Hitachi Metals, Ltd.

501 Hitachi Metals, Ltd.

Masaaki Tokunaga

Shigeho Tanigawa

Katsunori Iwasaki

Minoru Endoh

Chitoshi Hagi

Hiroshi Kogure

Noriaki Meguro

Yasuto Nozawa

Makoto Shinoda

Hirokazu Murayama

Kazuo Yamakawa

Kimio Uchida

Masahiro Takahashi

Akitoshi Hiraki

Disclosed is a Nd-Fe-B system magnet having coercive force iHc of 12 KOe or more and high maximum energy product (BH)max of 42 MGOe or more. The permanent magnet consists of 28 to 32 wt. % of Nd and Dy (Dy ranges from 0.4 to 3 wt. %), 6 wt. % or less of Co, 0.5 wt. % or less of Al, 0.9 to 1.3 wt. % of B, at least one of 0.05 to 2.0 wt. % of Nb and 0.05 to 2.0 wt. % of V, 0.02 to 0.5 wt. % of Ga, Fe and unavoidable impurities, having coercive force iHc of 12 KOe or more and maximum energy product (BH)max of 42 MGOe or more.

Nd-Fe-B system permanent magnet

A magnetically anistropic R-T-B magnet having crystal grains having aspect ratios of 2 or more and showing a substantially uniform maximum energy product distribution is produced by (a) rapidly quenching an alloy melt; (b) finely pulverizing the rapidly quenched alloy to provide magnetic powder; (c) mixing the magnetic powder with a carbon-containing additive; (d) coating the resulting mixture with a protective layer of a first lubricant such as BN substantially unreactive with the alloy components; (e) compressing it; (f) further coating the resulting compressed body with a second lubricant such as graphite or graphite+glass; and (g) further compressing it.

Magnetically anisotropic R-T-B magnet

A permanent magnet having good thermal stability, consisting essentially of the composition represented by the general formula:

Permanent magnet with good thermal stability

A magnetically anisotropic R-T-B magnet having crystal grains having aspect ratios of 2 or more and showing a substantially uniform maximum energy product distribution is produced by (a) rapidly quenching an alloy melt; (b) finely pulverizing the rapidly quenched alloy to provide magnetic powder; (c) mixing the magnetic powder with a carbon-containing additive; (d) coating the resulting mixture with a protective layer of a first lubricant such as BN substantially unreactive with the alloy components; (e) compressing it; (f) further coating the resulting compressed body with a second lubricant such as graphite or graphite+glass; and (g) further compressing it.

A magnetically anisotropic hot-worked magnet made of an R-T-B alloy containing a transition metal T as a main component, a rare earth element R including yttrium, and boron B; the magnet having the fine crystal grains having an average grain size of 0.02 -1.0 .mu.m, and having a carbon content of 0.8 weight % or less and an oxygen content of 0.5 weight % or less. The angular variance of orientation of the crystal grains is within 30.degree. from the C axes of the crystal grains when measured by X-ray. This magnet can be produced by mixing the magnet flakes with an additive composed of at least one organic compound having a boiling point of 50.degree. C. or higher.

Magnetically anisotropic hot-worked magnet and method of producing same

Anisotropic not-worked permanent magnets are made from an R-T-B alloyed powder to which is added a combination internal lubricant including a carbon-based material such as graphite and a glass material such as glass from the B.sub.2 O.sub.3 -SiO.sub.2 -BiO.sub.3 glass system. The internal lubricant provides improved formability during the hot-working step, such as die-upsetting, and provides finished magnet products wherein the individual grains are more uniformly plastically deformed throughout the product.

Magnetically anisotropic hotworked magnet and method of producing same

A the magnetically anisotropic magnetic powder having an average particle size of 1-1000 .mu.m and made from a magnetically anisotropic R-TM-B-Ga or R-TM-B-Ga-M alloy having an average crystal grain size of 0.01-0.5 .mu.m, wherein R represents one or more rare earth elements including Y, TM represents Fe which may be partially substituted by Co, B boron, Ga gallium, and M one or more elements selected from the group consisting of Nb, W, V, Ta, Mo, Si, Al, Zr, Hf, P, C and Zn. This is useful for anisotropic resin-bonded magnet with high magnetic properties.

