CN105225781A - A kind of high corrosion-resistant many Hard Magnetics principal phase Ce permanent magnet and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of rare earth permanent magnet materials, and relates to a high corrosion resistance multi-hard magnetic main phase Ce permanent magnet and a preparation method thereof. The permanent magnet is prepared by powder hydrogen absorption and oxygen control, and pre-sintering dehydrogenation process; in the final magnet, Ce is the rare earth element with the largest content by mass percentage, and the chemical formula of the permanent magnet is expressed by mass percentage: (Ce, Re) _a Fe _100-abc B _b TM _c consists of (Pr,La,Ce,Nd)-Fe-B, (Nd,Pr)-Fe-B and (Dy , Ho, Gd, Er)-Fe-B magnetic powder preparation of multiple hard magnetic main phases: the chemical formulas of each main phase are: (RL _{1-x ,} Cex ) _a1 Fe _100-a1-b1-c1 B _b1 TM _c1 ，(Nd _y Pr _1-y ) _a2 Fe _100-a2-b2-c2 B _b2 TM _c2 ，[RH _z ,(Nd,Pr) _1-z ] _a3 Fe _100-a3-b3-c3 B _b3 TM _c3 ; Among them, 0.25<x≤1.0, 0≤y≤1.0, 0<z≤1.0, 27≤a≤31, 0.8≤b≤1.5, 0.5≤c≤2, a1～a3, b1～b3, c1～c3 The value ranges of a, b, and c are the same respectively, Re is selected from rare earth elements, RL contains light rare earth elements, RH contains heavy rare earth elements, and TM is one or more of Ga, Co, Cu, Nb, and Al elements . The invention has the characteristics of high corrosion resistance and low weight loss rate, and its preparation technology is suitable for engineering scale production.

Description

A kind of high corrosion resistance multi-hard magnetic main phase Ce permanent magnet and preparation method thereof

technical field

The invention belongs to the technical field of rare earth permanent magnet materials, in particular to a Ce permanent magnet with high corrosion resistance and multiple hard magnetic main phases and a preparation method thereof.

Background technique

So far, NdFeB is still the permanent magnet material with the highest performance and is irreplaceable. As an intermetallic compound, Nd ₂ Fe ₁₄ B was synthesized by Russian scientists very early. There are many invention patents involving NdFeB, and the composition patents mainly belong to the US Naval Laboratory (DLN.Koon), which only covers the United States. The component patents of Hitachi Metals (inherited from Sumitomo Special Metals Corporation, SSMC) and Magnequench (inherited from General Motors, GM) (Dr.J.Croat, etc.) cover Japan, the United States, and Europe. However, since 2002, these patents have expired one after another, and by the end of 2014, all of Hitachi's original patents will expire. Based on the consideration of interests, on August 17, 2012, Hitachi Metals, Ltd. and its affiliated company, Hitachi Metals North Carolina, Ltd., took some Necessary measures, according to Section 337 of the "U.S. Tariff Act of 1930", proposed to the U.S. ITC that the sintered rare earth magnets exported to the U.S., imported by the U.S., or sold in the U.S. by 29 companies including China and the U.S. violated their registration in the U.S. patent. Eight Chinese companies were forced to sign a patent sales licensing contract with Hitachi, Japan, which extended the life of Japanese patents by 5-10 years and restricted the development of most Chinese rare earth companies in overseas markets.

In the research of partially replacing Nd with Ce and La, the General Iron and Steel Research Institute of the Ministry of Metallurgical Industry and Magnequench Magnetics (Tianjin) Co., Ltd. respectively filed Chinese patent applications CN1035737A and CN101694797, but prepared differently according to the methods proposed in the above patents/patent applications. All brand magnets need to melt alloys with multiple components, which increases the production cost; on the other hand, although Re (Re is La, Ce, Pr, Dy, Tb, Ho, etc.) rare earth elements are also added to the above-mentioned magnets, but directly Melting Re into the alloy will cause Re, especially La and Ce to replace Nd in the main phase too much and seriously deteriorate the performance of the magnet. In view of the fact that the anisotropy field HA and magnetic moment Js of Re ₂ Fe ₁₄ B are different, the General Institute of Iron and Steel Research filed Chinese patent applications CN102436892A, CN102800454A and CN103714939A respectively, which are characterized by the formation of a double (hard magnetic) main phase structure Magnets reduce the sintering temperature and give full play to the unique physical and chemical properties of Re ₂ Fe ₁₄ B grains (or particles) with different anisotropy constants k (corresponding to different anisotropy fields HA). The magnetic interaction between these particles, as well as between the particle interfaces, significantly increases the coercive force compared with single-alloy magnets of the same composition. In addition, the common feature of patent applications CN1035737A, CN102436892A and CN101694797 is that Nd accounts for the largest weight of the total rare earth in the magnet, and still belongs to the category of Nd-Fe-B magnets, while the patent applications CN103714939A and CN102800454A are La and Ce respectively. The weight of the total amount is the largest, and it does not belong to the category of Nd-Fe-B magnets, but the above-mentioned patent application belongs to dual (hard magnetic) main phase magnets, and the corrosion resistance of La, Ce, and magnets needs to be improved.

Contents of the invention

One of the purposes of the present invention is to provide a high corrosion resistance, (Pr, La, Ce)-Fe-B/(Nd, Pr)-Fe-B/(Dy, Ho, Gd, Er)-Fe- B/... multi-hard magnetic main phase permanent magnet.

Another object of the present invention is to provide a method for preparing the above-mentioned Ce permanent magnet with high corrosion resistance and multiple hard magnetic main phases.

In order to achieve the above object, the present invention provides the following technical solutions:

The invention provides a high corrosion resistance multi-hard magnetic main phase Ce permanent magnet, which is prepared by powder absorbing hydrogen to control oxygen and pre-sintering dehydrogenation;

In the final magnet, Ce is the rare earth element with the most content in terms of mass percentage, and the final magnet is composed of multiple hard magnetic main phases with different magnetocrystalline anisotropy constants k, and these hard magnetic main phases all have a 2:14:1 structure. It is composed of the following three main phases:

I) Light rare earth phase: (Pr, La, Ce, Nd)-Fe-B phase mainly composed of rare earth elements with high abundance of Ce and La, which may contain a small amount of Pr and Nd, but does not contain Dy, Ho and Gd , Er heavy rare earth element, which belongs to low saturation magnetic polarization Js and low anisotropy field HA phase, with low reverse magnetization ability;

II) Nd-Fe-B phase: the (Nd, Pr)-Fe-B phase is dominated by rare earth elements Nd and Pr, does not contain Ce, La, and does not contain Dy, Ho, Gd, Er heavy rare earth elements, It belongs to high and low saturation magnetic polarization Js and high anisotropy field HA phase, with high reverse magnetization ability;

III) Heavy rare earth phase: It is a (Dy, Ho, Gd, Er)-Fe-B phase containing Dy, Ho, Gd, Er heavy rare earth elements, which belongs to the low saturation magnetic polarization Js and high HA phase, and has a very strong anti-magnetization ability High, can contain Pr, Nd, but not Ce, La and Tb;

The chemical formulas of the three types of main phases and the final permanent magnet can be expressed as: (RL _{1-x ,} Cex ) _a1 Fe _100-a1-b1-c1 B _b1 TM _c1 , (Nd _y Pr _1-y ) _a2 Fe _100-a2-b2-c2 B _b2 TM _c2 , [RH _z ,(Nd,Pr) _1-z ] _a3 Fe _100-a3-b3-c3 B _b3 TM _c3 and (Ce,Re) _a Fe _{100 -abc} B _b TM _c ; among them, 0.25<x≤1.0, 0≤y≤1.0, 0<z≤1.0, 27≤a≤31, 0.8≤b≤1.5, 0.5≤c≤2, a1～a3, b1 The value ranges of ~b3, c1~c3 are the same as a, b, and c respectively, Re is several of La, Nd, Pr, Dy, Ho, Gd, Er rare earth elements, RL is La, Pr, Nd rare earth elements One or more of them, RH is one or more of Dy, Ho, Gd, Er rare earth elements, TM is one or more of Ga, Co, Cu, Nb, Al elements.

