JPS5837126A - Heat treatment for amorphous magnetic alloy - Google Patents

Abstract

PURPOSE:To obtain an excellent magnetic alloy of low watt loss in subjecting an amorphous magnetic alloy to a heat treatment by providing >=1 times of forestage treatments for a constant time at the temp. lower than a max. temp. prior to holding said alloy at the max. temp. CONSTITUTION:When the temp. at which the crystallization of an alloy to be heat treated initiates is defined as Tx( deg.C), the holding temp. in the 1st stage is set higher than Tx- about 300 deg.C and lower than Tx- about 180 deg.C and the time thereof is set at about >=20min. The holding temp. in the final stage is set higher by about 30 deg.C than that in the 1st stage and lower by about 50 deg.C than Tx and the time is set at about >=1min. Here, the final high temp. annealing of the multistages heat treatments is for thorough relieving of the residual strains of the material and the temp. and time may be set according to the compsns. of the alloy. In the case of >=3 stages of annealing, it is preferable to set heat cycles so as to increase the holding temp. stepwise.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for heat treating an amorphous alloy.

Recently, so-called non-crystalline (amorphous) alloys that do not have a crystalline structure have been developed from a liquid state to 104 to 104 degrees.
By rapid cooling at the high speed of s@c, it has become possible to manufacture a continuous ribbon shape.Amorphous alloys have a random structure, so in principle they have no anisotropy, and defects such as grain boundaries occur. There are characteristics such as no.

In particular, iron-based amorphous alloys containing iron as a main component exhibit excellent soft magnetism because of the above-mentioned properties. In addition, due to its high electrical resistivity, it has good AC characteristics and is attracting attention as an iron core material with low iron loss. Among them, iron or an alloy of a metal containing iron as a main component and a semimetal has a relatively high saturation magnetic flux density B8, and is therefore expected to be used as a power transformer material.

Generally, the saturation magnetic flux density B8 is almost determined by the composition of the alloy. Examples are shown in Table 1.

Iron loss, which is an important characteristic required of iron core materials along with saturation magnetic flux density, is power loss lost due to excitation current, and it goes without saying that the smaller the iron loss, the better.

By the way, iron loss greatly depends on the state of the material even if the composition is the same. For example, various factors such as the surface condition of the material, residual strain, impurities, or shape come into play.

These are essentially related to the arrangement of magnetic domains or the movement of domain walls.

Amorphous alloys generally have a wide distribution of residual strain when cast, resulting in large core losses. Strain relief annealing is performed to reduce iron loss. Strain relief annealing is generally a method in which the material is held at a temperature lower than the crystallization temperature for a certain period of time.

It is also well known that performing the above annealing while simultaneously applying a magnetic field or tension is effective in optimizing the alignment of the magnetic domains.

In any case, conventional heat treatment has consisted of a cycle of heating the material to a one-step holding temperature, holding it, and cooling it.

In contrast, the heat treatment method of the present invention is characterized by providing at least one preliminary treatment for a certain period of time at a lower temperature before holding at the maximum temperature, and the method of the present invention is adopted. As a result, excellent magnetism with lower iron loss can be obtained than with conventional heat treatment performed at one stage of holding temperature.

Next, the present invention will be explained in detail.

The material targeted by the present invention contains at least one type of F@eNi*Co with a total content of 100 at% of 70 to 8
5at9L B a 81 e Ct P # Go at 15 to 30 aiq11%, and if necessary, Cr * Mo1Nb + W e
V * Mn * Sn * At a
Sb e Tm a Zr+Ti 10
It is preferable to use an alloy in which at least 90 vol 4 or more is amorphous and contains at % or less.

When heat treating these alloys, the present invention provides the following:
It is characterized in that the temperature is successively maintained at at least two stages of increasing temperature.

That is, the crystallization initiation temperature of the alloy to be heat treated is Tx
(U), the holding temperature of the first stage is Tx-300
℃) High temperature (Tx -180℃ or lower temperature for more than 20 minutes,
The holding temperature of the final stage is at least 30°C lower than that of the first stage.
℃ higher and at least 50'C lower than Tx for at least 1 minute. Further, it is more effective to perform the heat treatment while applying a magnetic field and/or tension in the longitudinal direction of the material.

Table 1 shows the effect of providing a pre-treatment to maintain the temperature at a much lower temperature before maintaining it at the maximum temperature. It is clear that the effect of pre-treatment is not simply due to the extension of the annealing time, as even if the pre-treatment is omitted and the time of holding the steel at the maximum temperature is extended, it has almost no effect on improving iron loss. 0 Table 1 Wt4/lSo is frequency 50Hz% magnetic flux density 1.3TK
The first example of the influence of the temperature and time of the pre-treatment on the iron loss is shown in the first example.
In the case of F-788112B10 shown in the figure, the optimal processing condition t! The temperature range is 250 to 350℃, and 20℃ for 1 hour.
It's more than a minute. Similar trends are observed for other compositions.
When organized by crystallization temperature Tx, the appropriate pre-treatment conditions are Tx
-3Q Higher than 0℃ (Tx - 2 at lower temperature than -180℃
It was over 0 minutes.

