Hot pressed magnets formed from anisotropic powders

Claim 1

A method for forming a hot pressed iron-rare earth metal permanent magnet, the method comprising the steps of: providing platelet-shaped anisotropic iron-rare earth metal particles, wherein the anisotropic iron-rare earth metal particles are formed from a composition comprising, on an atomic percent basis, about 40 to about 90 percent iron or a mixture of cobalt and iron, about 10 to about 40 percent rare earth, and at least about 0.5 percent boron; and hot pressing a quantity of the anisotropic iron-rare earth metal particles in the absence of a magnetic alignment field such that the anisotropic iron-rare earth metal particles are substantially magnetically nonaligned during the hot pressing step, the hot pressing step forming the hot pressed anisotropic iron-rare earth metal permanent magnet, the hot pressed iron-rare earth metal permanent magnet having platelet-shaped grains and exhibiting a magnetic anisotropy and an energy product which is greater than that of a hot pressed isotropic magnet having a substantially similar composition, and which is less than that of a hot worked anisotropic magnet having a substantially similar composition; wherein the hot pressed anisotropic iron-rare earth metal permanent magnet exhibits an energy product of at least about 15 megaGaussOersteds.

Claim 2

A method for forming a hot pressed iron-rare earth metal permanent magnet, the method comprising the steps of: providing platelet-shaped anisotropic iron-rare earth metal particles, wherein the anisotropic iron-rare earth metal particles are formed from a composition comprising, on an atomic percent basis, about 40 to about 90 percent iron or a mixture of cobalt and iron, about 10 to about 40 percent rare earth, and at least about 0.5 percent boron; and hot pressing a quantity of the anisotropic iron-rare earth metal particles in the absence of a magnetic alignment field such that the anisotropic iron-rare earth metal particles are substantially magnetically nonaligned during the hot pressing step, the hot pressing step forming the hot pressed anisotropic iron-rare earth metal permanent magnet, the hot pressed iron-rare earth metal permanent magnet having platelet-shaped grains and exhibiting a magnetic anisotropy and an energy product which is greater than that of a hot pressed isotropic magnet having a substantially similar composition, and which is less than that of a hot worked anisotropic magnet having a substantially similar composition; wherein the hot pressed anisotropic iron-rare earth metal permanent magnet exhibits an energy product of at least about 15 megaGaussOersteds.

Claim 11

A method for forming a hot pressed iron-rare earth metal permanent magnet comprising, on a weight percent basis, about 26 to 32 percent rare earth wherein at least about 90 percent of this constituent is neodymium, about 0.7 to about 1.1 percent boron, and the balance being essentially iron, the method comprising the steps of: melt spinning a hot pressed iron-rare earth metal composition to form overquenched ribbons; forming isotropic iron-rare earth particles from the ribbons; hot pressing the isotropic iron-rare earth metal particles to form an isotropic magnet body; hot working the isotropic magnetic body so as to plastically deform the iron-rare earth metal particles of the isotropic magnet body, so as to form an anisotropic magnet body; comminuting the anisotropic magnet body so as to form platelet-shaped anisotropic iron-rare earth metal particles from the anisotropic magnet body; and hot pressing a quantity of the anisotropic iron-rare earth metal particles in the absence of a magnetic alignment field such that the anisotropic iron-rare earth metal particles are substantially magnetically nonaligned during the hot pressing step, the hot pressing step forming the hot pressed iron-rare earth metal permanent magnet; whereby the iron-rare earth metal permanent magnet exhibits an energy product of at least about 15 megaGaussOersteds.

Claim 12

A method for forming a hot pressed iron-rare earth metal permanent magnet comprising, on a weight percent basis, about 26 to 32 percent rare earth wherein at least about 90 percent of this constituent is neodymium, about 0.7 to about 1.1 percent boron, and the balance being essentially iron, the method comprising the steps of: melt spinning a hot pressed iron-rare earth metal composition to form overquenched ribbons; forming isotropic iron-rare earth particles from the ribbons; hot pressing the isotropic iron-rare earth metal particles to form an isotropic magnet body; hot working the isotropic magnetic body so as to plastically deform the iron-rare earth metal particles of the isotropic magnet body, so as to form an anisotropic magnet body; comminuting the anisotropic magnet body so as to form platelet-shaped anisotropic iron-rare earth metal particles from the anisotropic magnet body; and hot pressing a quantity of the anisotropic iron-rare earth metal particles in the absence of a magnetic alignment field such that the anisotropic iron-rare earth metal particles are substantially magnetically nonaligned during the hot pressing step, the hot pressing step forming the hot pressed iron-rare earth metal permanent magnet; whereby the iron-rare earth metal permanent magnet exhibits an energy product of at least about 15 megaGaussOersteds.