JPH02138706A - Anisotropic permanent magnet - Google Patents

Abstract

PURPOSE:To obtain a permanent magnet having excellent residual magnetic flux density and coercive force by a method wherein a rare earth-iron alloy, having R, Fe and B as the fundamental composition, is used as a base material, the length ratio of crystal grain in anisotropic direction and anti-anisotropic direction is limited within the prescribed range by conducting a heat treatment, and anisotropy rate is increased above a prescribed value. CONSTITUTION:The base material of the title permanent magnet is indicated by the formula R1-alpha-beta-gamma{Fe (Ni, Mn, Co)}alphaXbetaMgamma, Adelta. R expressed a rare-earth element, X expresses B, C and the like, M expresses Ti, Zr and the like, and A expresses Ru, Rh and the like. X is the element which contributes improvement in magnetic characteristics, and the magnetic characteristics are improved by forming a boride and the like by adding M. A is Pt group and increases corrosion-resisting property. Fe (Ni, Mn, Co) improves residual magnetic flux density Br and coercive force IHc. 0.6<=alpha<=0.85, 0<beta<0.15, 0<=gamma<=0.05, and 0<=gamma<=0.02 are used. A rolling processing is conducted at 500 to 1100 deg.C, and when the length ratio of crystal grain in anisotropic direction and anti-anisotropic direction is selected as 0.7 to 1.2, and also the prescribed anisotropy rate is selected as 50% or above, a high Br can be compatible with a high IHc.

Description

[Detailed description of the invention] [Purpose of the invention]

(Industrial Application Field) This invention is used as a component of various electrical products and automobiles, and is particularly applicable to residual magnetic flux density (Br) and coercive force (
The present invention relates to an anisotropic permanent magnet that is excellent in both magnetic properties of tl (c). (Prior art) In recent years, R,
Rare earth-iron permanent magnets containing Fe and B as basic components have been developed, and as their magnetic properties have further improved, their applications and amounts have been further expanded. Methods for producing such rare earth-iron permanent magnets include a method in which rare earth-iron permanent magnet alloy powder is press-molded in a magnetic field and sintered (sintering method; powder metallurgy method); There is a manufacturing method (plastic deformation method) in which iron-based alloy powder is temporarily formed by hot pressing or hot isostatic pressing, or the powder is subjected to plastic deformation such as forward extrusion or backward extrusion. Ta. In the latter plastic deformation method, when a rare earth-iron alloy is hot plastically deformed at a temperature of 500 to 1100''C, the crystal C-axis is aligned in the direction of compressive strain.
It is known that so-called anisotropic permanent magnets having high magnetic properties in that direction can be obtained. (Problem to be Solved by the Invention) However, when obtaining a permanent magnet anisotropically formed by such plastic deformation, the higher the processing rate during plastic deformation, the higher the residual magnetic flux density in the compression direction (Br
) increases and anisotropy progresses, but on the other hand, the coercive force (tHc
) was a problem. (Object of the Invention) This invention has been made in view of the above-mentioned conventional problems. Even when I did,
It is an object of the present invention to provide an anisotropic permanent magnet that can have a large coercive force (!Hc) and can achieve both high residual magnetic flux density and high coercive force.

[Structure of the invention]

