阅读说明：本技术 一种稀土永磁粉及其制备方法与应用 (Rare earth permanent magnet powder and preparation method and application thereof ) 是由 彭海军 罗阳 豆亚坤 杨远飞 于敦波 赵娜 谢佳君 于 2018-07-13 设计创作，主要内容包括：本发明属于稀土功能材料技术领域,具体涉及一种稀土永磁粉,并进一步公开其制备方法与应用。本发明所述的稀土永磁粉,通过向稀土永磁粉材料中同时复合添加一定量的合金元素Ce和Ti,可以起到细化晶粒的作用,而且可以抑制合金中软磁相的析出,有助于在晶界形成非磁性相,合金中不包含如α-Fe或者Fe<Sub>3</Sub>B之类的软磁相,同时Ce和Ti的同时添加会在R<Sub>2</Sub>Fe<Sub>14</Sub>B的晶界处形成细小弥散分布的富钛相,在磁化过程中,细小弥散分布的富钛相起到锭扎畴壁的作用,不仅降低了稀土永磁粉的成本,而且大大提高了磁粉的矫顽力。(The invention belongs to the technical field of rare earth functional materials, and particularly relates to rare earth permanent magnetic powder, and further discloses a preparation method and application thereof. According to the rare earth permanent magnet powder, a certain amount of alloy elements Ce and Ti are simultaneously added into the rare earth permanent magnet powder material in a compounding manner, so that the effect of grain refinement can be achieved, the precipitation of a soft magnetic phase in the alloy can be inhibited, the formation of a non-magnetic phase in a grain boundary is facilitated, and the alloy does not contain alpha-Fe or Fe 3 A soft magnetic phase such as B, and the simultaneous addition of Ce and Ti to R 2 Fe 14 And a fine and dispersedly distributed titanium-rich phase is formed at the crystal boundary of the magnetic powder B, and the fine and dispersedly distributed titanium-rich phase plays a role of ingot domain wall rolling in the magnetization process, so that the cost of the rare earth permanent magnetic powder is reduced, and the coercive force of the magnetic powder is greatly improved.)

1. The rare earth permanent magnet powder is characterized in that the general molecular formula of the main component of the permanent magnet powder is based on the atomic number (R)_1-aCe_a)_bFe_100-b-c-dTi_cB_dWherein R is selected from one of Nd, Pr or PrNd;

and the parameters a, b, c and d meet the following conditions: a is more than 0 and less than 1, b is more than or equal to 9 and less than or equal to 13, c is more than 0 and less than or equal to 7, and d is more than or equal to 5.8 and less than or equal to 6.4;

the rare earth permanent magnetic powder comprises R₂Fe₁₄The permanent magnetic phase of the B tetragonal structure consists of a permanent magnetic phase H phase and a crystal boundary titanium-rich phase T phase, the content of rare earth in the crystal boundary titanium-rich phase T is less than that in the permanent magnetic phase H phase, and the content of Ti in the crystal boundary titanium-rich phase T phase is greater than that in the permanent magnetic phase H phase.

2. The rare-earth permanent magnetic powder according to claim 1, wherein the parameters a, b, c and d satisfy the following conditions: a is more than or equal to 0.1 and less than or equal to 0.3, b is more than or equal to 11.5 and less than or equal to 12.5, c is more than or equal to 4 and less than or equal to 7, and d is more than or equal to 6.0 and less than or equal to 6.2.

3. The rare-earth permanent magnetic powder according to claim 1 or 2, wherein R is Nd.

4. The rare-earth permanent magnetic powder according to any one of claims 1 to 3, wherein the ratio of Ce/(Ce + R) in the T phase of the grain boundary titanium-rich phase is greater than that in the H phase of the permanent magnetic phase.

5. A rare earth permanent magnetic powder according to any one of claims 1 to 4, wherein the content of Ti in the intergranular Ti-rich phase T phase is more than 4 at.%, and the content of rare earth is less than 9 at.%.

6. A rare earth permanent magnet powder according to any of claims 1 to 5, wherein the average grain size of the permanent magnet phase H phase is less than 100 nm.

7. A rare earth permanent magnet powder according to any one of claims 1 to 6, wherein the average grain size of the grain boundary titanium-rich phase T phase is less than 10 nm.

8. A method for preparing rare earth permanent magnetic powder as claimed in any one of claims 1 to 7, which comprises the following steps:

(1) uniformly mixing raw materials corresponding to selected R, Ce, Fe, Ti and B elements according to a selected stoichiometric ratio, and melting, refining, cooling and casting at 1500-1550 ℃ under an inert atmosphere to obtain rare earth permanent magnet alloy ingots;

(2) heating and remelting the obtained rare earth permanent magnet alloy ingot to obtain alloy liquid, and performing quick quenching treatment on the obtained alloy liquid to obtain an alloy thin strip;

(3) and crushing, sieving and heat treating the alloy thin strip to obtain the rare earth permanent magnet powder with the selected molecular formula.

