JPH05195170A - Heat treatment method of amorphous metal fine wire - Google Patents

Abstract

PURPOSE:To manufacture an amorphous metal fine wire having twin stabilized magnetic characteristic by applying heat treatment with a specific condition after forming the amorphous metal wire rod manufactured by a water rapid cooling method to the fine wire by die wire drawing. CONSTITUTION:For example, molten Fe-Co-Si-B series alloy is injected into the water and rapidly cooled to manufacture the amorphous metal wire rod. After forming this amorphous metal wire rod to the metal fine wire by the die wire drawing so as to become >=30% of the last reduction of area, in the condition of applying the tension having >=10% of the tensile rupture strength in this fine wire, the heat treatment is executed at the temp. of >=250 deg.C and the crystallizing temp. or lower of this amorphous fine wire. Successively, the tension having the impressed tension in the preceding process is applied, or in the condition of non-tension, the heat treatment is again executed at >=250 deg.C and the crystallizing temp. or lower. Reverse magnetic field value is controlled to the optional value in the desired wide range to manufacture the amorphous metal fine wire having the twin stabilized magnetic characteristic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an amorphous metal fine wire which can be used for various uses such as an identification marker by changing the magnetization reversal magnetic field value. The present invention relates to a heat treatment method for thin wires.

[0002]

2. Description of the Related Art Hitherto, as a fine wire having a bistable magnetic property, a Wiegand wire utilizing the Wiegand effect has been known (Japanese Patent Laid-Open No. 47-8956). This is a double-structured metal wire having a core made of a soft magnetic material and a shell made of a hard magnetic material.

It is also known that amorphous metal fibers produced by the water quenching method show bistable magnetic properties.
(Journal of Applied Magnetics of Japan, Vol. 9, No. 2, 157, 1985
Year). That is, in the water quenching method, the internal stress of the amorphous metal fiber is solidified without being relaxed, so that the amorphous metal fiber having different stress states on the fiber surface and the central portion can be obtained.
Therefore, such an amorphous metal fiber causes abrupt magnetization reversal and exhibits bistable magnetic characteristics.

However, the above-mentioned Wiegand wire has a large magnetic field required to cause a change in magnetic flux of several tens of oersteds, requires asymmetric magnetic field excitation to exhibit bistable magnetic characteristics, and changes the magnetic flux in accordance with the change in magnetic flux. It has fatal drawbacks such as the generation phase position of the pulse voltage induced in the pickup coil wound around it is not constant and there is a momentary fluctuation (jitter). Yes, I haven't.

Further, the value of the magnetic field that causes magnetization reversal is smaller than that of the earth's magnetic field in the amorphous metal fiber obtained by the underwater quenching method, and it is easily affected by disturbance. Since the length required to generate a strong pulse is 6 cm or more, it is not suitable for a small element.

In order to solve these drawbacks, the inventors of the present invention first draw an amorphous metal fiber produced by an underwater quenching method by a die, heat-treat it under tension, and then quench it. Japanese Patent Laid-Open No. 63-24003 discloses a method for obtaining an amorphous metal thin wire having a bistable magnetic property. However, the magnetization reversal magnetic field value of the amorphous metal thin wire obtained by this method is up to about 2 (Oe), which is not sufficient for the purpose of variously changing the magnetization reversal magnetic field value such as an identification marker.

[0007]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to control the reversal magnetic field value to a desired wide range of arbitrary values and to obtain bistable magnetic characteristics. An object of the present invention is to provide a heat treatment method for an amorphous metal thin wire capable of producing an amorphous metal thin wire having

[0008]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that by applying a special treatment step to an amorphous metal thin wire produced by an underwater quenching method, The inventors have found that an amorphous metal thin wire having excellent bistable magnetic properties can be obtained, and have reached the present invention. That is, the present invention, an amorphous metal fine wire obtained by die drawing the amorphous metal fiber produced by the underwater quenching method to a final surface reduction rate of 30% or more, a tensile breaking strength of 10% or more of the thin wire A first step of heat-treating at a temperature of 250 ° C. or higher and a crystallization temperature or lower in a state of adding; and the thin wire obtained in the first step,
A second step of heat-treating at a temperature of 250 ° C. or higher and a crystallization temperature or lower in a state in which a tension lower than the applied tension of the first step is applied or in a state of no tension; The heat treatment method is as a gist.

