Disclosed are an MnBi sintered magnet exhibiting excellent thermal stability as well as excellent magnetic characteristics at high temperature, an MnBi anisotropic complex sintered magnet, and a method of preparing the same.

Disclosed are an MnBi sintered magnet exhibiting excellent thermal stability as well as excellent magnetic characteristics at high temperature, an MnBi anisotropic complex sintered magnet, and a method of preparing the same.

An object of the present invention is to provide an R-T-B based permanent magnet showing high residual magnetic flux density Br and coercive force HcJ. Provided is an R-T-B based permanent magnet in which, R is a rare earth element, T is an element other than the rare earth element, B, C, O or N, and B is boron. R at least includes Tb and T at least includes Fe, Cu, Co and Ga, and a total of R content is 28.05 to 30.60 mass %, Cu content is 0.04 to 0.50 mass %, Co content is 0.5 to 3.0 mass %, Ga content is 0.08 to 0.30 mass %, and B content is 0.85 to 0.95 mass %, relative to 100 mass % of a total mass of R, T and B, and Tb concentration reduces from outside to inside of the R-T-B based permanent magnet.

An object of the present invention is to provide an R-T-B based permanent magnet showing high residual magnetic flux density Br and coercive force HcJ. Provided is an R-T-B based permanent magnet in which, R is a rare earth element, T is an element other than the rare earth element, B, C, O or N, and B is boron. R at least includes Tb and T at least includes Fe, Cu, Co and Ga, and a total of R content is 28.05 to 30.60 mass %, Cu content is 0.04 to 0.50 mass %, Co content is 0.5 to 3.0 mass %, Ga content is 0.08 to 0.30 mass %, and B content is 0.85 to 0.95 mass %, relative to 100 mass % of a total mass of R, T and B, and Tb concentration reduces from outside to inside of the R-T-B based permanent magnet.

A NdFeB magnet containing cerium and a manufacturing method thereof are provided. The manufacturing method includes steps of: refining a part of raw materials pure iron, ferro-boron, and rare earth fluoride in a crucible, adding a rest of the raw materials into the crucible and refining, casting a refined solution to a surface of a water-cooled rotation roller through a tundish and forming alloy flakes, processing the alloy flakes containing at least two different compositions with hydrogen decrepitation, milling powders, magnetic field pressing, vacuum presintering, machining and sintering, and obtaining the NdFeB magnet containing cerium. The NdFeB magnet containing cerium has a density of 7.5-7.7 g/cm.sup.3 and an average particle size of 3-7 m; comprises a main phase and a grain boundary phase distributed around the main phase. A composite phase containing Tb is provided between the main phase and the grain boundary phase.

A NdFeB magnet containing cerium and a manufacturing method thereof are provided. The manufacturing method includes steps of: refining a part of raw materials pure iron, ferro-boron, and rare earth fluoride in a crucible, adding a rest of the raw materials into the crucible and refining, casting a refined solution to a surface of a water-cooled rotation roller through a tundish and forming alloy flakes, processing the alloy flakes containing at least two different compositions with hydrogen decrepitation, milling powders, magnetic field pressing, vacuum presintering, machining and sintering, and obtaining the NdFeB magnet containing cerium. The NdFeB magnet containing cerium has a density of 7.5-7.7 g/cm.sup.3 and an average particle size of 3-7 m; comprises a main phase and a grain boundary phase distributed around the main phase. A composite phase containing Tb is provided between the main phase and the grain boundary phase.

The negative electrode active material according to the present embodiment includes alloy particle containing an alloy component and oxygen of 0.50 to 3.00 mass %. The alloy component contains Sn: 13.0 to 40.0 at % and Si: 6.0 to 40.0 at %. The alloy particle contains: one or two phases selected from a D0.sub.3 phase in which the Si content is from 0 to 5.0 at % and a phase in which the Si content is from 0 to 5.0 at %; one or two phases selected from an phase in which the Si content is from 0 to 5.0 at % and an phase in which the Si content is from 0 to 5.0 at %; and an SiOx phase. The alloy particle has, in an X-ray diffraction profile, a peak having a largest integrated diffraction intensity in a range of 42.0 to 44.0 degrees of a diffraction angle 2.

The invention provides a high-performance permanent magnet. The permanent magnet has a composition that is expressed by a composition formula R.sub.pFe.sub.qM.sub.rCu.sub.tCo.sub.100-p-q-r-t, where R is at least one element selected from a rare earth element, M is at least one element selected from the group consisting of Zr, Ti, and Hf, p is a number satisfying 10.8p12.5 atomic percent, q is a number satisfying 25q40 atomic percent, r is a number satisfying 0.88r4.5 atomic percent, and t is a number satisfying 3.5t13.5 atomic percent. The permanent magnet also has a metallic structure that includes a main phase having a Th.sub.2Zn.sub.17 crystal phase, and a Cu-M rich phase having a higher Cu concentration and a higher M concentration than the main phase.

There is provided a production method and a production device for producing each of the rare earth sintered magnet sintered bodies without carrying a mold in a sintering furnace. The method includes feeding an alloy powder into a mold having side walls divided into two or more sections; filling the alloy powder into the mold to prepare a filled molded-body; orienting the alloy powder in the filled molded-body by applying a magnetic field to the filled molded-body to prepare an oriented filled-molded-body; detaching the side walls of the mold from the oriented filled-molded-body and retrieving the oriented filled-molded-body from the mold; and sintering the retrieved oriented filled-molded-body. The filling step and the orienting step are performed at different locations. A pulsed magnetic field can be applied in the orienting step and inside of the mold can be partitioned into a plurality of cavities by partitions.

There is provided a production method and a production device for producing each of the rare earth sintered magnet sintered bodies without carrying a mold in a sintering furnace. The method includes feeding an alloy powder into a mold having side walls divided into two or more sections; filling the alloy powder into the mold to prepare a filled molded-body; orienting the alloy powder in the filled molded-body by applying a magnetic field to the filled molded-body to prepare an oriented filled-molded-body; detaching the side walls of the mold from the oriented filled-molded-body and retrieving the oriented filled-molded-body from the mold; and sintering the retrieved oriented filled-molded-body. The filling step and the orienting step are performed at different locations. A pulsed magnetic field can be applied in the orienting step and inside of the mold can be partitioned into a plurality of cavities by partitions.