Mitsubishi Materials Corporation

Mitsubishi Kinzoku Kabushiki Kaisha

Mitsubishi Metal Corporation

Tamotsu Ogawa

Takuo Takeshita

Ryoji Nakayama

Yoshinari Ishii

The present invention provides a method for producing a rare earth alloy magnet powder exhibiting stable and superior magnetic properties using hydrogenation followed by dehydrogenation. In a method for producing a rare earth alloy magnet powder wherein a homogenized rare earth alloy magnet alloy material is subjected to hydrogenation at a temperature in a range between 750.degree. C. and 950.degree. C., followed by dehydrogenation at a temperature in a range between 750.degree. C. and 950.degree. C.; cooled; and crushed, both the hydrogenation and the dehydrogenation are carried out in a vacuum tube furnace; and the alloy material in the dehydrogenation step maintains a temperature drop of at most 50.degree. C. due to an endothermic reaction which occurs during the dehydrogenation step.

Method for producing rare earth alloy magnet powder

A hot press molded body or an HIP molded body having one of a composition comprising R: 10-20 atomic %, B: 3-20 atomic %, and a total amount of one or a plurality of Ga, Zr, and Hf: 0.001-5.0 atomic %, a remainder comprising Fe and unavoidable impurities; or a composition comprising R: 10-20 atomic %, B: 3-20 atomic %, and a total amount of one or a plurality of Ti, V, Nb, Ta, Al, and Si: 0.001-5.0 atomic %, a remainder comprising Fe and unavoidable impurities; or a composition comprising Co: 0.1-50 atomic % added to one of the above compositions, having an aggregate structure of crystallized grains having as a main phase thereof a R.sub.2 Fe.sub.14 B type or R.sub.2 (Fe, Co).sub.14 B type intermetallic compound having a tetragonal structure, the crystallized grains having dimensions of 0.05-20 .mu.m; and individual crystallized grains comprising more than 50 volume % of the total crystallized grains comprising the aggregate structure, have a value of less than 2 of a ratio b/a of a smallest grain diameter a and a largest grain diameter b.

Anisotropic rare earth-Fe-B system and rare earth-Fe-Co-B system magnet

There is disclosed a R--Fe--B or R--Fe--Co--B alloy permanent magnet powder which may contain Ga, Zr or Hf, or may further contain Al, Si or V. Each individual particle of the powder includes a structure of recrystallized grains containing a R.sub.2 Fe.sub.14 B or R.sub.2 (Fe,Co).sub.14 B intermetallic compound phase. The intermetallic compound phase has recrystallized grains of a tetragonal crystal structure having an average crystal grain size of 0.05 to 20 .mu.m. At least 50% by volume of the recrystallized grains of the aggregated structure are formed so that a ratio of the greatest dimension to the smallest dimension is less than 2 for each recrystallized grain. In order to manufacture the magnet powder, regenerative material and alloy material are prepared and their temperature is elevated in a hydrogen atmosphere. Then, the alloy material and the regenerative material are held in the same atmosphere at a temperature or 750.degree. C. to 950.degree. C., and then held in a vacuum at 750.degree. C. to 950.degree. C., and cooled and crushed. A bonded magnet produced using the above magnet powder is also disclosed.

Rare earth permanent magnet powder, method for producing same and bonded

A R-Fe-B or R-Fe-Co-B permanent magnet powder excellent in magnetic anisotropy and corrosion resistivity, having powder particles. The powder particles each consist essentially of, in atomic percentage:

Rare earth element-Fe-B or rare earth element-Fe-Co-B permanent magnet

There is disclosed a R-Fe-B or R-Fe-Co-B alloy permanent magnet powder which may contain Ga, Zr or Hf, or may further contain Al, Si or V. Each individual particle of the powder includes a structure of recrystallized grains containing a R.sub.2 Fe.sub.14 B or R.sub.2 (Fe,Co).sub.14 B intermetallic compound phase. The intermetallic compound phase has recrystallized grains of a tetragonal crystal structure having an average crystal grain size of 0.05 to 20 .mu.m. At least 50% by volume of the recrystallized grains of the aggregated structure are formed so that a ratio of the greatest dimension to the smallest dimension is less than 2 for each recrystallized grain. In order to manufacture the magnet powder, regenerative material and alloy material are prepared and their temperature is elevated in a hydrogen atmosphere. Then, the alloy material and the regenerative material are held in the same atmosphere at a temperature of 750.degree. C. to 950.degree. C., and then held in a vacuum at 750.degree. C. to 950.degree. C., and cooled and crushed. A bonded magnet produced using the above magnet powder is also disclosed.

Rare earth permanent magnet power, method for producing same and bonded

In a rare earth-iron-boron alloy magnet powder, each individual particle includes a recrystallized grain structure containing a R.sub.2 Fe.sub.14 B intermetallic compound phase as a principal phase thereof, wherein R represents a rare earth element. The intermetallic compound phase are formed of recrystallized grains of a tetragonal crystal structure having an average crystal grain size of 0.05 .mu.m to 50 .mu.m. For producing the above magnet powder, a rear earth-iron-boron alloy material is first prepared. Then, hydrogen is occluded inot the alloy material by holding the material at a temperature of 500.degree. C. to 1,000.degree. C. either in an atmosphere of hydrogen gas or in an atmosphere of hydrogen and inert gases. Subsequently, the alloy material is subjected to dehydrogenation at a temperature of 500.degree. C. to 1,000.degree. C. until the pressure of hydrogen in the atmosphere is decreased to no greater than 1.times.10.sup.-1 torr, and is subjected to cooling.

Rare earth-iron-boron magnet powder and process of producing same

In a rare earth-iron-boron alloy magnet powder, each individual particle includes a recrystallized grain structure containing a R.sub.2 Fe.sub.14 B intermetallic compound phase as a principal phase thereof, wherein R represents a rare earth element. The intermetallic compound phase are formed of recrystallized grains of a tetragonal crystal structure having an average crystal grain size of 0.05 .mu.m to 50 .mu.m. For producing the above magnet powder, a rear earth-iron-boron alloy material is first prepared. Then, hydrogen is occluded into the alloy material by holding the material at a temperature of 500.degree. C. to 1,000.degree. C. either in an atmosphere of hydrogen gas or in an atmosphere of hydrogen and inert gases. Subsequently, the alloy material is subjected to dehydrogenation at a temperature of 500.degree. C. to 1,000.degree. C. until the pressure of hydrogen in the atmosphere is decreased to no greater than 1.times.10.sup.-1 torr, and is subjected to cooling.

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Omiya, Japan

Tamotsu Ogawa