CN110767400B - Rare earth anisotropic bonded magnetic powder, preparation method thereof and magnet - Google Patents
Rare earth anisotropic bonded magnetic powder, preparation method thereof and magnet Download PDFInfo
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/047—Alloys characterised by their composition
- H01F1/053—Alloys characterised by their composition containing rare earth metals
- H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
- H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
- H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
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- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
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Abstract
A rare earth anisotropic bonded magnetic powder, its preparation method and magnet are provided, wherein the rare earth anisotropic bonded magnetic powder is RYFeMB; wherein R is Nd or PrNd, M is one or more of Nb, Ti, Zr, Ga and Si, and the mass fraction of R in the total mass is 28.5-30.5%; the mass fraction of the B in the total mass is 0.97-1.05%; the mass fraction of Y in the total mass is 0.1-5%; the M accounts for 10-50% of the mass fraction of the Y; the rest is Te. The coercive force temperature coefficient of the rare earth anisotropic bonded magnetic powder within 120 ℃ is larger than-0.5%/DEG C. According to the invention, by adding a certain proportion of yttrium Y element, the temperature coefficient of anisotropic magnetic powder is improved, and the heat resistance of the anisotropic magnetic powder is improved; meanwhile, the targeted addition of the M element effectively reduces the grain size deviation and improves the squareness of magnetic powder, so that the maximum magnetic energy product is not obviously reduced after the Y element is added.
Description
Technical Field
The invention relates to the technical field of magnetic materials, in particular to rare earth anisotropic bonded magnetic powder, a preparation method thereof and a magnet comprising the magnetic powder.
Background
The magnetic powder for bonding the neodymium iron boron permanent magnet material is mainly divided into two main categories of isotropy and anisotropy. The isotropic neodymium iron boron magnetic powder is prepared by a melt rapid quenching method at present, the maximum magnetic energy product is 12-16MGOe, and the maximum magnetic energy product of the prepared isotropic neodymium iron boron bonded magnet is not more than 12 MGOe. The anisotropic neodymium iron boron bonded magnetic powder is usually prepared by adopting an HDDR method, because of the particularity of the microstructure, namely the parallel arrangement of fine grains (200 plus 500nm) in the direction of an easy magnetization axis, the maximum magnetic energy product of the anisotropic bonded magnetic powder can reach 2-3 times of that of the isotropic bonded magnetic powder, and a high-performance anisotropic bonded magnet can be prepared by a die pressing or injection molding process and accords with the development trend of miniaturization, light weight and precision of motor devices, so that the market demands for the high-performance anisotropic magnetic powder are more and more urgent.
However, the bonded neodymium iron boron magnet prepared by the HDDR magnetic powder has the problem of insufficient heat resistance. For example, in applications such as automobiles where the magnet is exposed to high temperatures, if the heat resistance of the magnet is low, irreversible demagnetization is likely to occur. Therefore, as for the HDDR magnetic powder, the heat resistance is fully improved, and the HDDR magnetic powder can be applied to the fields of automobiles and the like to expand the application range.
There are two main ways to improve the heat resistance of anisotropic magnetic powder, i.e. to reduce the possibility of demagnetization at high temperature, i.e. to increase the coercive force of the magnetic powder at high temperature. The first is to improve the coercivity (room temperature coercivity) of anisotropic magnetic powder, so that the high temperature coercivity is correspondingly improved under the condition that the temperature coefficient is not changed. The second is to increase the temperature coefficient of the anisotropic magnetic powder, so that the high-temperature coercive force is correspondingly increased under the condition that the coercive force at room temperature is not changed.
At present, the first approach is mainly focused on improving the coercivity of anisotropic magnetic powder, and the first approach is mainly two approaches, one is to directly add heavy rare earth elements such as Tb and Dy, and the other is to add heavy rare earth elements or low-melting-point alloy elements through grain boundary diffusion. The former undoubtedly brings about great cost increase due to the addition of heavy rare earth; in the latter, due to the increase of the grain boundary diffusion process, the steps of diffusion source preparation, powder mixing, diffusion heat treatment and the like need to be added, so that the production process is more complicated, and the processing cost is increased.
