JPH0699769B2 - Thermal stability High magnetic flux density amorphous alloy - Google Patents

Description

TECHNICAL FIELD The present invention relates to a metal-metal amorphous soft magnetic alloy used in various magnetic heads and the like, and has excellent amorphous amorphous thermal stability and saturation magnetic flux density. And an amorphous alloy excellent in soft magnetic properties.

2. Description of the Related Art A metal-metal amorphous alloy is a metal having a conventional nonmetal-
It has a higher crystallization temperature and better corrosion resistance than non-metallic amorphous alloys. Furthermore, due to the structural characteristic of being amorphous, not only does it have no crystalline magnetic anisotropy that has a large effect on soft magnetic properties, but those containing Co as the main component also have a low magnetic speed, which means that they have good soft magnetic properties. It also serves as a. Therefore, it is attracting attention as a magnetic material used for a magnetic head that covers high processing temperatures such as glass bonding.

Problems to be Solved by the Invention On the other hand, in the conventional metal-metal type amorphous alloy, in a composition that emphasizes high magnetic flux density, the crystallization temperature T _X is lowered and the Curie temperature T _C of the magnetic material is lowered. (T _X <T _C ),
It becomes impossible to maintain the relationship of T _C <T _{X under} the condition that heat treatment of T _C or more for eliminating magnetic anisotropy is possible. In this case, heat treatment using a rotating magnetic field is necessary.

On the other hand, the crystallization temperature T _X is different from the scale of the crystallization temperature T _X.
Even if it is less than the above, when it is kept at a constant temperature for a long time, particularly in the case of an amorphous alloy, there is a great influence on the characteristics having a structure-sensitive factor such as initial magnetic permeability μ _i . That is, when it is incorporated in a practical element such as a magnetic head, which is indispensable for heat treatment, the amorphous alloy has a magnetic stability before the crystallization of the entire material, and a holding stability at a temperature of T _X or lower for such a soft magnetic property. Was a major problem (aging resistance).

Moreover, in consideration of the magnetic head bonding process using low melting point glass, durability of 450 ° C. or higher for several hours has been required.

The durability of such soft magnetic characteristics is hereinafter referred to as "thermal stability".

In the conventionally used metal-metal amorphous alloy (containing Co as a main component), a magnetic head having both high soft magnetic characteristics and high thermal stability with high saturation magnetic flux density as described above. If it is evaluated as a material, there is no one that is excellent in both characteristics and it is insufficient, so it is suitable for metal tape with high non-magnetic force.
There has been a demand for a material having a high magnetic flux density of Bs8000 to 8500G and having a thermal stability of 450 ° C. or higher for several hours, which can withstand the use of a low melting point glass as a head processing step.

The present invention has excellent thermal stability even at 450 to 500 ° C, and has a high saturation magnetic flux density (Bs8000) suitable for a high coercive force medium such as a metal tape.
It provides an amorphous alloy with good soft magnetic properties for magnetic heads with G).

Means for Solving the Problems The amorphous alloy according to the present invention is a quaternary alloy composed of Co, Nb, Ta and Zr, and when Co _X Nb _Y Ta _Z Zr _W is represented by atomic composition, X82%, 0.5% Y12%, 1.5% Z8.5%, W <5%
And 8.0% (Y + Z) 13.5%, X + Y + Z + W = 100
% Range.

Action Alloys with the above composition endure a heat treatment process at around 450 ° C and have a Bs of 800
It is 0-11000 Gauss.

The following conditions are necessary to become Bs8000Gauss.

X82% (1) Also, in order to amorphize, (Y + Z) 8% (2) is a necessary condition. Among these, Nb and Ta are main amorphizing elements and contribute to high thermal stability in the present invention, and Zr is also an amorphizing element, and Co- (N
b, Ta) system is added for the purpose of eliminating the negative magnetic permeability λ _S <O. By the way, Nb and Ta have the effect of making the alloy magnetostriction λ slightly negative, while Zr has the effect of making λ positive, so if the ratio of (Y + Z) and W is set to about 2 to 3: 1, the alloy A value with λ close to zero is obtained. Also, for Bs8000Gauss, since X is 82% and X + Y + Z + W = 100%, Y + Z + W <18%, which is the above-mentioned λ0 (Y +
Considering the ratio of Z) to W, it is necessary that (Y + Z) 13.5%, W <5% (3) because X82 and λ <10 ^-5 . Although the functions of Nb and Ta are similar, strictly speaking, Ta has a large effect of increasing the crystallization temperature T _X and increasing the thermal stability of the amorphous alloy, as compared with Nb, but Bs The reducing effect is greater than Nb, and it is Bs to balance both properly.
Necessary to obtain a thermally stable alloy at 8000 Gauss.
Considering this point and (Y + Z) <13.5%, it is necessary that 0.5% Y12%, 1.5% Z8.5% (4). The alloy system satisfying the above formulas (1) to (4) has Bs of 8000 to 11000 Gauss, and the glass bonding process at 450 ° C. is possible.