Described permanent magnet is prepared by following method:

1) Preparation of raw materials for multiple main phases: prepare the main phases without Dy, Ho, Gd, and Er heavy rare earth elements and the main phases containing Dy, Ho, Gd, and Er heavy rare earth elements respectively into 0.1-0.5 mm average thickness Quick-setting sheets and quick-quenching strips with an average thickness of 0.03-0.40mm are crushed and dehydrogenated by hydrogen to obtain magnetic powders of different particle sizes, which are then subjected to jet milling or mechanical ball milling for standby;

2) Preparation of magnet blanks: according to the equivalent composition of the final magnet, the prepared magnetic powders of different particle sizes are weighed in proportion and fully mixed, and the hydrogen content of the magnetic powder is adjusted at this time to be 200-2000ppm, and the mixed magnetic powder is oriented in the magnetic field forming, making a blank;

3) Sintering: Graded heat preservation in the range of 400-850°C, dehydrogenation and degassing, heat preservation for 30 minutes for each increase of 150°C, a total of 2-6 hours; graded heat preservation and sintering at a temperature of 850-1050°C for 1-4 hours; 650-900°C and 350-500°C for 1-4 hours of tempering treatment.

The permanent magnet converts a very small amount of ceria in the magnet into a stable trace amount of cerium oxide through dehydrogenation, sintering and tempering processes, suppresses the oxygen content in the final magnet, and improves the corrosion resistance of the magnet.

The particle sizes of different main phase magnetic powders are different, which are: fine magnetic powder with a particle size of 0.1-2μm, coarse magnetic powder with a particle size of 2-5μm, and nanocrystalline magnetic powder; the hard magnetic main phase with different anisotropy constants k in the final magnet occupies The volume fraction and particle size are different, and it has the characteristics of high corrosion resistance and small weight loss rate.

The multiple hard magnetic main phases of the permanent magnet include but are not limited to the following combinations:

1) It consists of a Nd-Fe-B main phase, a light rare earth (Ce, La, Nd, Pr)-Fe-B main phase and a heavy rare earth (Dy, Ho, Gd, Er)-Fe-B phase;

2) It consists of two main phases of light rare earth (Ce, La, Nd, Pr)-Fe-B and one heavy rare earth (Dy, Ho, Gd, Er)-Fe-B phase with different components;

3) It consists of a light rare earth (Ce, La, Nd, Pr)-Fe-B main phase and two heavy rare earth (Dy, Ho, Gd, Er)-Fe-B phases with different components;

4) Consists of one Nd-Fe-B main phase and two light rare earth (Ce, La, Nd, Pr)-Fe-B main phases with different components; or

5) A Nd-Fe-B main phase is composed of two heavy rare earth (Dy, Ho, Gd, Er)-Fe-B phases with different components.

The permanent magnet further has a fourth main phase magnet, a fifth main phase magnet or more main phase magnets.

The permanent magnet has the following multi-hard magnetic main phase structure:

1) A four-hard magnetic main phase structure composed of Ce-Fe-B and Nd-Fe-B, Pr-Fe-B, Dy-Fe-B; or

2) A four-hard magnetic main phase structure composed of (Pr, Ce)-Fe-B and Nd-Fe-B, (Pr, Gd)-Fe-B, (Ho, Gd)-Fe-B; or

3) Composed of (Pr, Ce)-Fe-B and Nd-Fe-B, (Pr, Dy)-Fe-B, (Ho, Gd)-Fe-B, (Nd, Gd, Er)-Fe-B Formed five hard magnetic main phase structure.

The invention provides a method for preparing a high corrosion resistance multi-hard magnetic main phase Ce permanent magnet. According to the performance requirements of the multi-hard magnetic main phase Ce-Fe-B permanent magnet alloy, different magnetocrystalline anisotropy constant k values are designed. The main phase alloy is to determine the phase structure composition of a variety of different multi-hard magnetic main phase Ce-Fe-B permanent magnets; in the final magnet, Ce is the rare earth element with the largest content by mass percentage, and the remaining rare earths are selected from La, Nd, One or two or more mixed rare earths in Pr, Dy, Ho, Gd, Er, the method comprises the following process steps:

(1) A variety of different hard magnetic main phase alloy raw materials are prepared respectively. These hard magnetic main phases all have a 2:14:1 structure and are composed of the following three types of main phases:

I) Light rare earth phase: (Pr, La, Ce)-Fe-B phase mainly composed of rare earth elements with high abundance of Ce and La, may contain a small amount of Pr and Nd, but does not contain Dy, Ho, Gd, Er Heavy rare earth elements, belonging to low saturation magnetic polarization Js and low anisotropy field HA phase, low reverse magnetization ability; composition is (RL _{1-x ,} Cex ) _a1 Fe _100-a1-b1-c1 B _b1 TM _c1 (wt.%);

II) Nd-Fe-B phase: the (Nd, Pr)-Fe-B phase is dominated by rare earth elements Nd and Pr, does not contain Ce, La, and does not contain Dy, Ho, Gd, Er heavy rare earth elements, It belongs to high and low saturation magnetic polarization Js and high anisotropy field HA phase, with high reverse magnetization ability; its composition is (Nd _y Pr _{1- y} ) _a2 Fe _100-a2-b2-c2 B _b2 TM _c2 (wt. %);

III) Heavy rare earth phase: It is a (Dy, Ho, Gd, Er)-Fe-B phase containing Dy, Ho, Gd, Er heavy rare earth elements, which belongs to the low saturation magnetic polarization Js and high HA phase, and has a very strong anti-magnetization ability High, can contain Pr, Nd, but does not contain Ce, La and Tb; its composition is [RH _z ,(Nd,Pr) _1-z ] _a3 Fe _{100-a3- b3-c3} B _b3 TM _c3 (wt.% );

Among them, the value ranges of a1～a3, b1～b3, c1～c3 are respectively the same as the value ranges of a, b, c in the final magnet (Ce, Re) _a Fe _100-abc B _b TM _c (wt.%) Same, 0.25<x≤1.0, 0≤y≤1.0, 0<z≤1.0, 27≤a≤31, 0.8≤b≤1.5, 0.5≤c≤2; Re is La, Nd, Pr, Dy, Ho, Some of Gd, Er rare earth elements, RL is one or more of La, Pr, Nd rare earth elements, RH is one or more of Dy, Ho, Gd, Er rare earth elements, TM is Ga , one or more of Co, Cu, Nb, Al elements;

(2) Smelt the raw materials prepared in step (1) separately, and pour the molten steel without Dy, Ho, Gd, and Er heavy rare earth elements onto the water-cooled copper alloy roller to obtain quick-setting steel with an average thickness of 0.1-0.5mm. piece;

A quick-quenched strip with a thickness of 0.03-0.40 mm is prepared from molten steel containing heavy rare earth elements Dy, Ho, Gd, and Er;

(3) The quick-setting sheet and the quick-quenching belt obtained in step (2) are subjected to hydrogen crushing respectively, and then dehydrogenated, respectively crushed, jet milled or mechanical ball milled to obtain coarse magnetic powder, fine magnetic powder and nanocrystalline magnetic powder;

(4) According to the equivalent composition (Ce, Re) _a Fe _100-abc B _b TM _c (wt.%) of the final magnet, determine the content of each main phase alloy of the multi-main phase magnet, and weigh the steps according to a certain proportion (3) Prepare magnetic powders with different particle sizes, add lubricant, mix in a mixer, and control the hydrogen content of the magnetic powder at this time at 200-2000ppm; under an inert gas protective atmosphere, orient the mixed magnetic powder in a magnetic field, and make into rough;

(5) Then put it into the sintering furnace and heat it in stages at 400-850°C, dehydrogenate and degas, heat it for 30 minutes every time it is increased by 150°C, a total of 2-6 hours, and sinter at a temperature of 850-1050°C for 1-4 Hours; then tempering treatment at 650-900°C and 350-500°C for 1-4 hours respectively.