Disclosure of Invention
In order to solve the problems, the invention provides the rare earth anisotropic bonded magnetic powder and the preparation method thereof, which improve the temperature coefficient of the anisotropic magnetic powder by adding yttrium Y element, and can effectively improve the heat resistance of the anisotropic magnetic powder on the premise of not increasing the production process, so that the anisotropic magnetic powder has excellent heat resistance. Meanwhile, the targeted addition of the M element effectively reduces the grain size deviation and improves the squareness of magnetic powder, so that the maximum magnetic energy product is not obviously reduced after the Y element is added.
In order to achieve the above purpose, the present invention adopts the following scheme:
the first aspect of the invention provides a rare earth anisotropic bonded magnetic powder, the rare earth anisotropic bonded magnetic powder comprises the components of RYFeMB;
wherein R is Nd or PrNd, M is one or more of Nb, Ti, Zr, Ga and Si, R accounts for 28.5 to 30.5 percent of the total mass, and B accounts for 0.97 to 1.05 percent of the total mass; the mass fraction of Y in the total mass is 0.1-5%; (ii) a
The M accounts for 10-50% of the mass fraction of the Y;
the balance being Fe; the coercive force temperature coefficient of the rare earth anisotropic bonded magnetic powder within 120 ℃ is larger than-0.5%/DEG C.
Further, the anisotropic bonded magnetic powder particles comprise a magnetic powder particle with a ratio of 2:14:1 is a main phase of a grain boundary structure and a grain boundary phase surrounding the main phase.
Further, the ratio of the content of M in the grain boundary phase to the content in the main phase is between 2 and 5.
Further, the grain size sigma of the main phase is 200-400nm, and the standard deviation of the grains is below 0.5 sigma.
Further, the mass fraction of Y in the total mass is 0.5-2%.
Further, the M accounts for 30% of the mass fraction of the mass of the Y.
The second aspect of the invention provides a method for preparing rare earth anisotropic bonded magnetic powder, which comprises the following steps:
hydrogen absorption disproportionation stage: placing the R-T-B series alloy in the rare earth anisotropic bonded magnetic powder into a rotary gas-solid reaction furnace, heating to a first temperature T1 under the hydrogen pressure of 0-0.1MPa, wherein the range of T1 is 760-860 ℃, then keeping the hydrogen pressure at a first pressure P1 and the range of P1 is 20-100kPa, and preserving the heat for 1-4 h to finish the treatment of the hydrogen absorption disproportionation stage;
slow dehydrogenation repolymerization stage: after the hydrogen absorption disproportionation stage is finished, keeping the temperature in the furnace to 800-;
a complete dehydrogenation stage: after the slow dehydrogenation repolymerization stage is finished, quickly vacuumizing to the hydrogen pressure below 1Pa to finish the complete dehydrogenation stage;
and (3) a cooling stage: and after the complete dehydrogenation stage is finished, cooling to room temperature to obtain the rare earth anisotropic bonded magnetic powder.
Further, between the hydrogen absorption disproportionation stage and the slow dehydrogenation repolymerization stage, the method also comprises the step of a tissue stabilization stage: after the hydrogen absorption disproportionation stage is finished, raising the temperature in the furnace to T2, simultaneously increasing the hydrogen pressure to P2, ensuring that T2 is more than or equal to T1 and P2 is more than or equal to P1, and finishing the treatment in the tissue stabilization stage.
Further, the cooling stage comprises a step cooling: after the complete dehydrogenation stage is completed, starting cooling, wherein the cooling speed is 30-50 ℃/min at the temperature of above 650 ℃; cooling at a temperature below 650 deg.C at a rate of 10-35 deg.C/min.
A third aspect of the invention provides a rare earth anisotropically bonded magnet comprising the rare earth anisotropically bonded magnetic powder as described above.
In summary, the present invention provides a rare earth anisotropic bonded magnetic powder, a method for preparing the same, and a magnet, wherein the rare earth anisotropic bonded magnetic powder is composed of RYFeMB; wherein R is Nd or PrNd, and M is one or more of Nb, Ti, Zr, Ga and Si; the mass fraction of Y in the total mass is 0.1-5%; the coercive force temperature coefficient of the rare earth anisotropic bonded magnetic powder within 120 ℃ is larger than-0.5%/DEG C. The preparation method comprises the steps of hydrogen absorption disproportionation, slow dehydrogenation and repolymerization, complete dehydrogenation and cooling, and the rare earth anisotropic bonded magnetic powder is finally obtained. According to the invention, by adding a certain proportion of yttrium Y element, the temperature coefficient of the anisotropic magnetic powder is improved, and the heat resistance of the anisotropic magnetic powder is improved. Meanwhile, the targeted addition of the M element effectively reduces the grain size deviation and improves the squareness of magnetic powder, so that the maximum magnetic energy product is not obviously reduced after the Y element is added.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.
