Method for producing nanocomposite magnet using atomizing method
AssigneeHitachi Metals, Ltd.
InventorsToshio Miyoshi, Hirokazu Kanekiyo, Satoshi Hirosawa
Life of this patent
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Abstract
A rare-earth alloy powder is obtained by rapidly cooling a melt of an alloy by an atomization process. The alloy has a composition represented by (Fe1-mTm)100-x-y-zQxRyTizMn, where T is at least one of Co and Ni, Q is at least one of B and C, R is at least one of the rare-earth metal elements and yttrium, and M is at least one of Nb, Zr, Mo, Ta and Hf. The mole fractions x, y, z, m and n satisfy 10 at %<x≦25 at %, 6 at %≦y<10 at %, 0.1 at %≦z≦12 at %, 0≦m≦0.5, and 0 at %≦n≦10 at %, respectively. By adding Ti to the alloy, the nucleation and growth of α-Fe during the rapid quenching process can be minimized.
Claims10
A nanocomposite magnet powder of an iron-based rare-earth alloy having a composition represented by the general formula:
- (Fe1-mTm)100-x-y-z-nQxRyTizMn (where T is at least one element selected from the group consisting of Co and Ni;
- Q is at least one element selected from the group consisting of B and C;
- R is at least one element selected from the group consisting of the rare-earth metal elements and yttrium;
- and M is at least one element selected from the group consisting of Nb, Zr, Mo, Ta and Hf), the mole fractions x, y, z, m and n satisfying the inequalities of:
- 10 at %<x≦25 at %;
- 6 at %≦y<10 at %;
- 0.1 at %≦z≦12 at %;
- 0≦m≦0.5;
- and
- 0 at %≦n≦10 at %, respectively,
- wherein the nanocomposite magnet powder is obtained by an atomization process and includes at least two types of ferromagnetic crystalline phases, in which an R2Fe14B type compound phase serving as a hard magnetic phase has an average grain size of 10 nm to 200 nm and a soft magnetic phase has an average grain size of 1 nm to 50 nm;
- a ferromagnetic iron-based boride phase and an α-Fe phase serving as the soft magnetic phase are present on a grain boundary or sub-boundary of the R2Fe14B type compound phase;
- and
- the average crystal grain size of the ferromagnetic iron-based boride phase and α-Fe is smaller than that of the R2Fe14B type compound phase.
A method of making an iron-based rare-earth alloy nanocomposite magnet powder, the method comprising the steps of:
- obtaining a rare-earth alloy magnet powder by rapidly cooling a melt of an alloy by an atomization process, the alloy having a composition represented by the general formula:
- (Fe1-mTm)100-x-y-z-nQxRyTizMn (where T is at least one element selected from the group consisting of Co and Ni;
- Q is at least one element selected from the group consisting of B and C;
- R is at least one element selected from the group consisting of the rare-earth metal elements and yttrium;
- and M is at least one element selected from the group consisting of Nb, Zr, Mo, Ta and Hf), the mole fractions x, y, z, m and n satisfying the inequalities of:
- 10 at %<x≦25 at %;
- 6 at %≦y<10 at %;
- 0.1 at %≦z≦12 at %;
- 0≦m≦0.5, and
- 0 at %≦n≦10 at %, respectively;
- and
- thermally treating the magnet powder, thereby forming a structure that includes at least two types of ferromagnetic crystalline phases, in which an R2Fe14B type compound phase serving as a hard magnetic phase has an average grain size of 10 nm to 200 nm and a soft magnetic phase has an average grain size of 1 nm to 50 nm;
- wherein
- a ferromagnetic iron-based boride phase and an α-Fe phase serving as the soft magnetic phase are present on a grain boundary or sub-boundary of the R2Fe14B type compound phase;
- and
- the average crystal grain size of the ferromagnetic iron-based boride phase and α-Fe is smaller than that of the R2Fe14B type compound phase.
Dependencies are inferred from the claim text.