In step (2), molten steel containing no Dy, Ho, Gd, and Er heavy rare earth elements is poured onto a water-cooled copper alloy roller with a line speed of 1 to 4 m/s, and the steel containing Dy, Ho, Gd, and Er heavy rare earth elements The molten steel of the element is poured to the water-cooled molybdenum alloy roller with a line speed of 15-40m/s.

In step (3), different main phase magnetic powders are prepared into magnetic powders with different particle sizes, namely: fine magnetic powder with a particle size of 0.1-2 μm, coarse magnetic powder with a particle size of 2-5 μm, and nanocrystalline magnetic powder.

Compared with prior art, the beneficial effect of the present invention is:

The first is the multi-primary phase structure control technology similar to the "plain concrete structure". The magnetic powder of different main phases is prepared into fine magnetic powder, coarse magnetic powder, nanocrystalline magnetic powder, etc. After powder mixing, orientation pressing and liquid phase sintering, Leads to fewer defects and porosity in the final magnet, improving intergranular phase corrosion resistance;

The second is to use powder hydrogen absorption and oxygen control, pre-sintering dehydrogenation technology to suppress the oxygen content in the final magnet, reduce the potential between the intergranular phase and the main phase, thereby reducing intergranular corrosion. This is not available in other prior art;

Again, the use of mixed rare earths avoids the waste caused by further separation of rare earths.

The invention only needs to smelt quick-setting tapes of several components to prepare magnets of a series of grades, and has a relatively high degree of freedom in adjusting the components. In order to avoid the diffusion of elements between different main phase particles, the present invention adopts a low-temperature sintering process, which is 20-50°C lower than the sintering temperature of conventional NdFeB magnets and single-alloy Ce magnets, and the sintering time is shortened by 30-60 minutes. Although the magnetic energy product of the magnet prepared by the present invention is at (BH) _max =25～45MGOe, which belongs to the middle and low grade range, the Ce magnet comparable to the conventional magnet is selected, and the magnet whose Ce content accounts for 20% of the total amount of rare earth is under humid and hot conditions (130 ℃, 100% RH), the weight loss rate is less than 3mg/m ² , which is much lower than the 6mg/m ² of conventional single-alloy NdFeB magnets containing Ce; The electrochemical corrosion current Icorr in the solution is less than 8×10 ^-6 (A·cm ² ); in (35°C, 5% NaCl) salt spray, the weight loss rate after corrosion for 168 hours is less than 2%. Its preparation technology is suitable for engineering scale production (see Figures 1 and 2, Tables 1 and 2).

Table 1 Corrosion current and potential of Ce magnet, conventional N33 and N45 NdFeB magnets in tap water

Table 2 Corrosion current and potential of Ce magnet, conventional N33 and N45 magnets in 3.5% NaOH solution

Description of drawings

Fig. 1 compares the electrochemical corrosion behavior (polarization curve) of Ce magnet of the present invention and conventional N33, N45 NdFeB magnet in tap water;

Fig. 2 compares the electrochemical corrosion behavior (polarization curve) of Ce magnet of the present invention and conventional N33, N45 NdFeB magnet in 3.5%NaOH solution;

3 is a schematic diagram of the structure of the magnet in Example 1 of the present invention;

Fig. 4 is a schematic diagram of the structure of the magnet in Example 4 of the present invention.

The reference signs therein are:

① Nd-Fe-B main phase grains

② Ce-Fe-B main phase grains

③ Dy-Fe-B main phase grains

④ is the main phase grain of Pr-Fe-B

⑤ Gd-Fe-B main phase grains

detailed description

The present invention is further described below in conjunction with embodiment.

The present invention does not require that the multi-main phase magnet must have a (Nd, Pr)-Fe-B main phase, a light rare earth (Ce, La, Nd, Pr)-Fe-B main phase and a heavy rare earth (Dy, Ho, Gd, Er)-Fe-B phase; it can also be composed of two light rare earth (Ce, La, Nd, Pr)-Fe-B main phases with different components and a heavy rare earth (Dy, Ho, Gd, Er)-Fe-B phase; it can also be composed of a light rare earth (Ce, La, Nd, Pr)-Fe-B main phase and two heavy rare earth (Dy, Ho, Gd, Er)-Fe with different components -B phase; it can also be composed of a (Nd,Pr)-Fe-B main phase and two light rare earth (Ce,La,Nd,Pr)-Fe-B main phases with different components; or a (Nd , Pr)-Fe-B main phase and two heavy rare earth (Dy, Ho, Gd, Er)-Fe-B phases with different components; and many other combinations.

The key here is to adjust the saturation magnetic polarization Js between different main phases and the obvious difference between the anisotropy field HA phase, as well as the particle size of different main phases, so as to make the structure of the magnet more compact, and control oxygen by absorbing hydrogen, Pre-sintering dehydrogenation reduces the oxygen content and impurities in the magnet, improves the purity of the magnet, and improves the corrosion resistance at the same time.

The invention provides a high corrosion resistance multi-hard magnetic main phase Ce permanent magnet. In the final magnet, Ce is the rare earth element with the most content by mass percentage, and forms magnetocrystalline anisotropy constants k different (Pr, La, Ce )-Fe-B/(Nd,Pr)-Fe-B/(Dy,Ho,Gd,Er)-Fe-B/... multi-phase (more than two) grain structure.

The permanent magnet is prepared by using powder to absorb hydrogen to control oxygen, pre-sintering dehydrogenation, and sintering and tempering processes to achieve low-oxygen production.

In the final magnet, Ce is the rare earth element with the most content by mass percentage, and the final magnet is composed of multiple hard magnetic main phases with different magnetocrystalline anisotropy constants k, and these hard magnetic main phases have the same 2:14:1 type structure, However, the components are different, and its components belong to two or three of the following three main phase types:

One type is (Pr, La, Ce)-Fe-B phase mainly composed of rare earth elements with high abundance of Ce and La, which may contain a small amount of Pr and Nd, but does not contain Dy, Ho, Gd, Er heavy rare earth elements, Belongs to low saturation magnetic polarization Js and low anisotropy field HA phase, with low reverse magnetization ability;

One type is (Nd,Pr)-Fe-B phase mainly composed of rare earth elements Nd and Pr, does not contain Ce, La, and does not contain Dy, Ho, Gd, Er heavy rare earth elements, and belongs to high and low saturation magnetic polarization Js And higher anisotropy field HA phase, higher reverse magnetization ability;

One is the (Dy, Ho, Gd, Er)-Fe-B phase containing Dy, Ho, Gd, Er heavy rare earth elements, which belongs to the low saturation magnetic polarization Js and high HA phase, and has a high reverse magnetization ability, which can contain Pr, Nd, but not Ce, La and Tb;

The chemical formulas of the three types of main phases and the final permanent magnet can be expressed as: (RL _{1-x ,} Cex ) _a1 Fe _100-a1-b1-c1 B _b1 TM _c1 , (Nd _y Pr _1-y ) _a2 Fe _100-a2-b2-c2 B _b2 TM _c2 , [RH _z ,(Nd,Pr) _1-z ] _a3 Fe _100-a3-b3-c3 B _b3 TM _c3 and (Ce,Re) _a Fe _{100 -abc} B _b TM _c ; among them, 0.25<x≤1.0, 0≤y≤1.0, 0<z≤1.0, 27≤a≤31, 0.8≤b≤1.5, 0.5≤c≤2, a1～a3, b1 The value ranges of ~b3, c1~c3 are the same as a, b, and c respectively, Re is several of La, Nd, Pr, Dy, Ho, Gd, Er rare earth elements, RL is La, Pr, Nd rare earth elements One or more of them, RH is one or more of Dy, Ho, Gd, Er rare earth elements, TM is one or more of Ga, Co, Cu, Nb, Al elements.

Four main phase magnets, five main phase magnets, etc. can also be designed according to needs.

