JPS58219704A - Manufacture of permanent magnet having high coercive force and high maximum energy product - Google Patents

Abstract

PURPOSE:To form a permanent magnet having a high coercive force and a high maximum energy product, by properly selecting the composition of an R2Co17 alloy, and subjecting the same to a heat treatment under specific conditions. CONSTITUTION:An R2Co17 alloy (wherein R is Y or a rare earth metal) is formed having a composition consisting essentially of 24.0-26.0wt% at least one of Y and a rare earth element, 5.0-25.0wt% Fe, 2.0-15.0wt% Cu, 0.1-1.5wt% Ni, 1.0-5.5wt% at least one of Zr and Hf, and the balance of Co and unavoidable impurities. This R2Co17 alloy is repeatedly subjected to such a treatment in an inert gas atmosphere that the alloy is heated to the temperature range of 750-900 deg.C at a heating rate not lower than 100 deg.C per hour and maintained at the temperature for 1-30min and is then continuously cooled down below 400 deg.C at a rate of 0.3-5 deg.C per minute. The alloy may contain 0.005-0.500% P.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention is based on the R
Co5 type alloy (hereinafter R is Y or rare earth element) has a high coercive force equivalent to 1I (C), and R2Co17 type alloy itself has a large maximum energy product (BHmax). The present invention relates to a method for manufacturing an R2CoB type rare earth metal permanent magnet that also holds the following characteristics.

Conventionally, it contains one or more of transition metals such as Fe, Cu, Ni, Mn, etc. as necessary within a range that does not impair crystal anisotropy, and further contains one or more of Y or rare earth elements. Rare earth metal permanent magnets composed of RCo type intermetallic compounds containing a predetermined amount of Co and the remainder being Co are used mainly in various meters, magnetic recording bodies, and accessories such as necklaces and earrings. It was widely used. Among these rare earth metal permanent magnets, those made of R2017 type intermetallic compound and those made of R2co 5 type intermetallic compound are generally known.

However, while the former R2ot7 type alloy permanent magnet has a high residual magnetic flux density (Br), that is, a high maximum energy product, it has a low coercive force, whereas the latter RCoB type alloy permanent magnet has a high coercive force. Each of them has the following characteristics, so in actual use,
The current situation is that each magnet must be used appropriately, taking advantage of its respective characteristics.

For this reason, we aim to solve the above-mentioned problem of having to use different types of magnets depending on the purpose of use, and to dramatically expand the field of application of permanent magnets. Various studies have been conducted to create permanent magnets that also have a high maximum energy product. As one of the methods, attempts have been made to subject R2Co17 type alloy to a high coercive force ratio by subjecting it to multi-stage heat treatment or isothermal heat treatment. However, there is a tendency for the residual magnetic flux density to decrease, resulting in a decrease in the maximum energy product, making it impossible to achieve the desired characteristics.

From the above-mentioned viewpoint, the present inventors first developed R2Co,...
When we investigated the cause of the lowest maximum energy product when heat-treating a type alloy, we discovered that it has been reported that lattice defects are observed in the R2C017 type alloy when it is held at high temperatures for a long time. Also, the occurrence of lattice defects due to this long-term high-temperature holding deteriorates the squareness, resulting in R
It was concluded that this causes a decrease in the residual magnetic flux density of the 2Co, type 7 alloy. Therefore, when performing heat treatment to improve the coercive force of R2Co, type 7 alloy, we focused on finding a means to suppress the occurrence of lattice defects in the alloy.
As a result of further research, we found that by limiting the composition of R2Co, □ type alloy to a specific composition range and applying heat treatment under specific conditions, the high maximum energy/product (residual flux density) of IR2Co, 7 type alloy ) while holding R
It was discovered that a permanent magnet with a coercive force as high as that of a CO, type alloy can be obtained.

Therefore, this invention was made based on the above findings, and includes one or more of Y and rare earth elements: 24.0 to 26.0%, Fe: 5.0 to 25.0%.
, Cu: 2.0~15.0%, Nl: 0.1~
1.5%, one or two of Zr and Hf and 10-55%, or further P:
0.005~0500% and the rest is Co and unavoidable impurities (wt%) R2Co, ヮ type alloy is heated to a temperature range of 750~900℃ at 100℃ per hour.
A high coercive force and a high maximum energy product can be achieved by repeating the process of raising the temperature at the above heating rate, holding it for 1 to 30 minutes, and then cooling it continuously at 0.3 to b in an inert gas atmosphere. It is characterized in that it manufactures a permanent magnet with.

