JP2710440B2 - Soft magnetic alloy film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a soft magnetic alloy film suitable for a magnetic head and the like.

[Prior Art] In the field of magnetic recording, a recording medium such as a magnetic tape has been promoted to have a high coercive force in order to increase a recording density. However, as a material of a magnetic head corresponding thereto, a saturation magnetic flux density (Bs) is required. High things are required.

As a conventional soft magnetic material (film) with a high saturation magnetic flux density, Fe
A typical example is a -Si-Al alloy (Sendust). In recent years, an amorphous alloy film mainly composed of Co, which is a ferromagnetic metal element, has been developed.

Further, as a recent attempt, the influence of the magnetocrystalline anisotropy of Fe (the adverse effect on soft magnetism) has been reduced by using an alloy film (Fe-C, Fe-Si, etc.) composed of fine crystals containing Fe as the main component. In some cases, a film having a high saturation magnetic flux density and excellent soft magnetic properties is obtained.

[Problems to be Solved by the Invention] By the way, devices incorporating a magnetic head tend to be reduced in size and weight, and are subject to vibration accompanying movement,
It is often used under adverse effects. Therefore, the magnetic head has excellent magnetic properties and, of course, excellent wear resistance to the magnetic tape,
It is required to have high durability in a humidity or corrosive atmosphere, that is, high environmental resistance, vibration resistance, and the like. For this reason, it is necessary to perform the gap formation, the incorporation into the case, and the like by glass welding, and the material of the magnetic head needs to be able to withstand the high temperature of the glass welding step in the head manufacturing process.

However, among the conventional soft magnetic alloy films, those made of sendust have a saturation magnetic flux density of about 10,000 G (Gauss), which is insufficient for a demand for higher density in the future. In addition, Co-based amorphous alloy films
Although high saturation magnetic flux density of more than 13000G has been obtained, when trying to increase the saturation magnetic flux density of conventional amorphous alloys, the amorphous forming elements Ti, Zr, Hf, Nb,
It is necessary to reduce the addition amount of Ta, Mo, W, etc., but if the addition amount is reduced, the stability of the amorphous structure decreases,
There is a problem that it cannot withstand the temperature required for glass welding (about 500 ° C. or higher).

Furthermore, the alloy film (Fe-C, Fe-Si, etc.) composed of fine crystals containing Fe as a main component causes crystal growth at a high temperature,
Soft magnetic properties deteriorate (400 ° C maximum for Fe-C)
Therefore, it is hard to say that it is suitable for glass welding.

Against this background, the present inventors have filed Japanese Patent Application No. 1-278220.
Patents have filed a patent application for a soft magnetic alloy film that solves the above problem.

One of the soft magnetic alloy films for which patent application is filed in Japanese Patent Application No. 1-278220 is a composition formula represented by FeaMcCd, wherein the composition ratio a is 50 to 96 in atomic%, c is 2 to 30, d is 0.5 to 25,
a + c + d = 100 was satisfied.

The other one is represented by the composition formula FeaTbMcCd, wherein the composition ratio a is 50 to 96 in atomic%, b is 0.1 to 10, c is 2 to 30,
d satisfies the relationship of 0.5 to 25 and a + b + c + d = 100.

The soft magnetic alloy film provided in this patent application has a high saturation magnetic flux density of 15000 G or more for some compositions, has high thermal stability compared to conventional various materials, and is sufficient under normal use environment. Although it has excellent corrosion resistance and environmental resistance, since it is mainly composed of Fe, there is a possibility that discoloration or rusting may occur when used in a bad environment.

The present invention solves the above problems, and provides a soft magnetic alloy film having low coercive force, high magnetic permeability, thermally stable characteristics, high saturation magnetic flux density, and good corrosion resistance. The purpose is to do so.

[Means for Solving the Problems] In order to solve the problems, the invention described in claim 1 has a composition formula represented by FeaCrcMdCe, and M represents Ti, Zr, Hf, V, Nb,
Ta, Mo, W are at least one metal element or a mixture thereof, and the composition ratios a, c, d, and e are 50 ≦ a ≦ 9 in atomic%.
5, 0.5 ≦ c ≦ 20, 2 ≦ d ≦ 25, 0.5 ≦ e ≦ 25, a + b +
The structure satisfies the relationship of c + d = 100, and its structure is basically composed of fine crystal grains having an average crystal grain size of 0.08 μm or less, and a part thereof includes a crystal phase of a carbide of the element M.

In order to solve the above problem, the invention described in claim 2 has a composition formula represented by FeaTbCrcMdCe, where T is a metal element or a mixture thereof composed of at least one of Co and Ni, and M is
Among Ti, Zr, Hf, V, Nb, Ta, Mo, and W, a metal element or a mixture of at least one of them, and the composition ratio a, b, c, d, and e is 50 ≦ a ≦ 95, 0.1 ≦ b ≦ 10, 0.5 ≦ c ≦ 20, 2 ≦
The relationship d ≦ 25, 0.5 ≦ e ≦ 25, a + b + c + d + e = 100 is satisfied, and the structure is basically composed of fine crystal grains having an average crystal grain size of 0.08 μm or less. It contains a crystalline phase.

