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US 10,096,412 B2Granted
Rare earth based magnet
AssigneeTDK Corporation
InventorsEiji Kato, Yoshinori Fujikawa, Taeko Tsubokura, Chikara Ishizaka, Katsuo Sato
Life of this patent
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Abstract
The present invention provides a rare earth based magnet including R2T14B main-phase crystal grains, and two-grain boundary phases between adjacent two R2T14B main-phase crystal grains, the two-grain boundary phases are controlled such that the thickness thereof is 5 nm or more and 500 nm or less, and it is composed of a phase with a magnetism different from that of a ferromagnet.
Claims14
A rare earth based magnet comprising:
- R2T14B main-phase crystal grains, where R is at least one element selected from the group consisting of rare earth elements, and T is Fe or the combination of Fe and Co,
- the rare earth based magnet contains M and Cu,
- M is at least one element selected from the group consisting of Al, Ge, Si, Sn, and Ga,
- contents of the elements relative to the total mass are shown as follows:
- R:
- 30.5 to 33 mass %,
- B:
- 0.7 to 0.92 mass %,
- M:
- 0.2 to 1.5 mass %,
- Cu:
- 0.1 to 0.7 mass %, and
- Fe:
- balance, substantially, and
- the total content of elements other than Fe occupying the balance:
- 5 mass % or lower,
- the content of heavy rare earth elements in total mass of the sintered magnet is 0.1 mass % or less, and
- two-grain boundary phases between adjacent two R2T14B main-phase crystal grains,
- wherein the two-grain boundary phases have an average thickness of the two-grain boundary phases in any section with respect to all measuring points in a range of 5 nm or more and 490 nm or less,
- the thickness of the two-grain boundary phases is the thickness evaluated via HRTEM,
- the measuring points are points in which three points are present on each two-grain boundary phase in any section,
- the three points which are present on each two-grain boundary phase are determined by two boundaries between the two-grain boundary phase and triple junctions connecting thereto, the interval between the two boundaries is quadrisected, and when three quadrisectors are drawn, the three points are located at positions of the three quadrisectors,
- a thickness of each two-grain boundary phase on which the three points are present is a distance between the two R2T14B main-phase crystal grains on the three quadrisectors,
- the average thickness of the two-grain boundary phases is an average of measured values of 60 measuring points in 20 arbitrarily selected two-grain boundary phases,
- at least some of the two-grain boundary phases are composed of a phase with a magnetism different from that of the R2T14B main-phase,
- the two-grain boundary phases contain a rare earth element and the atomic concentration of the rare earth element in at least one of the two-grain boundary phases is 90 at % or more,
- a R6T13M phase and a layer are formed in at least one of the two-grain boundary phases, the layer is a thin microcrystal layer, an amorphous layer, or a microcrystal-containing amorphous layer, and
- the layer is formed in the boundary between the R6T13M phases and the R2T14B main-phase crystal grains and a thickness of the layer is 0.5 nm or more and 1/10 of the thickness of the R6T13M two-grain boundary phase or less.
25 more elements
A rare earth based magnet comprising:
- R2T14B main-phase crystal grains, where R is at least one element selected from the group consisting of rare earth elements, and T is Fe or the combination of Fe and Co, and
- the rare earth based magnet contains M and Cu,
- M is at least one element selected from the group consisting of Al, Ge, Si, Sn, and Ga,
- contents of the elements relative to the total mass are shown as follows:
- R:
- 30.5 to 33 mass %,
- B:
- 0.7 to 0.92 mass %,
- M:
- 0.2 to 1.5 mass %,
- Cu:
- 0.1 to 0.7 mass %, and
- Fe:
- balance, substantially, and
- the total content of elements other than Fe occupying the balance:
- 5 mass % or lower,
- the content of heavy rare earth elements in total mass of the sintered magnet is 0.1 mass % or less, and
- two-grain boundary phases between adjacent two R2T14B main-phase crystal grains,
- wherein the two-grain boundary phases have an average thickness of the two-grain boundary phases in any section with respect to all measuring points in a range of 5 nm or more and 490 nm or less,
- the thickness of the two-grain boundary phases is the thickness evaluated via HRTEM,
- the measuring points are points in which three points are present on each two-grain boundary phase in any section,
- the three points which are present on each two-grain boundary phase are determined by two boundaries between the two-grain boundary phase and triple junctions connecting thereto, the interval between the two boundaries is quadrisected, and when three quadrisectors are drawn, the three points are located at positions of the three quadrisectors,
- a thickness of each two-grain boundary phase on which the three points are present is a distance between the two R2T14B main-phase crystal grains on the three quadrisectors,
- the average thickness of the two-grain boundary phases is an average of measured values of 60 measuring points in 20 arbitrarily selected two-grain boundary phases,
- a R6T13M phase and a layer are formed in at least one of the two-grain boundary phases, the layer is a thin microcrystal layer, an amorphous layer, or a microcrystal-containing amorphous layer,
- wherein the layer is formed in the boundary between the R6T13M phases and the R2T14B main-phase crystal grains and a thickness of the layer is 0.5 nm or more and 1/10 of the thickness of the R6T13M two-grain boundary phase or less.
23 more elements
Dependencies are inferred from the claim text.