9. The method for preparing rare earth permanent magnet powder according to claim 8, wherein the step (2) specifically comprises: adding the obtained alloy ingot into a quick quenching furnace, and remelting the alloy ingot by medium-frequency induction heating under the protection of inert gas to obtain alloy solution with the temperature of 1400-1420 ℃; and then the alloy solution is sprayed on the surface of a copper or copper alloy or molybdenum wheel with the surface linear velocity of more than 20m/s under the gravity or the air pressure difference of 0-0.04MPa, and the alloy solution is solidified and thrown out on the surface of the rotating wheel to form the alloy thin strip.

10. The method for preparing rare earth permanent magnet powder according to claim 8 or 9, wherein in the step (3), a water quenching treatment is further performed after the heat treatment step.

Technical Field

The invention belongs to the technical field of rare earth functional materials, and particularly relates to rare earth permanent magnetic powder, and further discloses a preparation method and application thereof.

Background

Neodymium iron boron (NdFeB) system rare earth permanent magnetic material is the permanent magnetic material with the best performance newly developed in the 80 s, and is widely applied to the fields of computers, information electronics, household appliances, wind power generation, national defense and the like due to the excellent magnetic performance. In addition, in the new energy-saving automobile which is rapidly developed in recent years, the market of the neodymium iron boron permanent magnet material is further increased due to the large use of the motor. However, with the increasing price of rare earth, especially neodymium, the price of the neodymium-iron-boron magnetic material also increases greatly, so that the use cost of users is obviously increased, and great impact is caused on the benign development of the whole market. Therefore, the development of new neodymium iron boron magnetic materials with low cost and high performance is a demand for market development.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to provide rare earth permanent magnetic powder to solve the problems that the magnetic performance is reduced too much due to the application of abundant rare earth elements in the prior art and the cost of neodymium-iron-boron rare earth permanent magnetic materials is high.

In order to solve the technical problems, the invention provides rare earth permanent magnet powder, wherein the general molecular formula of the main component of the rare earth permanent magnet powder is based on the atomic number (R)_1-aCe_a)_bFe_100-b-c-dTi_cB_dWherein R is selected from one of Nd, Pr or PrNd;

and the parameters a, b, c and d meet the following conditions: a is more than or equal to 0 and less than 1, b is more than or equal to 9 and less than or equal to 13, c is more than 0 and less than or equal to 7, and d is more than or equal to 5.8 and less than or equal to 6.4;

the rare earth permanent magnet powder comprises a permanent magnet phase H and a crystal boundary titanium-rich phase T, wherein the permanent magnet phase H has a structure shown as R₂Fe₁₄And the content of rare earth in the crystal boundary titanium-rich phase T phase is less than that in the permanent magnet phase H phase, and the content of Ti in the crystal boundary titanium-rich phase T phase is greater than that in the permanent magnet phase H phase.

Further, the parameters a, b, c and d satisfy the following conditions: a is more than or equal to 0.1 and less than or equal to 0.3, b is more than or equal to 11.5 and less than or equal to 12.5, c is more than or equal to 4 and less than or equal to 7, and d is more than or equal to 6.0 and less than or equal to 6.2.

More preferably, R is Nd.

The ratio of Ce/(Ce + R) in the T phase of the grain boundary titanium-rich phase is larger than that in the H phase of the permanent magnet phase, and the (Ce + R) represents the total rare earth content.

The content of Ti in the grain boundary titanium-rich phase T phase is more than 4at percent, and the content of rare earth is less than 9at percent.

The average grain size of the permanent magnetic phase H phase is less than 100nm, and preferably less than 50 nm.

The average grain size of the grain boundary titanium-rich phase T phase is less than 10nm, and preferably less than 5 nm.

The invention also discloses a method for preparing the rare earth permanent magnetic powder, which comprises the following steps:

(1) uniformly mixing raw materials corresponding to selected R, Ce, Fe, Ti and B elements according to a selected stoichiometric ratio, and melting, refining, cooling and casting at 1500-1550 ℃ under an inert atmosphere to obtain rare earth permanent magnet alloy ingots;

(2) heating and remelting the obtained rare earth permanent magnet alloy ingot to obtain alloy liquid, and performing quick quenching treatment on the obtained alloy liquid to obtain an alloy thin strip;

(3) and crushing, sieving and heat treating the alloy thin strip to obtain the rare earth permanent magnet powder with the selected molecular formula.

