JPS59205455A - Heat treatment of winding core made of amorphous alloy - Google Patents

Abstract

PURPOSE:To obtain the titled winding core improved in magnetic characteristics, especially, in iron loss characteristics and magnetic permeability, by applying preliminary stress removing annealing to an amorphous alloy thin strip in a specific temp. range between the crystallization temp. and the Curie temp. of said strip within a short time to wind up the same while applying final stress removing annealing to the wound strip at the crystallization temp. or less. CONSTITUTION:Prior to winding up an amorphous alloy thin strip with a composition of Fe79B13Si8 after quenching and solidifying the same, preliminary stress removing annealing to said strip at a temp. which is not high enough to exceed 100 deg.C above the crystallization temp. of said strip but not lower than a Curie temp., for example, 550 deg.C for one sec. In the next step, the thin strip is wound up by a winding core and, thereafter, final stress removing annealing is applied to the wound strip at a temp. 100 deg.C or more lower than the crystallization temp., for example, at 300 deg.C. By this method, a winding core made of an amorphous alloy remarkably improved in magnetic characteristics is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat treatment method for a wound core made of an amorphous alloy, and in particular to a method for heat treatment of a wound core made of an amorphous alloy. This is a major improvement.

In recent years, a method has been developed to produce a quenched ribbon directly from the molten metal by continuously supplying a molten metal or alloy onto a cooling body whose cooling surface moves at high speed and rapidly solidifying it. The chemical method has made it possible to easily manufacture amorphous alloy ribbons.

Such amorphous alloy ribbons generally have excellent magnetic properties, and in particular, amorphous alloy ribbons used for transformer core materials have a high saturation magnetic flux density and are also excellent in iron loss properties. In particular, the iron loss value is reduced to about b or less compared to the case where conventional silicon steel electrical steel sheets are used as the transformer material.

However, such amorphous alloys for transformer materials have high magnetostriction, so when used as a wound core, this high magnetostrictive property, combined with the influence of the curvature of a part of the corner of the core and the introduced strain, will affect the magnetic properties. (This caused the iron loss characteristics to deteriorate.)

Therefore, when an amorphous alloy ribbon is used as a wound core, it is essential to apply strain relief annealing after winding it into a predetermined shape in order to obtain good characteristics.

In addition, amorphous alloys exhibit excellent magnetic permeability and good high-frequency characteristics, so they are being considered for use as magnetic materials for various sensors and electronics. (In this case, strain relief annealing is still an essential requirement.

Figure 1 (Co, Fe, oB□aSls (at % or less)
The results of investigating the iron loss value after 60 minutes of strain relief annealing are shown as the relationship between the reciprocal of the radius r of the wound core and the iron loss value.

As is clear from the figure, the iron loss characteristics after strain relief annealing are
This is a significant improvement compared to before the annealing.

However, as the diameter of the wound core becomes smaller, the iron loss value increases.

In other words, even if such strain relief annealing is performed, if the winding diameter is still small, deterioration of iron loss characteristics cannot be avoided.

The present invention aims to advantageously solve the above-mentioned problems, and aims to further improve the magnetic properties of the amorphous alloy wound core by improving the heat treatment during the manufacturing process of the wound core.

Incidentally, it is generally believed that changes in amorphous alloys due to heat occur in the following order.

In other words, an amorphous alloy in a rapidly solidified state undergoes (1) disappearance of free volume, (2) then structural short-range order, and (3)
Then chemical short-range order arises, and (4) onwards,
Crystallization, that is, the formation of long-range order, occurs. Of each process listed above, (i
) is called strain removal or so-called structural relaxation, and is a process in which internal stress is removed. The displacement of atoms in this process remains within a range smaller than one atomic distance, but if the heating temperature becomes higher or for a longer time, the displacement of atoms becomes larger than one atomic distance, and the crystallization This was causing a change in the population. Therefore, strain relief annealing of wound cores, etc. must always be a heat treatment that does not result in the change described in (1) above, and applying more heat than that causes crystallization of the amorphous alloy and eventually deterioration of the magnetic properties. This means that in strain relief annealing of transformer-wound cores, toroid cores, etc., the annealing conditions that can completely remove strain and prevent iron loss from deteriorating are extremely close to the temperature conditions that cause crystallization. This shows that it is extremely disadvantageous for improving magnetic properties.