Next, the reason why the composition range of the alloy and the heat treatment conditions are limited as described above in the method for manufacturing a permanent magnet of the present invention will be explained. In addition, "%" in this specification shall mean "weight %."

A) Composition range of alloy (a) Y or rare earth element Y or rare earth element is an element that forms an intermetallic compound with Co to achieve excellent magnetic properties, but one or more of Y and rare earth elements If the total amount of 2 is less than 24.0%, desired magnetic properties cannot be secured;
If the content exceeds 6.0%, the holding power will decrease, so the content was set at 240 to 26.0%.

(bl Fe The Fe component has the effect of improving the residual magnetic flux density (Br), but if its content is less than 50%, the desired effect cannot be obtained in this effect; on the other hand, if it is contained in excess of 25.0%, Since this results in a decrease in coercive force (iHc), the content was determined to be 5.0 to 25.0%.

(C) Cu The CU component has the effect of improving coercive force (iHc), but if its content is less than 2.0%, the desired high coercive force cannot be secured, while if it exceeds 15.0%. If it is contained, the residual magnetic flux density will decrease, so the content is set to be between 2.0 and 150.

(d) Ni The N1 component has the effect of improving the squareness of the magnet and thereby increasing the maximum energy product (BHmax), but if its content is less than 0.1%, the desired effect cannot be obtained. On the other hand, if the content exceeds 15 degrees, the coercive force will decrease, so the content should be set at 01 to 1.
It was set at 5%.

(e) Zr and Hf These components have the effect of improving the coercive force and ensuring a high maximum energy product, but if their content is less than the ]O coefficient, the desired effect cannot be obtained. On the other hand, if the content exceeds 55 parts, the residual magnetic flux density decreases, so the content was set at 1.0 to 55 parts.

(f) P - ゞし□□□ The P component has the effect of forming a eutectic with the magnet constituents at a relatively low sintering temperature and producing a liquid phase during sintering in the magnet manufacturing process. Therefore, it is an element that is included as necessary when the sintering temperature must be lowered, but if the content is less than 0005%, the amount of liquid phase generated is small and it is difficult to achieve sintering at a low temperature. Not possible, on the other hand, 0
．． If the content exceeds 500%, the saturation magnetic flux density and coercive force will decrease, so the content should be reduced to 0.
．． It was set as 005-0500%.

B) Heat treatment conditions (a) Heating temperature At a heating temperature of less than 750°C, only the properties equivalent to those of the known R2C0I□ type alloy, that is, the property of having a high maximum energy product but a low coercive force, can be obtained. On the other hand, if the heating temperature exceeds 900℃, the residual magnetic flux density will decrease, so the heating temperature should be set to 750℃ or higher.
The temperature was set at 900°C.

(bl Retention time In principle, shorter retention times are preferable. However, if the retention time is less than 1 minute, it will not be possible to secure the desired high retention force, while if the retention time exceeds 30 minutes, the lattice The holding time was set to 1 to 30 minutes because the residual magnetic flux density began to decrease, which was thought to be due to the occurrence of defects.

(C) Temperature Raising Rate Since a desired high residual magnetic flux density cannot be secured at a heating rate of less than 100°C per hour, the heating rate was set at 10.0°C or more per hour.

b) Cooling rate The cooling rate is closely related to the number of repetitions of heat treatment, and those with a low cooling rate tend to require fewer repetitions.

However, at a cooling rate of less than 0.3°C per minute, it is not possible to secure the desired high residual magnetic flux density, while at a cooling rate of more than 5°C per minute, no matter how many heat treatments are repeated, sufficient coercive force cannot be obtained. Due to the inconvenience, the cooling rate was set to 03~5℃7m.
It was determined as m.

(e) Cooling end temperature 03~b If cooling is performed to a low temperature range, no effect will appear on the magnetic properties, but if this cooling end temperature is set to a high temperature exceeding 400°C, there will be a tendency for the holding force to decrease. Therefore, the upper limit of the cooling end temperature was set at 400°C.

Next, the method for manufacturing a permanent magnet of the present invention will be explained using Examples and comparing with Comparative Examples.

