JPS63219182A - Amorphous magnetic wire - Google Patents

Abstract

PURPOSE:To propagate, generate, and detect a magneto-elastic wave efficiently by a method wherein a part of an amorphous wire processed through cold wiredrawing is subjected to heat treatment so as to have a soft magnetic property large in magneto-elastic coupling. CONSTITUTION:After the whole magnetic wire 1 is processed through cold wiredrawing, only parts 2a and 2b of the wire 1 are subjected to heat treatment. Therefore, the magnetic wire 1 except the parts 2a and 2b propagates a magneto-elastic wave well. An exciting coil 3a is provided at the part 2a, whereby a magneto-elastic wave is easily generated when an A.C. magnetic field is applied. Furthermore, a detecting coil 3b is provided at the other part 2b, where a propagating magneto-elastic wave can be efficiently detected. Hereupon, the direct bias magnetic field adequate in intensity is applied on the coil 3a and 3b through Helmholtz coils 40a and 40b so as to make them generate or detect a magneto-elastic wave efficiently. By these processes, an amorphous magnetic wire provided with the parts generating or detecting a magneto-elastic wave with ease can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an amorphous magnetic wire having partially different magnetic properties, and has the property of generating and propagating magnetoelastic waves particularly efficiently. It can be applied to magnetoelastic wave devices such as frequency filters and delay lines, as well as to position sensors and nonvolatile memories.

[Prior Art] Conventionally, magnetoelastic wave devices include delay lines, filters,
It is widely applied to various types of sensors.

The characteristics required of the magnetic material used in this magnetoelastic wave device are: (1) It should be easy to generate magnetoelastic waves.

+2) To propagate m-air elastic waves with a small attenuation rate.

(3) It is easy to detect magnetoelastic waves.

and so on.

In recent years, amorphous magnetic materials have come to be used as materials that relatively satisfy these conditions.

Traditionally, amorphous magnetic materials have mainly been used in the form of thin films or ribbons, but recently, magnetic materials in the form of thin wires have been developed and are attracting attention.

The generation and detection of magnetoelastic waves in magnetic materials is based on the mechanism described below.

When a magnetic field is applied to a part of a magnetic material using a coil, etc.,
Along with this change, a change in magnetization occurs according to the magnetization curve. This change in magnetization causes magnetostriction, and this strain propagates in the magnetic material as an elastic wave, which is a magnetoelastic wave. Conversely, when magnetoelastic waves exist in a magnetic material, the strain accompanying the magnetoelastic waves causes a change in magnetization due to the Villeri effect, and this change in magnetization changes the surrounding magnetic field. Magnetoelastic waves can be detected by detecting changes in this magnetic field using a coil or the like.

As explained above, the magnetostriction characteristic or the Villery effect plays a major role in the generation and detection of magnetoelastic waves. That is, the smaller the coercive force (the softer the magnetic property), the larger the change in magnetization caused by a small change in the magnetic field, and the easier it is to generate and detect magnetoelastic waves. On the other hand, if the coercive force is large (if it is hard magnetic), magnetization changes will occur, and magnetoelastic waves will be generated.
Detection becomes difficult. Also, if the coercive force is the same, magnetostriction and
The larger the Villery effect, the easier it is to generate and detect magnetoelastic waves. Both the relationship between the magnetic field and magnetization, and the relationship between magnetization and strain in the magnetic body (ie, magnetostriction and the Vuilleri effect) govern the interaction between the magnetic field and strain in the magnetic body, ie, magnetoelastic coupling. The larger the magnetoelastic coupling, the more effective the magnetoelastic wave is.
It can be said to be a magnetic material that is easy to detect.

On the other hand, when a magnetoelastic wave propagates through a magnetic material, if the magnetoelastic coupling is large, a temporal change in magnetization occurs in the magnetic material due to the magnetoelastic wave, and eddy currents are generated, resulting in a propagation loss. growing. This propagation loss increases as the frequency of the magnetoelastic wave increases.

As explained above, the characteristics (1) and (3) required of the magnetic material used in the magnetoelastic wave device, and (
2) has a mutually exclusive relationship.

In other words, in materials with large magnetoelastic coupling, it is easy to generate and detect magnetoelastic waves, but the loss associated with propagation is large; on the other hand, in materials with small magnetoelastic coupling, magnetoelastic waves propagate with less attenuation. However, it is difficult to generate and detect.

As described above, it has been impossible to realize a magnetoelastic wave device that is efficient in all aspects of generation, propagation, and detection of magnetoelastic waves.

Another disadvantage of conventional magnetic materials is that when trying to generate magnetoelastic waves using a simple device such as a coil, the magnetic field generated by the current is applied over a relatively wide range of the magnetic material. Therefore, there was a problem in that the magnetoelastic waves generated in each minute part within that range interfered with each other, weakening the magnetoelastic waves. In detection, since changes in magnetization are picked up over a wide range, the respective electromotive forces interfere with each other, reducing detection efficiency. These problems also become more serious as the frequency of magnetoelastic waves increases.

As mentioned above, conventional magnetic materials have the disadvantage that they cannot generate and detect magnetoelastic waves and propagate them with high efficiency, and that they cannot generate, detect, and propagate magnetoelastic waves with high efficiency. The disadvantage is that the higher the frequency of the magnetoelastic waves handled, the lower the efficiency. For this reason, the signal transmission efficiency of the magneto-elastic wave device is low, and it has been difficult to put into practice a magneto-elastic wave device that can handle particularly high frequency signals.

As an attempt to improve the above-mentioned problem, for example, a method is known in which a magnetic material is used as a propagation path for magnetoelastic waves, and another type of means such as piezoelectric effect is used for the eloquence and detection of the magnetoelastic waves. However, according to this method, the problem arises that the structure becomes very complicated and the cost becomes high.

= 5- [Means for solving the problems] In order to improve the drawbacks of the above-mentioned prior art, the present invention cold-draws an amorphous magnetic wire (hereinafter referred to as rvAf!I wire). In addition to having hard magnetic properties with small magnetoelastic coupling, a portion of the material is heat-treated to give the heat-treated portion soft magnetic properties with large magnetoelastic coupling. That is, most of the single magnetic wire is made hard magnetic, and at least a portion has soft magnetic characteristics.

Therefore, a hard magnetic portion that has not been heat treated can be used for propagation of magnetoelastic waves, and a soft magnetic portion that has been heat treated can be used for generation or detection of magnetoelastic waves.

Therefore, the magnetic wire can efficiently propagate magnetoelastic waves and can efficiently generate or detect them.

Furthermore, in such a magnetic wire, since the magnetoelastic coupling is small in the hard magnetic portion that has not been heat treated, high frequency magnetoelastic waves can also be efficiently propagated. In addition, since the magnetoelastic coupling is large in the heat-treated soft magnetic part, magnetoelastic waves can be generated or detected efficiently, but in particular, the volume of the heat-treated part is Because it can be made small, regardless of the size of the coil for generation or detection,
The volume of the generating part or the detecting part in the magnetic wire can be reduced. Therefore, interference in generation or detection of magnetoelastic waves can be reduced, and generation and detection of magnetoelastic waves can be efficiently performed up to a high frequency range.

Note that, as in the embodiment shown below, if the heat treatment is performed in two places, one for the generation part and the other for the detection part of the magnetoelastic waves, both the generation and detection of the magnetoelastic waves can be performed efficiently.

Therefore, it is possible to realize a magnetoelastic wave device that can be used in a higher frequency range than conventional devices.

[Example] Hereinafter, the present invention will be described in detail based on the drawings.

In Fig. 1, 1 is a rotating liquid spinning method (published patent publication
It is a magnetic wire that is made into a thin wire using a technique such as that disclosed in Japanese Patent No. 55-64948), and then subjected to cold drawing throughout.

A portion of the magnetic wire 1, 2a, 2b, has a temperature below the crystallization temperature of the magnetic wire and above a temperature sufficient for the heat treatment effect to appear (for example, Fe77.5Si7.5, not shown later).
For a magnetic wire with a composition of B15, the crystallization temperature is 530''
C1 The heat treatment effect appeared at temperatures above 300°C. ) is the part that has been heat treated.

(For the crystallization temperature of magnetic lines, see [Isamu Ogasawara Japanese Society of Applied Magnetics, 45th Research Meeting Materials P, 17-24.19]
1986] FIG. 2 is a schematic diagram showing a method for measuring the characteristics shown in FIG. 3. 3a is an excitation coil provided in a part of the magnetic wire 1, and 3b is a detection coil provided in another part. 40
a, 40b and 41a, 41b are the respective coils 3a, 3
This is a Helmholtz coil attached to sandwich b.

Each of the coils 3a and 3b includes a Helmholtz coil 40.
A, 40b and 41a, 41b apply a DC bias magnetic field of optimum strength for generating and detecting magnetoelastic waves.

FIG. 3 shows actual measurement data of the composition of Fe77.58i7.5 815 using magnetic lines. The horizontal axis is time, and the vertical axis is
In (a), the excitation current applied to the excitation coil 3a is also
(b) to (e) represent the voltage generated in the detection coil 3b.