Therefore, in amorphous alloys where such strain relief annealing conditions and heat treatment conditions that cause crystallization are close to each other,
Even if annealing is performed at a temperature that is not likely to cause crystallization as in the past, that is, a temperature that is considerably lower than the appropriate strain relief annealing temperature, sufficient strain relief cannot be achieved, and therefore a satisfactory level of magnetism cannot be achieved. No improvement in characteristics could be expected.

As a result of intensive research to solve the above problem, the inventors found that even if an amorphous alloy is heated at a temperature close to its crystallization temperature, if the heating time is short, the alloy If crystallization does not occur and such preliminary strain relief annealing is performed, subsequent low temperature annealing can achieve effective strain removal, thus yielding unexpected results in improving magnetic properties. They found that it was possible to obtain

This invention is derived from the above knowledge.

That is, in the process of manufacturing a wound core using an amorphous alloy as a magnetic circuit material, the amorphous alloy ribbon obtained by rapid solidification is first heated at 100° above the crystallization temperature of the ribbon before winding. A short period of strain relief annealing is carried out at a temperature not exceeding 100°C, but not below the Curie temperature, and then being wound onto a wound core at a temperature of 100°C below the crystallization temperature. A means for solving the above problem is to perform final strain relief annealing at a temperature lower than .degree. C. or higher.

Hereinafter, this invention will be specifically explained based on the experimental results derived from it.

2nd V L , an amorphous alloy ribbon (crystallization temperature Tx: 480″C) having a composition of 1 g of Fe7oBtaS was immediately wound onto a toroidal core of 100 mm diameter after rapid solidification, and strain-removed at various temperatures for 1 hour. In the case of annealing (indicated by a circle in the figure) and in the case of preliminary strain relief annealing at 550°C for 1 second after rapid solidification, final strain relief was applied to a 100 amφ toroidal core at the winding temperature for 1 hour. The results of an investigation into the relationship between annealing temperature and iron loss value when annealing is performed are shown for comparison.

As is clear from the figure, when the two-stage strain relief annealing according to the present invention is performed, especially when the final strain relief annealing temperature is 100°C or more lower than the crystallization temperature, there is a significant iron loss compared to the conventional method. showed a decrease in value.

Next, in FIG. 8, the same <Fe7. B□a S: Amorphous alloy with the composition of Ls (crystallization temperature TX; 480
℃, the results of investigating the iron loss characteristics when pre-strain relief annealing is performed at various nearby temperatures and holding times are summarized in terms of the relationship between the pre-strain relief annealing temperature and iron loss value with holding time as a parameter. .

Now, in preliminary strain relief annealing, even if the annealing temperature exceeds the crystallization temperature of the ribbon, the holding time is 0.5 to 1.
If the temperature is about 0 seconds, the iron loss characteristics will be significantly improved as long as the temperature does not exceed about 580°C, that is, 100"C higher than the crystallization temperature, and if the holding time is 2 seconds,
Although the upper limit of the annealing temperature is lowered somewhat, it is still 53
In a temperature range of about 0'C, that is, within a temperature range not exceeding 50'C below the crystallization temperature, a remarkable effect on improving iron loss characteristics was observed.

However, when the pre-strain annealing temperature is lower than the Curie humidity, the effect of improving iron loss characteristics becomes poor.

Therefore, the lower limit of the pre-strain relief annealing temperature is set to one Curie temperature, but the reason why the iron loss improvement effect is reduced when the preliminary strain relief annealing temperature is lower than one Curie temperature is considered to be as follows.

In general, ferromagnetic materials exhibit ferromagnetism as long as they have short-range magnetic order even when the temperature is increased. The Curie temperature is the temperature at which this magnetic order is completely eliminated, but annealing in a temperature range where no such magnetic order exists is anisotropic because the effect on the atomic arrangement becomes random. It is thought that this makes it difficult to generate clusters due to the targeted atomic arrangement, etc., but in this respect, the above effect is poor at temperatures below one Curie temperature. By the way, the crystallization temperature and Curie temperature of a few amorphous alloys are as follows.

When the annealing is carried out at a temperature in the range of 0.5 to 1 second, the holding time is about 0.5 to 1 second, and when the annealing temperature is not more than 59°C than the crystallization temperature, the holding time is 0.5 seconds. ~2
It is preferable that the time is about seconds.

Further, in the final strain relief annealing, the annealing time tends to become longer because heat dissipation increases due to the increase in the volume of the wound core. For this reason, if the annealing temperature is high, crystallization becomes easy, so it is necessary to perform the annealing at a temperature of 100° C. or lower than the crystallization temperature. This is also confirmed from the results shown in Figure 2 above.
This has also been confirmed from numerous experimental results by the inventors.