The magnet is composed of multi-phase (more than two) (La, Ce)-Fe-B/(Nd, Pr)-Fe-B/(Dy, Ho, Gd, Er)-Fe-B/… granular structure, The volume fraction and grain size of hard magnetic main phases with different anisotropy constant k are different. The reason why the particles of different hard magnetic phases are required to be different in size is because the present invention adopts a control technology similar to "plain concrete structure" to prepare magnetic powders of different main phases into fine magnetic powders, coarse magnetic powders, nanocrystalline magnetic powders, etc., resulting in the final The density of the magnet is increased, and the defects and voids in the magnet are reduced. We know that cerium is easily oxidized to form oxygen-deficient ceria, and CeO ₂ has unique oxygen storage and release properties, and has unique functions in water vapor shift and reforming reactions. At the same time, _CeO2 also has an "open" fluorite structure, which can form solid solutions with many transition metal oxides. Aiming at the valence property of cerium oxide, the present invention converts a very small amount of cerium oxide (CeO ₂ ) in the magnet into a stable trace amount of cerium oxide (Ce ₂ O ₃ ) by setting the dehydrogenation, sintering and tempering processes. ), which suppresses the oxygen content in the final magnet, leading to an increase in the corrosion resistance of the magnet, which is a technique never seen in Ce permanent magnets. The present invention can also directly use mixed rare earths with defined components.

The invention provides a high corrosion resistance, multi-main phase Ce permanent magnet preparation method, according to the performance requirements of the multi-hard magnetic main phase Ce-Fe-B permanent magnet alloy, design the main phase with different k values (anisotropy constants) Alloy, so as to determine the phase structure composition of Ce-Fe-B permanent magnets with different multi-hard magnetic main phases, such as multi-phase permanent magnets composed of Ce-Fe-B and Nd-Fe-B, Pr-Fe-B, Dy-Fe-B Hard magnetic main phase structure, or multiple hard magnetic main phases composed of (Pr, Ce)-Fe-B and Nd-Fe-B, (Pr, Dy)-Fe-B, (Ho, Gd)-Fe-B Structure; in the final magnet, Ce is the rare earth element with the most content in terms of mass percentage, and 0% to 75% of the total rare earth content is replaced by one or both of La, Nd, Pr, Dy, Ho, Gd, Er One or more mixed rare earth substitutes. The method comprises the following process steps:

(1) A variety of different hard magnetic main phase alloy raw materials are prepared respectively. These hard magnetic main phases have the same 2:14:1 structure, but their components are different, and their components belong to two of the following three main phase types or three classes:

One type is (Pr, La, Ce)-Fe-B phase mainly composed of rare earth elements with high abundance of Ce and La, which may contain a small amount of Pr and Nd, but does not contain Dy, Ho, Gd, Er heavy rare earth elements, It belongs to low saturation magnetic polarization Js and low anisotropy field HA phase, with low reverse magnetization ability; the composition is (RL _{1-x ,} Cex ) _a1 Fe _100-a1-b1-c1 B _b1 TM _c1 (wt.% );

One type is (Nd,Pr)-Fe-B phase mainly composed of rare earth elements Nd and Pr, does not contain Ce, La, and does not contain Dy, Ho, Gd, Er heavy rare earth elements, and belongs to high and low saturation magnetic polarization Js And higher anisotropy field HA phase, higher magnetization reversal ability; its composition is (Nd _y Pr _1-y ) _a2 Fe _{100-a2-b2- c2} B _b2 TM _c2 (wt.%);

One is the (Dy, Ho, Gd, Er)-Fe-B phase containing Dy, Ho, Gd, Er heavy rare earth elements, which belongs to the low saturation magnetic polarization Js and high HA phase, and has a high reverse magnetization ability, which can contain Pr, Nd, but not Ce, La and Tb; its composition is [RH _z ,(Nd,Pr) _1-z ] _a3 Fe _100-a3-b3-c3 B _b3 TM _c3 (wt.%);

Among them, the value ranges of a1～a3, b1～b3, c1～c3 are respectively the same as the value ranges of a, b, c in the final magnet (Ce, Re) _a Fe _100-abc B _b TM _c (wt.%) Same, 0.25<x≤1.0, 0≤y≤1.0, 0<z≤1.0, 27≤a≤31, 0.8≤b≤1.5, 0.5≤c≤2; Re is La, Nd, Pr, Dy, Ho, Some of Gd, Er rare earth elements, RL is one or more of La, Pr, Nd rare earth elements, RH is one or more of Dy, Ho, Gd, Er rare earth elements, TM is Ga , one or more of Co, Cu, Nb, Al elements;

It is also possible to add a fourth main phase, a fifth main phase, a sixth main phase, etc. with a microstructure or a nanocrystalline structure according to design requirements.

(2) Smelting the prepared raw materials in step (1) separately, pouring molten steel containing no Dy, Ho, Gd, and Er heavy rare earth elements onto water-cooled copper alloy rolls with a line speed of 1 to 4 m/s to obtain an average Quick-setting sheet with a thickness of 0.1-0.5mm;

The molten steel containing heavy rare earth elements Dy, Ho, Gd and Er is poured onto a water-cooled molybdenum alloy roll with a line speed of 15-40 m/s to obtain a rapidly quenched strip with a thickness of 0.03-0.40 mm.

(3) The quick-setting sheet and the quick-quenching belt obtained in step (2) are subjected to hydrogen crushing, and then dehydrogenated to obtain coarsely crushed magnetic powder, which is then subjected to jet milling or mechanical ball milling.

(4) According to the equivalent composition (Ce,Re) _a Fe _100-abc B _b TM _c (wt.%) of the final magnet, determine the multi-phase magnet (Pr,La,Ce,Nd)-Fe-B/( The content of each main phase alloy in Nd,Pr)-Fe-B/(Dy,Ho,Gd,Er)-Fe-B/…, respectively weigh the magnetic powders with different particle sizes prepared in step (3) according to a certain proportion, and add The lubricant is mixed in a mixer, and the hydrogen content of the magnetic powder is controlled at this time to be 200-2000ppm; under an inert gas protective atmosphere, the mixed magnetic powder is oriented and formed in a magnetic field to form a blank.

(5) Then put it into the sintering furnace and heat it in stages at 400-850°C, dehydrogenate and degas, heat it for 30 minutes every time it is increased by 150°C, a total of 2-6 hours, and sinter at a temperature of 850-1050°C for 1-4 Hours; then tempering treatment at 650-900°C and 350-500°C for 1-4 hours respectively. Cerium is easily oxidized at high temperature to form oxygen-deficient ceria, and there are quite a lot of oxide phases between ceria and ceria, all of which are unstable. During this process, hydrogen reduces cerium oxide CeO ₂ into stable cerium oxide (Ce ₂ O ₃ ), and the valence of cerium changes from 4 to 3, which reduces the oxygen content in the magnet.

In step (2), molten steel containing no Dy, Ho, Gd, and Er heavy rare earth elements is poured onto a water-cooled copper alloy roller with a line speed of 1 to 4 m/s, and the steel containing Dy, Ho, Gd, and Er heavy rare earth elements The molten steel of the element is poured to the water-cooled molybdenum alloy roller with a line speed of 15-40m/s.

In step (3), different main phase magnetic powders are prepared into magnetic powders with different particle sizes, namely: fine magnetic powder with a particle size of 0.1-2 μm, coarse magnetic powder with a particle size of 2-5 μm, and nanocrystalline magnetic powder.

The following is a detailed description of the embodiments based on the technical solution of the present invention, so that the present invention can be better understood. However, it should be noted that the following examples are for illustration purposes only, and the protection scope of the present invention is not limited to the following examples.

Embodiment 1-is Ce-Fe-B/Nd-Fe-B/Dy-Fe-B three hard magnetic main phase structure

Design composition (Ce _0.5 Nd _0.45 Pr _0.05 ) ₂₉ Fe _68.1 B _0.9 TM ₂ (TM=Ga, Co, Cu, Nb).

(1) The raw materials were prepared respectively according to the alloy mass percentage composition Ce ₂₉ Fe _68.15 B _0.85 TM ₂ , Nd _28.5 Fe _68.6 B _0.9 TM ₂ and Dy _29.1 Fe _68.9 B ₁ TM ₂ .

