JPS6283423A - Manufacture of permanent magnetic sheet having easily magnetized axis in direction vertical to sheet surface - Google Patents

Abstract

PURPOSE:To easily manufacture the titled permanent magnet sheet in industrial scale, by forming sheet contg. a specified quantity of columnar crystals from molten alloy having a specified compsn. while controlling cooling condition, applying recrystallization annealing, magnetic field impressing annealing, aging annealing under specific conditions. CONSTITUTION:Molten alloy having a compsn. indicating a chemical formula Fe100-x-y-zCrxCoyMz is rapidly cooled and solidified to form sheet by ultrarapid cooling method. In the formula, M is at least one kind selected from Ti, Zr, V, Nb, Ta, Mo, W, Mn, Cu, Si, Sn, P, Al, B, x is 10-35wt%, y is 3-35wt% and z is 1.0-10wt%. Thereat, cooling condition is controlled corresponding to the desired thickness of sheet and crystalline structure of sheet is made to that contg. >=30% columnar crystals. Next, sheet is recrystallization annealed at 800-1,300 deg.C range, then annealed at 600-750 deg.C range under magnetic field impression in the direction vertical to sheet surface. Further, it is aging annealed at temp. of <= magnetic field annealing temp.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing a permanent magnet plate having magnetic anisotropy perpendicular to the plate surface, with the <001> direction aligned in the direction perpendicular to the plate surface. .

In recent years, permanent magnets have been used in the things that are familiar to us, such as magnetic thumbtacks, instruments,
It is used in a wide variety of fields, from telephones, speakers, and motors to magnetrons and talistrons in the biotechnology field.

Important performance parameters in designing and using this permanent magnet are residual magnetic flux density Br, coercive force 11c, and maximum energy product (fill) max.

FIG. 7 shows these parameters. It goes without saying that for a permanent magnet, the larger both Dr and Ilc, the better. flc is a measure of the coercive force that holds Br against the demagnetizing field. (fill)max is the maximum value on the energy product curve created by calculating the product of B and H for each demagnetization curve in the second quadrant shown in Figure 7, and the magnet has a unit volume. It means the maximum amount of energy that can be held.

(Prior art) Generally, high-performance permanent magnets are hard and brittle, as seen in alnico, ferrite, and rare earth permanent magnets, and therefore have poor workability.Therefore, there are significant limitations on manufacturing methods. Ta.

For example, Alni:j has been limited to a casting method, while ferrite and rare earth materials have been limited to a powder sintering method in which the respective compound powders are sintered.

Due to manufacturing constraints, such high-performance permanent magnets are often made in block shapes, and plate-shaped magnets can be made without any restrictions on manufacturing methods, such as Cunifue, Cunico, and Pikaroy, which are easy to process. It was limited. However, in terms of performance, it was far inferior to alnico, ferrite, and rare type systems.

In this regard, recently, as shown in Japanese Patent Application Laid-open No. 59-83751, it has been shown that the energy product (IllI) max Fe-['lr-[nio-based alloys have attracted attention as having -C
There is.

(Problems to be Solved by the Invention) Recently, the use of plate magnets has increased rapidly, and depending on the use, materials that require magnetic anisotropy perpendicular to the plate surface are required. Fe-Cr-G.

Even in alloy magnets, the magnetic anisotropy in the direction perpendicular to the plate surface is not necessarily good, partly due to the imperfections that have been produced by conventional methods such as rolling, and improvement has been desired.

This invention advantageously solves the problems described in -F.
Even such a plate-shaped magnet has an axis of easy magnetization in the direction perpendicular to the plate surface, that is, it has an axis of easy magnetization in the direction perpendicular to the plate surface. The purpose of this invention is to propose an advantageous manufacturing method for a permanent magnet having a shaft.

(Means for solving the problem) The main structure of the present invention for obtaining a material having a <001> axis in the direction perpendicular to the plate surface in a plate-shaped permanent magnet is as follows.

That is, the chemical formula: Fe1oo-o-y-z cr)l
COY MZ where M: Ti, lr, V, N
b, Ta, Mo, W, Mn.

At least one selected from Cu, Si, Sn, P, AA and B: 10 to 35 wt%.

y: 3 to 35 wt% z + 1.0 to 10 wt% When rapidly solidifying a molten alloy having a composition shown by the following super-quenching method to form a thin plate, the cooling conditions must be adjusted to correspond to the desired sheet material for the thin plate. By grinding, the crystal structure of the thin plate is changed to a structure containing 30% or more columnar crystals, and then the thin plate is
Recrystallization annealing is performed in the temperature range of 00 to 1300°C, then annealing is performed in the temperature range of 600 to 750°C under the application of a magnetic field in the direction perpendicular to the plate surface, and then aging annealing is performed at a temperature below the magnetic field annealing temperature. A method for producing a permanent magnet plate having an axis of easy magnetization in a direction perpendicular to the plate surface.

