Permanent magnet
A permanent magnet including R and T. R are rare earth elements including Sm and at least one selected from Y and Gd. T is Fe alone or Fe and Co. T maybe partly substituted with M, and M is one or more selected from Ti, V, Cr, Mo, W, Zr, Hf, Nb, Ta, Al, Si, Cu, Zn, Ga and Ge. In a total content of R, Sm content is 60 at % or more and 95 at % or less, and a total content of Y and Gd is 5 at % or more and 35 at % or less. The permanent magnet includes main phase crystal grains having a ThMn 12 type crystal structure.
1. A permanent magnet comprising R and T, wherein R are rare earth elements comprising Sm and at least one selected from Y and Gd,
T consists of Fe or Fe and Co,
Sm content is 60 at % or more and 95 at % or less with respect to a total content of R and a total content of Y and Gd is 5 at % or more and 35 at % or less with respect to the total content of R,
the permanent magnet comprises main phase crystal grains having a ThMn 12 type crystal structure, and
an area ratio of the main phase crystal grains satisfying 0.1 μm≤Dv≤10 μm and 0.7≤(Di/Dv)≤2.0 is 70% or more,
where a grain size of each of the main phase crystal grains is Di and an average grain size of the main phase crystal grains is Dv in a cut section obtained by cutting the permanent magnet.
2. A permanent magnet comprising R and T, wherein R are rare earth elements comprising Sm and at least one selected from Y and Gd,
T consists of Fe or Fe and Co,
T is partly substituted with M,
M is one or more selected from Ti, V, Cr, Mo, W, Zr, Hf, Nb, Ta, Al, Si, Cu, Zn, Ga and Ge, and
Sm content is 60 at % or more and 95 at % or less with respect to a total content of R and a total content of Y and Gd is 5 at % or more and 35 at % or less with respect to the total content of R,
the permanent magnet comprises main phase crystal grains having a ThMn 12 type crystal structure, and
an area ratio of the main phase crystal grains satisfying 0.1 μm≤Dv≤10 μm and 0.7≤(Di/Dv)≤2.0 is 70% or more,
where a grain size of each of the main phase crystal grains is Di and an average grain size of the main phase crystal grains is Dv in a cut section obtained by cutting the permanent magnet.
3. The permanent magnet according to claim 1 , having a composition of (R1 a/100 R2 b/100 R3 c/100 )(Fe (100-d)/100 Co d/100 ) x M y , wherein R1 is Sm,
R2 is one or more selected from Y and Gd,
R3 is one or more selected from rare earth elements besides R1 and R2, and
M is one or more selected from Ti, V, Cr, Mo, W, Zr, Hf, Nb, Ta, Al, Si, Cu, Zn, Ga and Ge, having atomic ratios of
60≤a≤95,
5≤b≤35,
0≤c≤20,
0≤d≤50,
10.0≤x≤12.0,
0≤y≤2.0,
a+b+c=100, and
10.0≤x+y≤12.0.
4. The permanent magnet according to claim 3 , wherein M is one or more selected from Ti and V, having an atomic ratio of 0<y≤2.0.
5. The permanent magnet according to claim 3 , wherein R3 is one or more selected from Ce and Pr, having an atomic ratio of 0<c≤20.
6. The permanent magnet according to claim 2 , having a composition of (R1 a/100 R2 b/100 R3 c/100 )(Fe (100-d)/100 Co d/100 ) x M y , wherein R1 is Sm,
R2 is one or more selected from Y and Gd,
R3 is one or more selected from rare earth elements besides R1 and R2, and
M is one or more selected from Ti, V, Cr, Mo, W, Zr, Hf, Nb, Ta, Al, Si, Cu, Zn, Ga and Ge, having atomic ratios of
60≤a≤95,
5≤b≤35,
0≤c≤20,
0≤d≤50,
10.0≤x≤12.0,
0≤y≤2.0,
a+b+c=100, and
10.0≤x+y≤12.0.
7. The permanent magnet according to claim 6 , wherein M is one or more selected from Ti and V, having an atomic ratio of 0<y≤2.0.
8. The permanent magnet according to claim 6 , wherein R3 is one or more selected from Ce and Pr, having an atomic ratio of 0<c≤20.