Rare earth permanent magnet and its preparation
AssigneeShin-Etsu Chemical Co., Ltd.
InventorsHiroaki Nagata, Tadao Nomura, Takehisa Minowa
Life of this patent
Estimating the term…
Abstract
A rare earth permanent magnet is prepared by disposing a powdered metal alloy containing at least 70 vol % of an intermetallic compound phase on a sintered body of R—Fe—B system, and heating the sintered body having the powder disposed on its surface below the sintering temperature of the sintered body in vacuum or in an inert gas for diffusion treatment. The advantages include efficient productivity, excellent magnetic performance, a minimal or zero amount of Tb or Dy used, an increased coercive force, and a minimized decline of remanence.
Claims12
A rare earth permanent magnet, which is prepared by
- disposing an alloy powder on a surface of an original sintered body of the composition Ra-T1b-Bc wherein R is at least one element selected from rare earth elements inclusive of Y and Sc, T1 is at least one element selected from Fe and Co, B is boron, “a,” “b” and “c” indicative of atomic percent are in the range:
- 12≦a≦20, 4.0≦c≦7.0, and the balance of b, said alloy powder having the composition R11-M1j wherein R1 is at least one element selected from rare earth elements inclusive of Y and Sc, M1 is at least one element selected from the group consisting of Al, Si, C, P, Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, Hf, Ta, W, Pb, and Bi, “i” and “j” indicative of atomic percent are in the range:
- 63<j≦89 and the balance of i, and containing at least 70% by volume of an intermetallic compound phase, and
- heat treating the sintered body having the alloy powder disposed on its surface at a temperature equal to or below the sintering temperature of the original sintered body in vacuum or in an inert gas,
- wherein at least one element of R1 and at least one element of M1 in the alloy powder is diffused to grain boundaries in the interior of the sintered body, near grain boundaries within sintered body primary phase grains or a combination thereof;
- and
- wherein the coercive force of the rare earth permanent magnet is increased over the magnetic properties of the original sintered body.
A rare earth permanent magnet, which is prepared by
- disposing an alloy powder on a surface of an original sintered body of the composition Ra-T1b-Bc wherein R is at least one element selected from rare earth elements inclusive of Y and Sc, T1 is at least one element selected from Fe and Co, B is boron, “a,” “b” and “c” indicative of atomic percent are in the range:
- 12≦a≦20, 4.0≦c≦7.0, and the balance of b, said alloy powder having the composition R11 -M1j wherein R1 is at least one element selected from rare earth elements inclusive of Y and Sc, M1 is at least one element selected from the group consisting of Si, C, P, V, Mn, Zn, Ga, Ge, Zr, Nb, Mo, In, Sn, Sb, Hf Pb , and Bi, “i” and “j” indicative of atomic percent are in the range:
- 15≦j≦99 and the balance of i, and containing at least 70% by volume of an intermetallic compound phase, and
- heat treating the sintered body having the alloy powder disposed on its surface at a temperature equal to or below the sintering temperature of the original sintered body in vacuum or in an inert gas,
- wherein at least one element of R1 and at least one element of M1 in the alloy powder is diffused to grain boundaries in the interior of the sintered body or near grain boundaries within sintered body primary phase grains;
- and
- wherein the coercive force of the rare earth permanent magnet is increased over the magnetic properties of the original sintered body.
Dependencies are inferred from the claim text.