Samarium-iron-nitrogen alloy powder and method for producing same

Patent metadata

Field	Value
Publication number	US-11453057-B2
Application number	US-201716081299-A
Country	US
Kind code	B2
Filing date	Feb 28, 2017
Priority date	Mar 4, 2016
Publication date	Sep 27, 2022
Grant date	Sep 27, 2022

Abstract

A samarium-iron-nitrogen alloy powder according to one embodiment of the present invention is characterized in that a value obtained by dividing the hydrogen content of the samarium-iron-nitrogen alloy powder by the BET specific surface area of the samarium-iron-nitrogen alloy powder is less than or equal to 400 ppm/(m2/g), and a value obtained by dividing the oxygen content of the samarium-iron-nitrogen alloy powder by the BET specific surface area of the samarium-iron-nitrogen alloy powder is less than or equal to 11,000 ppm/(m2/g).

First claim

The invention claimed is:

1. A samarium-iron-nitrogen alloy powder characterized in that:
a value obtained by dividing a hydrogen content of the samarium-iron-nitrogen alloy powder by a BET specific surface area of the samarium-iron-nitrogen alloy powder is in a range of from 200 ppm/m 2 /g) to 400 ppm/(m 2 /g);
a value obtained by dividing an oxygen content of the samarium-iron-nitrogen alloy powder by the BET specific surface area of the samarium-iron-nitrogen alloy powder is less than or equal to 11,000 ppm/(m 2 /g);
an average particle diameter of the samarium-iron-nitrogen alloy powder is less than or equal to 1 μm; and
a coercivity of the samarium-iron-nitrogen alloy powder is at least 18 kOe when the average particle diameter is 1 μm and the coercivity increases as the average particle diameter decreases from 1 μm, to 0.63 μm.

2. The samarium-iron-nitrogen alloy powder according to claim 1 , wherein
a value c/a obtained by dividing a lattice constant c along the c-axis direction of the samarium-iron-nitrogen alloy powder by a lattice constant a along the a-axis direction of the samarium-iron-nitrogen alloy powder is greater than or equal to 1.447 and less than or equal to 1.450.

3. The samarium-iron-nitrogen alloy powder according to claim 1 , wherein a maximum energy product of the samarium-iron-nitrogen alloy powder is greater than or equal to 35 MGOe.

4. The samarium-iron-nitrogen alloy powder according to claim 1 , wherein
the average particle diameter of the samarium-iron-nitrogen alloy powder is in a range of from 0.63 μm to 1 μm.

5. The samarium-iron-nitrogen alloy powder according to claim 1 , wherein
the average particle diameter of the samarium-iron-nitrogen alloy powder is in a range of from 0.63 μm to 0.93 μm.

6. A method for producing a samarium-iron-nitrogen alloy powder having an average particle diameter of less than or equal to 1 μm, the method comprising:
performing a reduction-diffusion process on a samarium-iron alloy precursor powder to produce a samarium-iron alloy powder;
nitriding the samarium-iron alloy powder;
washing the nitrided samarium-iron alloy powder with a solvent capable of dissolving calcium; and
dehydrogenating the washed powder to produce the samarium-iron-nitrogen alloy powder such that a value obtained by dividing a hydrogen content of the samarium-iron-nitrogen alloy powder by a BET specific surface area of the samarium-iron-nitrogen alloy powder is in a range of from 200 ppm/(m 2 /g) to 400 ppm/(m 2 /g), and a value obtained by dividing an oxygen content of the samarium-iron-nitrogen alloy powder by the BET specific surface area of the samarium-iron-nitrogen alloy powder is less than or equal to 11,000 ppm/(m 2 /g);
wherein the reduction-diffusion process step, the nitriding step, the washing step, and the dehydrogenating step are carried out in a non-oxidizing atmosphere, and the samarium-iron-nitrogen alloy powder has a coercivity of at least 18 kOe when the average particle diameter is 1 μm and the coercivity increases as the average particle diameter decreases from 1 μm to 0.63 μm.

7. The method for producing a samarium-iron-nitrogen alloy powder according to claim 6 , further comprising a step of:
pulverizing the dehydrogenated powder.

Assignees

• Okada Shusuke
• Suzuki Kazuyuki
• Takagi Kenta
• Ozaki Kimihiro
• Enokido Yasushi
• Aist
• Tdk Corp

Inventors

• Okada Shusuke
• Suzuki Kazuyuki
• Takagi Kenta
• Ozaki Kimihiro
• Enokido Yasushi

Classifications

• B22F1/145

  Chemical treatment, e.g. passivation or decarburisation · CPC title

• B22F1/00

  Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties · CPC title

• C22C32/0068

  only nitrides · CPC title

• C22C33/02

  by powder metallurgy · CPC title

• H01F41/02

  for manufacturing cores, coils, or magnets (H01F41/14 takes precedence; for dynamo-electric machines H02K15/00) · CPC title