The invention is realized by the following technical scheme:
the first aspect of the invention provides a rare earth anisotropic bonded magnetic powder, the rare earth anisotropic bonded magnetic powder comprises the components of RYFeMB; wherein R is Nd or PrNd, M is one or more of Nb, Ti, Zr, Ga and Si, R accounts for 28.5 to 30.5 percent of the total mass, and B accounts for 0.97 to 1.05 percent of the total mass; the mass fraction of Y in the total mass is 0.1-5%; the balance being iron; the M accounts for 10-50% of the mass fraction of the Y; the coercive force temperature coefficient of the rare earth anisotropic bonded magnetic powder within 120 ℃ is larger than-0.5%/DEG C.
Preferably, the mass fraction of M in the total mass is 0.5-2%.
Preferably, M is 30% by mass of Y. The main phase of Nd-Fe-B2Fe14B, the main phase of the analogous yttrium iron boron is Y2Fe14B. Y does not contain 4f electrons due to yttrium element2Fe14The anisotropy field of B magnetic crystal is lower, the coercive force of yttrium iron boron is lower than that of neodymium iron boron, but Y2Fe14The temperature coefficient of the coercive force of B is positive within a certain temperature range (room temperature to 100 ℃), so that the yttrium element can enter a main phase by adding a certain proportion of yttrium element into the anisotropic neodymium iron boron magnetic powder, and the neodymium element is partially replaced on a specific crystal position, so that the temperature coefficient of the coercive force of the anisotropic neodymium iron boron magnetic powder can be effectively reduced, and the heat resistance of the anisotropic neodymium iron boron magnetic powder is improved. The addition proportion of the yttrium element is between 0.1 and 5 percent, too much addition inevitably causes great reduction of the comprehensive magnetic property of the magnetic powder, and too little addition starts fromThe coercive force temperature coefficient is not reduced, and the heat resistance is improved.
Meanwhile, the addition of the M element can realize the effects of enabling the grain size of the crystal grains to be uniform and reducing the size deviation of the crystal grains, and the squareness of the magnetic powder is improved, so that the maximum magnetic energy product is not obviously reduced after the Y element is added. The adding proportion of the M element is calculated according to the adding amount of Y, the adding amount is 10% -50% of the mass of Y, too much adding inevitably causes the great reduction of the comprehensive magnetic performance of the magnetic powder, too little adding does not improve the squareness of the magnetic powder, and the effect of not obviously reducing the maximum magnetic energy product is kept.
Wherein the calculation formula of the coercivity temperature coefficient within 120 ℃ is as follows:
(coercivity at 120 ℃ C./20 ℃ (room temperature defined in general) coercivity-1)/(120-20)
At present, the coercivity temperature coefficient of anisotropic bonded magnetic powder is around-0.56%/deg.C. The coercive force temperature coefficient of the bonded magnetic powder prepared by the invention can be more than-0.5%/DEG C.
Further, the anisotropic bonded magnetic powder particles comprise a magnetic powder particle with a ratio of 2:14:1 is a main phase of a crystal structure and a grain boundary phase surrounding the main phase. The anisotropic bonded magnetic powder particles are mainly made of a compound with a stoichiometric ratio of chemical elements of 2:14:1, and are called as a main phase; a layer of rare earth-rich phase with the thickness of 1-5nm exists between the crystal grains of the main phase of the 2:14:1 type compound, and the phase is called a grain boundary phase
Further, the ratio of the content of M in the grain boundary phase to the content in the main phase is greater than 2. The element M is enriched in the crystal boundary phase, so that the pinning effect on the crystal boundary is favorably realized, the appearance of abnormally grown crystal grains is inhibited, and the crystal grain size of the anisotropic bonded magnetic powder is uniform.