Anisotropic magnetic powder and magnet thereof and method of producing

A thermally stable permanent magnet with reduced irreversible loss of flux and improved intrinsic coercivity iHc of 15 KOe or more having the following compositon:

Permanent magnet having good thermal stability and method for

Anisotropic hot-worked permanent magnets are made from an R-T-B alloyed powder to which is added a combination internal lubricant including a carbon-based material such as graphite and a glass material such as glass from the B.sub.2 O.sub.3 --SiO.sub.2 --BiO.sub.3 glass system. The internal lubricant provides improved formability during the hot-working step, such as die-upsetting, and provides finished magnet products wherein the individual grains are more uniformly plastically deformed throughout the product.

A magnetically anisotropic hot-worked magnet made of an R-T-B alloy containing a transition metal T as a main component, a rare earth element R including yttrium, and boron B; the magnet having fine crystal grains having an average grain size of 0.02-1.0 .mu.m, and having a carbon content of 0.8 weight % or less than an oxygen content of 0.5 weight % or less. The angular variance of orientation of the crystal grains is within 30.degree. from the C axes of the crystal grains when measured by X-ray. This magnet can be produced by mixing the magnet flakes with an additive composed of at least one organic compound having a boiling point of 50.degree. C. or higher.

Anisotropic hot-worked permanent magnets are made from an R-T-B alloyed powder to which is added a combination internal lubricant including a carbon-based material such as graphite and a glass material such as glass from the B.sub.2 O.sub.3 -SiO.sub.2 BiO.sub.3 glass system. The internal lubricant provides improved formability during the hot-working step, such as die-upsetting, and provides finished magnet products wherein the individual grains are more uniformly plastically deformed throughout the product.

A process for manufacturing a rare earth-iron-boron alloy permanent magnet by, after sintering, keeping the sintered alloy at temperatures of 750.degree.-1000.degree. C. for 0.2-5 hours, slowly cooling it at a cooling rate of 0.3.degree.-5.degree. C./min. to temperatures between room temperature and 600.degree. C.; annealing it at temperatures of 550.degree.-700.degree. C. for 0.2-3 hours, and rapidly cooling it at a cooling rate of 20.degree.-400.degree. C./min. The permanent magnet contains a matrix, a B-rich phase and a Nd-rich phase. In grain boundaries of the matrix phases covered by bcc phases, thin, fine plates of the bcc phases projecting into the matrix phases are once increased by the first heat treatment and slow cooling and then eliminated by the annealing.

Process for manufacturing permanent magnet

A method of producing a neodymium-iron-boron permanent magnet alloy having a composition of 25.0-50.0 weight % of neodymium, 0.3-5.0 weight % of boron and balance substantially iron, including the steps of adding metal calcium, calcium hydride or a mixture thereof as a reducing agent to neodymium fluoride, iron and boron (or ferroboron), and further adding thereto at least one of calcium chloride, sodium chloride and potassium chloride as a flux, melting the resulting mixture in an inert gas atmosphere, or in a reducing gas atmosphere or substantially in vacuum at 1,000.degree.-1,300.degree. C., thereby reducing said neodymium fluoride to provide said alloy with as small a calcium content as 0.1 weight % or less. The starting materials may contain dysprosium fluoride and niobium to provide Nd-Dy-Fe-B-Nb alloys containing 0.5-15.0 weight % Dy and 0.05-5.0 weight % Nb. This method makes it possible to produce Nd-Fe-B or Nd-Dy-Fe-B-Nb permanent magnet alloys with as small a calcium content as 0.1 weight % or less directly from starting materials. Accordingly, it is economically advantageous over the conventional reduction method which produces mother alloys.

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Fukaya, Japan

Masaaki Tokunaga