FIG. 4(a) shows a tone burst current passed through the excitation coil 3a, and the magnetic field generated by this current generates a magnetoelastic wave in a portion of the sample near the excitation coil 3a. When this magnetoelastic wave propagates through the sample and reaches the detection coil 3b, the detection coil 3b has
), a voltage force corresponding to the magnetoelastic wave is generated.

Figure (b) shows the voltage waveform when the sample is a magnetic wire that has been formed into a fine wire by the above-mentioned spinning method in a rotating liquid, and the propagation delay time td required for propagation through the sample.
Magnetoelastic waves are detected with a delay from the bamboo-excited tone burst current.

The axial magnetization curve of this sample is shown in Figure 4 fa).

FIG. 3(C) shows a voltage waveform when a sample is a magnetic wire that has been formed into a thin wire by spinning in a rotating liquid and then cold-drawn over its entirety.

Cold drawing is generally performed for the purpose of reducing the wire diameter, but experiments have shown that at the same time, the coercive force increases, as seen in the magnetization curve in Figure 4(b). It has been confirmed by.

As the coercive force increases, the magnetoelastic coupling becomes smaller, making it difficult to generate and detect magnetoelastic waves, and as shown in Figure 3 [C], the detected magnetoelastic waves are cold-drawn. The level is much smaller than before. However, it is known that in this case, the magnetoelastic wave becomes close to a pure elastic wave, so the eddy current loss decreases and the transmission W1 loss also becomes extremely small.

FIG. 3(d) shows a voltage waveform when the entire magnetic wire formed into a thin wire shape and subjected to cold drawing is heat-treated at 400°C.

In this case, as shown in Fig. 4 fc), the coercive force decreases again and the magnetoelastic coupling increases, so as shown in Fig. 3 b
) is detected. However, the propagation loss has returned to the same level.

As explained above, cold drawing processing makes it difficult to generate and detect magnetoelastic waves, but they also propagate more easily, and subsequent heat treatment conversely makes it easier to generate and detect magnetoelastic waves, but they do not propagate. It becomes difficult.

The magnetic wire 1 shown in FIG. 1 has been cold-drawn over its entirety, and then heat-treated only on portions 2a and 2b. Therefore, this magnetic wire 1 has a heat-treated portion 2
Magnetoelastic waves are efficiently propagated except for a12b. Furthermore, magnetoelastic waves can be easily generated by providing an excitation coil 3a on one of the heat-treated portions 2a and applying an alternating magnetic field.

Furthermore, if the detection coil 3b is provided in the other portion 2b, the propagating magnetoelastic waves can be detected efficiently.
An excitation coil 3a is provided in each of the two heat-treated parts 2a and 2b.
, the detection waveform when the detection coil 3b is provided is shown in Fig. 3 (e
). Figures (b) and (C).

It can be seen that a larger signal is detected compared to (and fd).

FIG. 5 shows another embodiment, in which the magnetic wire 1 is entirely cold-drawn, and one side of the magnetic wire 1 is provided with a narrow heat-treated portion 2a°. , a portion 2b- is provided which is heat-treated over a wide range.

As shown in FIG. 6, an excitation coil 3a' is provided over a wide range for a narrow heat-treated part 2a' of the magnetic wire 1, and a wide excitation coil 3a' is provided for a wide range of heat-treated part 2b' of the magnetic wire 1. A narrow detection coil 3b' is provided.

In this case, if a tone burst or pulsed magnetic field is applied over a wide range by the excitation coil 3a'' and the propagation delay time td of the generated magnetoelastic wave is measured, the narrow heat-treated portion 2a° and the detection coil 3b' can be separated. You can find the distance between.

Such a device connects the magnetic wire 1 to two coils 3a'',
By making it movable with respect to 3b', it can be applied as a position sensor.

FIG. 7 shows still another embodiment, in which magnetic wire 1 is entirely cold-drawn as in the above embodiment.
In this case, only an arbitrary portion of the predetermined portions 2-1 to 2-5 is subjected to heat treatment.

In this example, only portions 2-2, 2-4, and 2-5 are heat treated. 2b' is each of the above parts 2-1 to 2
This is the part that was heat-treated at a position away from -5.

With respect to the magnetic wire 1, excitation coils 3-1 to 3-5 are placed at positions corresponding to predetermined portions 2-1 to 2-5, respectively, as shown in FIG. 2b
A detection coil 3b' is provided at a position corresponding to '.