This invention will be specifically explained below.

First, the reason why the component composition of the material is limited to the above range in this invention will be explained.

Cr, 10 to 35% Cr is a useful component that forms a matrix, which is a non-magnetic Cr-rich α2 phase, but if its content is less than 10%, this α2 phase will not form a matrix and will form a two-phase matrix. After separation, it becomes a precipitated phase, and the Fe-rich α phase conversely becomes a matrix phase, making it impossible to obtain sufficient permanent magnetic properties. Furthermore, since the spinodal decomposition temperature decreases, it takes a long time for two-phase separation by spinodal decomposition. On the other hand, 35%
If the value exceeds 0.05 m, a Re-[':r-based elongated phase begins to precipitate in a part of the alloy, making it extremely brittle and difficult to process. Furthermore, since the spinodal decomposition temperature decreases, it takes a long time for two-phase separation.

Furthermore, the Fe-rich α1 phase decreases, and the permanent magnet properties deteriorate. Therefore, the Cr content end was limited to a range of 10 to 35%.

CO: 3 to 35% CO raises the spironodal decomposition temperature of this alloy system by I to complete two-phase separation in a shorter time, and at the same time raises the Curie temperature by L, reducing the effect of the magnetic field applied during spindal decomposition. However, if the content is less than 3%, a sufficient increase in the spinodal decomposition temperature and a sufficient magnetic field treatment effect due to the Curi temperature temperature of 35% If it exceeds 3% to 35%, the CO content is 3 to 35%.
limited to the range of

M: l, 0 to 10% Ti, Zr, V, Nb, represented by Coconi symbol MF,
Ta, Mo.

W, Mn, CLI, Si, Sn, P, ^1
and B are equally elements that alloy with Fe to form the α phase, prevent the expansion of the T phase loop of the P e -Cr alloy, and narrow the range of T→α change during cooling. It is.

In this alloy system, a single α phase as a supersaturated cooling body is required before spinodal decomposition, and good permanent magnet properties cannot be obtained if the r phase is mixed. Therefore, whether used alone or in combination, if the content is less than 1.0%, the T phase will remain during cooling to room temperature, and a supersaturated solid solution state of a single α phase cannot be achieved. Therefore, by inducing spinodal decomposition, only α1 and α2 phases have 2
It is difficult to phase separate the carp, and some r-phase coexists, resulting in deterioration of magnetism. On the other hand, if it exceeds 10%, the alloy becomes brittle and the workability deteriorates.In addition, the saturation magnetic flux density of the alloy decreases, and as a result, (t]tl)max deteriorates, so the content should be 1.0 to 10%. limited to the range of

Next, the procedure for manufacturing a thin alloy plate according to the present invention will be explained in detail in the order of steps.

First, a molten alloy adjusted to a suitable composition range as described above is made into a thin plate by an ultra-quench cooling method. As the ultra-quenching method, any conventionally known method such as a quasi-roll method or a twin-roll method can be used.

Now, this invention utilizes the columnar crystal structure formed when the molten metal is rapidly solidified in order to align the axis of easy magnetization in the direction perpendicular to the plate surface. It is important to control the crystal structure so that it contains

Factors that influence the columnar crystallinity of the quenched ribbon include plate thickness, cooling rate, thermal conductivity of the rolls, and thermal conductivity between the molten steel and the rolls.

For example, if the same cooling roll is used and the injection pressure and injection amount of the molten metal are constant, the columnar crystallinity of the obtained quenched ribbon is uniquely determined by the cooling rate relative to the plate thickness.

Therefore, under the above conditions, it is not possible to find a simple relationship between the number of rotations (rotational speed) of the cooling roll during production of the quenched ribbon and the plate thickness, and between the plate thickness and the columnar crystal ratio. can. For example, the above relationship in the case of 22Cr-15Co-Fe alloy is as shown in Figures 1 and 2, and when the plate thickness is 0.5 mm or less, the
The above cooling conditions may be used.

In addition, under the above conditions, in order to achieve a columnar crystal ratio of 30% or more (limited to cases where the thickness of the thin ribbon to be asked is 0.5 mm or less, it is necessary to obtain a columnar crystal ratio of 30% or more) (limited to cases where the thickness of the ribbon is 0.5 mm or less; In order to increase the crystallinity to 30% or more, the setting conditions as described above should be adjusted to 10%.
What is necessary is to change the quenching rate to 4° C./sec or more.

