R-T-B based sintered magnet

Patent metadata

Field	Value
Publication number	US-10388440-B2
Application number	US-201615344245-A
Country	US
Kind code	B2
Filing date	Nov 4, 2016
Priority date	Nov 13, 2015
Publication date	Aug 20, 2019
Grant date	Aug 20, 2019

Abstract

An R-T-B based sintered magnet includes R 2 T 14 B crystal grains. A grain boundary formed by the two or more adjacent R 2 T 14 B crystal grains includes an R—N—O—C concentrated part having higher concentrations of “R”, N, O, and C than those in the R 2 T 14 B crystal grains. “R” of the R—N—O—C concentrated part includes Y. A ratio of Y atom to “R” atom in the R—N—O—C concentrated part is 0.65 or more and 1.00 or less. A ratio of O atom to “R” atom in the R—N—O—C concentrated part is more than 0 and 0.20 or less. A ratio of N atom to “R” atom in the R—N—O—C concentrated part is 0.03 or more and 0.15 or less.

First claim

The invention claimed is:

1. An R-T-B based sintered magnet comprising R 2 T 14 B crystal grains, wherein:
“R” represents at least one rare earth element including Y,
“T” represents Fe or Fe and Co,
a grain boundary formed by the two or more adjacent R 2 T 14 B crystal grains includes an R—N—O—C concentrated part having higher concentrations of “R”, N, O, and C than those in the R 2 T 14 B crystal grains,
“R” of the R—N—O—C concentrated part includes Y,
a ratio of an average concentration of Y atom to an average concentration of “R” atom in the R—N—O—C concentrated part is 0.65 or more and 1.00 or less,
a ratio of an average concentration of O atom to the average concentration of “R” atom in the R—N—O—C concentrated part is more than 0 and 0.20 or less,
a ratio of an average concentration of N atom to the average concentration of “R” atom in the R—N—O—C concentrated part is 0.03 or more and 0.15 or less, and
an area ratio of the R—N—O—C concentrated part occupied in an area of the grain boundary on a cut surface of the R-T-B based sintered magnet is 0.20 or more and 0.75 or less.

Assignees

• Tdk Corp

Inventors

• Tada Atsushi

Classifications

• C21D3/06

  Extraction of hydrogen · CPC title

• H01F1/08

  pressed, sintered, or bound together · CPC title

• C22C38/005

  containing rare earths, i.e. Sc, Y, Lanthanides · CPC title

• B22F9/04

  starting from solid material, e.g. by crushing, grinding or milling ({C22C1/1084 takes precedence}; crushing, grinding or milling, in general, see the relevant subclasses, e.g. B02C) · CPC title

• B22F2009/044

  by jet milling · CPC title