(2) Melt the prepared raw materials separately. First, put the raw materials into the quick-setting crucible of the intermediate frequency induction melting furnace, power on for preheating when the vacuum degree reaches above 10 ^-2 Pa, stop vacuuming and fill with high-purity Ar after the vacuum degree reaches above 10 ^-2 Pa again, Make the Ar pressure in the furnace reach 0.08MPa for smelting. After all the raw materials are melted, they are refined by electromagnetic stirring, and then the molten steel is cast on a water-cooled copper roller with a line speed of 4m/s to produce a quick-setting sheet with an average thickness of 0.3mm.

(3) The prepared three kinds of quick-setting tablets were put into the hydrogenation furnace for hydrogen crushing, and then dehydrogenated, and the anti-oxidation lubricant and the hydrogen crushing magnetic powder were mixed in a ratio of 3-7ml/kg under a protective atmosphere. Then carry out jet milling separately, Ce ₂₉ Fe _68.15 B _0.85 TM ₂ and Nd _28.5 Fe _68.6 B _0.9 TM ₂ hydrogen breaker jet milling, the rotation speed of the sorting wheel is controlled at 3000r/min, and the particle size of the obtained magnetic powder is about 3μm; Dy _29.1 When Fe _68.9 B ₁ TM ₂ Hydrogen Breaking Powder Jet Mill, the rotation speed of the sorting wheel is controlled at 5000r/min, and the particle size of the obtained magnetic powder is about 2μm.

(4) Fully mix the three magnetic powders prepared in step (3) in proportion according to the designed composition. The equivalent composition of the mixed magnetic powder is (Ce _0.5 Nd _0.45 Pr _0.05 ) ₂₉ Fe _68.1 B _0.9 TM ₂ (TM=Ga, Co , Cu, Nb). Regulate the hydrogen content of the magnetic powder at this time to 1000ppm; under the protective atmosphere of inert gas, orientate the mixed magnetic powder in a magnetic field with a magnetic field strength of 2.3T, and then perform cold isostatic pressing to make a blank.

(5) Then put it into the sintering furnace and heat it up to 400°C, keep it warm for 30 minutes, and then keep it warm for 30 minutes every time it is increased by 150°C. After dehydrogenation and degassing are completed, raise the temperature to 1010°C for sintering for 4 hours. Then, tempering treatment was carried out at 800° C. and 450° C. for 4 hours, respectively.

Finally, a multi-main phase Ce-Fe-B/Nd-Fe-B/Dy-Fe-B structure magnet was obtained, and the magnetic properties of the magnet were measured by the NIM-2000HF permanent magnet material standard measuring device, and the wet heat condition (130°C, 100% The weight loss rate under RH) is as shown in table 3.

Magnetic performance and weight loss rate of the magnet of table 3 embodiment 1

Example 2 - (La, Ce, Nd)-Fe-B/Nd-Fe-B/(Ho, Dy, Pr, Nd)-Fe-B three main phase structure

Equivalent composition (Ce _0.45 La _0.05 Nd _0.3 Pr _0.15 Ho _0.02 Dy _0.03 ) ₃₀ Fe _68.39 B _0.94 TM _0.67 (TM=Ga, Co, Cu, Nb).

(1) According to mass percentage (La _0.08 Ce _0.75 Nd _0.05 Pr _0.12 ) ₃₀ Fe _68.4 B _0.9 TM _0.7 , Nd ₃₀ Fe _68.3 B _1.1 TM _0.6 and (Ho _0.15 Dy _0.25 Nd _0.4 Pr _0.2 ) ₃₀ Fe _68.4 B ₁ TM ₀ Prepare raw materials separately.

(2) Melt the prepared raw materials separately. First, put the raw materials into the quick-setting crucible of the intermediate frequency induction melting furnace, power on for preheating when the vacuum degree reaches above 10 ^-2 Pa, stop vacuuming and fill with high-purity Ar after the vacuum degree reaches above 10 ^-2 Pa again, Make the Ar pressure in the furnace reach 0.08Mpa for smelting. After all the raw materials are melted, apply electromagnetic stirring for refining. Then (La _0.08 Ce _0.75 Nd _0.05 Pr _0.12 ) ₃₀ Fe _68.4 B _0.9 TM _0.7 and Nd ₃₀ Fe _68.3 B _1.1 TM _0.6 The molten steel is cast onto a water-cooled copper roll with a line speed of 4m/s to produce a quick-setting sheet with an average thickness of 0.3mm. (Ho _0.15 Dy _0.25 Nd _0.4 Pr _0.2 ) ₃₀ Fe _68.4 B ₁ TM _0.6 molten steel was poured onto a water-cooled molybdenum alloy roll with a line speed of 23m/s to obtain a quenched strip with a thickness of about 0.1mm.

(3) The prepared quick-setting sheet and the quick-quenching belt are respectively loaded into a hydrogenation furnace for hydrogen crushing, then the dehydrogenation is taken out, and the anti-oxidation lubricant and the hydrogen crushing magnetic powder are used in a ratio of 3 to 7ml/kg under a protective atmosphere mix. Carry out jet mill respectively again subsequently, the rotating speed of sorting wheel is controlled at 3000r/min when Nd ₃₀ Fe _68.3 B _1.1 TM _0.6 and (La _0.08 Ce _0.75 Nd _0.05 Pr _0.12 ) ₃₀ Fe _68.4 B _0.9 TM _0.7 hydrogen broken powder jet mill, The particle size of the obtained magnetic powder is about 3 μm; (Ho _0.15 Dy _0.25 Nd _0.4 Pr _0.2 ) ₃₀ Fe _68.4 B ₁ TM _0.6 Hydrogen powder-breaking jet mill, the rotation speed of the sorting wheel is controlled at 5000r/min, and the particle size of the obtained magnetic powder is about 2 μm. The particle size of the magnetic powder is further reduced to about 0.10 μm by high-energy ball milling.

(4) Fully mix the three magnetic powders prepared in step 3 at a ratio of 11:8:1 according to the designed composition. The equivalent composition of the mixed magnetic powder is (Ce _0.45 La _0.05 Nd _0.3 Pr _0.15 Ho _0.02 Dy _0.03 ) ₃₀ Fe _68.39 B _0.94 TM _0.67 (TM = Ga, Co, Cu, Nb). At this time, the hydrogen content of the magnetic powder is controlled at 200ppm; the mixed magnetic powder is oriented and formed in a magnetic field with a magnetic field strength of 2.3T to make a blank.

(5) Then put it into the sintering furnace and start to heat up to 450°C, keep it warm for 30 minutes, and then keep it warm for 30 minutes every time it is increased by 125°C, after dehydrogenation and degassing are completed, raise the temperature to 1020°C for sintering for 4 hours. Then, tempering treatment was carried out at 870° C. and 460° C. for 4 hours, respectively.

Finally, a multi-main phase (La, Ce, Nd)-Fe-B/Nd-Fe-B/(Ho, Dy, Pr, Nd)-Fe-B structure magnet was obtained, and the NIM-2000HF permanent magnet material standard measuring device was used to measure The magnetic properties of the magnets and the weight loss rate under humid heat conditions (130° C., 100% RH) are shown in Table 4.

Magnetic performance and weight loss rate of table 4 embodiment 2 magnets

Example 3 - (Ce, Nd)-Fe-B/(Nd, Pr)-Fe-B/(Dy, Nd)-Fe-B three hard magnetic main phase structure

Design composition (Nd _0.34 Ce _0.35 Dy _0.08 Pr _0.23 ) ₃₁ Fe ₆₇ B _1.5 TM _0.5 (TM=Ga, Cu, Al).

(1) According to the alloy mass percentage composition (Ce _0.6 Nd _0.4 ) ₃₁ Fe ₆₇ B _1.5 TM _0.5 , (Nd _0.9 Pr _0.1 ) ₃₁ Fe ₆₇ B _1.5 TM _0.5 and ₍ Dy _0.7 Nd _0.3 ) ₃₁ Fe ₆₇ B _1.5 TM _0.5 Raw materials were prepared respectively, among which, Ce, La, Nd, and Pr were mixed rare earths with a certain ratio.

