Grain boundary engineering
This disclosure is directed to sintered bodies comprising grains and a grain boundary composition, wherein: (a) the grains comprise a composition substantially represented by a formula G 2 M 14 B, where G is Nd, Dy, Pr, Tb, or a combination thereof, and M is Co, Fe, Ni, or a combination thereof, wherein the grains are optionally doped with one or more rare earth elements; and (b) the grain boundary composition is an alloy composition substantially represented by the formula: Nd 8.5-12.5 Dy 35-45 Co 32-41 Cu 3-6.5 Fe 1.5-5 , wherein the subscript values are atom percent relative to the total composition of the alloy composition. Corresponding populations of particles are also disclosed.
1. A sintered body comprising grains and a grain boundary composition, wherein:
(a) the grains comprise a composition represented by a formula G 2 M 14 B, where G is Nd, Dy, Pr, Tb, or a combination thereof, and M is Co, Fe, Ni, or a combination thereof, wherein the grains are optionally doped with one or more rare earth elements; and
(b) the grain boundary composition is an alloy composition represented by the formula: Nd 8.5-12.5 Dy 35-45 Co 32-41 Cu 3-6.5 Fe 1.5-5 , wherein the subscript values are atom percent relative to the total composition of the alloy composition.
2. The sintered body of claim 1 , wherein G comprises Nd.
3. The sintered body of claim 1 , wherein G comprises Dy.
4. The sintered body of claim 1 , wherein G comprises Pr.
5. The sintered body of claim 1 , wherein G comprises Tb.
6. The sintered body of claim 1 , wherein M comprises Fe.
7. The sintered body of claim 1 , wherein M comprises Co.
8. The sintered body of claim 1 , wherein M comprises Ni.
9. The sintered body of claim 1 , wherein the grains comprise one or more of (i) Nd 2 Fe 14 B; (ii) Dy 2 Fe 14 B: (iii) Pr 2 Fe 14 B; (iv) Tb 2 Fe 14 B; (v) Nd 2 Co 14 B; (vi) Pr 2 Co 14 B; (vii) Tb 2 Co 14 B; (viii) Nd 2 Ni 14 B; (ix) Pr 2 Ni 14 B; (x) Tb 2 Ni 14 B.
10. The sintered body of claim 1 , wherein the grains are doped with one or of Nd, Gd, Tb, La, Ce, Yb, Ho, or Eu.
11. The sintered body of claim 1 having an oxygen content of less than 1.98 atom %.
12. The sintered body of claim 1 that is magnetic.
13. The sintered body of claim 1 that exhibits, at 25° C.:
(a) a remanence (Br) in a range of from 1.29 T to 1.423 T; (b) a coercivity (iHc) in a range of from 1042 kA/m to 1900 kA/m;
(c) an energy product (BH max ) in a range of from 323 kJ/m 3 to 391 kJ/m 3 ; or
(d) a combination of two or more of (a) to (c).
14. A device comprising a sintered body of claim 1 , the device being a starter motor, anti-lock braking system, fuel pump, fan, loudspeaker, microphone, telephone ringer, switch, relay, hard-disk drive, stepper motor, servo-motor, magnetic resonance imager, windmill generator, robot, electronic sensor, magnetic separator, guidance system, or a satellite.
15. A population of particles comprising:
(a) a first fractional population of demagnetized particles represented by a formula G 2 M 14 B, where G is Nd, Dy, Pr, Tb, or a combination thereof, and M is Co, Fe, Ni, or a combination thereof, wherein the demagnetized particles are optionally doped with one or more rare earth elements; and
(b) a second fractional population of additive particles represented by a composite formula: Nd 8.5-12.5 Dy 35-45 Co 32-41 Cu 3-6.5 Fe 1.5-5 , wherein the subscript values are atom percent relative to the total composition of the additive particles.
16. The population of particles of claim 15 , wherein the demagnetized particles are optionally doped with one or more of Nd, Pr, Dy, Gd, Tb, La, Ce, Yb, Ho, or Eu.
17. The population of particles of claim 15 , wherein the first and second fractional populations of particles are compressed in a green body.
18. The population of particles of claim 17 , wherein the first and second fractional populations of particles are uniformly distributed in the green body.