The high-temperature annealing performed at the end of the multi-stage heat treatment of the present invention is intended to completely remove strain remaining in the material, and the annealing temperature and time may be set depending on the composition of the alloy. However, the temperature should be at least 30°C higher than the temperature of the first stage. Further, in order to avoid crystallization, the temperature should be selected to be at least 50° C. lower than the crystallization temperature.

When performing multi-stage annealing of three or more stages, it is preferable to set the thermal cycle so that the holding temperature is increased in stages.

Furthermore, it is effective to carry out the heat treatment of the present invention while applying a magnetic field and/or tension in the longitudinal direction of the material. It is better to apply the magnetic field and tension to around 150° C. even during cooling.

Although it is not clear why the method of the present invention, which includes pre-stage heat treatment that is maintained at a relatively low temperature, is more effective in improving iron loss than conventional single-stage heat treatment, the inventor of the present invention speculates as follows. . There is more than one relaxation process for an amorphous structure in a non-equilibrium state, and the final state should differ depending on the temperature conditions. It is believed that the pre-treatment performed at a relatively low temperature in the present invention acts to stabilize the amorphous state, making the subsequent high-temperature treatment for magnetic modification more effective. Let me explain.

Example I A master alloy having a composition of F@78Si121hO was melted in a high-frequency furnace [2. The molten alloy was slipped on the outer periphery of a steel roll rotating at a circumferential speed of 20 WV/ssc, and then introduced into the atmosphere through a toroidal nozzle. Amorphous thin film having a width of 25 mm and a thickness of approximately 30 μm was prepared by ejecting the resin. This was annealed at 290° C. for 80 minutes while applying a magnetic field of 300 @ in the longitudinal direction of the z, followed by annealing at 380° C. for 30 minutes, and then cooled to 150° C. for about 60 minutes while the magnetic field was applied. The magnetic properties of the annealed material measured with a single plate measuring device were as follows.

W L3/'+Oo, o 68 wattABl
1.46T However, Wl,5/rio indicates the iron loss at 50Hz and 1.3T, and the magnetic flux density at B1 [magnetic field 10.

On the other hand, for comparison, the magnetic properties of materials with the same composition annealed at 380°C for 30 minutes and 60 minutes were
l, s, 4o were 0.092W and 0.101W, tVkgB1 was 1.44T and 1.46T.

It is clear from the results of this comparative example that the pre-treatment is not simply an effect of extending the annealing time.

Fix one end of the gun and hang a 100g weight from the other end of the gun. Annealing was performed at 380° C. for 30 minutes while applying tension to the tube. In this case, the magnetic properties when no magnetic field is applied and when it is applied are Wl and s/ba are 0.081 wa, respectively.
t%/IQF and 0.062 wat%/ky, BI
Hl was 45T and 1.44T.

Example 2 A 25-inch wide amorphous resin was prepared using a master alloy having a composition of F678.5817B13.501 in the same manner as in Example 1. This? The temperature was increased from 250℃ to 350℃ at a rate of 1' while applying a magnetic field of 4000℃ in the longitudinal direction.
The temperature was increased over 100 minutes at a rate of C/min. Continue to 380℃
The magnetic properties after annealing for 30 minutes were as follows.

Wt5Ao o, o 73 wt%AgB,
1.51T The magnetic properties of materials with the same composition annealed at 380° C. for 30 and 60 minutes were as follows, respectively.

Wts, 4o O,089 and 0.091 wa
tt/kgB1 1.5offi and 1.52
T

[Brief explanation of the drawing]

Figure 1 shows two-stage heat treatment (the second stage is 380℃ x 3)
10 is a drawing showing the influence of the pre-processing conditions during 0 minutes and while applying a magnetic field of 300 seconds. ○: Iron loss decreased by 10% or more compared to VC without pretreatment △: Iron loss decreased by 5 to 10 cm compared to no pretreatment ×: No effect.

Claims (4)

[Claims] (1) A method for heat treating an amorphous magnetic alloy, which is characterized by holding the amorphous magnetic alloy at at least two progressively higher temperatures for a predetermined period of time. (2) The holding temperature in the first stage is higher than Tx -3000 and lower than Tx~180°C for 20 minutes or more, and the holding temperature in the final stage is at least 30°C higher than the holding temperature in the first stage, Tx The method according to claim m1, characterized in that the heat treatment is performed at a temperature at least 50° C. lower for 1 minute or more. (Here, TxLti is the crystallization initiation temperature ('C) of the alloy when the temperature is raised at a rate of 10 °C per minute.) (3) When heat treating an amorphous magnetic alloy, a magnetic field and/or tension is applied in the longitudinal direction of the material, and the temperature is maintained at at least two stepwise levels for a predetermined period of time. Heat treatment method for magnetic alloys. (4) Holding temperature k at Ilx stage: Tx at a temperature lower than -300°C, Tx at a temperature lower than -180°C for 20 minutes or more. The holding temperature of the final stage is at least 3 times higher than the holding temperature of the first stage.
The method according to claim 3, characterized in that the heat treatment is performed at a temperature 0°C higher and at least 50°C lower than Tx for 1 minute or more (where Tx is heated at a rate of 10°C per minute). is the crystallization initiation temperature (C) of the alloy of