JPH0693391A - Amorphous alloy having thermal stability and high magnetic flux density - Google Patents

Abstract

PURPOSE:To obtain an amorphous alloy with thermal stability and high mag netic flux density, having stable soft-magnetic properties of high initial permeabil ity and also having high saturation magnetic flux density, by specifying a compo sition consisting of Co, Nb, Ta, and Zr. CONSTITUTION:This alloy is an amorphous alloy, with thermal stability and high magnetic flux density, having a composition represented by coXNbYTaZZrW (where(X+Y+X+W)=100%, by atomicm X=82%, 0.5<=Y<=12%, 1.5<=Z<=8.5%, W<5%, and 8.0<=Y+z<=13.5% and, as necessary, 9.5<=Y+Z<=13.5%. This alloy has a soft-magnetic property of >=500 initial permeability even after subjected to heat treatment at >=450 deg.C by low-melting glass bonding, etc., and also has >=8000 Gauss saturation magnetic flux density. This amorphous alloy can be easily obtained by using a sputtering technique.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal-metal amorphous soft magnetic alloy used for various magnetic heads, etc., and has excellent amorphous amorphous thermal stability, high saturation magnetic flux density and soft magnetic characteristics. It provides an excellent amorphous alloy.

[0002]

2. Description of the Related Art A metal-metal amorphous alloy has a higher crystallization temperature and a higher corrosion resistance than the conventional metal-nonmetal amorphous alloy having a nonmetal. Furthermore, due to its structural characteristic of being amorphous, not only does it have no crystalline magnetic anisotropy that greatly affects the soft magnetic characteristics, but also those containing Co as the main component have a low magnetic speed, and thus have good soft magnetic characteristics. 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.

[0003]

On the other hand, in the conventional metal-metal type amorphous alloy, the crystallization temperature T _X is lowered and the Curie temperature T _C of the magnetic material is lowered in the composition in which high magnetic flux density is emphasized. (T _X <T _C ), and T _{C under the} condition that heat treatment of T _C or more for eliminating magnetic anisotropy is possible.
<The relationship of T _X cannot be maintained. In this case, heat treatment using a rotating magnetic field is necessary.

[0004] On the other hand, the crystallization temperature T _X be the measure of the level of less separately crystallization temperature T _X, the structure of _i such particularly initial permeability μ For long retention to the amorphous alloy at a constant temperature It has a great influence on the characteristics having sensitive factors. That is, when it is incorporated in a practical element such as a magnetic head, which is indispensable for heat treatment, the amorphous alloy retains its magnetic stability before the crystallization of the entire material, and the holding stability of the soft magnetic characteristic at a temperature of T _X or lower. Was a major problem (aging resistance).

Moreover, in consideration of the magnetic head bonding process using a 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 a soft magnetic characteristic having a high saturation magnetic flux density and a thermal stability as described above. If you evaluate it as a material,
There is nothing excellent in both characteristics and it is insufficient. It has a high magnetic flux density of B _S ≧ 8000 to 8500G suitable for a metal tape having a high non-magnetic force, and can withstand the use of a low melting point glass as a head processing step. There has been a demand for a material having a thermal stability of several degrees Celsius or higher for several hours.

The present invention is excellent in thermal stability even at 450 to 500 ° C., and has good soft magnetic characteristics for a magnetic head having a high saturation magnetic flux density (B _S ≧ 8000 G) suitable for a high coercive force medium such as a metal tape. And an amorphous alloy having

[0008]

The amorphous alloy according to the present invention is a quaternary alloy of Co, Nb, Ta and Zr.
_{When X} Nb _Y Ta _Z Zr _w is represented by atomic composition, X ≧ 8
2%, 0.5% ≦ Y ≦ 12%, 1.5% ≦ Z ≦ 8.5%, W <
5% and 8.0% ≦ (Y + Z) ≦ 13.5%, X + Y + Z
Within the range of + W = 100%, it has an initial permeability of 500 or more as a soft magnetic property even after a heat treatment at 450 ° C.,
Moreover, it has a saturation magnetic flux density of 8000 Gauss or more.

[0009]

The alloy having the above composition withstands a heat treatment process at around 450 ° C. and has a B _S of 8000 to 11000 Gauss.

The following conditions are necessary for B _S ≧ 8000 Gauss. X ≧ 82% ····································································································································· (1) Among them, 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 C
It is added for the purpose of eliminating the negative magnetic permeability λ _S <O of the o- (Nb, Ta) system. 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 that the ratio of (Y + Z) to W is approximately 2 to 2.
A ratio of 3: 1 gives alloys with λ close to zero. For B _S ≧ 8000 Gauss, X ≧ 82% and X + Y
Since + Z + W = 100%, Y + Z + W = <18%
Therefore, considering the ratio of (Y + Z) and W where λ = 0, (Y + Z) ≦ 13.5%, W <5% (3), X ≧ 82 and λ It is necessary for < ^10-5 . The functions of Nb and Ta are similar, but strictly speaking T
Although the effect of increasing the crystallization temperature T _x and increasing the thermal stability of the amorphous alloy is greater than that of a and Nb, B _S
Is more effective than Nb, and proper balance between the two is necessary to obtain a thermally stable alloy with B _S ≧ 8000 Gauss. This point and (Y + Z) <1
Considering 3.5%, it is necessary that 0.5% ≦ Y ≦ 12%, 1.5% ≦ Z ≦ 8.5% (4). The alloy system satisfying the above formulas (1) to (4) has B _s of 8000 to 11000 Gauss, and a glass bonding process at 450 ° C. is possible.