In this invention, as mentioned above, in order to align the axis of easy magnetization in the direction perpendicular to the plate surface, it is necessary to utilize the columnar crystal structure formed when the molten metal is ultra-rapidly solidified. The columnar crystal structure in the cast state is (
It is a structure in which the 1[]0) plane is parallel to the plate surface and the <001> direction is perpendicular.

Figure 3 shows 22Cr-15Co-I with a plate thickness of 0.3 mm.
A microscopic cross-sectional structure photograph of a quenched ribbon of Mn--Pe alloy composition is shown, and the figure also shows its (2n[l) pole figure. as
-90% or more of the crystals in the cast state are columnar crystals. When such a material is annealed at 1100° C. for 10 minutes, the crystal grains become coarse and become giant grains that extend through the thickness of the plate, as shown in FIG. 4a.

At this time, the texture seen from the pole figure is (100)<Qv
w>, it is necessarily <001> in the direction perpendicular to the plate surface.
The directions will be aligned. Here, the <001> direction is Fe
For CC alloys, such as those represented by , the axis of easy magnetization is shown, and in thermal theory, the <001> direction is also the axis of easy magnetization for the alloy system of the present invention.

On the other hand, the structure of the quenched ribbon obtained through the same manufacturing process has a columnar crystal ratio of 30 as shown in Figure 5a.
% (equiaxed crystallinity is 70% or more -1-), even if annealing is performed at 1100°C for 10 minutes,
As shown in FIG. 6a, the crystal grains do not penetrate through the thickness of the plate. Furthermore, as is clear from the pole figure in Figure 5, the texture of the plate surface is (100) < Dv in the as-cast state.
w>, but after annealing, the orientation becomes random as shown in FIG. Therefore, in such a structure, the <0[)1> orientation is random with respect to the plate surface,
It's not facing vertically. This behavior of grain growth is shown in the as-cast state.
This is because the proportion of equiaxed crystals contained in the thickness center layer is large.

Here, crystal grains with random orientation and not penetrating the plate thickness are mostly formed when the content of equiaxed crystals is more than 70%, so the proportion of columnar crystals is 30% or more and the proportion of equiaxed crystals is 7.
Therefore, it is important to keep it below 0%. Note that applying rolling to a skin pass level to the plate obtained in this manner does not cause any problem.

Thereafter, the quenched ribbon whose columnar height ratio has been controlled to 30% or more as described above is subjected to recrystallization annealing in a temperature range of 800°C to 1300°C to grow crystal grains. If the annealing temperature is less than 800°C, there is a disadvantage that recrystallization takes a long time, whereas if it exceeds 1300°C, the surface may melt depending on the alloy composition, and it is also preferable from the standpoint of equipment and operation. Therefore, the annealing temperature was limited to a range of 800 to 1300°C.

As described above, a permanent magnet material has been completed by completion of recrystallization annealing, but its magnetic properties are still far from satisfactory. Therefore, by further performing magnetic field annealing and aging annealing, the permanent magnet properties are improved.

Magnetic field annealing is performed for the purpose of inducing so-called initial spinodal decomposition, but if the annealing temperature is less than 600°C, spinodal decomposition takes a long time and is uneconomical; If it exceeds , the alloy becomes an α single phase, making spinodal decomposition difficult, and the effect of applying a magnetic field to approach the Curie point of this alloy system is diminished. Therefore, the spinodal decomposition due to magnetic field annealing is 600
The temperature was set to 750°C. At this time, the direction of application of the magnetic field must be perpendicular to the plate surface.

Further, it is desirable that the strength of the magnetic field is about 0.5 kOe or more. In actual operation, it is preferable to perform spinodal decomposition using a continuous furnace or the like that can apply a magnetic field in a direction perpendicular to the plate surface.

Then, after or in succession to the magnetic field annealing described above, age annealing is performed at a temperature below the magnetic field annealing temperature without applying a magnetic field. This aging annealing is intended to reach an equilibrium composition for each phase separated into two phases by spinodal decomposition, and at the same time to make the Cr-rich phase non-ferromagnetic at room temperature. When annealing is performed at a temperature exceeding the magnetic field annealing temperature to obtain an equilibrium composition, the obtained Cr-rich phase does not become a complete nonmagnetic phase.

In such age annealing, it is desirable that the volume of each phase after two-phase separation is in a ratio of 1:1, and by doing so, extremely excellent coercive force and (B)I) ma × is obtained.