If more reliable glass bonding is attempted, the melting point of glass becomes high, and an amorphous alloy that is stable even at 500 ° C is generally required. At this time, it is necessary to increase the (Y + Z) to 9.5% (Y + Z) (5) by emphasizing thermal stability by sacrificing Bs to some extent. The alloy system satisfying the formulas (1), (3), and (5), which replaces the formula (2) with the formula (6), can withstand a glass bonding process at 500 ° C with Bs of 8000 to 9500 Gauss. all right. It has been found that these amorphous alloy systems are difficult to produce by the liquid quenching method and can be easily obtained by using the sputtering method.

Example FIG. 1 shows Co _X Nb _Y Ta _{Z of} a saturation magnetic flux density Bs8000G of the present invention.
As an example to show the thermal stability of Zr _W system, Co _82.9 Nb
_10.9 Ta _2.2 Zr _4.0 Amorphous material, Co _84.9 Nb _5.6 Ta _5.8 Zr
_{3.7 For} amorphous materials, in order to see the deterioration of the initial permeability μ _i when kept at a constant temperature for 1 to 10 ³ minutes in each temperature range from approximately 450 ° C to 600 ° C, the transformation of soft magnetic phase disappearance 3 is a TTT phase diagram (time-temperature-transformation diagram) which is used as a reference of FIG. In the figure, μ _i is measured under an AC magnetic field of 1 m0e, and μ _i 〜 500 at 1 MHz value is the soft magnetic inferior point (marked with ▲). That is, the left side of the line connecting the ▴ points at each temperature shows the good (stable) soft magnetic phase with μ _i 500, and the right side shows the poor soft magnetic phase with μ _i <500. In the above embodiment, 1.
A bipolar high-frequency sputtering device (input voltage 450 W) was used as a preparation method under a gas pressure of 5 × 10 ⁻² Torr Ar (film thickness of about 5 μm.
m).

The above temperature range of 450 to 600 ℃ is approximately the above Co _X Nb _Y Ta _Z Z
The temperature is about 100 ° C. below the crystallization temperature of the r _W system (that is, the crystallization temperature is 550 ° C. or higher), which corresponds to the working temperature of working heat treatment with a low melting point glass such as a magnetic head. Co _82.9 Nb _10.9 Ta _2.2 Zr _4.0 and Co _84.9 Nb _5.6 Ta _5.8
The saturation magnetic flux densities Bs of Zr _3.7 materials are Bs to 8500G and Bs to 90, respectively.
0G, all of which have the characteristics of Bs8000G, 500
In the heat treatment at ℃, the durability time based on μ _i 500 is 100 minutes and 150 minutes as shown in FIG. 3, respectively, and it can sufficiently withstand the heat treatment using the low melting point glass. It has thermal stability. However, in FIG. 3, the former is T _C 500 ° C <T _X , so the anisotropy can be eliminated by heat treatment without a magnetic field, whereas the latter is 50
Since 0 ° C. <T _X T _C, it is necessary that all heat treatments are performed in a rotating magnetic field.

Similarly, for the Co-Nb-Ta-Zr quaternary system, including the above two examples, Nb = 0.5 at% to 12 at%, Ta = 1.5 at% to 8.5 at%, Co82
Table 1 summarizes the examples of the actual compositions in which the composition ratios of Nb, Ta, and Zr were changed in the range of%, and the Bs values, μ _i 500 at the heat treatments at 450 ° C and 500 ° C are also shown in the table. The durability time as a standard is shown.

The magnetic field conditions in the heat treatment are also added.

Of the examples shown in Table 1, for the examples A to G, Bs
It has a high saturation magnetic flux density of 8000, but for A and B, it is 500 ° C against the standard of soft magnetic characteristics of μ _i 500.
Since it exhibits a durability of less than 30 minutes in the heat treatment, it is insufficient as an amorphous material for heat treatment at 500 ° C. in magnetic head processing.

In the case of F, Bs <8000G is slightly low (7500
G).

However, it is understood that B to G have not only Bs8000G but also thermal stability based on the above criteria. This is because when the element ratio of this quaternary alloy is expressed as Co _X Nb _Y Ta _Z Zr _W , Nb is 0.5Y12at% Ta is 1.5at% Z8.5at%, and both of the above conditions are satisfied at the same time. And the sum of Y and Z is in the range of 9.5Y + Z13.5. At the same time, Co that leads to a high Bs value is equivalent to X82at%.

In this case, with respect to the composition value W of Zr, the condition of the ternary system is satisfied at the same time, and W <5 and X + Y + Z + W = 100at% are satisfied for the above reason.

