JPS6089539A - Amorphous magnetic alloy having low magnetostriction - Google Patents

Abstract

PURPOSE:To reduce the absolute value of magnetostriction of an amorphous Co- Nb-Zr alloy, to increase the saturation magnetic flux density, and to improve the heat resistance and corrosion resistance by substituting Cr, Mo, V, Ta or W for part of Nb in the alloy. CONSTITUTION:Cr, Mo, V, Ta, or W is substituted for part of Nb in an amorphous magnetic Co-Nb-Zr alloy to provide a composition represented by a formula Coa(Nb1-xMx)bZrc [where 81<=a<=95(atom%), 2.5<=c<=5, a+b+c=100, c/(b+c)>0.25, when M is Cr, Mo, V or Ta, 0<x<=0.5, and when M is W, 0<x<= 0.2]. The resulting amorphous magnetic alloy having low magnetostriction is suitable for use as the material of a magnetic head having high performance formed by a thin film forming technique such as sputtering.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a low magnetostriction amorphous magnetic alloy, which has a high saturation magnetic flux density and is particularly suitable as a magnetic head material. This invention relates to an amorphous magnetic alloy as a component.

[Background of the invention]

In recent years, magnetic recording technology has made significant progress with the development of high coercive force tapes and high performance magnetic head materials for the same tapes. In particular, when using a metal tape with high coercive force, there is a significant increase in output and C/N (output-to-noise ratio) compared to conventional methods in the high recording density region from a recording wavelength of several μm to 1 μm or less. This has been achieved, and significant improvements in recording density are being achieved in fields such as VTRs that require high recording density. However, in magnetic heads that use ferrite, which has been conventionally used in VTRs, the saturation magnetic flux density of ferrite is approximately 5000 caus or less, so the recording magnetic field is not large enough, and high coercivity metal tapes are used entirely. To achieve this, a magnetic head using a metallic magnetic material with a high saturation magnetic flux density has become necessary. Conventionally used metallic magnetic materials include crystalline alloys such as pe-ht-sl alloys and Fe--Nr alloys9, and recently developed amorphous magnetic alloys. Fe
Crystalline alloys such as -ht-sI system or Fe-Ni system have magnetocrystalline anisotropy because they are crystals.
In order to obtain excellent magnetic properties suitable for a magnetic head, particularly high magnetic permeability, the composition must be close to zero in the magnetocrystalline anisotropy. In addition, in order to use it in a magnetic head, the magnetostriction constant must also be made close to zero, and therefore the usable composition is extremely limited, making it difficult to control the composition. Since the amorphous '6 magnetic alloy does not have the above-mentioned magnetocrystalline anisotropy, only the magnetostriction constant needs to be adjusted, and the usable composition is relatively wide, and deterioration of magnetic permeability due to induced magnetic anisotropy can be prevented by appropriate heat treatment. It has a variety of advantages, such as the ability to obtain an alloy with high saturation magnetic flux density and low coercive force that cannot be obtained with crystalline alloys, and the ability to reduce eddy current loss due to its high drowsiness resistance. Among these amorphous magnetic alloys, metal-metal amorphous alloys that do not contain metalloid elements have a higher crystallization temperature than metal-metalloid amorphous alloys, and also have excellent corrosion resistance and wear resistance. Therefore, it is promising for use in magnetic heads.

Conventionally, these amorphous magnetic alloys have been produced by a splat cooling method, and thin plate-like alloys having a thickness of 10 to 50 μm have been obtained. On the other hand, in recent years, it has become common to fabricate amorphous magnetic alloys using thin film forming techniques such as sputtering, and amorphous magnetic alloys with compositions that are difficult to fabricate due to sample oxidation, etc. It is now possible to create Furthermore, with thin film formation technology, it is easy to stack amorphous alloy films and insulating films such as oxides in multiple layers. , it is possible to provide a material suitable for magnetic heads for computers. Furthermore, it is expected to be applied to a belly-to-edge magnetic head or a thin-film magnetic head in which amorphous magnetic alloy gold is used only near the gap of the magnetic head and magnetic ferrite is used elsewhere.

Among metal-metal type amorphous magnetic alloys, Zr-containing amorphous magnetic alloys that are relatively easy to produce and have excellent properties are disclosed in, for example, JP-A-55-138049 and JP-A-56-844.
No. 39 and Japanese Unexamined Patent Publication No. 155339/1983. These publications state that if the Zr content is less than 5% or 7%, it is difficult to produce an amorphous alloy or the alloy becomes brittle, which is not preferable.

However, the present inventors fabricated these Zr-based amorphous magnetic alloy thin films by sputtering method and measured their properties, and found that Zr
The magnetostriction constant (including the magnetostriction constant zero at compositions where the
It was discovered that there exists a region with excellent magnetic properties in which the absolute value is extremely small, and this is described in Japanese Patent Application No. S5-65276, Specification 1.

