JPS6139507A - Neodymium-iron permanent magnet - Google Patents

Abstract

PURPOSE:To enhance the Curie point of the titled permanent magnet without having substantial deterioration in the value of magnetic characteristics, especially in the density of residual magnetic flux, as well as to obtain the permanent magnet having excellent environmental temperature characteristics by a method wherein a magnetic anisotropic alloy consisting of neodymium, boron, germanium and iron of specific ratio, is used. CONSTITUTION:A composition consisting of 25-35wt% neodymium, 0.5-2.5wt% boron, 0.1-10wt% germanium and Fe of the remaining (provided that the impurities such as oxygen, nitrogen and the like are 200ppm or less) is weighed, and an ingot is formed in a high frequency melting furnace. Then, after the ingot is crushed using a jaw crusher, for example, it is coarsely pulverized using a disc mill, and the alloy powder of 3-5mu m in grain size is obtained using a ball mill. Then, the magnetic powder is molded in the magnetic field intensity of 10,000 oersted by applying pressure of 2 ton/cm<2> of a horizontal type magnetic field press (the applying directions of magnetic field and the direction of pressure of press are at right angle) for the purpose of giving orientational property to the magnetic powder. Besides, a heat treatment is performed in vacuum at 1,100 deg.C for 1hr for the purpose of accomplishing high density, cooled in the furnace, and an aging treatment is performed at 610 deg.C for the purpose of improving coercive force.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a neodymium-iron-boron-gersimanium quaternary permanent magnet, which can be used in a wide range of applications from watches and various electrical products to computer peripheral terminals and printers. available in the field.

[Conventional technology]

Hitherto, rare earth-iron permanent magnet alloys up to ternary systems have been published and reported, and such a conventional system is disclosed, for example, in Japanese Patent Application Laid-Open No. 59-46008.

[Problem that the invention seeks to solve]

Conventional neodymium-iron-boro 23-element alloy magnets contain a large amount of IFe (more than 60wt%) to improve performance, but on the other hand, the Curie point is low and only 30% IFe is added when boron is added.
When used in practical applications at around 0℃, the surface magnetic flux density changes greatly and is unstable depending on the operating environment temperature.1 For example, it is difficult to use in fields that require high precision and quality, such as stepping motors for watches. 0 In order to improve such drawbacks, the present invention aims to obtain a permanent magnet that does not significantly reduce the feelability value, especially the residual magnetic flux density, improves the Curie point, and has excellent environmental temperature characteristics. There is.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention takes into account that an effective means for improving the Curie point in rare earth-transition metal intermetal compounds is to use additive elements to create a multi-element system.
Based on the neodymium-iron-boron ternary system, many groups I!
i. A system was prepared and tried.

As a result, the present invention is based on the discovery that the composition indicated in the second claim described above is one method for solving the problem. Note that adding more than 10.0% of Ge causes a significant decrease in magnetic flux density.
O limited to wt% or less [effect] In general, in rare earth-iron compounds, when an element such as B is added, the yθ-Fe interatomic distance increases,
It has been reported that Curi's score is improved and stabilized.

(Reference Bunyu, materials from the 35th research meeting sponsored by the Japanese Society of Applied Magnetics) Also in the present invention, by adding Ge,
It is thought to have the effect of contributing to an improvement in curri by one point.

[Example 1] The present invention will be explained in detail below.

Neodymium 33.5 wt%, boron 1.3 wt%
, germanium Q, 5 wt%, residual Fe (however, impurities such as oxygen and nitrogen are 200 ppm or less), and an ingot is prepared in a high frequency melting furnace.
Thereafter, it is pre-pulverized to a size of 1 m square using a show crusher, coarsely crushed to a size of 50 to 100 μm using a disk mill, and then further crushed to a particle size of 3 to 5 μm using a ball mill to obtain alloy powder. Next, in order to impart orientation to the magnetic powder, it is molded using a horizontal magnetic field press (in the pressure direction of the press for increasing the applied force of the magnetic field) at a pressure of 2 tons/- in a magnetic field strength of 10,000 oersteds. For the purpose of achieving even higher density, 1100"0X in vacuum
The material was subjected to a 1H treatment and cooled in a furnace, and then an aging treatment was performed at 610° C. for 1 hour to develop the coercive force.

For sample measurement, cut out from the block and horizontal coaxial compensation 4
Measurement was performed using a π knee H coil.

The results are shown below for the conventional ternary system N d that does not contain Go.
A comparison with the case of -F e -B system is shown in Table 1.

Table 1: Although there is a small decrease in residual magnetic flux density compared to the conventional six-element system, it can be seen that the temperature at one point of Keeley has increased by up to 210℃.
The temperature characteristics of the surface magnetic flux density of the bare magnet body at temperatures ranging from -20°C to +80°C are shown in the attached drawings. From this figure, Nd-F
It can be seen that the e-B ternary permanent magnet material can be used as a magnet for precision electronic parts (for example, a rotor magnet for an electronic wristwatch) only by adding Ge to make it a quaternary permanent magnet material.

〔Effect of the invention〕

As explained above, the present invention is based on the conventional ternary/A"dP
The surface magnetic flux density of θ-B magnets is greatly affected by the environmental temperature in which they are used, and they have been somewhat unreliable. However, by adding Ge, the Curie point has been significantly improved, and therefore The fact that it is now possible to provide magnets with excellent temperature characteristics is of great industrial value in fields where surface magnetic flux accuracy is strongly required.

[Brief explanation of drawings]

The figure shows the influence of surface magnetic flux density of this system magnet due to environmental temperature.

Claims (1)

[Claims] Neodymium (Nd) 25-35wt%, boron (B) 0.
5-2.5wt%, germanium (Ge) 0.1-10
．． A permanent magnet characterized by being a magnetically anisotropic alloy comprising 0 wt% of residual Fe.