Further, the grain size sigma of the main phase is 200-400nm, and the standard deviation of the grains is below 0.5 sigma. The rare earth anisotropic bonded magnetic powder has a recrystallization aggregate structure specific to an R-T-B magnet obtained by HDDR treatment, that is, a structure having an average crystal grain diameter of 200 to 400 nm. The crystal grains constituting the recrystallized texture are a 2:14:1 type compound phase. Each powder particle of the HDDR magnetic powder contains a large number of fine crystal grains. The average particle diameter and standard deviation of these crystal grains were measured by observing a cross section of the magnetic powder with a Transmission Electron Microscope (TEM). Specifically, the average grain size and standard deviation of crystal grains can be determined by image analysis of each crystal grain of a TEM image obtained from a sample of magnetic powder processed into a thin sheet by Focused Ion Beam (FIB) or the like. Wherein the particle size of the individual crystal grains is calculated as a projected area equivalent diameter in a TEM image of the individual crystal grains, and the average particle size can be obtained by simply averaging the equivalent diameters of the individual crystal grains. Further, the standard deviation is obtained by statistical calculation from the average particle diameter and the particle diameter of each crystal grain. For rare earth anisotropic magnetic powder, the more uniform the grain size, the higher the squareness of the corresponding demagnetization curve, and the higher the maximum magnetic energy product. Therefore, the smaller the standard deviation of the crystal grain size, the more uniform the crystal grain size and the higher the maximum magnetic energy product of the magnetic powder. The standard deviation of the grain size of the rare earth anisotropic magnetic powder is below 0.5 times of the average grain diameter of the grains. Other documents are silent as to this.
The second aspect of the invention provides a method for preparing rare earth anisotropic bonded magnetic powder, which comprises the following steps:
hydrogen absorption disproportionation stage: the rare earth anisotropic bonded magnetic powder RYFeMB alloy is characterized in that R accounts for 28.5 to 30.5 percent of the total mass, and B accounts for 0.97 to 1.05 percent of the total mass; the mass fraction of Y in the total mass is 0.1-5%; the M accounts for 10-50% of the mass fraction of the Y; placing the alloy in a rotary gas-solid reaction furnace, heating to a first temperature T1 under the hydrogen pressure of 0-0.1MPa, wherein the range of T1 is 760-860 ℃, then keeping the hydrogen pressure at a first pressure P1 and the range of P1 is 20-100kPa, and preserving heat for 1-4 h to finish the treatment of a hydrogen absorption disproportionation stage;
slow dehydrogenation repolymerization stage: after the hydrogen absorption disproportionation stage is finished, keeping the temperature in the furnace to 800-;
a complete dehydrogenation stage: after the slow dehydrogenation repolymerization stage is finished, quickly vacuumizing to the hydrogen pressure below 1Pa to finish the complete dehydrogenation stage;
and (3) a cooling stage: and after the complete dehydrogenation stage is finished, cooling to room temperature to obtain the rare earth anisotropic bonded magnetic powder.
Further, between the hydrogen absorption disproportionation stage and the slow dehydrogenation repolymerization stage, the method also comprises the step of a tissue stabilization stage: after the hydrogen absorption disproportionation stage is finished, raising the temperature in the furnace to T2, simultaneously increasing the hydrogen pressure to P2, ensuring that T2 is more than or equal to T1 and P2 is more than or equal to P1, and finishing the treatment in the tissue stabilization stage.
Further, the cooling stage comprises a step cooling: after the complete dehydrogenation stage is completed, starting cooling, wherein the cooling speed is 30-50 ℃/min at the temperature of above 650 ℃; cooling at a temperature below 650 deg.C at a rate of 10-35 deg.C/min.
A third aspect of the invention provides a rare earth anisotropically bonded magnet comprising the rare earth anisotropically bonded magnetic powder as described above.
The present invention will be further described with reference to the following specific examples.
Example 1:
the preparation component is Nd28.5Y0.5FebalGa0.25B1And (3) alloying. bal represents the remainder, and specifically, bal is 100-28.5-0.5-0.25-1.
Placing the alloy in a rotary gas-solid reaction furnace, heating to a first temperature T1 under the hydrogen pressure of 0.01MPa, wherein the T1 is 850 ℃, then keeping the hydrogen pressure at a first pressure P1 and the P1 is 30kPa, and preserving heat for 2h to finish the treatment of the hydrogen absorption disproportionation stage;
after the hydrogen absorption disproportionation stage is finished, raising the temperature in the furnace to T2, wherein the temperature of T2 is 900 ℃, simultaneously increasing the pressure of hydrogen to P2, and the pressure of P2 is 100kPa, and preserving the heat for 0.5h to finish the treatment of the tissue stabilization stage.
