Permanent magnets
AssigneeTDK Corporation
InventorsKoichi Yajima, Osamu Kohmoto, Tetsuhito Yoneyama
Life of this patent
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Abstract
A permanent magnet having high coercivity and energy product contains rare earth elements, boron, at least one element of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W, and a blance of Fe or Fe and Co, and consists of a primary phase of substantially tetragonal grain structure, or a mixture of such a primary phase and an amorphous or crystalline rare earth element-poor auxiliary phase wherein the volume ratio of auxiliary phase to primary phase is smaller than a specific value.
Claims19
A permanent magnet formed from a magnetically hard material having a composition represented by the formula:
- R.sub.x T.sub.(100-x-y-z) B.sub.y M.sub.z
- where
- R is at least one member selected from the rare earth elements including Y,
- T is Fe or a mixture of Fe and Co,
- B is boron,
- M is at least one member selected from the group consisting of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W,
- 5.5.ltoreq.x<11.76,
- 2.ltoreq.y<15, and
- 0<z.ltoreq.10, and
- wherein said permanent magnet is obtained by rapid quenching from a molten alloy having said composition and wherein said permanent magnet comprises a primary phase of substantially tetragonal grain structure and at least one auxiliary phase selected from amorphous and crystalline R-poor auxiliary phases, said auxiliary phase being present as a grain boundary layer, wherein the volume ratio of auxiliary phase to primary phase, v, is smaller than the value given by the formula:
- [0.1176/(100-z)-x]/x.
A permanent magnet formed from a magnetically hard material having a composition represented by the formula:
- R.sub.x T.sub.(100-x-y-z) B.sub.y M.sub.z
- where
- R is at least one member selected from the rare earth elements including Y,
- T is Fe or a mixture of Fe and Co,
- B is boron,
- M is a mixture of at least one member selected from the group consisting of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W, and at least one member selected from the group consisting of Cu, Ni, Mn and Ag,
- 5.5.ltoreq.x<11.76,
- 2.ltoreq.y<15, and
- 0<z.ltoreq.10, and wherein said permanent magnet is obtained by rapid quenching from a molten alloy having said composition and wherein said permanent magnet consists of a primary phase of substantially tetragonal grain structure and at least one auxiliary phase selected from amorphous and crystalline R-poor auxiliary phases, said auxiliary phase being present as a grain boundary layer, wherein the volume ratio of auxiliary phase to primary phase, v, is smaller than the value given by the formula:
- ps
- [0.1176/(100-z)-x]/x.
Dependencies are inferred from the claim text.