Amorphous metals that can be used in the present invention include Fe and
/ Or Co with an alloy composition of 70-90 atomic% of a metallic elemental component containing at least 50% and an amorphous elemental component of 30-10 atomic% such as Si, B, P, C and mixtures thereof. Preferably there is. In order to improve the characteristics of such an amorphous metal, elements other than Fe and Co may be contained. For example, Cr and Mo to improve the touch resistance,
Or Mn, Nb, Ti and
Elements such as W are contained in the amorphous metal.

The amorphous metal fine wire that can be used in the present invention is produced by an underwater quenching method. An example of the underwater quenching method is JP-A-57-525.
No. 50 publication. In this document, a water film is formed on the inner wall of the drum by rotating a drum containing water, and a molten alloy is ejected from the spinning film nozzle of about 100 to 150 μm into the water film to form a metal having a circular cross section. I'm getting a fine line.

Thus, an amorphous metal thin wire having a wire diameter of about 110 to 150 μm is usually obtained. The magnetic hysteresis loop of this amorphous metal thin wire is shown in FIG. Although the magnetic hysteresis loop of FIG. 1 has a bistable magnetic property, the magnetic field of magnetization reversal is as small as 0.08 Oersted. Further, the reversal magnetization amount is about half of the saturation magnetization amount, which is not sufficient.

In the present invention, the above-mentioned amorphous metal fine wire produced by the underwater quenching method is first prepared by, for example, Japanese Patent Laid-Open No. 57-16051.
It is thinned to the final wire diameter by the die drawing method described in No. 30 so that the surface reduction rate is 30% or more.

The area reduction is expressed by the formula (S ₀ -S), where S _{0 is} the cross-sectional area of the amorphous metal thin wire before drawing and S is the cross-sectional area of the amorphous metal thin wire after drawing. It is the value (%) indicated by / S ₀ × 100. The reason why the surface reduction rate is required to be 30% or more in the present invention is that the following tension heat treatment is required to competitively balance the relaxation of the internal stress of the drawing and the homogenization of the stress distribution by the applied tension. This is because the multiaxial internal stress applied by the die wire drawing treatment is required to a certain extent or more.

As shown in FIG. 2, the amorphous metal thin wire thus obtained has a large coercive force of several tens oersteds or more, but does not exhibit bistable magnetic characteristics, so to speak, it is magnetically semi-hard. Has magnetic properties.

Next, in the present invention, in the first step, a tension of 10% or more of the tensile breaking strength of the thin wire is applied.
This amorphous metal thin wire is heat-treated at a temperature of 250 ° C. or higher and a crystallization temperature or lower.

By such a tension heat treatment, a large magnetic anisotropy due to the tension is given to the amorphous metal thin wire in the fiber axis direction. Tensile strength is required at least 10% or more of the breaking strength, because stress relaxation is required at least so that stress relaxation does not occur during cooling after heat treatment. A DC bias magnetic field may be applied at the same time as tension is applied during heat treatment. In this case, the effect of the combined magnetic anisotropy of the action of tension and the action of magnetic field is obtained.

If the heat treatment temperature is lower than 250 ° C. in the first step, the internal residual stress of the thin wire is not sufficiently relaxed, so that the magnetic characteristics are not improved.

Then, in the second step, the tension applied to the first step is equal to or less than the applied tension, or the tension is not applied.
The thin wire obtained in the first step is heat-treated at a temperature of 0 ° C. or higher and a crystallization temperature or lower.

During the tension heat treatment, the relaxation of the irregular residual stress contained in the die wire drawing process and the homogenization of the stress in the fiber axis direction due to the tension application progress competitively. Therefore, it is extremely difficult to control the degree of progress of the both by only one step of the tension heat treatment, and there is a limit in controlling the bistable magnetic characteristics.

Therefore, by adopting a multi-stage tension heat treatment method as in the method of the present invention, the stress in the fiber axis direction can be made uniform, and bistable magnetic characteristics can be easily obtained, and the magnetization reversal magnetic field value thereof can be obtained. Can be controlled over a wide range.

In that case, the tension heat treatment in the second step is mainly aimed at homogenizing the stress in the fiber axis direction, so that the applied tension is the first.
The value is preferably lower than the tension during tension heat treatment in the process. If the heat treatment temperature exceeds the crystallization temperature in the second step, the wire becomes brittle and the magnetic characteristics deteriorate.

