阅读说明：本技术 压力热处理驱动Nd-Cu晶界扩散改善钕铁硼磁性的方法 (Method for improving neodymium iron boron magnetism by driving Nd-Cu grain boundary diffusion through pressure heat treatment ) 是由 柴晓峰 毛建星 邹买金 于 2019-08-29 设计创作，主要内容包括：本发明公开了一种压力热处理驱动Nd-Cu晶界扩散改善钕铁硼磁性的方法,具体步骤如下：采用真空快淬工艺制备Nd-Cu粉料,分别取纯度99.5％金属钕和纯度99.5％铜金属按重量比例3:7配比,配比好的材料放入真空熔炼炉内熔炼注锭,再将合金锭放入真空快淬炉中制成Nd-Cu粉末,将Nd-Cu粉料和热压钕铁硼MQP-M型粉料按0.88：100的重量比例配比,将配好的粉料倒入到真空混料机中均匀混合；取混合粉料放到压机上压制并保压。本发明的有益效果为：通过压力热处理驱动Nd-Cu晶界扩散与传统热压钕铁硼压制的磁环两者之间的对比,传统热压钕铁硼压制内禀矫顽力为15kOe,按本发明的混合材料配比参数,采用我们压力热处理驱动Nd-Cu晶界扩散的方法其Br提高到14.6kG,Hcj提高到20KOe,(BH)m提高到51.1MGOe,退磁曲线方形度Hk/Hci>90％。(The invention discloses a method for improving neodymium iron boron magnetism by driving Nd-Cu grain boundary diffusion through pressure heat treatment, which comprises the following specific steps: preparing Nd-Cu powder by adopting a vacuum rapid quenching process, respectively taking metal neodymium with the purity of 99.5% and copper metal with the purity of 99.5% according to the weight ratio of 3:7, putting the proportioned materials into a vacuum smelting furnace for smelting and ingot injection, then putting an alloy ingot into the vacuum rapid quenching furnace for preparing Nd-Cu powder, and mixing the Nd-Cu powder and hot-pressed neodymium iron boron MQP-M powder according to the weight ratio of 0.88: 100, pouring the prepared powder into a vacuum mixer for uniform mixing; and (3) placing the mixed powder on a press for pressing and maintaining the pressure. The invention has the beneficial effects that: according to the proportion parameters of the mixed material, Br is improved to 14.6kG, Hcj is improved to 20KOe, and (BH) m is improved to 51.1MGOe, and the squareness degree of a demagnetization curve Hk/Hci is more than 90%.)

1. A method for improving the magnetism of neodymium iron boron by driving Nd-Cu grain boundary diffusion through pressure heat treatment is characterized in that: the method comprises the following specific steps: preparing Nd-Cu powder by adopting a vacuum rapid quenching process, respectively taking metal neodymium with the purity of 99.5% and copper metal with the purity of 99.5% according to the weight ratio of 3:7, putting the proportioned materials into a vacuum smelting furnace for smelting and ingot injection, then putting an alloy ingot into the vacuum rapid quenching furnace for preparing Nd-Cu powder, and mixing the Nd-Cu powder and hot-pressed neodymium iron boron MQP-M powder according to the weight ratio of 0.88: 100, pouring the prepared powder into a vacuum mixer for uniform mixing; and (3) placing the mixed powder on a press for pressing and maintaining the pressure.

2. The method for improving the magnetic property of the neodymium iron boron by driving Nd-Cu grain boundary diffusion through pressure heat treatment according to claim 1, wherein the method comprises the following steps: and putting the mixed powder on a vacuum press for pressing, and maintaining the pressure and the temperature.

3. The method for improving the magnetic property of the neodymium iron boron by driving Nd-Cu grain boundary diffusion through pressure heat treatment according to claim 1, wherein the method comprises the following steps: 70g of the mixed powder is taken and put on a 100-ton press to be pressed under the pressure of 6 ton/square centimeter and the pressure is maintained for 20 seconds, and the density of the alphacrine is 6.0g/cm³-6.2g/cm³(ii) a On putting the vacuum press of 63 tons again with the pooh, heat the product to 700 ℃ under the state of high vacuum to 5 tons/square centimeter's pressure is suppressed and is kept warm for 15 seconds, and the density of this moment magnetism pooh is at 7.3g/cm³-7.5g/cm³(ii) a The pooh is placed on a 100-ton press, the product is heated to 815 ℃, pressed at a pressure of 2 tons/square centimeter and subjected to pressure maintaining for 25 seconds, and the density of the magnetic ring is 7.5g/cm³-7.6g/cm³。

Technical Field

The invention relates to the technical field of permanent magnet materials, in particular to a method for improving the magnetism of neodymium iron boron by driving Nd-Cu grain boundary diffusion through pressure heat treatment.

Background

The neodymium iron boron permanent magnet material is a latest result of development of rare earth permanent magnet materials, is called as maga because of excellent magnetic property, is a permanent magnet with the strongest magnetic force at present, has the advantages of small volume, light weight, extremely high magnetic energy product and coercive force, high energy density and the like, and has the advantages of small size, light weight, high magnetic energy product and coercive force, and the like, so that the neodymium iron boron permanent magnet material is widely applied to modern industry and electronic technology.

With the rapid development of ndfeb magnets in many fields in recent years, sintered ndfeb magnets are widely used in various fields with excellent performance, so that the miniaturization, light weight and thinning of computer hardware, instruments and meters, electroacoustic motors, sensors, magnetic separation and magnetization equipment become possible. Due to the mutual action of Van der Waals force, London force and magnetic force among the raw material powder of the micron-sized neodymium-iron-boron magnet, the powder is easy to agglomerate into secondary powder particles, small particle groups are formed, the powder is poor in flowability and difficult to orient, a rare earth-rich phase in a crystal boundary of the magnet is finally lost or discontinuous, and the diffusion effect of heavy rare earth elements such as Dy/Tb towards the interior of the magnet along the crystal boundary can be influenced when the crystal boundary diffusion treatment is carried out.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a method for improving the magnetism of neodymium iron boron by driving Nd-Cu grain boundary diffusion through pressure heat treatment.