(Means for Solving the Problems) An anisotropic permanent magnet according to the present invention is made of R, Fe. A permanent magnet made of a rare earth-iron alloy containing B as a basic component and magnetically anisotropically made by hot working,
The ratio of the length of the crystal grains in the anisotropic direction to the length of the crystal grains in the anti-anisotropic direction is in the range of 1.2 to 0.7, and the anisotropy rate (% or more) expressed by the following formula is The structure of the anisotropic permanent magnet is a means for solving the above-mentioned conventional problems.The anisotropic permanent magnet according to the present invention is made of R, Fe. The material is a rare earth-iron alloy having as a basic component, more specifically: Of (7)
) One or more kinds, X is B, C, N, Si. 1M of one or more of P is TiZr, )If
, V, Nb, Ta, Cr, Mo, W. One or more of Au, Cu, Zn, Ga, In, T, and Q, and A is Ru, Rh, and Pd. It is more desirable to use one or more of Os, Ir, and Pt. Among the above, Fe (Ni, Mn, Co). It is an element group effective for improving the residual magnetic flux density (Br), and it is preferable that a part of Fe, more preferably 0 in atomic ratio
．． 10 or less Fe to Ni. It is possible to substitute M n , CO and Ni. Coercive force (BHC, IHC) can be improved by adding an appropriate amount of Mn, and heat resistance can be improved by increasing the Curie point by adding an appropriate amount of CO, and a good maximum energy product ((BH) max) can be achieved. In order to obtain 0.60≦α≦0.85, it is more desirable. In addition, the X element is an element that contributes to improving magnetic properties,
When M element is added, it combines with some of these elements to form borides, carbides, nitrides, and silicides. It is possible to improve the magnetic properties by forming phosphides, etc.
It is particularly desirable to set the value to 05. Furthermore, since the platinum group element group which is element A contributes to improving corrosion resistance, it may be added as necessary in the range of O≦δ≦0.02. The anisotropic permanent magnet according to the present invention uses the above-mentioned more desirable composition as a material, and is made magnetically anisotropic by applying hot processing to this magnet material. The magnet material to be processed may be a powder or a cast body (ingot). Among these, when an alloy material made of powder is magnetically anisotropic by hot working, for example, molten rare earth-iron alloy can be used as the powder by spark erosion method, gas atomization method, vacuum method, etc. atomization method,
Centrifugal atomization method. The powder is rapidly cooled using a rotating electrode method, etc., and the centrifugal quenching method, in which molten rare earth-iron alloy is injected through a nozzle onto the inner wall of a rapidly rotating cooling drum to rapidly solidify it, is used. One roll method involves injecting molten metal onto the outer wall of a rotating drum to solidify it, and the twin roll method involves injecting molten alloy onto the contact surfaces of two drums that rotate at high speed and rapidly solidify them. After forming a thin ribbon using a method such as a method, the thin ribbon is crushed into powder. When applying hot working to such a rare earth-iron alloy material made of powder or a rare earth-iron alloy material made of a cast body, for example, rolling processing, extrusion processing, hot pressing, hot processing, etc. Hydrostatic pressure processing, upset processing, etc. are used, and the processing is carried out at an elevated temperature of, for example, about 500 to 1100°C. In this case, if the processing temperature for the alloy material is too low, cracks will occur during processing, which is undesirable, and if the processing temperature is too high, the crystal grains will become coarse, which will adversely affect the magnetic properties, which is not preferable. In the anisotropic permanent magnet according to the present invention, the ratio of the length of the crystal grains in the anisotropic direction to the length of the crystal grains in the anti-anisotropic direction is in the range of 1.2 to 0.7, The anisotropy rate expressed by the following formula % formula % (2) is greater than or equal to %. In this case, the length of the crystal grains in the anisotropic direction and the length of the crystal grains in the anti-anisotropic direction are If the ratio is too small, the residual magnetic flux density (B
Although r) increases and the degree of anisotropy increases, the coercive force (xHc) decreases and sufficient bacteriomagnetic force cannot be obtained, which is undesirable.On the other hand, if the L ratio is too large, the residual magnetic flux density (Br ) decreases, making it impossible to obtain satisfactory anisotropy and, in this case, as well, sufficient coercive force cannot be obtained. Therefore, the above-mentioned ratio is preferably in the range of 1.2 to 0.7, or 1.0. It is preferable to set it in the range of -0.7. In addition, if the anisotropy rate is too small, sufficient anisotropy will not be obtained and the residual magnetic flux density (Br) in the anisotropic direction will be a low value, so sufficient anisotropy cannot be obtained. Thus, the anisotropy rate is preferably 50% or more. When the raw material is rare earth-iron alloy powder, it is more desirable that the average crystal grain size is 0.5 pm or less, which can further improve the magnetic properties. It becomes like this. (Function of the invention) The anisotropic permanent magnet according to the present invention has the length of the crystal grains in the anisotropic direction and the length of the crystal grains in the anti-anisotropic direction, which are magnetically anisotropically made by hot working. The ratio is in the range of 1.2 to 0.7, and the anisotropy rate (%) expressed by the following formula % formula (2) or higher is obtained. The residual magnetic flux density (Br) in the anisotropic direction has a large value, and the length of the crystal grains in the anisotropic direction is regulated relative to the length of the crystal grains in the anti-anisotropic direction. Coercive force in the anisotropic direction (
The IHC) value is also large, making it an anisotropic permanent magnet with excellent magnetic properties that have both high residual magnetic flux density and high coercive force. (Example) Backyard■'' 30.5% by weight Nd - 5.0% by weight Co - 0.9% by weight B - 0.1% by weight A - balance F
A rare earth-iron alloy having a composition of E was melted, and the molten alloy was ultra-quenched by a single roll method in an argon atmosphere to form a ribbon-like thin strip. Next, the ribbon-like thin strip is crushed into powder, and then 68
Various anisotropic permanent magnets shown in Table 1 were produced by hot pressing in the range of 0 to 750"0 and further performing upset processing in the range of 700 to 800 °C. When we investigated the magnetic properties of permanent magnets, we found that
The results are also shown in Table 1. As shown in Table 1, the ratio of the grain length in the anisotropic direction to the grain length in the anti-anisotropic direction is in the range of 1.2 to 0.7, and the anisotropic Invention example 1 which is more than % (%)
For permanent magnets No. 2 and 3.4, the residual magnetic flux density (Br) in the anisotropic direction is 11 KG or more, and at the same time the coercive force (!Hc
) also has a high value of 10 KOe or more, making it an anisotropic permanent magnet that has both high residual magnetic flux density and high coercive force. On the other hand, in the permanent magnet of Comparative Example 1 in which the average crystal grain size is 0.6 μm and the anisotropy ratio (Br/ΣBr) is less than (%), the residual magnetic flux density (Br) in the anisotropic direction is small. Comparative Example 2 where the ratio of the crystal grain length in the anisotropic direction to the crystal grain length in the anti-anisotropic direction is less than 0.7. , 3.4, the residual magnetic flux density (Br) in the anisotropic direction showed a large value, but the coercive force (IHC>4.nik) was a small value.Example 2 High Frequency By induction furnace, 36.0 wt% Pr-5,0 wt% Co-0,5 wt% B-4,0 wt% Cu-1,0
A rare earth-iron alloy having a composition of Zr by weight and balance Fe was produced, and the molten alloy was cast into a water-cooled copper mold in an argon atmosphere. Next, by cutting and grinding the ingot obtained by casting, a processed material with a diameter of 20 mm and a thickness of 13 mm is produced, and the processed material is subjected to upset processing at a temperature of 700 to 800°C. Various anisotropic permanent magnets shown in the table were manufactured. Next, we investigated the magnetic properties of each anisotropic permanent magnet, and found that
The results are also shown in Table 2. As shown in Table 2, the ratio of the grain length in the anisotropic direction to the grain length in the anti-anisotropic direction is in the range of 1.2 to 0.7, and the anisotropy rate ( % or more, the residual magnetic flux density (Br) in the anisotropic direction is II
KG or more and at the same time coercive force (wHc) is 13KOe
These values are quite high, making it an anisotropic permanent magnet that has both high residual magnetic flux density and high coercive force. On the other hand, Comparative Example 5, in which the ratio of the length of the crystal grain in the anisotropic direction to the length of the crystal grain in the anti-anisotropic direction is smaller than 0.7,
In the permanent magnet No. 6, the residual magnetic flux density in the anisotropic direction (B r
) had a large value, but the coercive force (IHC) had a small value.