In order to show that these examples are superior to the thermal stability of the FeCoSiB-based amorphous material having Bs8000G of the conventionally known metal-nonmetal-based amorphous alloy, Similarly, FIG. 2 shows a TTT phase diagram in which the deterioration of μ _i at 450 ° C. to 600 ° C. is used as the transformation criterion of soft magnetic loss. It can be seen that the thermal stability region of the soft magnetic phase (μ _i 500) is smaller than that of the alloy system of the present invention in FIG.

On the other hand, when the examples of Table 1 were heat treated at 450 ° C., μ _i 500
If the durability time against the standard of soft magnetic characteristics is evaluated, all of the examples A to G can withstand the heat treatment at this temperature, and Bs = 8000 to 11000 Gauss, and in the composition range having a higher saturation magnetic flux density. Can also be used as a usable amorphous film. Therefore, when glass having a low melting point around 450 ° C. is used, it has a great application effect on magnetic head processing.

Similarly, the composition range in this case is the element ratio of the quaternary alloy.
When expressed as Co _X Nb _Y Ta _Z Zr _W , Nb is 0.5 at% Y12 at% Ta is 1.5 at% Z8.5 at% and both of the above conditions are satisfied at the same time, and Y and Z are satisfied.
Corresponds to the case where the sum of is within the range of 8.0at% Y + Z13.5at%.

Similarly, for Co, Zr is X82at% W <5at%, and between X, Y, Z and W, X + Y + Z + W = 100at% is satisfied.

Table 2 shows, as a comparative example with the present invention, the saturation magnetic flux density value and 450 ° C. of the sputtered film of each alloy composition of CoNbZr ternary alloy system.
The initial permeability characteristic values after heat treatment are summarized. CoNb without Ta
As shown in the example of Table 2 in the Zr ternary alloy film, for example, even if only one element of Ta escapes from the CoNbTaZr system of the present invention, a high saturation magnetic flux density alloy having a stable initial magnetic permeability after heat treatment is obtained. You can see that it becomes difficult. This is shown in Table 1 as CoNbTaZr
It is clear from comparison with the characteristic value of the alloy film after heat treatment at 450 ° C. In other words, the combination of the four elements of the present invention is 8000
It can be seen that it is a unique alloy system that satisfies the practical requirements of having both a high saturation magnetic flux density of Gauss or higher and an initial magnetic permeability of 500 or higher after heat treatment at 450 ° C.

EFFECTS OF THE INVENTION According to the Co _X Nb _Y Ta _Z Zr _W alloy of the present invention, soft magnetic properties are inferior due to heat treatment at a high temperature such as low melting point glass processing in various magnetic heads conventionally using a high magnetic flux density material. In contrast to the large restrictions, a long time (several hours or more) at a high heat treatment temperature of 450 ° C or even 500 ° C
It is possible to realize a high magnetic flux density soft magnetic alloy excellent in thermal stability and capable of maintaining good soft magnetic characteristics even when subjected to heat treatment by.

Therefore, even if a magnetic head is manufactured by performing a glass bonding process using this material, good soft magnetic characteristics can be maintained even at a high temperature in the bonding process, and the head processing yield is improved in the manufacturing of the magnetic head. In addition, sufficient head characteristics can be obtained as a magnetic head suitable for a high coercive force magnetic recording medium.

[Brief description of drawings]

FIG. 1 is a time-temperature-transformation state diagram (TTT state diagram) obtained from the temperature change of the initial permeability when the Co—Nb—Ta—Zr alloy in the example of the present invention is held at each temperature. FIG. 2 is a conventionally known TTT phase diagram (of Bs8000G) of a Co—Fe—Si—B alloy, and FIG. 3 is Co _84.9 Nb _5.6 Zr _3.7 Ta _5.8 and Co _{82.9 in the} example of the present invention. Nb _10.9 Zr _4.0 Ta _2.2
Is a graph showing the deterioration of μ _i by the isothermal heat treatment at 500 ° C.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Gyoutoku 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-58-185742 (JP, A) JP-A-58-84957 (JP, A) JP-A-60-89539 (JP, A)

Claims (3)

[Claims] 1. A composition represented by Co _X Nb _Y Ta _Z Zr _W , wherein X + Y + Z + W = 100, X82,0.5 in atomic composition percentage.
Y12,1.5Z8.5, W <5 and 8.0Y + Z13.5
The initial magnetic permeability is 500 or more after the heat treatment at 450 ° C in the glass bonding process, and it is 8,000 Gau.
A thermally stable, high flux density amorphous alloy with a saturation flux density of ss or higher. 2. The heat stable high magnetic flux density amorphous alloy according to claim 1, wherein 9.5Y + Z13.5. 3. The thermally stable high magnetic flux density amorphous alloy according to claim 1, wherein a sputter vapor deposition method is used as a means for preparing the alloy.