(2) Melt the prepared raw materials separately. First, put the raw materials into the quick-setting crucible of the intermediate frequency induction melting furnace, power on for preheating when the vacuum degree reaches above 10 ^-2 Pa, stop vacuuming and fill with high-purity Ar after the vacuum degree reaches above 10 ^-2 Pa again, Make the Ar pressure in the furnace reach 0.08Mpa for smelting. After all the raw materials are melted, electromagnetic stirring is applied to refine, and then (Ce _0.6 Nd _0.4 ) ₃₁ Fe ₆₇ B _1.5 TM _0.5 and (Nd _0.9 Pr _0.1 ) ₃₁ Fe ₆₇ B _1.5 TM _0.5 molten steel is cast to a line speed of 4m/s A quick-setting sheet with an average thickness of 0.3 mm was prepared on a water-cooled copper roller. (Dy _0.7 Nd _{0. 3} ) ₃₁ Fe ₆₇ B _1.5 TM _0.5 molten steel was poured onto a water-cooled molybdenum alloy roll with a line speed of 26m/s to obtain a quenched strip with a thickness of about 0.09mm.

(3) The prepared three kinds of quick-setting tablets were put into the hydrogenation furnace for hydrogen crushing, and then dehydrogenated, and the anti-oxidation lubricant and the hydrogen crushing magnetic powder were mixed in a ratio of 3-7ml/kg under a protective atmosphere. Then carry out jet mill respectively, (Nd _0.9 Pr _0.1 ) ₃₁ Fe ₆₇ B _1.5 TM _0.5 and (Ce _0.6 Nd _0.4 ) ₃₁ Fe ₆₇ B _1.5 TM _0.5 Hydrogen powder breaking jet mill, the speed of the sorting wheel is controlled _at 3000r /min, the particle size of the obtained magnetic powder is about 3μm; (Dy _0.7 Nd _0.3 ) ₃₁ Fe ₆₇ B _1.5 TM _0.5 Hydrogen powder breaking jet mill, the rotation speed of the sorting wheel is controlled at 5000r/min, and the particle size of the obtained magnetic powder is about 2μm.

(4) Fully mix the three magnetic powders prepared in step 3 in proportion according to the designed composition. The equivalent composition of the mixed magnetic powder is (Nd _0.34 Ce _0.35 Dy _0.08 Pr _0.23 ) ₃₁ Fe ₆₇ B _1.5 TM _0.5 (TM=Ga, Co , Cu, Nb), adjust the hydrogen content of the magnetic powder at this time to 1000ppm; under the protective atmosphere of inert gas, orientate the mixed magnetic powder in a magnetic field with a magnetic field strength of 2.3T, and then perform cold isostatic pressing to make a blank.

(5) Then put it into the sintering furnace and start to heat up to 400°C, keep it warm for 30 minutes, then keep it warm for 30 minutes every time it is increased by 150°C, after dehydrogenation and degassing, raise the temperature to 1050°C for sintering for 4 hours. Then, tempering treatment was carried out at 800° C. and 450° C. for 4 hours, respectively.

Finally, multi-phase (Ce, Nd)-Fe-B/(Nd, Pr)-Fe-B/(Dy, Nd)-Fe-B magnets are obtained. The magnetic properties of the magnets were measured using the NIM-2000HF standard measuring device for permanent magnet materials, and the weight loss rate under humid heat conditions (130° C., 100% RH) is shown in Table 5.

Magnetic performance and weight loss rate of table 5 embodiment 3 magnets

Example 4--Ce-Fe-B/Nd-Fe-B/Pr-Fe-B/Gd-Fe-B four hard magnetic main phase structure

Design composition (Ce _0.6 Pr _0.1 Nd _0.25 Gd _0.05 ) ₃₁ Fe _67.39 B _0.94 TM _0.67 (TM=Ga, Cu, Al).

(1) According to the composition of alloy mass percentage Ce ₃₁ Fe _67.39 B _0.94 TM _0.67 , Nd ₃₁ Fe _67.39 B _0.94 TM _0.67 , Pr ₃₁ Fe _67.39 B _0.94 TM _0.67 and (Gd _0.65 Nd _0.35 ) ₃₁ Fe _67.39 B _{0.94 TM} respectively raw material.

(2) Melt the prepared raw materials separately. First, put the raw materials into the quick-setting crucible of the intermediate frequency induction melting furnace, power on for preheating when the vacuum degree reaches above 10 ^-2 Pa, stop vacuuming and fill with high-purity Ar after the vacuum degree reaches above 10 ^-2 Pa again, Make the Ar pressure in the furnace reach 0.08Mpa for smelting. After all the raw materials are melted, they are refined by electromagnetic stirring, and then the molten steel of Ce ₃₁ Fe _67.39 B _0.94 TM _0.67 , Nd ₃₁ Fe _67.39 B _0.94 TM _0.67 and Pr ₃₁ Fe _67.39 B _0.94 TM _0.67 is cast to a line speed of 4m/s On a water-cooled copper roll, a quick-setting sheet with an average thickness of 0.3 mm was produced. (Gd _0.65 Nd _0.35 ) ₃₁ Fe _67.39 B _0.94 TM _0.67 molten steel was poured onto a water-cooled molybdenum alloy roll with a line speed of 22m/s to obtain a quenched strip with a thickness of about 0.12mm.

(3) The prepared four kinds of quick-setting tablets were respectively put into a hydrogenation furnace for hydrogen crushing, then removed for dehydrogenation, and the anti-oxidation lubricant and hydrogen crushing magnetic powder were mixed in a ratio of 3-7ml/kg under a protective atmosphere. Then carry out jet milling separately, Ce ₃₁ Fe _67.39 B _0.94 TM _0.67 and Nd ₃₁ Fe _67.39 B _0.94 TM _0.67 hydrogen powder jet milling, the rotation speed of the sorting wheel is controlled at 3000r/min, and the particle size of the obtained magnetic powder is about 3 μm; Pr ₃₁ Fe _67.39 B _0.94 TM _0.67 and (Gd _0.65 Nd _0.35 ) ₃₁ Fe _67.39 B _0.94 TM _0.67 Hydrogen breaker jet mill with the rotation speed of the sorting wheel at 5000r/min, and the particle size of the obtained magnetic powder is about 2μm.

(4) Fully mix the three magnetic powders prepared in step 3 in proportion according to the designed composition. The equivalent composition of the mixed magnetic powder is (Ce _0.6 Pr _0.1 Nd _0.25 Gd _0.05 ) ₃₁ Fe _67.39 B _0.94 TM _0.67 (TM=Ga, Cu , Al). At this time, the hydrogen content of the magnetic powder is controlled at about 1500ppm; under an inert gas protective atmosphere, the mixed magnetic powder is oriented and formed in a magnetic field with a magnetic field strength of 2.3T, and then cold isostatic pressed to make a blank.

(5) Then put it into the sintering furnace and start to heat up to 350°C, keep it warm for 30 minutes, and then keep it warm for 30 minutes every time it is increased by 150°C, after the dehydrogenation and degassing are completed, raise the temperature to 1030°C for sintering for 4 hours. Then, tempering treatment was carried out at 830° C. and 450° C. for 4 hours, respectively.

Finally, a brand of multi-(permanent magnet) main phase Ce-Fe-B/Nd-Fe-B/Pr-Fe-B/Gd-Fe-B magnet was obtained, and the NIM-2000HF permanent magnet material standard measuring device was used to measure the magnet The magnetic properties and the weight loss rate under humid heat conditions (130°C, 100% RH) are shown in Table 6.

Magnetic performance and weight loss rate of table 6 embodiment 4 magnets

Example 5—(Ce, Nd)-Fe-B/Nd-Fe-B/(Gd, Ho, Er)-Fe-B three hard magnetic main phases

Design composition (Ce _0.7 Nd _0.24 Gd _0.03 Ho _0.02 Er _0.01 ) ₃₁ Fe _67.39 B _0.94 TM _0.67 (TM=Ga, Cu, Al).