【Effect of the invention】

The anisotropic permanent magnet according to the present invention is made of R, Fe. A permanent magnet made of a rare earth-iron alloy containing B as a basic component and magnetically anisotropically made by hot working,
The ratio of the length of the crystal grains in the anisotropic direction to the length of the crystal grains in the anti-anisotropic direction is in the range of 1.2 to 0.7, and the anisotropy rate (% or more) expressed by the following formula is Because of this, the residual magnetic flux density (Br) in the anisotropic direction has a large value, and at the same time the coercive force (lHc) also has a large value. This is a permanent magnet that is anisotropically anisotropic and has both high residual magnetic flux density and high coercivity, and has the remarkable effect of being a permanent magnet that exhibits stable magnetic properties against temperature changes.Patent Applicant Daido Steel Co., Ltd.

Claims (1)

[Claims] (1) A permanent magnet made of a rare earth-iron alloy whose basic components are R, Fe, and B, and magnetically anisotropically made by hot working, with the length of crystal grains in the anisotropic direction The ratio of the grain length in the anti-anisotropic direction is 1.2 to 0.
7, and the anisotropy rate expressed by the following formula: anisotropy rate (%) = residual magnetic flux density in the anisotropic direction / sum of residual magnetic flux densities in three orthogonal directions x 100 is 50% or more. An anisotropic permanent magnet characterized by: