| 摘要 |
PROBLEM TO BE SOLVED: To provide an R-T-B-based permanent magnet suitable as a variable magnetic force magnet for variable magnetic flux motor, having high residual magnetic flux density and low coersive force, and capable of changing a magnetic force reversibly by a small external magnetic field.SOLUTION: An R-T-B-based permanent magnet contains main phase particles of a compound having a composition (RY)TB(R is a rare earth element consisting of one kind or more of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, T is Fe or one kind or more of transition metal element where Fe and Co are essential, 0.2≤x≤0.7). The residual magnetic flux density Br is 1.1 T or more, the coersive force HcJ is 400 kA/m or less, and the ratio Hex/HcJ of an external magnetic field Hex and a coersive force HcJ, required for bringing the residual magnetic flux density Br to 0, is 1.10 or less. |