FIG. 3 shows an example of a magnetic hysteresis loop of an amorphous metal thin wire when the tension heat treatment of the first step is performed by the method of the present invention. As shown in the same drawing, although the rise of the magnetization reversal is slightly sharpened only by the tension heat treatment in the first step, the bistable magnetic characteristics are not yet exhibited.

FIG. 4 shows a magnetic hysteresis loop when the amorphous metal thin wire after the tension heat treatment in the first step is further subjected to the tension heat treatment in the second step. Figure 4 (a) shows that when the tension heat treatment temperature of the second step is performed at a relatively high temperature (400 ° C),
Then, FIG. 4B shows the case where the tension heat treatment of the second step is performed at a relatively low temperature (340 ° C.). As is clear from FIG.
By performing the tension heat treatment in a step, the amorphous metal thin wire exhibits bistable magnetic characteristics, and the magnetic field value at which the magnetization reversal occurs can be controlled by changing the heat treatment temperature in the second step.

[0024]

[Operation] The change of magnetization of a general magnetic material is as follows. When an external magnetic field in the opposite direction (for example, the minus direction) is applied to a magnetic substance that is saturated in one direction (for example, the plus direction),
In the reverse magnetic domain formation limit magnetic field (represented by H *), a magnetic domain in the reverse direction, that is, in the negative direction is generated. When the external magnetic field is further increased, the reverse magnetic domain is gradually increased, and finally reaches the domain wall propagation critical magnetic field (represented by Ho), and the negative magnetic domain is rapidly expanded. Then, when the external magnetic field is further increased, the magnetic domain in the positive direction becomes smaller and smaller, and finally disappears into a so-called negative saturation state.

However, in the case of a magnetic material in which the inverse magnetic domain formation limit magnetic field H * is larger than the domain wall propagation critical magnetic field Ho, even if magnetized in the positive direction, any magnetic domain in the negative direction will be immediately generated. It is ready for movement (propagation).

Therefore, when the external magnetic field becomes larger than the inverse magnetic domain formation critical magnetic field, as soon as the negative magnetic domain is formed, the domain wall moves immediately, the negative magnetic domain expands momentarily, and the magnetization occurs in an instant. Inversion occurs. That is, it has a bistable magnetic characteristic in which a stable state magnetized in the positive or negative direction is alternately maintained.

The inverse magnetic domain forming critical magnetic field and the domain wall propagation limiting magnetic field are closely related to the internal stress of the magnetic material and its distribution, and it is important to give the internal stress uniformly in order to obtain excellent bistable magnetic characteristics. Is.

The method of the present invention relaxes the residual stress of the irregular distribution in the amorphous metal thin wire introduced during the die drawing,
This method is a method of obtaining bistable magnetic properties by multistage tension heat treatment in which high tension is applied in the first step to perform heat treatment in the first step and then heat treatment is performed in a low tension state in the second step when the stress in the fiber axial direction is made uniform.

Due to the effect of the uniform distribution of the stress in the fiber axis direction introduced by the multi-stage tension heat treatment and the magnetostriction of the amorphous metal thin wire, the direction of the fiber axis becomes a strong easy axis of magnetization as the domain wall energy density increases. It is possible to obtain an amorphous metal thin wire that exhibits extremely excellent bistable magnetic characteristics.

[0030]

EXAMPLES The present invention will be described more specifically by way of examples.

[0031]

Example 1 An amorphous metal thin wire having a composition of Co ₃₉ Fe ₃₉ Si ₉ B ₁₃ (subscript indicates atomic%) was prepared by a water quenching method. The wire diameter was 125 μm, and the crystallization temperature was 561 ° C. This amorphous metal thin wire was drawn by a die at room temperature to prepare an amorphous metal thin wire having a wire diameter of 50 μm. The breaking strength of the thin wire was 350 kg / mm ² .

The thin wire thus obtained was subjected to the tension heat treatment in the first step under the conditions shown in Table 1, then at a temperature of 400 ° C. and a tension of 0.5.
The tension heat treatment of the second step was performed under the condition of kg / mm ² . The measurement results of the bistable magnetic properties (measurement length: 40 mm) of the obtained amorphous metal thin wire are shown in Table 1 below.