After the hydrogen absorption disproportionation stage is finished, keeping the temperature in the furnace to 850 ℃, adjusting the hydrogen pressure in the furnace to 3kPa, keeping the temperature and the pressure for 0.5h, and finishing the treatment of the slow dehydrogenation repolymerization stage;
after the slow dehydrogenation repolymerization stage is finished, quickly vacuumizing to the hydrogen pressure below 1Pa to finish the treatment of the complete dehydrogenation stage;
and (3) a cooling stage: after the complete dehydrogenation stage is finished, starting cooling, wherein the cooling speed is 30 ℃/min at the temperature of more than 650 ℃; cooling to room temperature at a cooling speed of 20 ℃/min below 650 ℃ to obtain the rare earth anisotropic bonded magnetic powder.
Example 2:
the preparation component is Nd28.5Y0.5FebalNb0.15B1And (3) alloying. bal represents the remainder, and specifically, bal is 100-28.5-0.5-0.15-1.
Other rare earth anisotropic bonded magnetic powder was obtained in the same manner as in example 1.
Example 3:
the preparation component is Nd28.5Y0.5FebalZr0.05B1And (3) alloying. bal represents the remainder, and specifically, bal is 100-28.5-0.5-0.05-1.
Other rare earth anisotropic bonded magnetic powder was obtained in the same manner as in example 1.
Example 4:
the preparation component is Nd28.5Y5FebalGa0.3Nb0.2B1And (3) alloying. bal represents the remainder, and specifically, bal ═ 100-28.5-5-0.3-0.2-1.
Other rare earth anisotropic bonded magnetic powder was obtained in the same manner as in example 1.
Example 5:
the preparation component is Nd28.5Y5FebalTi1.5B1And (3) alloying. bal represents the remainder, and specifically, bal ═ 100-28.5-5-1.5-1.
Other rare earth anisotropic bonded magnetic powder was obtained in the same manner as in example 1.
Example 6:
the preparation component is Nd28.5Y5FebalSi0.5B1And (3) alloying. bal represents the remainder, and specifically, bal is 100-28.5-5-0.5-1.
Other rare earth anisotropic bonded magnetic powder was obtained in the same manner as in example 1.
Example 7:
the preparation component is Nd28.5Y2FebalGa0.5Nb0.5B1And (3) alloying. bal represents the remainder, and specifically, bal ═ 100-28.5-2-0.5-0.5-1.
Other rare earth anisotropic bonded magnetic powder was obtained in the same manner as in example 1.
Example 8:
the preparation component is Nd28.5Y2FebalGa0.1Ti0.1B1And (3) alloying. bal represents the remainder, and specifically, bal ═ 100-28.5-2-0.1-0.1-1.
Other rare earth anisotropic bonded magnetic powder was obtained in the same manner as in example 1.
Example 9:
the preparation component is Nd28.5Y2FebalGa0.2Ti0.2Nb0.2B1And (3) alloying. bal represents the remainder, and specifically, bal ═ 100-28.5-2-0.2-0.2-0.2-1.
Other rare earth anisotropic bonded magnetic powder was obtained in the same manner as in example 1.
Comparative example 1:
the preparation component is Nd28.5FebalGa0.3Nb0.2B1And (3) alloying. bal represents the remainder, and specifically, bal is 100-28.5-0.3-0.2-1.
Other rare earth anisotropic bonded magnetic powder was obtained in the same manner as in example 1.
Table 1:
as can be seen from table 1 above, in the embodiment of the present invention, a specific proportion of yttrium Y element is added, and the coercivity temperature coefficient within 120 ℃ is significantly improved and the heat resistance is further improved as compared with the comparative example. In summary, the present invention provides a rare earth anisotropic bonded magnetic powder and a method for preparing the same, wherein the rare earth anisotropic bonded magnetic powder comprises RYFeMB; wherein R is Nd or PrNd, and M is one or more of Nb, Ti, Zr, Ga and Si; the mass fraction of R in the total mass is 28.5-30.5%; the mass fraction of the B in the total mass is 0.97-1.05%; the mass fraction of Y in the total mass is 0.1-5%; the M accounts for 10-50% of the mass fraction of the Y; the coercive force temperature coefficient of the rare earth anisotropic bonded magnetic powder within 120 ℃ is larger than-0.5%/DEG C. The preparation method comprises the steps of hydrogen absorption disproportionation, slow dehydrogenation and repolymerization, complete dehydrogenation and cooling, and the rare earth anisotropic bonded magnetic powder is finally obtained. According to the invention, by adding a certain proportion of yttrium Y element, the temperature coefficient of the anisotropic magnetic powder is improved, and the heat resistance of the anisotropic magnetic powder is improved; meanwhile, the targeted addition of the M element effectively reduces the grain size deviation and improves the squareness of magnetic powder, so that the maximum magnetic energy product is not obviously reduced after the Y element is added. It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.
