Alloy for r-t-b-based rare earth sintered magnet, process of producing alloy for r-t-b-based rare earth sintered magnet, alloy material for r-t-b-based rare earth sintered magnet, r-t-b-based rare earth sintered magnet, process of producing r-t-b-based rare earth sintered magnet, and motor

Abstract

An alloy for R-T-B-based rare earth sintered magnets which contains R which is a rare earth element; T which is a transition metal essentially containing Fe; a metallic element M containing one or more metals selected from Al, Ga and Cu; B and inevitable impurities, in which R accounts for 13 at % to 15 at %, B accounts for 4.5 at % to 6.2 at %, M accounts for 0.1 at % to 2.4 at %, T accounts for balance, a proportion of Dy in all rare earth elements is in a range of 0 at % to 65 at %, and the following Formula 1 is satisfied,0.0049Dy+0.34≦B / TRE≦0.0049Dy+0.36  Formula 1wherein Dy represents a concentration (at %) of a Dy element, B represents a concentration (at %) of a boron element, and TRE represents a concentration (at %) of all the rare earth elements.

Description

[0001]The present invention relates to an alloy for R-T-B-based rare earth sintered magnets, a process of producing the alloy for R-T-B-based rare earth sintered magnets, an alloy material for R-T-B-based rare earth sintered magnets, an R-T-B-based rare earth sintered magnet, a process of producing the R-T-B-based rare earth sintered magnet, and a motor, and particularly to an alloy for R-T-B-based rare earth sintered magnets and an alloy material for R-T-B-based rare earth sintered magnets which have excellent magnetic properties and from which R-T-B-based rare earth sintered magnets that are preferably used for motors can be obtained.[0002]Priority is claimed on Japanese Patent Application No. 2011-151815 filed Jul. 8, 2011, Japanese Patent Application No. 2011-229289 filed Oct. 18, 2011, Japanese Patent Application No. 2012-060259 filed Mar. 16, 2012, and Japanese Patent Application No. 2012-149560 filed Jul. 3, 2012, the contents of which are incorporated herein by reference.BAC...

AI Technical Summary

Benefits of technology

The patent text describes a new composition of rare earth magnets that has a high coercive force. The composition includes a main phase containing R2Fe14B and a grain boundary with two different phases: one rich in rare earth elements and one rich in transition metal elements. The inventors found that the inclusion of a small amount of rare earth element in the grain boundary phase improves the coercive force. Additionally, the patent discusses the use of a specific alloy that contains rare earth element, transition metal element, in addition to other metals like aluminum or copper. The rare earth element accounts for a certain percentage of the alloy, while the transition metal element is present in a higher amount. This alloy has a uniform distribution of the grain boundary phases, which results in a magnet with a large coercive force and a reduced amount of rare earth element.

Problems solved by technology

However, in the related art, there were cases in which it was not possible to obtain an R-T-B-based magnet having a sufficiently large coercive force (Hcj) even when metal elements such as Al, Si, Ga and Sn were added to an R-T-B-based alloy.

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