Examples of the present invention will be described below.

・Examples 1 to 4 Fe7oB, amorphous alloy with a composition of S18 (
Crystallization temperature: 480°C Single crystallization temperature: 480°C
) was heated to 550'C, 1 prior to winding.
The results of investigating the iron loss value are shown when preliminary strain relief annealing was performed for 2 seconds, then the core was wound onto a wound core with a diameter of 100 mm, and final strain relief annealing was performed at 300°825.350 and 375°C. ] Shown below. For comparison, we used the conventional method in which the core was immediately wound into a thin ribbon after quenching without performing preliminary strain relief annealing, and strain relief annealing was performed. It is also listed in Table 1.

As is clear from the results in Table 1, all of the products that were subjected to preliminary strain relief annealing prior to the final strain relief annealing according to the present invention (Examples 1 to 4) were obtained according to the conventional method (Conventional Examples 1 to 4). The iron loss characteristics are improved compared to 4).

Example 5 Amorphous alloy having a composition of Fe5co7□B□2Si12 (crystalization temperature 480°C, Curie temperature: 44
0°C) was rapidly cooled into a thin ribbon, subjected to preliminary strain relief annealing at 500°C for 1 second, then wound around a toroid core with an inner diameter of 10 mm, subjected to final strain relief annealing at 380°C for 110 minutes, and forced air cooling. It was cooled by

The effective magnetic permeability µe of the obtained toroid core at a frequency of 1 kHz was measured and found to be µe-5X10', which means that the effective magnetic permeability of the toroid core obtained according to the conventional method without pre-strain annealing is lXl0'. It's a lot better than what it was.

Example 6 Fe. Amorphous alloy with the composition Ni40B20 (crystallization temperature = 450°C, Curie temperature 890°C)
The rapidly solidified ribbon was first subjected to preliminary strain relief annealing at 450°C for 0.5 seconds, then wound around a toroid core having an inner diameter of IQfm, and then subjected to final strain relief annealing at 300°C for 5 minutes.

When the effective magnetic permeability μe of the obtained toroid core at a frequency of 1 kHz was measured, μe was 7×10. This value is 1Le without preliminary strain relief annealing.
-2X It is several steps better than 10').

The component system of the amorphous alloy targeted by this invention is not particularly limited, but includes Fe-B-si, a high magnetic flux density material, Fe-B-si alloy, and F-based alloy, a high magnetic permeability material.
It is particularly suitable for application to e-Ni-B-(Si)-based alloys, as well as low magnetostrictive materials such as Co-F and e-B-;(Si)-based alloys.

As described above, according to the present invention, toroid cores such as transformer-wound cores and motor cores in which amorphous alloy is used as a magnetic circuit material, and sensors and electronics-related parts in which amorphous alloy is wound in a toroidal shape are used. Great for improving magnetic properties.

[Brief explanation of the drawing]

Fig. 1 is a graph showing the iron loss characteristics of an amorphous alloy wound core having a composition of Fe79B18''18 before and after strain relief annealing, as a relationship between the reciprocal of the winding diameter and the iron loss value W10150. Figure 3 is a graph comparing the difference in pupil of amorphous alloy wound cores with the same composition with and without preliminary strain relief annealing. It is a graph showing the influence of annealing temperature and holding time on iron loss characteristics.Patent applicant: Kawasaki Steel Co., Ltd. Temperature ('C

Claims (1)

[Claims] In the process of manufacturing a wound core using an amorphous alloy as a magnetic circuit material, an amorphous alloy ribbon obtained by rapid solidification is first heated at a temperature lower than the crystallization temperature of the ribbon before winding. A short pre-strain relief annealing is carried out at a temperature not higher than 100°C, but not lower than the Curie temperature, and then after being wound into a wound core, the temperature is lower than the crystallization temperature. is 1
A method for heat treating a wound core of an amorphous alloy ribbon, the method comprising performing final strain relief annealing at a temperature lower than 00°C. 2. A patent in which the preliminary strain relief annealing is a heat treatment for 0.5 to 1 second at a temperature within a range of not more than 100°C higher than the crystallization temperature of the amorphous alloy and not lower than the Curie temperature. The method according to claim 1. & The prestrain relief annealing is a heat treatment for 0.5 to 2 seconds at a temperature in the range of not more than 50°C above the crystallization temperature of the amorphous alloy and not below the Tsukühli temperature. A method according to claim 1.