Claims (8)
1. The rare earth anisotropic bonded magnetic powder is characterized in that the rare earth anisotropic bonded magnetic powder is RYFeMB;
wherein R is Nd or PrNd, M is one or more of Nb, Ti, Zr and Ga, R accounts for 28.5-30.5% of the total mass, and B accounts for 0.97-1.05% of the total mass;
the mass fraction of Y in the total mass is 0.1-5%;
the M accounts for 10-50% of the mass fraction of the Y;
the balance being Fe;
the coercive force temperature coefficient of the rare earth anisotropic bonded magnetic powder within 120 ℃ is larger than-0.5%/DEG C;
the anisotropic bonded magnetic powder particles comprise a magnetic powder formed by mixing 2:14:1 is a main phase of a grain boundary structure and a grain boundary phase surrounding the main phase;
the ratio of the content of M in the grain boundary phase to the content in the main phase is between 2 and 5.
2. The rare earth anisotropic bonded magnetic powder according to claim 1, wherein the grain size σ of the main phase is 200-400nm, and the standard deviation of the grains is 0.5 σ or less.
3. The rare earth anisotropic bonded magnetic powder according to claim 1 or 2, wherein Y accounts for 0.5 to 2% by mass of the total mass.
4. A rare earth anisotropically bonded magnetic powder according to claim 1 or 2, wherein M is 30% by mass of the mass fraction of Y.
5. A method of producing a rare earth anisotropically bonded magnetic powder according to any one of claims 1 to 4, comprising the steps of:
hydrogen absorption disproportionation stage: placing the raw material alloy in the rare earth anisotropic bonded magnetic powder in a rotary gas-solid reaction furnace, heating to a first temperature T1 under the hydrogen pressure of 0-0.1MPa, wherein the range of T1 is 760-860 ℃, then keeping the hydrogen pressure at a first pressure P1 and the range of P1 is 20-100kPa, and preserving the heat for 1-4 h to finish the treatment of a hydrogen absorption disproportionation stage;
slow dehydrogenation repolymerization stage: after the hydrogen absorption disproportionation stage is finished, keeping the temperature in the furnace to 800-;
a complete dehydrogenation stage: after the slow dehydrogenation repolymerization stage is finished, quickly vacuumizing to the hydrogen pressure below 1Pa to finish the complete dehydrogenation stage;
and (3) a cooling stage: and after the complete dehydrogenation stage is finished, cooling to room temperature to obtain the rare earth anisotropic bonded magnetic powder.
6. The method according to claim 5, characterized in that it further comprises, between the hydrogen uptake disproportionation stage and the slow dehydrogenation repolymerization stage, a step of tissue stabilization stage: after the hydrogen absorption disproportionation stage is finished, raising the temperature in the furnace to T2, simultaneously increasing the hydrogen pressure to P2, ensuring that T2 is more than or equal to T1 and P2 is more than or equal to P1, and finishing the treatment in the tissue stabilization stage.
7. The method of claim 5, wherein the cooling stage comprises a step cooling: after the complete dehydrogenation stage is completed, starting cooling, wherein the cooling speed is 30-50 ℃/min at the temperature of above 650 ℃; cooling at a temperature below 650 deg.C at a rate of 10-35 deg.C/min.
8. A rare earth anisotropically bonded magnet comprising the rare earth anisotropically bonded magnetic powder according to any one of claims 1 to 4.
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| US4983232A (en) * | 1987-01-06 | 1991-01-08 | Hitachi Metals, Ltd. | Anisotropic magnetic powder and magnet thereof and method of producing same |
| JPH10135019A (en) * | 1997-06-23 | 1998-05-22 | Aichi Steel Works Ltd | Anisotropic magnetic powder |
| CN104625079A (en) * | 2015-01-28 | 2015-05-20 | 北矿磁材科技股份有限公司 | Preparing method of rare earth iron-boron-based anisotropy magnetic powder and prepared magnetic powder |
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