earth permanent magnet comprising a R2T14B magnetic phase and a non-magnetic grain boundary phase wherein Bi is dispersed, with a value obtained by dividing a coercive force Hcj by a weight percentage of Bi (Hcj/weight percentage of Bi) is 8,000 (kA/m×1/wt %) or greater.
Dependencies are inferred from the claim text.