(1) According to the alloy mass percentage composition (Ce _0.9 Nd _0.1 ) ₃₁ Fe _67.39 B _0.94 TM _0.67 , Nd ₃₁ Fe _67.39 B _0.94 TM _0.67 , [(Gd,Ho,Er) _0.7 Nd _0.3 ] ₃₁ Fe _67.39 B _0.94 TM _0.67 Prepare raw materials separately.

(2) Melt the prepared raw materials separately. First, put the raw materials into the quick-setting crucible of the intermediate frequency induction melting furnace, power on for preheating when the vacuum degree reaches above 10 ^-2 Pa, stop vacuuming and fill with high-purity Ar after the vacuum degree reaches above 10 ^-2 Pa again, Make the Ar pressure in the furnace reach 0.08Mpa for smelting. After the raw materials are completely melted, electromagnetic stirring is applied to refine, and then (Ce _0.9 Nd _0.1 ) ₃₁ Fe _67.39 B _0.94 TM _0.67 and Nd ₃₁ Fe _67.39 B _0.94 TM _0.67 molten steel is cast onto a water-cooled copper roller with a line speed of 4m/s , to produce quick-setting sheets with an average thickness of 0.3 mm. [(Gd,Ho,Er) _0.6 Nd _0.4 ] ₃₁ Fe _67.39 B _0.94 TM _0.67 molten steel was poured onto a water-cooled molybdenum alloy roll with a line speed of 26m/s to obtain a quenched strip with a thickness of about 0.1mm.

(3) The prepared three kinds of quick-setting tablets were put into the hydrogenation furnace for hydrogen crushing, and then dehydrogenated, and the anti-oxidation lubricant and the hydrogen crushing magnetic powder were mixed in a ratio of 2-6ml/kg under a protective atmosphere. Then carry out jet milling respectively, (Ce _0.9 Nd _0.1 ) ₃₁ Fe _67.39 B _0.94 TM _0.67 and Nd ₃₁ Fe _67.39 B _0.94 TM _0.67 hydrogen powder jet milling, the rotation speed of the sorting wheel is controlled at 2500r/min, obtained The particle size of the magnetic powder is about 3 μm; [(Gd, Ho, Er) _0.6 Nd _0.4 ] ₃₁ Fe _67.39 B _0.94 TM _0.67 Hydrogen powder breaker air mill, the rotation speed of the sorting wheel is controlled at 5200r/min, and the particle size of the obtained magnetic powder is about 2 μm. Then. The particle size of the magnetic powder is further reduced to about 0.15 μm by high energy ball milling.

(4) Fully mix the three magnetic powders prepared in step 3 in proportion according to the designed composition. The equivalent composition of the mixed magnetic powder is (Ce _0.7 Nd _0.24 Gd _0.03 Ho _0.02 Er _0.01 ) ₃₁ Fe _67.39 B _0.94 TM _0.67 . At this time, the hydrogen content of the magnetic powder is controlled at about 900ppm; under the protective atmosphere of inert gas, the mixed magnetic powder is oriented and formed in a magnetic field with a magnetic field strength of 2.3T, and then cold isostatic pressed to make a blank.

(5) Then put it into the sintering furnace and start to heat up to 350°C, keep it warm for 30 minutes, and then keep it warm for 30 minutes every time it is increased by 150°C, after dehydrogenation and degassing are completed, raise the temperature to 1010°C for sintering for 4 hours. Then, tempering treatment was carried out at 830° C. and 450° C. for 4 hours, respectively.

Finally, a brand of multi-hard magnetic main phase (Ce, Nd)-Fe-B/Nd-Fe-B/(Gd, Ho, Er)-Fe-B magnet was obtained. The magnetic properties of the magnets were measured using the NIM-2000HF standard measuring device for permanent magnet materials, and the weight loss rate under humid heat conditions (130° C., 100% RH) is shown in Table 7.

Magnetic performance and weight loss rate of table 7 embodiment 4 magnets

Claims (10)

1. high corrosion-resistant many Hard Magnetics principal phase Ce permanent magnet, is characterized in that: this permanent magnet adopts powder to inhale hydrogen control oxygen, presintering Oxidative Dehydrogenation is standby;

In final magnet, Ce is the rare earth element dividing content maximum by mass percentage, and final magnet is made up of multiple Hard Magnetic principal phases that magnetocrystalline anisotropy constant k is different, and these Hard Magnetic principal phases all have 2:14:1 type structure, is combined by following three class principal phases:

I) light rare earth phase: based on Ce, La abundant rare earth element (Pr, La, Ce, Nd)-Fe-B phase, can contain a small amount of Pr, Nd, but not containing Dy, Ho, Gd, Er heavy rare earth element, belong to low saturated pole intensity Js and less anisotropy field HA phase, magnetic reversal ability is lower;

II) Nd-Fe-B phase: based on rare earth element nd, Pr (Nd, Pr)-Fe-B phase, not containing Ce, La, also not containing Dy, Ho, Gd, Er heavy rare earth element, belong to just saturated pole intensity Js and comparatively high anisotropy field HA phase, magnetic reversal ability is higher;

III) heavy rare earth phase: be that belong to low saturated pole intensity Js and high HA phase, magnetic reversal ability is very high, can contain Pr, Nd containing Dy, Ho, Gd, Er heavy rare earth element (Dy, Ho, Gd, Er)-Fe-B phase, but not containing Ce, La and Tb;

The chemical formula of described three class principal phases and final permanent magnet can be expressed as by mass percentage: (RL _1-x, Ce _x) _a1fe _100-a1-b1-c1b _b1tM _c1, (Nd _ypr _1-y) _a2fe _100-a2-b2-c2b _b2tM _c2, [RH _z, (Nd, Pr) _1-z] _a3fe _100-a3-b3-c3b _b3tM _c3(Ce, Re) _afe _100-a-b-cb _btM _c; Wherein, 0.25<x≤1.0,0≤y≤1.0,0<z≤1.0,27≤a≤31,0.8≤b≤1.5,0.5≤c≤2, a1 ~ a3, b1 ~ b3, the span of c1 ~ c3 is identical with a, b, c respectively, Re is several in La, Nd, Pr, Dy, Ho, Gd, Er rare earth element, RL is one or more in La, Pr, Nd rare earth element, and RH is one or more in Dy, Ho, Gd, Er rare earth element, and TM is Ga, Co, one or more in Cu, Nb, Al element.

2. high corrosion-resistant many Hard Magnetics principal phase Ce permanent magnet according to claim 1, is characterized in that: described permanent magnet is prepared by following methods:

1) many major phase raw materials prepares: will not be prepared into containing the principal phase of Dy, Ho, Gd, Er heavy rare earth element and the principal phase containing Dy, Ho, Gd, Er heavy rare earth element rapid-hardening flake that average thickness is 0.1 ~ 0.5mm respectively and average thickness is the rapid tempering belt of 0.03 ~ 0.40mm,, dehydrogenation broken through hydrogen, obtain varigrained magnetic, carry out airflow milling or mechanical ball milling again, for subsequent use;

2) magnet blank is prepared: according to the equivalent component of final magnet, take prepared varigrained magnetic respectively in proportion and fully mix, regulate and control the hydrogen content of now magnetic at 200 ~ 2000ppm, magnetic oriented moulding in magnetic field of mixing, makes blank;

3) sinter: through 400 ~ 850 DEG C of scope classifications insulation, dehydrogenation, degassed, often improve 150 DEG C of insulations 30 minutes, totally 2 ~ 6 hours; Temperature 850 ~ 1050 DEG C of classification heat preservation sinterings 1 ~ 4 hour; Then the temper of 1 ~ 4 hour is carried out respectively 650 ~ 900 DEG C and 350 ~ 500 DEG C.

3. high corrosion-resistant many Hard Magnetics principal phase Ce permanent magnet according to claim 1, it is characterized in that: described permanent magnet is by dehydrogenation, sintering and tempering process, the ceria of minute quantity in magnet is made to transform into stable micro-cerium sesquioxide, suppress the oxygen content in final magnet, improve the corrosion resistance of magnet.

