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AssigneeShowa Denko K.K.
InventorShiro Sasaki
Estimating the term…
Disclosed is a rare earth magnet in the R-T-B (rare earth element-transition metal-boron) system that is made from an improved composition and properties of main phase alloy in the R-T-B system containing Pr and a boundary alloy. Disclosed also is a manufacturing method of the rare earth magnet alloy flake by a strip casting method with improved rotating rollers such that the alloy flake has a specified fine surface roughness and has a small and regulated amount of fine R-rich phase regions. Consequently, the alloy flake for the rare earth magnet does not containing α-Fe and has a homogeneous morphology so that the rare earth magnet formed by sintering or bonding the alloy flakes exhibits excellent magnetic properties.
A main phase alloy for a rare earth magnet to be processed through a two-alloy-blending method, the main phase alloy containing R (R represents at least one rare earth element including Y) in an amount of 26 to 30% by mass and B in an amount of 0.9 to 1.1% by mass, with the balance being T (T represents transition metals including Fe as an essential element), characterized in that R has a Pr content of at least 5% by mass and the main phase alloy has a percent volume of region containing α-Fe on the basis of the entire microstructure of 5% or less, and wherein at least one surface thereof has a surface roughness, as represented by 10-point average roughness (Rz), falling within a range of 5 μm to 50 μm.
A method for producing a main phase alloy for a rare earth magnet to be processed through a two-alloy-blending method, the main phase alloy containing R (R represents at least one rare earth element including Y) in an amount of 26 to 30% by mass and B in an amount of 0.9 to 1.1% by mass, with the balance being T (T represents transition metals including Fe as an essential element), wherein R has a Pr content of at least 5% by mass and the main phase alloy has a percent volume of region containing α-Fe on the basis of the entire microstructure of 5% or less, and wherein at least one surface thereof has a surface roughness, as represented by 10-point average roughness (Rz), falling within a range of 5 μm to 50 μm, the process comprising a centrifugal casting method including depositing and solidifying a molten metal on an inner surface of a cylindrical mold which is rotating.
Dependencies are inferred from the claim text.