R-T-B based permanent magnet

1. An R-T-B based permanent magnet, wherein:

a ratio (Hex/HcJ) of the external magnetic field of Hex to the coercivity (HcJ) is 1.10 or less, and the residual magnetic flux density of Br2 satisfies the relationship of Br2/Br≥0.90, where:

Hex is the external magnetic field required for obtaining a residual magnetic flux density Br of 0,

Br2is the residual magnetic flux density obtained after applying the external magnetic field of Hex, then applying an external magnetic field of 0.95 HcJ,

the residual magnetic flux density Br is 1.2 T or more, and

the coercivity (HcJ) is less than 640 kA/m.

2. The R-T-B based permanent magnet of claim 1 , comprising:

main phase grains with a composition of (R1 1−x R2 x ) 2 T 14 B, wherein:

R1 is rare earth element(s) composed of one or more elements selected from the group consisting of Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; and

R2 is element(s) containing at least one selected from the group consisting of Y, La and Ce;

T is one or more transition metal elements including Fe or a combination of Fe and Co; and

0.2≤x≤0.7.

3. A rotating machine comprising the R-T-B based permanent magnet of claim 1 .

4. A rotating machine comprising the R-T-B based permanent magnet of claim 2 .

5. The R-T-B based permanent magnet of claim 1 , wherein the coercivity (HcJ) is 487 kA/m or less.

6. A rotating machine comprising the R-T-B based permanent magnet of claim 5 .