Process for producing permanent magnet materials

Claim 2

A process for producing permanent magnet materials of the Fe-B-R type comprising: preparing a metallic powder having a mean particle size of 0.3-80 microns and a composition consisting essentially of by atomic percent, 12-24% R wherein R is at least one rare earth element selected from the group consisting of Nd, Pr, La, Ce, Tb, Dy, Ho, Er, Eu, Sm, Gd, Pm, Tm, Yb, Lu and Y and at least 50% of R consists of Nd and/or Pr, 4-24 % B, and at least 52% Fe, compacting said metallic powder, and sintering the resultant body at a temperature of 900-1200 degrees C. in a nonoxidizing or reducing atmosphere.

Claim 3

A process as defined in claim 1, wherein said metallic powder comprises Co which is substituted for Fe in an amount not exceeding 50 atomic percent wherein the Curie temperature of the sintered body is higher than the Curie temperature of a corresponding sintered body containing no Co.

Claim 4

A process as defined in claim 1, wherein said metallic powder comprises at least one of additional elements M in amount(s) not exceeding the values by atomic percent as specified hereinbelow provided that, when two or more elements M are added, the total amount thereof shall not exceed the largest value among said specified values of the elements actually added: ______________________________________ 3.3% Ti, 6.5% Ni, 5.0% Bi, 6.8% V, 10.1% Nb, 8.5% Ta, 5.7% Cr, 6.2% Mo, 6.0% W, 6.0% Mn, 6.5% Al, 1.4% Sb, 4.5% Ge, 1.9% Sn, 3.8% Zr, and 3.8 % Hf. ______________________________________

Claim 5

A process as defined in claim 3, wherein said metallic powder comprises Co which is substituted for Fe in an amount not exceeding 50 atomic percent wherein the Curie temperature of the sintered body is higher than the Curie temperature of a corresponding sintered body containing no Co.

Claim 6

A process as defined in any one of claims 1-4 wherein the metallic powder is prepared by melting metallic material, cooling the resultant alloy and pulverizing the alloy to form said metallic powder.

Claim 7

A process as defined in claim 5, wherein the cooling is made under such a condition that yields a substantially crystalline state.

Claim 8

A process as defined in any one of claims 1-4, wherein the metallic powder is prepared by heating a mixture of rare earth oxide and other metallic materials with a reducing agent to reduce the rare earth oxide.

Claim 9

A process as defined in any one of claims 1-4, wherein the compacting is carried out in a magnetic field whereby the sintered body has a maximum energy product of at least 10 MGOe.

Claim 10

A process as defined in any one of claims 1-4, wherein said metallic powder comprises, by atomic percent, 12-20% R, and 5-18% B, and the compacting is carried out without applying a magnetic field whereby the sintered body has a maximum energy product of at least 4 MGOe.

Claim 11

A process as defined in any one of claims 1-4, wherein the sintering is carried out at 1000-1180 degrees C.

Claim 12

A process as defined in claim 9, wherein the sintering is carried out at 1000-1180 degrees C.

Claim 13

A process as defined in claim 1, wherein the sintering is carried out in an inert gas atmosphere or in a vacuum.

Claim 14

A process as defined in claim 12, wherein the vacuum is 10 -2 Torr or less.

Claim 15

A process as defined in claim 12, wherein the sintering is conducted in the atmosphere of a normal pressure or a reduced pressure.

Claim 16

A process as defined in any one of claims 1-4, wherein the mean particle size of the metallic powder is 1.0-40 microns.

Claim 17

A process as defined in claim 15, wherein the mean particle size of the metallic powder is 2-20 microns.

Claim 18

A process as defined in any one of claims 1-4, wherein R is 12.5-20%, and B is 4-20%.

Claim 19

A process as defined in claim 17, wherein R is 13-19%, and B is 5-11%.

Claim 20

A process as defined in claim 2 or 4 wherein Co does not exceed 35%.

Claim 21

A process as defined in claim 19 wherein Co does not exceed 25%.

Claim 22

A process as defined in claim 2 or 4, wherein Co is 5% or more.

Claim 23

A process as defined in claim 9, wherein R is 12-16% and B is 6-18% whereby the sintered body has a maximum energy product of at least 7 MGOe.

Claim 24

A process as defined in any one of claims 1-4, wherein said metallic powder is selected so as to maintain the amount of Si in the resultant sintered body at a value not exceeding 5 atomic percent.

Claim 25

A process as defined in any one of claims 1-4, wherein the metallic powder is an alloy powder having said composition.

Claim 26

A process as defined in any one of claims 1-4, wherein the metallic powder is a mixture of alloy powders making up said composition.

Claim 27

A process as defined in any one of claims 1-4, wherein the metallic powder is a mixture of an alloy or alloys having an Fe-B-R base composition and a powder metal having a complementary composition making up the final composition of said metallic powder.

Claim 28

A process as defined in claim 26, wherein said powdery metal comprises an alloy or alloys of the componental elements of said final composition.

Claim 29

A process as defined in claim 26, wherein said powdery metal comprises a componental element(s) of said final composition.

Claim 30

A process as defined in claim 17, wherein the impurites do not exceed the values, by atomic percent, specified below: ______________________________________ 2.0% Cu, 2.0% C, 2.0% P, 4.0% Ca, 4.0% Mg, 2.0% O, 5.0% Si, and 2.0% S. ______________________________________ provided that the sum of the impurities does not exceed 5%.

Claim 31

A process as defined in claim 9, wherein the amount of Fe is at least 62 atomic percent.

Claim 32

A process as defined in any one of claims 1-4, wherein R is Nd and/or Pr.

Claim 33

A process as defined in claim 31, wherein R is Nd.