[0033]

[Table 1] 1st Process Temperature 1st Process Tension Bistability Characteristics Switching magnetic field Br / Bs (℃) (kg / mm ² ) (Presence) (Oe) 395 100 Yes 2.58 0.78 400 100 Yes 2.21 0.88 400 120 Yes 1.64 0.95 400 140 Yes 0.76 0.97 410 80 Yes 1.88 0.88 410 100 Yes 1.25 0.97 410 120 Yes 0.76 0.97 420 70 Yes 1.30 0.92 420 90 Yes 0.80 0.96 *) the second step is carried out at a temperature of 400 ° C. / tension 0.5 kg / mm ² It was

Bistable magnetic characteristics can be obtained by a multi-step tension heat treatment of a combination of the first step and the second step,
It was shown that the switching field value can be controlled by changing the tension heat treatment conditions in the first step.

[0035]

Example 2 An amorphous metal thin wire obtained in the same manner as in Example 1 was subjected to the first test under the conditions of a temperature of 300 ° C. and a tension of 140 kg / mm ² .
The tension heat treatment of the step was performed, and then the tension heat treatment of the second step was performed under the conditions shown in Table 2. The measurement results of the bistable magnetic properties of the obtained amorphous metal thin wires are shown in Table 2 below.

[0036]

[Table 2] Second process temperature Second process tension Bistability characteristics Inversion magnetic field Br / Bs (℃) (kg / mm ² ) (Presence) (Oe) 340 0.5 Yes 4.05 0.69 350 0.5 Yes 3.20 0.71 360 0.5 Yes 2.26 0.86 370 0.5 Yes 1.60 0.76 390 0.5 Yes 0.79 0.93 400 0.5 Yes 0.55 0.94 380 20 Yes 0.95 0.95 *) The first step was performed under the conditions of temperature 300 ° C / tension 140 kg / mm ² .

Bistable magnetic characteristics can be obtained by the multi-stage tension heat treatment of the combination of the first step and the second step,
It was shown that the switching field value can be controlled by changing the tension heat treatment conditions in the second step.

[0038]

Comparative Example 1 An amorphous metal thin wire obtained in the same manner as in Example 1 was subjected to tension heat treatment in the first step and the second step under the conditions shown in Table 3 below. Table 3 shows the measurement results of the bistable magnetic properties of the obtained amorphous metal thin wires.

[0039]

[Table 3] 1st process temperature 1st process tension 2nd process temperature 2nd process tension Bistability characteristics (℃) (kg / mm ² ) (℃) (kg / mm ² ) (Presence) 440 1 415 140 None 465 20 440 10 No 465 20 415 110 No 420 70 400 100 No 250 100 400 0.5 No 400 100 250 0.5 No

As shown in Table 3, the tension in the first step is 20 kg.
If it is as low as / mm ² or less, bistable magnetic properties cannot be obtained regardless of the tension condition of the second step. Even if the tension in the first step is 10% or more of the breaking strength, if the tension in the second step exceeds the tension in the first step, bistable magnetic properties cannot be obtained.

[0041]

According to the present invention, it is possible to manufacture an amorphous metal thin wire having bistable magnetic characteristics by controlling the switching field value to an arbitrary value in a desired wide range.

[Brief description of drawings]

FIG. 1 is a graph showing an example of a magnetic hysteresis loop of an amorphous metal thin wire manufactured by an underwater quenching method.

FIG. 2 is a graph showing an example of a magnetic hysteresis loop of an amorphous metal thin wire obtained by drawing an amorphous metal thin wire with a die.

FIG. 3 is a graph showing an example of a magnetic hysteresis loop of an amorphous metal thin wire subjected to the tension heat treatment of the first step of the present invention.

FIG. 4 (a) is an example of a magnetic hysteresis loop of an amorphous metal thin wire in which the tension heat treatment of the first step of the present invention and the tension heat treatment of the second step are further performed under a relatively high temperature condition; It is a graph which shows an example of the magnetic hysteresis loop of the amorphous metal thin wire which performed the tension heat treatment of the 2nd process after the tension heat treatment of the 1st process of this invention on comparatively low temperature conditions.

Claims (1)

[Claims] 1. An amorphous metal fine wire obtained by die-drawing an amorphous metal fiber produced by an underwater quenching method to a final reduction of area of 30% or more is applied with a tension of 10% or more of the tensile breaking strength of the thin wire. A first step of heat-treating at a temperature of 250 ° C. or higher and a crystallization temperature or lower in the applied state; and a thin wire obtained in the first step, to which a tension equal to or lower than the applied tension in the first step is applied or without tension. A second step of heat-treating at a temperature of 250 ° C. or higher and a crystallization temperature or lower in the state;