Rare earth bonded magnet and rare earth-iron-boron type magnet alloy
AssigneeToda Kogyo Corporation
InventorsMasaaki Hamano, Minoru Yamasaki, Akihisa Indue, Akira Takeuchi, Yuji Omote
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Abstract
A rare earth bonded magnet obtained by mixing two types of magnetic powders (A) and (B) in the present invention has a high residual magnetic flux density (Br), a large intrinsic coercive force (iHc) and a large maximum energy product ((BH)max) in spite of a low rare earth element content, and shows an excellent rust preventability. A rare earth-iron-boron type magnet alloy of the present invention has a residual magnetic flux density (Br) as high as not less than 10 kG, an intrinsic coercive force (iHc) as large as not less than 3.5 kOe and a large maximum energy product ((BH)max) and which has an excellent rust preventability.
Claims29
A rare earth bonded magnet having a maximum energy product ((BH)max) of not less than 11 MGOe, comprising:
- a magnet powder (A) represented by the following formula (1), which comprises Nd.sub.2 Fe.sub.14 B.sub.1 type crystals, which has an intrinsic coercive force (iHc) of not less than 7 kOe and which has an average particle diameter of not less than 100 .mu.m:
- R.sub.a (Fe.sub.(1-d) Co.sub.d).sub.(100-a-b-c) M.sup.1.sub.b B.sub.c( 1)
- wherein M.sup.1 is at least one element selected from the group consisting of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Mn, Cu and Ni, R is a least one element selected from the group consisting of Nd, Pr, Dy, Tb and Ce, a is 8 to 11, b is 0.1 to 10, c is 2 to 10 and d is 0 to 0.2;
- a magnetic powder (B) represented by the following formula (2), which has an average particle diameter of not more than 50 .mu.m:
- R.sub.x Fe.sub.(100-w-x-y-z) Co.sub.y M.sup.2.sub.z B.sub.w( 2)
- wherein M.sup.2 is at least one element selected from the group consisting of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Mn, Cu, Ga, Zn, In, Sn, Bi, Ag and Si, R is one element selected from the group consisting of Nd, Pr, Dy, Tb and Ce, x is 5 to 10, y is 1 to 9, z is 0.1 to 5, w is 2 to 7, and x+w is not less than 9;
- and
- a binder resin,
- said rare earth bonded magnet being produced by compounding magnet powder (A), magnet powder (B) and binder resin, and molding the obtained mixture.
A rare earth-iron-boron magnet alloy having a residual magnetic flux density (Br) of not less than 10 kG and a maximum energy product ((BH)max) of not less than 13 MGO3, consisting essentially of a composition represented by the following formula (5):
- R.sub.x Fe.sub.(100-w-x-y-z) Co.sub.y M.sup.4.sub.z B.sub.w( 5)
- wherein R is one element selected from the group consisting of Nd, Pr, Dy, Tb and Ce, M.sup.4 is at least one element selected from the group consisting of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Mn, Cu, Ga, Ag and Si, x is 5 to 9, y is 1.0 to 9.0, z is 0.1 to 5, w is 2 to 7, (x+w) is not less than 9 and (y+z) is not less than 5,
- which rare earth-iron-boron type magnet alloy comprises a structure in which each of a soft magnetic crystalline phase containing .alpha.Fe, bccFe and a solid solution of .alpha.Fe or bccFe and M.sup.4 and a hard magnetic crystalline phase constituted by Nd.sub.2 Fe.sub.14 B.sub.1 tetragonal crystals is precipitated from a soft magnetic amorphous phase, in which the ratio of said soft magnetic amorphous phase is not more than 10 area % based on the total alloy structure, and the balance is a crystalline phase comprising said soft magnetic crystalline phase and said hard magnetic crystalline phase, and in which the ratio of said soft magnetic crystalline phase is not less than 50 area % based on the total crystalline structure and the balance is said hard magnetic crystalline phase.
A rare earth-iron-boron type magnet alloy having a residual magnetic flux density (Br) of not less than 10 kG and a maximum energy product ((BH)max) of not less than 13 MGOe, consisting essentially of a composition represented by the following formula (5):
- R.sub.x Fe.sub.(100-w-x-y-z) Co.sub.y M.sup.4.sub.z B.sub.w( 5)
- wherein R is one element selected from the group consisting of Nd, Pr, Dy, Tb and Ce, M.sup.4 is at least one element selected from the group consisting of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Mn, Cu, Ga, Ag and Si, x is 5 to 9, y is 1.0 to 9.0, z is 0.1 to 5, w is 2 to 7, (x+w) is not less than 9 and (y+z) is not less than 5.
Dependencies are inferred from the claim text.