The object of the present invention is achieved by the following technical means. A method for improving neodymium iron boron magnetism by driving Nd-Cu grain boundary diffusion through pressure heat treatment comprises the following specific steps: preparing Nd-Cu powder by adopting a vacuum rapid quenching process, respectively taking metal neodymium with the purity of 99.5% and copper metal with the purity of 99.5% according to the weight ratio of 3:7, putting the proportioned materials into a vacuum smelting furnace for smelting and ingot injection, then putting an alloy ingot into the vacuum rapid quenching furnace for preparing Nd-Cu powder, and mixing the Nd-Cu powder and hot-pressed neodymium iron boron MQP-M powder according to the weight ratio of 0.88: 100, pouring the prepared powder into a vacuum mixer for uniform mixing; and (3) placing the mixed powder on a press for pressing and maintaining the pressure.

Further, the mixed powder is put on a vacuum press for pressing, and the pressure and the heat are maintained.

Further, 70g of the mixed powder was put on a 100-ton press and pressed under a pressure of 6 ton/cm for 20 seconds, at which time the density of perimidine is 6.0g/cm³-6.2g/cm³(ii) a On putting the vacuum press of 63 tons again with the pooh, heat the product to 700 ℃ under the state of high vacuum to 5 tons/square centimeter's pressure is suppressed and is kept warm for 15 seconds, and the density of this moment magnetism pooh is at 7.3g/cm³-7.5g/cm³(ii) a The pooh is placed on a 100-ton press, the product is heated to 815 ℃, pressed at a pressure of 2 tons/square centimeter and subjected to pressure maintaining for 25 seconds, and the density of the magnetic ring is 7.5g/cm³-7.6g/cm³。

The invention has the beneficial effects that: for the sintered neodymium iron boron, the influence of Nd-Cu diffusion on the sintered neodymium iron boron is small because Cu is rapidly diffused into a grain boundary, but the microstructure is almost kept unchanged. According to the proportion parameters of the mixed material, Br is improved to 14.6kG, Hcj is improved to 20KOe, and (BH) m is improved to 51.1MGOe, and the squareness degree of a demagnetization curve Hk/Hci is more than 90%.

Drawings

FIG. 1 is a microscopic view showing the diffusion of Nd-Cu along grain boundaries driven by pressure according to the present invention.

Detailed Description

The invention will be described in detail below with reference to the following drawings:

The invention discloses a method for improving neodymium iron boron magnetism by driving Nd-Cu grain boundary diffusion through pressure heat treatment.

The invention adopts a vacuum rapid quenching process to prepare Nd-Cu powder, and respectively takes metal neodymium with the purity of 99.5 percent and copper metal with the purity of 99.5 percent according to weightthe materials are proportioned according to the ratio of 3:7, the proportioned materials are put into a vacuum smelting furnace for smelting and ingot injection, then alloy ingots are put into a vacuum quick quenching furnace for preparing Nd-Cu powder, and the Nd-Cu powder and hot-pressed neodymium iron boron MQP-M type powder produced by Tianjin Mackelen magnet are mixed according to the weight ratio of 0.88: 100, pouring the prepared powder into a vacuum mixer to be uniformly mixed according to the external diameter of normal productionInner diameterProduct example with a height of 28.5: 1. 70g of the mixed powder is taken and put on a 100-ton press to be pressed under the pressure of 6 ton/square centimeter and the pressure is maintained for 20 seconds, and the density of the alphacrine is 6.0g/cm³-6.2g/cm³. 2. On putting the vacuum press of 63 tons again with the pooh, heat the product to 700 ℃ under the state of high vacuum to 5 tons/square centimeter's pressure is suppressed and is kept warm for 15 seconds, and the density of this moment magnetism pooh is at 7.3g/cm³-7.5g/cm³. 3; the pooh is placed on a 100-ton press, the product is heated to 815 ℃, pressed at a pressure of 2 tons/square centimeter and subjected to pressure maintaining for 25 seconds, and the density of the magnetic ring is 7.5g/cm³-7.6g/cm³. Compared with a magnetic ring pressed by the traditional hot-pressed neodymium iron boron, the intrinsic coercivity of the traditional hot-pressed neodymium iron boron is 15kOe, Br is improved to 14.6kG, Hcj is improved to 20KOe, (BH) m is improved to 51.1MGOe, and the square degree of a demagnetization curve Hk/Hci is improved by adopting the method for driving Nd-Cu grain boundary diffusion through pressure heat treatment>90％。

FIG. 1 shows a microscopic view of the diffusion of Nd-Cu along grain boundaries driven by pressure according to the present invention, wherein a, the direction of pressure, b, no pressure, and therefore, the grains are disordered, and c, the arrangement of the grains under pressure is improved. The magnetic property changes of the injection magnet and the reference magnet at each stage are summarized. From the experimental results, it can be seen that Nd-Cu injected into the magnet has better magnetic performance than the reference magnet. It is worth mentioning that, in the existing diffusion experiment, along with the diffusion of the eutectic alloy, the improvement of the intrinsic coercive force of the magnet is basically at the expense of remanence. On the basis of a reference magnet, the results realize the synchronous improvement of coercive force, remanence and magnetic energy product.

It should be understood that equivalent substitutions and changes to the technical solution and the inventive concept of the present invention should be made by those skilled in the art to the protection scope of the appended claims.