The step (2) specifically comprises: adding the obtained alloy ingot into a quick quenching furnace, and remelting the alloy ingot by medium-frequency induction heating under the protection of inert gas to obtain alloy solution with the temperature of 1400-1420 ℃; and then the alloy solution is sprayed on the surface of a copper or copper alloy or molybdenum wheel with the surface linear velocity of more than 20m/s under the gravity or the air pressure difference of 0-0.04MPa, and the alloy solution is solidified and thrown out on the surface of the rotating wheel to form the alloy thin strip.

In the step (3), a step of water quenching is further included after the heat treatment step.

The general molecular formula of the rare earth permanent magnet powder is based on the atomicity (R)_1-aCe_a)_bFe_100-b-c-dTi_cB_dWherein R is selected from one of Nd, Pr or PrNd; the magnetic powder is composed of a magnetic powder containing R₂Fe₁₄The permanent magnetic phase H with a tetragonal structure B and the crystal boundary titanium-rich phase T, wherein the content of rare earth in the phase T is less than that of the phase H, and the content of Ti in the phase T is more than that of the phase H. The rare earth permanent magnetic powder of the invention is prepared by mixingThe rare earth permanent magnetic powder material is simultaneously added with a certain amount of alloy elements Ce and Ti in a compounding way, which can play a role of refining grains, can inhibit the precipitation of a soft magnetic phase in the alloy and is beneficial to forming a non-magnetic phase in a grain boundary, and the alloy does not contain alpha-Fe or Fe₃A soft magnetic phase such as B, and the simultaneous addition of Ce and Ti to R₂Fe₁₄And a fine and dispersedly distributed titanium-rich phase is formed at the crystal boundary of the magnetic powder B, and the fine and dispersedly distributed titanium-rich phase plays a role of ingot domain wall rolling in the magnetization process, so that the cost of the rare earth permanent magnetic powder is reduced, and the coercive force of the magnetic powder is greatly improved.

According to the rare earth permanent magnet powder, a certain amount of alloy elements Ce and Ti are simultaneously added into the rare earth permanent magnet powder material in a compounding manner, and after the added Ti is added, a formed titanium-rich phase can be combined with part of cerium, so that the proportion of cerium in an H phase is reduced, the anisotropy field of the H phase is further increased, the coercive force is improved, and the problems and the defects that when the rare earth permanent magnet powder does not contain Ti, almost all cerium, neodymium and boron in the material enter the H phase, the anisotropy field of the material is reduced, and the coercive force is prone to decrease are well solved. Therefore, further, the ratio of the content of cerium and rare earth in the T phase is controlled to be larger than that in the H phase; and the Ti content in the T phase is further controlled to be more than 4 at.%, and the rare earth content is controlled to be less than 9 at.%, so that the coercive force of the permanent magnetic powder is further effectively improved.

In addition, for nanocrystalline permanent magnet materials, the grain size has a significant effect on magnetic properties, and the magnetic properties drop sharply when the grains are too coarse, particularly after more than 100 nm. Thus, the grain size of the H phase in the present invention is less than 100nm, preferably, the grain size of the H phase is less than 50 nm; the grain size of the T phase is less than 10nm, preferably, the grain size of the T phase is less than 5 nm.

In the present invention, since Ce and Ti are added, part of remanence is sacrificed because Nd is in the tetragonal phase of rare earth-iron-boron₂Fe₁₄B has the highest remanence, and R is preferably Nd in the present invention in order to maintain suitably high remanence and magnetic energy product while maintaining high coercive force. Similarly, the amount of a is preferably 0.1. ltoreq. a.ltoreq.0.3, 11.5. ltoreq. b.ltoreq.12.5C is more than or equal to 4 and less than or equal to 7, and d is more than or equal to 6.0 and less than or equal to 6.2, so as to obtain higher coercive force.

The synthesis method of the permanent magnetic powder adopts the mode of firstly preparing a whole or partial amorphous thin strip, and then crushing and crystallizing the thin strip into the permanent magnetic powder, so that the strict control of the temperature, the pressure difference and the wheel speed in the rapid quenching process is favorable for forming stable whole or partial amorphous, and is favorable for obtaining better performance.

Drawings

In order that the present disclosure may be more readily and clearly understood, the following detailed description of the present disclosure is provided in connection with specific embodiments thereof and the accompanying drawings, in which,

FIG. 1 is a hysteresis loop of permanent magnetic powder prepared in examples 5 and 7 of the present invention;

fig. 2 is a graph of the organization structure of the permanent magnet powder prepared in example 5 of the present invention and the rare earth and titanium contents of the permanent magnet phase and the titanium-rich phase marked thereon.

Fig. 3 shows the structure of the permanent magnetic powder prepared in example 7 of the present invention and the distribution of rare earth and titanium elements marked in the permanent magnetic phase and the titanium-rich phase.

Detailed Description