R-T-B based permanent magnet
An R-T-B permanent magnet that contains: main-phase grains composed of an R 2 T 14 B compound (where R is a rare earth element, T is a transition metal element, and B is boron); and grain boundaries. R includes Ce. The R-T-B permanent magnet has a Ce content of 15-35 mass % with respect to the total R content. The grain boundaries include an R-rich phase and an R-T phase. In a cross section of the R-T-B permanent magnet, the surface area ratio S(R-T) of the R-T phases with respect to the grain boundaries is 0.60-0.85.
1 . An R-T-B based permanent magnet comprising main phase grains including an R 2 T 14 B compound (in which R includes a rare earth element, T includes a transition metal element, and B represents boron), and a grain boundary, wherein
R at least includes Ce,
an amount of Ce to a total amount of R in the R-T-B based permanent magnet is within a range of 15 mass % or more and 35 mass % or less,
an amount of Co is within a range of 0.50 mass % or more and 3.00 mass % or less with respect to 100 mass % of the R-T-B based permanent magnet as a whole,
the grain boundary includes an R-rich phase and an R-T phase, and
an area ratio of the R-T phase to the grain boundary in one cross section of the R-T-B based permanent magnet represented by S (R-T) is within a range of 0.60 or larger and 0.85 or smaller.
2 . The R-T-B based permanent magnet according to claim 1 , wherein an amount of Ga is within a range of 0 mass % or more and 0.2 mass % or less.
3 . The R-T-B based permanent magnet according to claim 1 , wherein the R-T-B based permanent magnet include substantially neither La nor Y.
4 . The R-T-B based permanent magnet according to claim 2 , wherein the R-T-B based permanent magnet include substantially neither La nor Y.
5 . The R-T-B based permanent magnet according to claim 1 , wherein a total amount of R is within a range of 30.00 mass % or more and 34.00 mass % or less with respect to 100 mass % of the R-T-B based permanent magnet as a whole.
6 . The R-T-B based permanent magnet according to claim 1 , wherein a total amount of R is within a range of 32.00 mass % or more and 34.00 mass % or less with respect to 100 mass % of the R-T-B based permanent magnet as a whole.
7 . The R-T-B based permanent magnet according to claim 1 , wherein an amount of B is within a range of 0.70 mass % or more and 0.95 mass % or less with respect to 100 mass % of the R-T-B based permanent magnet as a whole.
8 . The R-T-B based permanent magnet according to claim 1 , wherein an amount of B is within a range of 0.80 mass % or more and 0.90 mass % or less with respect to 100 mass % of the R-T-B based permanent magnet as a whole.
9 . The R-T-B based permanent magnet according to claim 1 , wherein the S (R-T) is within a range of 0.60 or larger and 0.80 or smaller.
10 . The R-T-B based permanent magnet according to claim 1 , wherein the S (R-T) is within a range of 0.64 or larger and 0.80 or smaller.
11 . The R-T-B based permanent magnet according to claim 1 , wherein an amount of Co is within a range of 2.00 mass % or more and 3.00 mass % or less with respect to 100 mass % of the R-T-B based permanent magnet as a whole.
12 . The R-T-B based permanent magnet according to claim 1 , wherein an amount of Ga is within a range of 0 mass % or more and 0.20 mass % or less with respect to 100 mass % of the R-T-B based permanent magnet as a whole.
13 . The R-T-B based permanent magnet according to claim 1 , wherein an amount of Al is within a range of 0.20 mass % or more and 1.00 mass % or less with respect to 100 mass % of the R-T-B based permanent magnet as a whole.
14 . The R-T-B based permanent magnet according to claim 1 , wherein an amount of Cu is within a range of 0 mass % or more and 0.50 mass % or less with respect to 100 mass % of the R-T-B based permanent magnet as a whole.
15 . The R-T-B based permanent magnet according to claim 1 , wherein an amount of Zr is within a range of 0.10 mass % or more and 1.00 mass % or less with respect to 100 mass % of the R-T-B based permanent magnet as a whole.
16 . The R-T-B based permanent magnet according to claim 1 , wherein a total amount of heavy rare earth elements is within a range of 0 mass % or more and 0.10 mass % or less with respect to 100 mass % of the R-T-B based permanent magnet as a whole.
17 . The R-T-B based permanent magnet according to claim 1 , wherein an amount of C is within a range of 0 mass % or more and 0.3 mass % or less with respect to 100 mass % of the R-T-B based permanent magnet as a whole.
18 . The R-T-B based permanent magnetic according to claim 1 , wherein elements other than the group consisting of R, B, Co, Ga, Al, Cu, Zr, and C is Fe and inevitable impurities, and an amount of the inevitable impurities is 0 or more and 0.5 mass % or less with respect to 100 mass % of the R-T-B based permanent magnet as a whole.