Iron-rare earth-boron-refractory metal magnetic nanocomposites
AssigneeSantoku Corporation
InventorsBao-Min Ma, Charles O. Bounds, Wen Cheng Chang, Qun Chen
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Abstract
Magnetic nanocomposite materials including iron, rare earth elements, boron, refractory metal and, optionally, cobalt are disclosed. Neodymium and lanthanum are preferred rare earth elements. The amounts of Nd, La, B and refractory metal are controlled in order to produce both hard and soft magnetic phases, as well as a refractory metal boride precipitated phase. The refractory metal boride precipitates serve as grain refiners and substantially improve the magnetic properties of the nanocomposite materials. The materials are particularly suitable for making bonded magnets.
Claims50
A permanent magnet material characterized by magnetic properties of BHmax>8 MGOe, Br>7.2 KG and Hci>6 KOe and having the chemical formula:
- ((RE)1−y(La)y)vFe100−v−w−x−z CowMzBx,
- wherein RE is at least one element selected from the group consisting of Pr and Nd;
- M is at least one refractory metal selected from the group consisting of W, Ti, V, Nb, Hf;
- Cr, Zr and Mo;
- v=about 9.5 to about 11.5 atomic percent
- w=0 to about 15 atomic percent
- x=about 9.5 to about 11 atomic percent
- y=about 0.05 to about 0.15
- z=about 2 to about 3 atomic percent
- the material having been made by rapid cooling from melt as ribbons, filaments, particulates or powders at a cooling rate between 104 to 106 degrees C/second followed by annealing at temperatures between 650 to 750 degrees C for 0.01 seconds to 120 minutes, the material consisting of the following phases:
- (i) a hard magnetic phase RE2Fe14B with an average grain size between 10 to 100 nanometers,
- (ii) one or more soft magnetic phases selected from the group consisting of α-Fe, α-(Fe,Co), Fe3B, (Fe,Co)3B, Fe2B and (Fe,Co)2B each having an average grain size between 2 to 60 nanometers,
- (iii) one or more metal M boride precipitated phases with an average size of 1 to 30 nanometers wherein M is one element selected from the group consisting of Ti, V, Nb, Hf, Cr, Zr and Mo.
A magnetic material having permanent magnetic properties of BHmax>8 MGOe, Br>7.2 KG and Hci>6 KOe,
- having the chemical formula:
- ((RE)1−y(La)y)v Fe 100−v−w−x−z CowMzBx,
- wherein RE is at least one element selected from the group consisting of Pr and Nd;
- M is at least one refractory metal selected from the group consisting of W, Ti, V, Nb, Hf, Cr, Zr and Mo;
- v=about 9.5 to about 11.5 atomic percent
- w=0 to about 15 atomic percent
- x=about 9.5 to about 11 atomic percent
- y=about 0.05 to about 0.15
- z=about 2 to about 3 atomic percent,
- comprising a composite of the following phases with sizes in nanometer ranges:
- (i) a RE2(Fe,Co)14B hard magnetic phase with average grain size from about 10 to 100 nanometers,
- (ii) at least one soft magnetic phase selected from the group consisting of α-Fe, α-(Fe,Co), Fe3B, (Fe,Co)3B, Fe2B and (Fe,Co)2B the at least one soft magnetic phase having an average grain size of from 2 to 60 nanometers, and
- (iii) a refractory metal boride precipitated phase with an average particle size of 1 to 30 nanometers wherein the refractory metal is one or more of the elements from the group consisting of Ti, Nb, Hf, V, Mo, Cr and Zr.
Dependencies are inferred from the claim text.