According to a third aspect of the present invention, in order to solve the above-described problem, the structure according to the first or second aspect has a structure in which the average particle diameter is basically
The structure has a mixture of crystal grains of 0.08 μm or less and an amorphous phase.

 Hereinafter, the present invention will be described in more detail.

As a method of forming the alloy film, the alloy film is sputtered,
It is manufactured by a thin film forming apparatus such as evaporation. As the sputtering apparatus, existing apparatuses such as RF bipolar sputtering, DC sputtering, magnetron sputtering, tripolar sputtering, ion beam sputtering, and facing target type sputtering can be used.

As a method of adding C into the film, a graphite pellet is placed on a target plate to serve as a code target, and this is sputtered. Alternatively, a target containing no C (Fe-Cr-M or Fe-Cr-M type) is used. -T-Cr-M
And a reactive sputtering method in which a gas atmosphere in which an inert gas such as Ar is mixed with a hydrocarbon gas such as methane (CH ₄ ) can be used. It is easy to control the C concentration of
A film having an excellent concentration can be obtained.

Since the film thus produced contains an amorphous phase in a considerable proportion and is unstable,
Microcrystals are deposited by performing a heat treatment of heating to about 400 to 700 ° C. By performing this heat treatment without a magnetic field, a static magnetic field, or a rotating magnetic field, excellent soft magnetic characteristics can be obtained. Further, this heat treatment can be performed also as a glass welding step in the manufacturing process of the magnetic head.

Note that the step of depositing the microcrystals does not need to be performed completely, and it suffices if a considerable number (preferably 50% or more) of the microcrystals are deposited. Therefore, the remaining amorphous component does not hinder the improvement of the characteristics.

Hereinafter, the reasons for limiting the components as described above will be described.

Fe is a main component and is an element bearing magnetism, and a ≧ 50% is required to obtain a saturation magnetic flux density of at least ferrite (Bs 5000 G) or more. In order to obtain good soft magnetic properties, a ≦ 95% must be satisfied.

The element T (that is, Co, Ni) is an element added for the purpose of adjusting magnetostriction. In the case of the Fe-MC film, when the heat treatment temperature is low, the magnetostriction becomes positive, and when the heat treatment temperature is high, the magnetostriction becomes negative. When a high heat treatment temperature (glass welding temperature) is required, the magnetostriction can be made almost zero by adding an appropriate amount of Ni and Co, which have the effect of making the magnetostriction positive. If the heat treatment temperature is appropriate, the addition of element T is not particularly necessary, but the addition of T must be b ≦ 10% so that the positive magnetostriction does not increase to the order of +10 ⁻⁵ or more.

Element M is necessary for improving soft magnetic properties,
Further, it combines with C to form carbide fine crystals. In order to maintain good soft magnetic characteristics, it is necessary to satisfy d ≧ 2%. However, if the amount is too large, the saturation magnetic flux density decreases. Therefore, it is necessary to satisfy d ≦ 25%.

C is necessary for improving soft magnetic properties and improving heat resistance, and combines with C and the element M to form carbide fine crystals. In order to maintain good soft magnetic properties and thermal stability, it is necessary to satisfy e ≧ 0.5%. However, if the amount is too large, the saturation magnetic flux density decreases. There is.

The fine crystals of the carbide of element M act as pinning sites for the magnetic domain walls, have the function of improving the high-frequency characteristics of magnetic permeability, and are uniformly dispersed in the film, so that the fine crystals of Fe grow by heat treatment and become soft magnetic. It has the function of preventing damage. In other words, when the Fe crystal grains grow and become large, the adverse effect of the magnetocrystalline anisotropy increases and the soft magnetic properties deteriorate, but the fine crystals of the carbide of the element M act as barriers for the Fe grain growth, and the soft magnetic properties deteriorate. Prevent deterioration of magnetic properties.

The reasons for limiting the components of Fe, element T, element M and C described above are the same as in the case of Japanese Patent Application No. 1-278220.

Cr is an element added to improve corrosion resistance. However, unless c ≧ 0.5%, the effect of improving corrosion resistance does not appear. If c ≧ 20%, the saturation magnetic flux density becomes too low (below ferrite), which is not preferable.

And, since the metal structure is basically composed of microcrystals of 0.08 μm or less, it is excellent in thermal stability as compared with amorphous, can reduce the number of added elements, and can increase the saturation magnetic flux density .

