Permanent magnet, and motor and power generator using the same
In one embodiment, a permanent magnet includes: a composition expressed by R p Fe q M r Cu s Co 100-p-q-r-s (R is a rare-earth element, M is at least one element selected from Zr, Ti, and Hf, 10≤p≤13.5 at %, 25≤q≤40 at %, 1.35≤r≤1.75 at %, and 0.88≤s≤13.5 at %); and a metallic structure including Th 2 Zn 17 crystal phases each having a Fe concentration of 25 at % or more, and Cu-rich crystal phases each having a Cu concentration of from 25 at % to 70 at %. An average thickness of the Cu-rich crystal phases is 20 nm or less, and an average distance between the Cu-rich crystal phases is 200 nm or less.
1. A permanent magnet, comprising:
a composition expressed by a composition formula:
R p Fe q M r Cu s Co 100-p-q-r-s ,
wherein R is at least one element selected from the group consisting of rare-earth elements, M is at least one element selected from the group consisting of zirconium (Zr), titanium (Ti), and hafnium (Hf), p satisfies 11.24≤p≤13.5 at %, q satisfies 25≤q≤40 at %, r satisfies 1.35≤r≤1.72 at %, and s satisfies 0.88≤s≤5.33 at %; and
a metallic structure including Th 2 Zn 17 crystal phases each having a Fe concentration of 25 at % or more, and Cu-rich crystal phases each having a Cu concentration of from 25 at % to 70 at %,
wherein an average thickness of the Cu-rich crystal phases is 20 nm or less, and an average distance between the Cu-rich crystal phases is 200 nm or less, and
wherein a coercive force of the magnet is 1640 kA/m or more and 1710 kA/m or less, and a residual magnetization of the magnet is 1.185 T or more and 1.229 T or less.
2. The permanent magnet according to claim 1 , wherein the average thickness of the Cu-rich crystal phases is from 4 nm to 16 nm.
3. The permanent magnet according to claim 1 , wherein the average distance between the Cu-rich crystal phases is from 20 nm to 160 nm.
4. The permanent magnet according to claim 1 , wherein the Fe concentration of the Th 2 Zn 17 crystal phase is 28 at % or more.
5. The permanent magnet according to claim 1 , wherein 50 at % or more of the element R is samarium (Sm).
6. The permanent magnet according to claim 1 , wherein 50 at % or more of the element M is zirconium (Zr).
7. A motor comprising the permanent magnet of claim 1 .
8. The motor according to claim 7 , wherein the motor is a variable magnetic flux motor comprising the permanent magnet as a variable magnet.
9. A power generator comprising the permanent magnet of claim 1 .
10. The permanent magnet according to claim 1 , wherein q satisfies 28≤q≤40 at %.
11. The permanent magnet according to claim 1 , wherein q satisfies 30≤q≤40 at %.
12. A permanent magnet, comprising:
a composition expressed by a composition formula:
R p Fe q M r Cu s (Co 1-t A t ) 100-p-q-r-s ,
wherein R is at least one element selected from the group consisting of rare-earth elements, M is at least one element selected from the group consisting of zirconium (Zr), titanium (Ti), and hafnium (Hf), A is at least one element selected from the group consisting of nickel (Ni), vanadium (V), chromium (Cr), manganese (Mn), aluminum (Al), gallium (Ga), niobium (Nb), tantalum (Ta), and tungsten (W), p satisfies 11.24≤p≤13.5 at %, q satisfies 25≤q≤40 at %, r satisfies 1.35≤r≤1.72 at %, s satisfies 0.88≤s≤5.33 at %, and t is an atomic ratio satisfying 0≤t≤0.2; and
a metallic structure including Th 2 Zn 17 crystal phases each having a Fe concentration of 25 at % or more, and Cu-rich crystal phases each having a Cu concentration of from 25 at % to 70 at %,
wherein an average thickness of the Cu-rich crystal phases is 20 nm or less, and an average distance between the Cu-rich crystal phases is 200 nm or less, and
wherein a coercive force of the magnet is 1640 kA/m or more and 1710 kA/m or less, and a residual magnetization of the magnet is 1.185 T or more and 1.229 T or less.