JPH0651898B2 - Soft magnetic amorphous alloy - Google Patents

Description

The present invention relates to an amorphous alloy suitable for application to a so-called composite type magnetic head and the like. More specifically, the present invention relates to an amorphous alloy.
The present invention relates to the improvement of the corrosion resistance of this amorphous alloy.

[Conventional technology]

For example, in a magnetic recording / reproducing apparatus such as a VTR (video tape recorder), high density and high frequency of a recording signal are being advanced, and in response to the high density recording, magnetic powder is used as a magnetic recording medium and Fe. , So-called metal tapes using powders of ferromagnetic metals such as Co and Ni, and so-called vapor deposition tapes obtained by depositing a ferromagnetic metal material on a base film by vapor deposition have been used. Since this type of magnetic recording medium has a high coercive force Hc, it is required that the head material of the magnetic head used for recording and reproduction also has a high saturation magnetic flux density Bs. However, the shortage of the saturation density Bs is a problem.

Therefore, it is considered to use a metal magnetic material having a high saturation magnetic flux density Bs, such as Sendust or Permalloy, as the head material.
It has a large practical drawback such as a decrease in magnetic permeability in a high frequency region due to eddy current loss and poor wear resistance.

Therefore, conventionally, the magnetic gap portion is formed by an amorphous alloy (amorphous alloy) thin film formed by, for example, a liquid quenching method or a vacuum deposition technique, and the core portion is formed by a ferrite material. A composite type magnetic head sandwiched between core parts has been proposed. As described above, by forming a magnetic head by combining different kinds of magnetic materials, magnetic properties and wear resistance are improved as compared with the case where the magnetic head is composed of a single oxide magnetic material such as an amorphous alloy or a ferrite material. Sex is greatly improved.

However, in the magnetic head configured by joining the amorphous alloy thin film and the oxide magnetic material as described above,
It has been found that the amorphous alloy thin film is easily rusted and tends to be significantly corroded. It is considered that the magnetic head is affected by humidity and a battery is formed by a potential difference generated between different kinds of materials, and the amorphous alloy thin film that is a metal is electrolytically corroded by the discharge, This greatly reduces the reliability of the magnetic head, which is a major obstacle to practical use.

Therefore, in order to improve the corrosion resistance of the amorphous alloy, C
Attempts have been made to add r or the like, but in this case, the saturation density of the amorphous alloy is lowered, and it becomes difficult to secure magnetic properties.

[Problems to be solved by the invention]

Thus, an amorphous alloy satisfying both corrosion resistance and magnetic properties has not yet been realized, and further improvement is desired.

Therefore, the present invention has been proposed in response to the demands of the technical field as described above, and is excellent in corrosion resistance and magnetic characteristics, particularly permeability and magnetic flux density in the video band are equal to or higher than those of conventional ones. It is intended to provide an amorphous alloy.

[Means for solving problems]

The present inventors have developed a soft magnetic amorphous alloy having excellent corrosion resistance and excellent magnetic properties, and as a result of extensive research over a long period of time, as a result, a new composition in which Si and B are partially replaced with Ta is obtained. The inventors have found that a (Co.Ni.Fe)-(Si.B) -based amorphous alloy is suitable for this purpose, and completed the present invention.

That is, the soft magnetic amorphous alloy of the first invention of the present application is M
^I _a Si _b B _c Ta _d (where M ^I is Co, Ni, F
Among e, 1 type or 2 types or more containing Co is represented. ), The composition range is atomic%, and 2 <b <8 6 ≦ c <9 6 ≦ d <12 14 <c + d 18 <b + c + d <22 a + b + c + d = 100. Is.

The soft magnetic amorphous alloy of the second invention of the present application is M ^I _a
Si _b B _c Ta _d−e M ^II _e (where M ^I is Co, N
represents one or more of i and Fe containing Co,
M ^II represents at least one of Cr, Nb, V and Mo. ), The composition range is atomic%, and 2 <b <8 6 ≦ c <9 6 ≦ d <12 0.1 ≦ e ≦ 4 14 <c + d 18 <b + c + d <22 a + b + c + d + e = 100. It is characterized by.

That is, the amorphous alloy according to the present invention contains one or more of Co, Ni and Fe as metal elements, Si and B as semimetal elements, and T
Since the alloy contains a, the addition of Ta can improve the corrosion resistance without deteriorating the magnetic properties.

Here, in the amorphous alloy of the present invention, each constituent element,
Particularly, the proportions of Si, B, and Ta are important, and if the proportions of these elements are too large or too small, it is difficult to improve both magnetic properties and corrosion resistance.

For example, if the Si content is 2 atomic% or less, it becomes difficult to produce an amorphous alloy.

Similarly, if the content of B is less than 6 atomic%, it becomes difficult to produce an amorphous alloy, and conversely, if the content of B is 9 atomic% or more, corrosion resistance deteriorates.

On the other hand, Ta needs to be 6 atomic% or more in order to maintain corrosion resistance, but if the content of Ta is 12 atomic% or more, it becomes difficult to produce an amorphous alloy.

Further, when the total amount of Si, B and Ta is 18 atomic% or less, it is difficult to produce an amorphous alloy, and when the total amount of these is 22 atomic% or more, it is difficult to secure the magnetic flux density.

Within the above range, the total amount of B and Ta preferably exceeds 14 atom%. If this total amount is 14 atomic% or less, it becomes difficult to produce an amorphous alloy.