The present inventors further improved the magnetostriction constant (absolute value) by substituting a part of Nb in the o-Nb-4r amorphous alloy with elements such as Cr, Motv, Ta, and W. It has been found that an amorphous magnetic alloy with high saturation magnetic flux density, excellent heat resistance, and corrosion resistance can be obtained while keeping the magnetic flux density small.

[Purpose of the invention]

The purpose of the present invention is to create a high-performance amorphous magnetic alloy that has a significantly small absolute value of magnetostriction, a high saturation magnetic flux density, and is excellent in heat resistance and corrosion resistance, especially a high-performance alloy made using thin film forming technology such as sputtering. The object of the present invention is to provide an alloy suitable as a magnetic head material.

[Summary of the invention]

In order to achieve the above object, the present invention uses Co-Nb-Z
A part of the Nb of the r-based amorphous magnetic alloy is replaced by Cu.

When substituted with Mo, V, Ta or W, and the respective contents are expressed as Co, (Nbt-xMX)bZr,
81≦a≦95.2.5≦C (5, a
10s10c=ioo, c/(b10c)) 0.25, and when M is Cr1M0IV or Ta, Q' 0〈X
The composition should satisfy ≦0.2.

As mentioned above, conventional 7. It has been said that it is difficult to manufacture an amorphous alloy in which r is an amorphous finishing element when the Zr content is 5% or less.

However, with the advancement of thin film 1'μ manufacturing technology such as sputtering, the composition range that can be made amorphous is expanding to the region of 5% Zr or less. On the other hand, the amorphous alloy # film with r of 5% or more is 7. Since r is a metal that is extremely susceptible to oxidation, it has caused problems in oxidation resistance. Such oxidation resistance is important when thin film magnetic materials are used after undergoing various high-temperature processes, such as in thin film heads. From the above point of view, in the present invention, the Zr content is set to 5 or more F.

The CO content affects the saturation magnetic flux density B8 of the alloy of the present invention and is %
If Co is less than 81%, the BS is less than about 8 kG, and a magnetic head using this sample cannot obtain a sufficient recording magnetic field for a high coercive force tape, and cannot achieve its purpose.

Furthermore, if Co exceeds 95%, an amorphous alloy cannot be obtained.

%As stated in the publication No. 58-65276, Co-N
b-' Zr-based amorphous alloy film has a magnetostriction constant of zero when the ratio of Zr to the sum of Nb and Zr contents is 0.2 to 0.25. A part of Nb in this amorphous alloy is replaced by Cr, Mo
, V,', pa, and W, the content of Zr is changed to C, Nb, and Qr.

When the sum of the contents of Mo+V, Ta, and W is b, the composition with a magnetostriction constant of zero changes to a value in which C/(b+C) is 0.2 to 0.25 or more. When the CO# degree is constant, increasing the Zr# degree leads to an improvement in the crystallization temperature and an expansion of the amorphous formation range. Therefore, C/(b
It is desirable that the straightness of 10) is larger. Further, it is necessary that the magnetostriction of the magnetic head material be near zero. Therefore, part of the Nb in the C0-Nb-'l,r-based amorphous alloy is replaced by Cr.

By replacing with MO, V, Ta or W, the value of C/(b10) at which the magnetostriction becomes zero can be increased,
It is possible to increase the crystallization temperature TX and expand the range of amorphous formation. Furthermore, corrosion resistance can be improved by adding these elements, especially Cr. The amount of Nb to be replaced is determined by replacing the element with Qr.

In the case of Mo, ¥, or Ta, the content should be 0.5 or less, when the sum of the contents of Nb and the substituting element is 1, and if the substituting element contains W, the content should be 0.2 or less. If the above value is exceeded, there is a possibility that the composition where the magnetostriction is close to zero becomes 5% or more of Zr.

The amorphous alloy of the present invention will be explained below using examples.

[Embodiments of the invention]

Example Table 1 shows the percent properties of the amorphous alloy JIG (JIG) of the present invention produced using a high-frequency dual sputtering device. The rgon pressure at the time of production was 5 .

[Effects of the Invention] As described above, according to the present invention, an amorphous alloy film having a significantly small absolute value of a magnetostriction constant, a high saturation magnetic flux density, and excellent heat resistance, corrosion resistance, and oxidation resistance can be obtained. Ta.

Continuation of page 1 @ Inventor Kudo Touka Kokubunji City Higashikoigakubo 1-28 Hatachi Hitachi, Ltd. Central Research Laboratory

Claims (1)

[Claims] 1. The compositional formula is Coa (Nbt-xMX)bZrc, M is at least one element selected from the group consisting of Cr, MO, V, 1) a, W, and a
, b, c are expressed as atomic cents, 81≦a≦
95.2.5≦c (5 satisfies a+b+c=ioo, C/(b+C)) 0.25, and M is Cr,
In the case of Mo, V or Ta, Q (x≦0.5,
When 84 contains W, it is a low-wire fully amorphous magnetic alloy that affirms O<X≦02.