4. high corrosion-resistant many Hard Magnetics principal phase Ce permanent magnet according to claim 1, is characterized in that: the granularity of different principal phase magnetic is different, is respectively: the thick magnetic of the thin magnetic of particle diameter 0.1-2 μm, particle diameter 2-5 μm and nanocrystalline magnetic; In final magnet, the volume fraction shared by Hard Magnetic principal phase of different anisotropy constant k is not identical with granular size, has high corrosion-resistant and the little feature of weight-loss ratio.

5. high corrosion-resistant many Hard Magnetics principal phase Ce permanent magnet according to claim 1, is characterized in that:

Multiple Hard Magnetic principal phases of this permanent magnet comprise and are not limited to following combination:

1) be made up of mutually a Nd-Fe-B principal phase, light rare earth (Ce, La, Nd, Pr)-Fe-B principal phase and heavy rare earth (Dy, Ho, Gd, Er)-Fe-B;

2) be made up of mutually different light rare earth (Ce, La, Nd, the Pr)-Fe-B principal phase of two components and heavy rare earth (Dy, Ho, Gd, Er)-Fe-B;

3) be made up of mutually heavy rare earth (Dy, Ho, Gd, the Er)-Fe-B that light rare earth (Ce, La, Nd, Pr)-Fe-B principal phase is different with two components;

4) be made up of light rare earth (Ce, La, Nd, the Pr)-Fe-B principal phase that a Nd-Fe-B principal phase is different from two components; Or

5) heavy rare earth (Dy, Ho, Gd, the Er)-Fe-B that Nd-Fe-B principal phase is different from two components is formed mutually.

6. high corrosion-resistant many Hard Magnetics principal phase Ce permanent magnet according to claim 1, is characterized in that: described permanent magnet has the 4th principal phase magnet, the 5th principal phase magnet or more principal phase magnet further.

7. high corrosion-resistant many Hard Magnetics principal phase Ce permanent magnet according to claim 5, is characterized in that: described permanent magnet has following many Hard Magnetics principal phase structure:

1) the four Hard Magnetic principal phase structures be made up of Ce-Fe-B and Nd-Fe-B, Pr-Fe-B, Dy-Fe-B; Or

2) the four Hard Magnetic principal phase structures be made up of (Pr, Ce)-Fe-B and Nd-Fe-B, (Pr, Gd)-Fe-B, (Ho, Gd)-Fe-B; Or

3) the five stiffness magnetic principal phase structure be made up of (Pr, Ce)-Fe-B and Nd-Fe-B, (Pr, Dy)-Fe-B, (Ho, Gd)-Fe-B, (Nd, Gd, Er)-Fe-B.

8. the preparation method of high corrosion-resistant many Hard Magnetics principal phase Ce permanent magnet according to claim 1, it is characterized in that: according to the performance requirement of many Hard Magnetics principal phase Ce-Fe-B permanent-magnet alloy, design the main-phase alloy of different magnetocrystalline anisotropy constant k value, determine the phase structure composition of multiple difference many Hard Magnetics principal phase Ce-Fe-B permanent magnet; In final magnet, Ce is the rare earth element dividing content maximum by mass percentage, and all the other rare earths are the one or two or more mishmetal be selected from La, Nd, Pr, Dy, Ho, Gd, Er, and the method comprises following processing step:

(1) prepare multiple different Hard Magnetic main-phase alloy raw material respectively, these Hard Magnetic principal phases all have 2:14:1 type structure, are combined by following three class principal phases:

I) light rare earth phase: based on the abundant rare earth element of Ce, La (Pr, La, Ce)-Fe-B phase, a small amount of Pr, Nd can be contained, but not containing Dy, Ho, Gd, Er heavy rare earth element, belong to low saturated pole intensity Js and less anisotropy field HA phase, magnetic reversal ability is lower; Composition is (RL _1-x, Ce _x) _a1fe _100-a1-b1-c1b _b1tM _c1(wt.%);

II) Nd-Fe-B phase: based on rare earth element nd, Pr (Nd, Pr)-Fe-B phase, not containing Ce, La, also not containing Dy, Ho, Gd, Er heavy rare earth element, belong to just saturated pole intensity Js and comparatively high anisotropy field HA phase, magnetic reversal ability is higher; Its composition is (Nd _ypr _{1- y}) _a2fe _100-a2-b2-c2b _b2tM _c2(wt.%);

III) heavy rare earth phase: be that belong to low saturated pole intensity Js and high HA phase, magnetic reversal ability is very high, can contain Pr, Nd containing Dy, Ho, Gd, Er heavy rare earth element (Dy, Ho, Gd, Er)-Fe-B phase, but not containing Ce, La and Tb; Its composition is [RH _z, (Nd, Pr) _1-z] _a3fe _{100-a3- b3-c3}b _b3tM _c3(wt.%);

Wherein, the span of a1 ~ a3, b1 ~ b3, c1 ~ c3 respectively with final magnet (Ce, Re) _afe _100-a-b-cb _btM _c(wt.%) a in, b, c span is identical, 0.25<x≤1.0,0≤y≤1.0,0<z≤1.0,27≤a≤31,0.8≤b≤1.5,0.5≤c≤2; Re is several in La, Nd, Pr, Dy, Ho, Gd, Er rare earth element, and RL is one or more in La, Pr, Nd rare earth element, and RH is one or more in Dy, Ho, Gd, Er rare earth element, TM is Ga, Co, Cu, one or more in Nb, Al element;

(2) distinguish the raw material that melting step (1) prepares, be poured on water-cooled copper alloy roller by the molten steel not containing Dy, Ho, Gd, Er heavy rare earth element, obtained average thickness is the rapid-hardening flake of 0.1 ~ 0.5mm;

Molten steel containing Dy, Ho, Gd, Er heavy rare earth element is obtained the rapid tempering belt of thickness at 0.03 ~ 0.40mm;

(3) rapid-hardening flake step (2) obtained respectively and rapid tempering belt carry out hydrogen fragmentation, and then, dehydrogenation, respectively through fragmentation, airflow milling or mechanical ball milling, obtains thick magnetic, thin magnetic and nanocrystalline magnetic;

(4) according to the equivalent component (Ce, Re) of final magnet _afe _100-a-b-cb _btM _c(wt.%), determine the content of each main-phase alloy of many principal phases magnet, take the different magnetic of granularity prepared by step (3) by a certain percentage respectively, additional lubricant, mix in batch mixer, and the hydrogen content regulating and controlling now magnetic is at 200 ~ 2000ppm; Under inert gas shielding atmosphere, magnetic oriented moulding in magnetic field will be mixed, make blank;

(5) then put into sintering furnace to be incubated 400 ~ 850 DEG C of scope classifications, dehydrogenation, degassed, often improve 150 DEG C of insulations 30 minutes, totally 2 ~ 6 hours, temperature 850 ~ 1050 DEG C of classification heat preservation sinterings 1 ~ 4 hour; Then the temper of 1 ~ 4 hour is carried out respectively 650 ~ 900 DEG C and 350 ~ 500 DEG C.

9. the preparation method of high corrosion-resistant many Hard Magnetics principal phase Ce permanent magnet according to claim 7, it is characterized in that: in step (2), molten steel not containing Dy, Ho, Gd, Er heavy rare earth element is poured on the water-cooled copper alloy roller that linear velocity is 1 ~ 4m/s, the molten steel containing Dy, Ho, Gd, Er heavy rare earth element is poured into the water-cooled molybdenum alloy roller that linear velocity is 15 ~ 40m/s.

10. the preparation method of high corrosion-resistant many Hard Magnetics principal phase Ce permanent magnet according to claim 7, it is characterized in that: in step (3), different principal phase magnetic is prepared into the different magnetic of granularity, is respectively: the thick magnetic of the thin magnetic of particle diameter 0.1-2 μm, particle diameter 2-5 μm and nanocrystalline magnetic.