Example First, a molten alloy of a predetermined composition (
However, after adjusting the state in which the P component is not contained] and making an ingot by the usual method, it is coarsely crushed using a show crusher and a pulperizer, and then crushed in a vibration mill to obtain fine particles with an average particle size of 4 μm. A powder was obtained. Each of this fine powder and a raw material powder obtained by further blending and mixing a predetermined amount of P powder with this fine powder was heated to 10 to 15 KOe.
Transverse magnetic field forming at a pressure of about 2 tons/cnl in a magnetic field of
Green compact with a density of approximately 61/cnt (5, Omm
25+++mx25. mm), then held in a high-purity argon stream at a temperature of 1200°C for 2 hours to sinter and solutionize it, and then cooled in argon gas to obtain the products shown in Table 1. Alloys 1 to [phase] having the final component composition shown were obtained. In addition, the first
The * mark in the table indicates that the component content deviates from that of the alloy targeted by the method of the present invention.

Subsequently, each of the alloys ■ to [phase] having the above-mentioned component compositions is heat-treated in a high-purity argon atmosphere under the conditions shown in Table 2 to form rare earth metals. A permanent magnet (including Y) was obtained. In addition,
The * mark in Table 2 indicates that either the alloy composition or the heat treatment conditions are outside the range of the method of the present invention.

Next, the residual magnetic flux density (
Br), coercive force (iHc), and maximum energy product (BHmax) were measured, and the measurement results are shown in Table 2 together with those of the known R2Co1'7 type alloy magnet and RCo5 type alloy magnet.

From the results shown in Table 2, the magnets obtained by methods 1 to 37 of the present invention all have a high maximum energy product equivalent to the conventional R2Co17 type alloy magnet, and a high coercive force such as the conventional RCoB type alloy magnet. On the other hand, as seen in Comparative Methods 38 to 55, when any of the alloy composition and heat treatment conditions are out of the range of the method of the present invention, the residual magnetic flux of the resulting magnet is Density 1 Coercive force.

It is clear that the characteristics of at least one of the maximum energy product and the maximum energy product are inferior.

According to this invention, while maintaining the high maximum energy product of the R2Co, □ type combined magnet itself,
It is possible to obtain a permanent magnet of the R2C0+7 type alloy which has a high coercive force equivalent to that of the RCo5 type alloy magnet. Since it is possible to provide permanent magnets with better magnetic properties than type alloy magnets at a lower cost, conventionally RCoB type alloy magnets and R2C type alloy magnets have been used.
R2C
ol 7 type alloy magnets only - can be applied, and since it has both the characteristics of high maximum energy product and high coercive force, it can open up new application fields and bring industrially useful effects. It is possible.

Procedural Amendment (Imported) July 15, 1980 Kazuo Wakasugi, Commissioner of the Japan Patent Office 1, Indication of Case Patent Application 1982-102117 5 2, Title of Invention Permanent magnet having high coercive force and high maximum energy product Manufacturing method 3, person making amendment 4, agent voluntarily (1) The following sentence is inserted between page 17, line 16 and line 17 of the specification.

Claims (1)

[Scope of Claims] (1) One or more of 'y and rare earth elements. 24.0~26.0%, Fe: 5.0~25.0
%, Cu2.0~15.0%, Ni: 0.1~
15%', one or two of Zr and Hf-: 1.0 to 55%, and the remainder is CO and inevitable impurities (weight ratio) R2Co1□ type alloy (however, RlY or rare earth elements) at 750-900℃
The process of raising the temperature at a rate of 100°C or more per hour to a temperature range of 100°C or more, holding it for 1 to 30 minutes, and then continuously cooling it to below 03°C to 03°C is repeated in an inert gas atmosphere. A method for producing a permanent magnet having a high coercive force and a high maximum energy product, characterized by: (2) One or more of Y and rare earth elements: 24.0
~26.0%, Fe: 5.0~25.0%,
Cu: 2, O~15.0% + N1: 0.1~
1.5%, one or two of Zr and Hf:
Contains a ratio of 10 to 5.5, and P: 0.005
R2Co1□ type alloy (with a composition (weight %) containing up to 0.500% and the remainder consisting of Co and unavoidable impurities)
However, if the temperature of RAM or rare earth elements) is increased to a temperature range of 750 to 900 degrees Celsius at a rate of 100 degrees Celsius or more per hour,
Production of a permanent magnet having a high coercive force and a high maximum energy product, characterized by repeating a process of holding for 1 to 30 minutes and then continuously cooling to below 03 to b°C in an inert gas atmosphere. Method.