(Example) Sampling Example I From a molten alloy having the composition Fes5Cr22-CO12-Mn+, the injection pressure was 1.5 atm, the injection speed was kept constant at 1.5 kg/s, and the roll rotation speed was (a). 120 Orpm, (b) Thickness 0.3 + by the twin roll method under the conditions of changing to 700 rpm.
Thin plates of nm (thin plate^) and 0.5 mm (thin plate B) were respectively created.

The columnar height of each of these thin plates in the as-cast state was about 8 for thin plate A.

These thin plates A and B were then subjected to recrystallization annealing at 1000°C for 10 minutes.
Annealed at 660°C for 10 minutes under the application of a magnetic field of e.
Subsequently, multi-stage aging annealing was performed at 600°C for 5 hours, at 575°C for 5 hours, at 550°C for 5 hours, and then at 500°C for 10 hours without applying a magnetic field.

As a result of measuring the magnetomotive force of both thin plates thus obtained using a Gaussmeter, thin plate A was 600G, while thin plate B was 350G.
It was G. It is clear that the axis of easy magnetization of the thin plate Δ is aligned in the direction perpendicular to the plate surface.

Example 2 Injection pressure: 1.6 atm, injection amount: 0.
The rotation speed of each roll is kept constant at 6 kg/s (a)
(b) 600 rpm.

(C) Under changing conditions of 1200 rpm・Thickness 0
．． Thin plates of 20 mm (thin plate C), 0.35 mm (thin plate D) and 0.52 mm (thin plate B) were prepared.

The columnar crystallinity of these thin plates C, D and E is 95, respectively.
．． 58 and 28%.

These thin plates C, D and E were then subjected to recrystallization annealing at 980°C for 12 minutes.
Annealing was performed at 665°C for 10 minutes under the application of a magnetic field of 575°C, followed by annealing at 600°C for 5 hours without applying a magnetic field.
Multi-stage aging annealing was performed at 550°C for 5 hours, then at 500°C for 10 hours.

When the magnetomotive force of each thin plate thus obtained was measured using a Gaussmeter, the magnetomotive force of both thin plates C and D was 600G, while that of thin plate E was only 370G.

(Effect of the invention) ka<C1 According to this invention, P e -Cr -C
o For M-based permanent magnets, the axis of easy magnetization can be aligned perpendicular to the plate surface by actively utilizing the characteristics of the crystal structure unique to the ultra-quenching method, and the magnetic field application direction during magnetic field annealing is also perpendicular to the plate surface. The plate shape 61 has particularly excellent magnetic properties in the direction perpendicular to the plate surface because the directions match! i
Stone can be easily produced on a commercial scale.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between cooling roll rotation speed and plate thickness. Figure 2 is a graph showing the relationship between plate thickness and columnar crystal percentage of the quenched ribbon. Figure 3 a and b are graphs showing the relationship between plate thickness and plate thickness. , 22Cr- with a columnar crystal ratio of over 90%
15Co-IMn-Re alloy rapidly solidified thin ribbon microscopic cross-sectional structure photograph and (200) pole figure. (200)
The pole figures, Figures 5a and b, are for 22Cr with a columnar crystal ratio of less than 30%.
-15Co-IMn-Fe alloy quenched ribbon microscopic H cross section m
Fig. 6a, 1) shows the microscopic cross-sectional structure photograph and (200) polar figure of the above ribbon after annealing at 1100°C for 10 minutes.
) Pole figure, Figure 7 is a demagnetization curve and an energy product curve diagram of a permanent magnet.

Claims (1)

[Claims] 1. Chemical formula: Fe_1_0_0_-_x_-_y_-_
zCr_xCo_yM_z where M: Ti, Zr, V,
Nb, Ta, Mo, W, Mn, Cu, Si, Sn, P,
A molten alloy having a composition of at least one selected from Al and B, x: 10 to 35 wt%, y: 3 to 35 wt%, z: 1.0 to 10 wt%, is rapidly solidified by an ultra-quenching method. When forming a thin plate, the crystal structure of the thin plate is made to include 30% or more of columnar crystals by adjusting the cooling conditions corresponding to the desired thickness of the thin plate, and then the thin plate is
Recrystallization annealing is performed in the temperature range of 00 to 1300°C, then annealing is performed in the temperature range of 600 to 750°C under the application of a magnetic field in the direction perpendicular to the plate surface, and then aging annealing is performed at a temperature below the magnetic field annealing temperature. A method for producing a permanent magnet plate having an axis of easy magnetization in a direction perpendicular to the plate surface.