JPS61143546A - Amorphous alloy for magnetic head - Google Patents

Abstract

PURPOSE:To obtain the amorphous alloy for magnetic heads having superior wear resistance and high thermal stability by providing a composition satisfying specific conditions in the amorphous alloy consisting of the four elements of Co, Fe, Si, and B. CONSTITUTION:The amorphous alloy consisting of the four elements of Co, Fe, Si, and B has a composition formula represented by the formula, where (c+d)=1, (b)=23-27 atomic%, and (c)/(c+d)=0.55-0.65; that is, the value of (b) represents the concentration of semimetals (Si, B), and when (b) exceeds 27 atomic%, the saturation magnetic flux density decreases, and when (b) is <=23 atomic%, the permeability decreases.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a magnetic alloy for a magnetic head, and more particularly to an amorphous alloy for a magnetic head containing Co as a main component.

Current magnetic head materials include crystalline metal materials such as permalloy and sendust, and M n -Z n ferrite, N
Oxide materials such as i-Zn ferrite are primarily used. Crystalline metal materials have the advantage of having a higher saturation magnetic flux density than ferrite, which is an oxide material. degree), the magnetic permeability decreases significantly.

On the other hand, ferrite has a large resistivity and exhibits excellent electromagnetic conversion characteristics even in a high frequency band, and also exhibits high wear resistance, so the Mn-Zn type is mainly used in video heads. However, since ferrite has a small saturation magnetization, recording distortion occurs and there is a lot of noise.

Generally, high-density recording uses a high frequency band. Therefore, the core material for a high-density magnetic head needs to be made thinner or have a larger resistivity ρ in order to prevent deterioration of magnetic permeability due to eddy current loss. Sendust has a large saturation magnetization and a high resistivity compared to permalloy, but it is brittle and cannot be made into a thin plate.

In recent years, amorphous alloys that do not have a crystalline structure.

Excellent magnetic and mechanical properties were found.

In other words, since amorphous alloys do not have a crystalline structure, their resistivity ρ is several times higher than that of crystalline metal alloys, and their coercive force is small because they do not have magnetocrystalline anisotropy. It has high magnetic permeability and also has a Vikers hardness of about 1000, which is higher than crystalline metals.

In addition, the composition that makes magnetostriction zero has basically been elucidated and is being studied as a core material for magnetic heads.

However, the use of amorphous alloys as magnetic helad cores for higher density recording requires not only low frequency ranges but also I M
It is necessary to have high magnetic permeability in a high frequency band of Hz or higher. To achieve this, ■ it must have a high specific resistance, and ■ it must have a high initial permeability.

■Have high wear resistance.

■Have high thermal stability.

need to be satisfied.

We have discovered that an amorphous alloy that satisfies all of ■■■■ can only be obtained in a very narrow composition range.

(Objective of the Invention) The present invention discloses a composition range that satisfies all of the above conditions (1) to (2) in an amorphous alloy of four elements Co, Fe, Si, and B. In other words, the present invention is an amorphous alloy that has a high initial magnetic permeability and a high specific resistance, so it exhibits a magnetic permeability higher than that of ferrite even in a band of I MHz or higher, and also exhibits excellent wear resistance and high thermal stability. is to be submitted.

(Embodiment of the invention) The alloy of the present invention is (Fe1-a, Coa) x -b(S
ic, B d)b, especially c,
d and b are limited. In the formula, c+d==1 and a is known to be about 0.94 in order to normally make the magnetostriction zero.

The reasons for limiting the composition of the amorphous alloy for a magnetic head of the present invention are as follows. First, the value of b is a metalloid (St, B
), but if b exceeds 27 atomic %, the saturation magnetic flux density decreases, making it undesirable as a core material for a magnetic head.On the other hand, if the semimetal concentration is 20 atomic % or less, magnetic permeability decreases, resulting in a uniform It becomes difficult to form amorphous alloy. Also, 4
To stably obtain an amorphous thin plate strip with a thickness of 0 μm or more,
It is necessary that the metalloid temperature is 23 atomic % or more.

Hereinafter, a detailed explanation will be given using examples.

(Example) Amorphous alloy thin plate strips having the compositions shown in the table were produced according to the single roll liquid quenching method. That is, molten metal is jetted out from a quartz nozzle placed on one rotating steel roll under the pressure of argon gas.

The roll rotation speed was 500 to 2000 rpm, and the ejected gas pressure was 0.1 to IKg/an2. The produced thin plate had a width of about 25 m, a thickness of 32 to 49 μm, and a length of about 20 to 3 mm.

It was confirmed by X-ray diffraction that all the produced thin plates were in an amorphous phase, and the magnetostriction was on the order of 104 and almost zero. The crystallization temperature was determined using a DSCC (element scanning calorimeter). Thickness was measured using a micrometer. The magnetic permeability is 10nwn in outer diameter, which is made by punching out a thin ribbon.
Winding wire (1
20 turns each on the secondary side) and was stabilized using the inductance method. Furthermore, the magnetic permeability was liquid quenched:
The condition of the ring obtained from the 4th band and excluding some samples, the ring was annealed (100℃ to 500℃
After holding for 10 minutes, water quenching was carried out (holding temperature was 10° C.), and measurements were taken at room temperature.

As the initial magnetic permeability, the effective magnetic permeability at 0.3 m0e and I KHz was adopted. Saturation magnetization (σS) was measured with a VSM in a magnetic field of 10 KOe. Specific resistance was measured by the four-terminal method.

