Permanent magnets

Claim 2

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≦x<11.76, 2≦y<15, and 0<z≦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.

Claim 3

The permanent magnet of claim 1 wherein 5.5≦x≦11.

Claim 4

The permanent magnet of claim 1 wherein the quotient of the volume ratio of auxiliary phase to primary phase, v, divided by the value given by the formula: [0.1176(100-z)-x]/x ranges from 0.15 to 0.95.

Claim 5

The permanent magnet of claim 1 wherein the primary phase has an average grain size of from 0.01 to 3 μm.

Claim 6

The permanent magnet of claim 1 wherein the auxiliary phase is present as a grain boundary layer having an average width of up to 0.3 μm.

Claim 7

The permanent magnet of claim 1 which consists of the primary and auxiliary phases wherein the R content of the auxiliary phase is up to 9/10 of that of the primary phase in atomic ratio.

Claim 8

The permanent magnet of claim 1 wherein the primary phase has an R content of from 6 to 11.76 atom %.

Claim 9

The permanent magnet of claim 1 in the form of powder.

Claim 10

The permanent magnet of claim 1, which is in the form of a ribbon.

Claim 11

The permanent magnet of claim 8, wherein said powder is obtained by comminuting a ribbon.

Claim 12

The permanent magnet of claim 8 or 10 wherein the ribbon has a thickness of from 30 to 60 μm.

Claim 13

The permanent magnet of claim 8 which is obtained by compacting the powder.

Claim 14

The permanent magnet of claim 8 which is obtained by hot plastic processing of the powder.

Claim 15

The permanent magnet of claim 8 which is obtained by mixing the powder with a binder.

Claim 16

The permanent magnet of claim 1 which is obtained by rapid quenching from a molten alloy such that the quotient of the volume ratio of auxiliary phase to primary phase, v, divided by the value given by the formula: [0.1176(100-z)-x]/x may range from 0.15 to 0.95.

Claim 17

The permanent magnet of claim 1 which is obtained by rapid quenching from a molten alloy such that the quotient of the volume ratio of auxiliary phase to primary phase, v, divided by the value given by the formula: [0.1176(100-z)-x]/x may range from 0.2 to 1.2, and then heat treating such that said quotient may range from 0.15 to 0.95.

Claim 18

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≦x<11.76, 2≦y<15, and 0<z≦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.

Claim 19

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≦x<11.76, 2≦y<15, and 0<z≦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.

Claim 20

The permanent magnet of claim 17 which consists of the primary and auxiliary phases wherein the R content of the auxiliary phase is up to 9/10 of that of the primary phase in atomic ratio.

Claim 21

The permanent magnet of claim 17 wherein the primary phase has an R content of from 6 to 11.76 atom %.