Furthermore, in the above composition, a part of Ta is Cr, N
You may substitute with at least 1 sort (s) of b, V, and Mo. The substitution amount of these elements is preferably within the range of 0.1 to 4.0 atomic%.

On the other hand, as the metal element, one kind or two or more kinds are selected and used from Co, Ni, and Fe. In this case, it is preferable to select and use so that the magnetostriction becomes zero.

The amorphous alloy ribbon according to the present invention can be produced by amorphizing the alloy material set in such a composition range by a usual method, for example, a liquid quenching method.

The liquid rapid cooling method is a method of rapidly cooling and supercooling a molten alloy material to freeze its structure to make it amorphous, and a typical method is a centrifugal method, a single roll method, a twin roll method, or the like. Is. Each of these methods melts an alloy material in an electric furnace or a high-frequency furnace, ejects the molten alloy from the tip hole of the crucible by gas pressure, and causes contact solidification on the surface of the rotating cooling rotor. Of these methods, the optimum method may be selected according to the desired form of the amorphous alloy.

[Action]

Thus, it is a metal-metalloid amorphous alloy (Co.
Ni / Fe)-(Si / B) type amorphous alloy Si and B
By substituting a part of Ta with Ta, the corrosion resistance is improved, and at the same time, magnetic characteristics such as magnetic permeability and magnetic flux density are secured.

〔Example〕

Hereinafter, the present invention will be described with reference to specific examples, but it goes without saying that the present invention is not limited to these examples.

Example. The alloy material having the composition shown in the following table is heated and melted,
An amorphous alloy ribbon was produced by the single roll method using the apparatus shown in the figure.

That is, the above alloy material is first heated and melted by the high frequency coil 2 in the nozzle 1 made of quartz.

Then, the molten alloy 3 thus melted is jetted from the tip opening of the nozzle 2 by increasing the gas pressure in the nozzle 2, brought into contact with the roll 4 rotating at a high speed, rapidly cooled, and solidified to be amorphous. A fine alloy ribbon 5 is obtained.

For each of the obtained amorphous alloy ribbons, coercive force H
c, magnetic flux density B and corrosion resistance were investigated. The results are shown in the table below.

From this table, in each of the examples according to the present invention, the corrosion resistance is excellent, and at the same time, the magnetic characteristics such as the magnetic flux density are the same as those of the conventional one (T
It can be seen that it is ensured to be equal to or more than the one that does not include a).

The corrosion resistance was judged from the anodic polarization curve. That is, by examining the anodic polarization curve in a solution of acid or the like (0.5% NaCl aqueous solution here), the corrosion resistance of various materials to the solution can be qualitatively and quantitatively known. For example, FIG. 1 shows an example of an anodic polarization curve. In this figure, points A and B are active portions, and current flows due to anodic dissolution of the material set in the anode. When it exceeds point B, it suddenly becomes passive and reaches point C. Points C to D are in a stable passive state, and after passing point D, they are in a passive state and current flows again. Here, generally, a material having a low potential at the point B and a small current value at the point B is easily passivated and has good corrosion resistance. When it is not passivated, the corrosion resistance is better when the potential at the point A where the current starts to flow is higher. In the case of the present embodiment, since no passivation is performed, it is determined by the potential at the point A where the current starts flowing.
FIG. 2 shows an anodic polarization curve in the vicinity of point A in Example 2 in comparison with that of the comparative example. In the comparative example, a current starts flowing from a negative potential and corrosion resistance is low. It can be seen that with No. 2, a current starts to flow from around +0.5 V and has sufficiently high corrosion resistance.

Further, in Example 2, the frequency characteristic of magnetic permeability was examined. Results are shown in FIG.

From FIG. 3, it can be seen that the above-mentioned Example 2 has a magnetic permeability equivalent to that of the comparative example in the band of 1 MHz or more.

〔The invention's effect〕

As is clear from the above description, the amorphous alloy of the present invention contains Co, Ni, and Fe as metal elements, Si and B as metalloid elements, and part of Si and B is Ta. Since they are replaced, the corrosion resistance is greatly improved and magnetic characteristics such as magnetic flux density and magnetic permeability in the video band are secured. Therefore, by using this amorphous alloy for a composite type magnetic head for video, it is possible to manufacture a magnetic head which is free from rust and corrosion and has excellent recording and reproducing characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a characteristic diagram showing the anodic polarization curve, and FIG. 2 is a characteristic diagram showing the anodic polarization curve of the example of the present invention in comparison with that of the comparative example. FIG. 3 is a characteristic diagram showing the magnetic permeability frequency characteristic of one embodiment of the present invention in comparison with that of the comparative example. FIG. 4 is a schematic view showing an example of a method for producing an amorphous alloy ribbon.

Claims (2)

[Claims] 1. A composition formula of M ^I _a Si _b B _c Ta _d (wherein M ¹ represents one or more of Co, Ni, and Fe containing Co), and the composition range thereof. Is atomic%
And 2 <b <8 6 ≦ c <9 6 ≦ d <12 14 <c + d 18 <b + c + d <22 a + b + c + d = 100. 2. M ^I _a Si _b B _c T _ad-e M ^II _e (where M ^I represents one or more of Co, Ni, and Fe containing Co, and M ^II represents Cr, Nb). , V, Mo)), and the composition range is atomic%, and 2 <b <8 6 ≤c <9 6 ≤d <12 0.1 ≤e≤414 14 <c + d. 18 <b + c + d <22 a + b + c + d + e = 100 The soft magnetic amorphous alloy characterized by the above.