[Action] In the soft magnetic alloy film, the structure is mainly composed of Fe-rich crystals, and the addition of a component that reduces the saturation magnetic flux density is restricted. Since the magnetic moment and the Curie temperature are high, a high saturation magnetic flux density can be obtained. In addition, the elements M and C
And the metal structure is composed of fine crystal grains, and the adverse effect on the soft magnetism due to the magnetocrystalline anisotropy is reduced, so that good soft magnetic properties can be obtained. Furthermore,
Since the carbide of the element M precipitates and suppresses the growth of crystal grains containing Fe as a main component, the crystal grains do not become coarse even when heated in the glass welding step. Furthermore, since a specific amount of Cr is added, the corrosion resistance is improved and the environment resistance is excellent.

[Examples] (1) Film formation An alloy film having the composition shown in Table 1 below was formed using an RF bipolar sputtering apparatus.

The target used was Ta, Cr, Ni,
Using a composite target formed by appropriately arranging graphite pellets, sputtering was performed in an Ar gas atmosphere to form a thin film having a thickness of 5 to 6 μm.

(2) Heat treatment After film formation, annealing was performed at 550 ° C. for 20 minutes.
Two types of annealing were performed, one in a static magnetic field and the other in a non-magnetic field.

(3) Measurement The static magnetic field was measured for the alloy film manufactured as described above and a Cr-free alloy film formed by sputtering (an alloy film according to the invention filed in Japanese Patent Application No. 1-278220). The saturation magnetic flux density (Bs), initial magnetic permeability (μ, atl MHz), and coercive force (Hc) after annealing or after no-magnetic-field annealing were measured. The following results are shown in Table 1.

The comparative example of Sample 1 in Table 1 was previously applied for a patent by the present inventors, in which only the addition of Cr was omitted. It was also found that deterioration of soft magnetic properties such as coercive force was hardly a problem.

A soft magnetic alloy film prepared in the same manner as above was placed in pure water.
Table 2 below shows the results of visually determining the discoloration state after immersion for 240 hours.

From the results shown in Table 2, it became clear that the corrosion resistance can be improved by adding Cr.

[Effects of the Invention] As described in detail above, the present invention is a soft magnetic alloy film mainly composed of fine crystal grains containing Fe as a main component, and the addition of a component that reduces the saturation magnetic flux density is limited. Therefore, a high saturation magnetic flux density can be obtained. Further, unlike a conventional amorphous alloy film, a film exhibiting high magnetic permeability can be obtained even when heat treatment is performed in the absence of a magnetic field, and the process can be simplified as compared with the case where heat treatment is performed by applying a magnetic field.

In addition, elements M (Ti, Zr, Hf, V, Nb, Ta, Mo.W) and C, which improve soft magnetism, are added, and the metal structure is composed of fine crystal grains, and the crystal magnetic Since the adverse effect on soft magnetism due to anisotropy is reduced, good soft magnetic properties can be obtained.

Furthermore, since the crystal is composed of fine crystal grains and the added element M forms a carbide with C, the crystal grains are not coarsened even when heated in the glass welding step, and the above characteristics are maintained. It is suitable as a material for a magnetic head having high performance required for high-density recording.

Furthermore, by adding the element T (Co, Ni) in addition to the above composition and adjusting the magnetostriction, it is possible to prevent the soft magnetic properties from deteriorating due to various strains generated in the magnetic head manufacturing process.

And since a specific amount of Cr is added to the above components, Fe
The base alloy has excellent corrosion resistance and does not cause discoloration or rust even under adverse effects.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location G11B 5/31 G11B 5/31 C

Claims (3)

(57) [Claims] 1. A composition formula represented by FeaCrcMdCe, wherein M is Ti, Zr,
Among Hf, V, Nb, Ta, Mo, and W, a metal element or a mixture of at least one of them, and the composition ratios a, c, d, and e are 50% a ≦ 95 0.5 ≦ c ≦ 20 in atomic%. 2 ≦ d ≦ 25 0.5 ≦ e ≦ 25 a + c + d + e = 100, and the structure is basically composed of fine crystal grains having an average crystal grain size of 0.08 μm or less. A soft magnetic alloy film comprising a crystalline phase. 2. The composition formula is represented by FeaTbCrcMdCe, where T is Co, N
i is a metal element composed of at least one of i or a mixture thereof, and M is at least one of Ti, Zr, Hf, V, Nb, Ta, Mo, and W
A metal element or a mixture thereof, comprising a composition ratio a,
b, c, d, and e are atomic%, and the following relationship is satisfied: 50 ≦ a ≦ 95 0.1 ≦ b ≦ 10 0.5 ≦ c ≦ 20 2 ≦ d ≦ 25 0.5 ≦ e ≦ 25 a + b + c + d + e = 100 A soft magnetic alloy film comprising fine crystal grains having an average crystal grain size of 0.08 μm or less, and partially including a crystal phase of a carbide of the element M. 3. The soft magnetic alloy film according to claim 1, wherein the structure is a mixture of fine crystal grains having an average crystal grain size of 0.08 μm or less and an amorphous phase.