When a tone burst current as shown in FIG. 9(a) is applied to the excitation coils 3-1 to 3-5, the heat-treated portion 2-2
．． Magnetoelastic waves are generated simultaneously in parts 2-4 and 2-5, but hardly any magnetoelastic waves are generated in parts 2-1 and 2-3 which are not heat-treated. When the magnetoelastic wave propagates and reaches the other heat-treated portions 2b', a tone burst voltage is detected in the detection coil 3b'. Heat treated part 2b'
Since the distances from the detection coil 3b' are different from each other, propagation times td 2 , td 4 , and fd5 are required for the magnetoelastic waves generated in each part to reach the other heat-treated part 2b'. A series of tone burst voltages are generated as shown in Figure (b). Since almost no magnetoelastic waves are generated in the non-heat-treated portions 2-1.2-3, the propagation time td1 corresponding to the distance between these portions 2-1.2-3 and the other heat-treated portion 2b' is
No tone burst signal is detected in fd3. That is,
The coils 3-1 to 3-5 and 3b determine which part is being heat-treated among the predetermined parts 2-1 to 2-5.
− can be known.

Such magnetic wires can be used as nonvolatile memory. For example, if the heat-treated part (a magnetoelastic wave is detected at the corresponding delay time) is "1" and the non-heat-treated part is rOJ, then the information that "magnetic line 1 in this example is r01Oll" is You will have it.

By selecting the portion to be heat-treated among the five portions 2-1 to 2-5, information on any five pins 1 can be embedded in the magnetic wire.

FIG. 10 shows an example of a method of selectively heat-treating a portion of the magnetic wire.

6a and 6b are metal jigs that hold the magnetic wire 1 and serve as electrodes; 7 is a switch; and 8 is a constant current power source.

When the switch 7 is closed, the magnetic 1
Due to the current flowing through 1i11, the magnetic wire 1 is moved by the jig 5a,
Only the portion 2 between 5b is heated and heat treated. In addition, by irradiating a portion of the magnetic wire 1 with infrared rays, laser light, or the like, a selected portion can be easily heat-treated.

[Effects of the Invention] As described above, the present invention is made by fabricating a fine wire by a technique such as spinning in a rotating liquid, and then cold drawing it, so that magnetic valves and h-waves can be transmitted. It becomes easier to
Furthermore, by applying partial heat treatment to one or more selected portions of the magnetic wire, it is possible to provide an amorphous magnetic wire in which a portion where magnetoelastic waves can be easily generated or detected is formed. It is something.

Compared to conventional magnetic materials, such amorphous magnetic wires have
Since magnetoelastic waves can be easily generated or detected, and magnetoelastic waves can be propagated with little attenuation, it is ideal as a material for various magnetoelastic wave devices. Good thing: by making the heat-treated part smaller, the part where magnetoelastic waves are generated or detected can be made smaller, and the interference of magnetoelastic waves can be reduced, so magnetoelastic wave devices can be used in higher frequency ranges than conventional ones. make it possible to realize

In addition, since the magnetic wire of the present invention can generate or detect magnetoelastic waves only in a portion, it can be applied to the fields of non-volatile memory and position detection sensors, which have not been applied before. .

Furthermore, the magnetic wire of the present invention requires only cold drawing of a single magnetic wire and heat treatment of at least a selected portion, so the structure is simple, highly reliable, and extremely inexpensive. It has the effect of being able to provide

[Brief explanation of the drawing]

Fig. 1 is a front view showing an embodiment of the present invention, Fig. 2 is a front view of the magnetic wire shown in Fig. 1 provided with an excitation coil and a detection coil, and Fig. 3 is an excitation current waveform diagram and a detected voltage. A waveform diagram, FIG. 4 is a magnetization curve showing the coercive force of the magnetic wire, FIG. 5 is a front view showing the second embodiment, and FIG. 6 is a diagram showing the magnetic wire shown in FIG. 5 provided with an excitation coil and a detection coil. 7 is a front view showing the third embodiment, FIG. 8 is a front view of the magnetic wire shown in FIG. 7 provided with an excitation coil and a detection coil, and FIG. 9 is a front view of the third embodiment. Fig. 10 is a cross-sectional view showing an example of the heat treatment method according to the present invention. 1 is a magnetic wire, 2 is a heat treatment part, and 3a is a diagram of an excitation current waveform and a detected voltage waveform. is an excitation coil, 3b
It is a detection coil. (Patent applicant: G-Eco Co., Ltd.)
(C)Oq diagram fs diagram O6 diagram Off diagram A8 diagram

Claims (1)

[Claims] An amorphous magnetic wire that has been cold-drawn and is characterized in that it has been partially heat-treated at at least one location.