Figure 1 shows the relationship between specific resistance ρ and c/e+d, b=2
In the range of 3 to 27yX%, ρ is higher as c/c+d is larger.

Figure 2 shows the influence of b and c/c + d on the crystallization temperature. Various reports have already been made regarding this relationship, but in our experiments c/c + d was approximately 0.
A rapid change in crystallization temperature was found around 65. That is, when c/c+d<0.65, the crystallization temperature becomes low. This fact is different from what has already been reported.

Figure 3 shows the wear amount per 100hr and c/c+d.
The relationship between them is an indication. The amount of wear was measured by making an ordinary audio type magnetic head from liquid-quenched amorphous, mounting it on a commercially available cassette type deck, and using a commercially available normal tape. Also, the amount of wear is c
/c+d is almost constant between 0.2 and 0.4, gradually decreases when it becomes larger than 0.4, and becomes almost constant when it is 0.55 or more. It can be seen that good wear resistance is exhibited when c/c+d is 0.55 or more.

Figure 4 shows the relationship between the initial magnetic permeability μi and c/c+d of amorphous materials with various compositions that have been rapidly cooled.
When /e+d is 0.4 or less, it takes a low constant value, and from 0.4 to
It increases rapidly at 0.6 and gradually approaches a high constant value.
That is, when the liquid is rapidly cooled, the larger C/c + d is, the higher μi is, and more preferably c/c + d is 0.55 or more.

It is generally known that the magnetic permeability of amorphous magnetic alloys can be improved by annealing under appropriate conditions. Therefore, we investigated the effect of annealing on magnetic permeability.

Figure 5 shows amorphous alloys (No. 16 to 19) with b=24 and various e/c+d compositions at various temperatures.
After annealing for 0 minutes, water quenching was performed, and the relationship between the initial magnetic permeability measured in that state and the annealing temperature is shown. The effect of annealing temperature on the initial permeability in amorphous alloys with various compositions is similar, with c/c+d of 0.5, 0.
A high μi was obtained in No. 63, and it was confirmed that the improvement in initial permeability due to annealing was large in these compositions. The maximum value of μi after various annealing in each sample was compared, and μ
Arranging c/c + d in descending order of i, 0.63
．． They were 0.50, 0.67, and 0.18.

FIG. 6 shows the results of an investigation of the heat treatment effect on μi in the case of b=25b, similar to FIG. 5. Comparing the maximum values of μi after various annealing in each sample, and arranging c/c + d in descending order of μi, the results are 0.64° and 0.60.
0.50.0.40.0.68.0.20.

FIG. 7 shows, similarly to FIG. 5, μ
These are the results of investigating the effect of heat treatment on i.

Comparing the maximum values of μi after various roasting in each sample, and arranging c/c + d in descending order of μi.

0.63.0.50, 0.40.0.20.0.76
Met.

Figure 8 shows the relationship between the maximum value of μi obtained after annealing and c/c+d for various compositions ab=23.25e27
In any case, μi is c/c + d is approximately 0
．． The maximum value is around 6.

Also, from the viewpoint of practical materials, it is necessary to take into account variations in properties. For example, when considering heat treatment operations, it is important to obtain high magnetic permeability over a wide heat treatment temperature range.
Increase mass productivity or reliability of materials.

FIG. 9 shows the annealing temperature range (ΔT) in which the value μi>10′ is obtained. The value μ1=10′ is considered to be close to the value required for the Herad core material. T! Permalloy and Sendust, which are currently used as core materials for heads, have a μi of approximately this value.

As d increases, ΔT also increases, but the saturation magnetic flux density decreases. In the case of c+d=24.25.27, the curves are similar, and ΔT takes a large value for each d when C/C+d is around 0.5 to 0.65.

A summary of what has been said above is as follows.

Specific resistance p c/c+d→Large crystallization temperature c/c+d<0.65 Wear resistance
0.55<c/c+dtt i(A s Q)
'0.55<c/c+dμi (after heat treatment) 0.
50<c/c+d<0.65μi (ΔT) 0.
To satisfy both conditions: 5<c/c+d<0.65.

0.55<c/c+d<0.65 It must be.

It is well known that the initial magnetic permeability, wear resistance, and specific resistance of amorphous magnetic alloys can be improved by substitution or addition of other elements, and the following has been observed in the alloys of the present invention as well. .

[Brief explanation of drawings]

Figure 1 shows the specific resistance ρ of the amorphous alloy and Si/Si+B (=c
Figure 2 shows the relationship between crystallization temperature and b
(=temperature of Si + B) and c/c + d. Figure 3 shows the relationship between the amount of wear per 100 hours and c/c + d.
Figure 4 shows the relationship between the initial magnetic permeability μi of the amorphous alloy
and c/c+d, and FIG. 5 is a diagram showing the relationship between the annealing temperature range and c/c+d. ~ ~ ~ ~ or -〇 (transformation) Hibisai (Geo 9 (Me) Ω・cm) First time rate wear amount (ILIm/ 1001'Y) ~ ω j′ ψ Φ
Figure 7 Figure 8 α2 0.3 0.4 0.5 0.6 0
．． 77t+d! 9Figure 00.1 α2 Q3 0.4 Q5 0.6 0
7C/c1d Procedural amendment (voluntary) April 22, 1985

Claims (1)

[Claims] Compositional formula (Fe, Co)_1-b (Sic, Bd) b, where c+d=1 b=23-27 atomic % c/c+d=0.55-0.65. Amorphous alloy for magnetic heads.