Permanent magnet alloy having improved heat resistance and process for production thereof
AssigneeDowa Mining Co., Ltd.
InventorsMasami Kamada, Michio Obata, Yuichi Sato
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Abstract
A permanent magnet alloy having an improved heat resistance comprising, in terms of % by atom, 0.1 to 15 at. % C, 0.5 to 15 at. % B, provided that C and B in total account for 2 to 30 at. %; 40% or less Co (exclusive), 0.5 to 5 at. % in total of Dy and Tb, 8 to 20 at. % R. where R represents at least one element selected from the group consisting of Nd, Pr, Ce, La, Y, Gd, Ho, Er, and Tm; with the balance being Fe and unavoidable impurities.
Claims21
A permanent magnet alloy having an improved heat resistance comprising, in terms of percent by atom ( at. %), a composition of:
- 0.1 to 15 at. % C,
- 0.5 to 15 at. % B,
- provided that C and B in total account for 2 to 30 at. %;
- 40 at. % or less Co, exclusive of zero percent,
- 0.5 to 5 at. % in total of Dy and Tb,
- 8 to 20 at. % R, where R represents at least one element selected from the group consisting of Nd, Pr, Ce, La, Y, Gd, Ho, Er, and Tm;
- with the balance being Fe and unavoidable incidental impurities.
A sintered magnet alloy based on R—B—C—Co—Fe having an improved heat resistance and comprising a composition according to claim 7, wherein the irreversible demagnetization at 200° C. according to the following equation (1) is 0% to −20%, where iHc is 13 KOe or higher:
- Irreversible Demagnetization at 200° C. =100×(A200−A25)/A25 (1)
- where A25 represents a flux value of a magnet measured at room temperature, on a specimen prepared into a shape such that its permeance coefficient Pc is 1 and magnetized at 50 KOe;
- and
- A200 represents a flux value of a magnet measured on the same specimen subjected to the measurement of A25, which was maintained at 200° C. for 120 minutes and then cooled to room temperature, for the measurement.
Dependencies are inferred from the claim text.