If more reliable glass bonding is attempted, the melting point of the glass becomes high, and an amorphous alloy that is stable even at 500 ° C. is generally required. In this case, it is necessary to increase (Y + Z) to be 9.5% ≦ (Y + Z) ………… (5) by emphasizing thermal stability at the expense of B _S. . The alloy system satisfying the formulas (1), (3), and (5), in which the formula (2) is replaced by the formula (6), can withstand a glass bonding process at 500 ° C. with B _S of 8000 to 9500 Gauss. I understood. 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.

[0012]

EXAMPLE FIG. 1 shows the saturation magnetic flux density B of the present invention._S≧ 80
00G Co_XNb_YTa_ZZr _WShows the thermal stability of the system
As an example for_82.9Nb_10.9Ta_2.2Zr_4.0
Amorphous material and Co_84.9Nb_5.6Ta_5.8Zr_3.7Non
For crystalline materials, each from approximately 450 ° C to 600 ° C
1-10 in the temperature range³If kept at a constant temperature for a minute
Mushroom initial permeability μ_iTo see the subordination of the soft magnetic phase disappearance
TTT phase diagram (time-temperature-transformation diagram) as a reference for transformation
Is shown. Μ in the figure_iIs under an alternating magnetic field of 1 mOe
At 1MHz value_i~ 500 is inferior in soft magnetic
It is the lower point (marked with a triangle). That is, the △ mark at each temperature
The left side of the connected line is μ_iGood (stable) soft magnetic phase of ≧ 500
On the right is μ_iShows a subordinate soft magnetic phase of <500
It In the above embodiment, 1.5 × 10^-2Torr A
Bipolar high frequency sputtering equipment (input voltage 45
0 W) was used as a preparation method (film thickness of about 5 μm).

The above temperature range of 450 to 600 ° C. corresponds to about 100 ° C. below the crystallization temperature of the above Co _X Nb _Y Ta _Z Zr _W system, and corresponds to the working temperature of working heat treatment with a low melting point glass such as a magnetic head. To do. Above Co
_82.9 Nb _10.9 Ta _2.2 Zr _{4. 0} and Co _84.9 Nb _5.6 T
a _5.8 Zr _3.7 The saturation magnetic flux density B _S of each material is Bs to 8
500 G and B _{S to} 900 G, both of which are B _S ≧ 8
Despite having the characteristics of 000G, in the heat treatment at 500 ° C., the durability times based on μ _i ≧ 500 are 100 minutes and 150 minutes, respectively, as shown in FIG. It has sufficient thermal stability to withstand heat treatment. However, in FIG.
The former is T _C ≦ 500 ° C. <T _X , so that the anisotropy can be eliminated by heat treatment without a magnetic field, while the latter is 5
Since 00 ° C. <T _X ≦ T _C , all heat treatments in a rotating magnetic field are required.

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%, and Co ≧ 82% in range, the composition ratios of Nb, Ta, and Zr are shown in Table 1. B _S value, 450
The endurance time based on μ _i ≧ 500 in the heat treatment at ° C and 500 ° C is shown.

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

[0016]

[Table 1]

Of the examples shown in Table 1, the examples A to G have a high saturation magnetic flux density of B _S ≧ 8000, but A and B have a soft magnetic property of μ _i ≧ 500. In the heat treatment at 500 ° C., the durability is less than 30 minutes, which is insufficient as an amorphous material for heat treatment at 500 ° C. in magnetic head processing.

For the example of F, B _S <8000G
Moderately low (7500G). However, for B to G, not only B _S ≧ 8000 G, but also the thermal stability based on the above criteria is found to be combined. This means that when the element ratio of this quaternary alloy is expressed by Co _X Nb _Y Ta _Z Zr _W , Nb is 0.5 ≦ Y ≦ 12at% Ta is 1.5at% ≦ Z ≦ 8.5at%. Yes, this corresponds to the case where both the above conditions are simultaneously satisfied and the sum of Y and Z is in the range of 9.5 ≦ Y + Z ≦ 13.5. Further, for Co that is simultaneously connected to a high B _S value, it corresponds to X ≧ 82 at%. In this case, regarding the composition value W of Zr, it is a case where the above conditions of the ternary system are simultaneously satisfied, and W <5 and X + Y + Z + W = 100 at% are satisfied for the above reason.

Fe having a B _S ≧ 8000 G, which is a conventionally known metal-nonmetal type amorphous alloy in these examples.
In order to show that the CoSiB-based amorphous material is superior in thermal stability, the same temperature as that of the FeCoSiB-based material at 450 ° C.
FIG. 2 shows a TTT phase diagram in which the deterioration of μ _i at ˜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, if the examples of Table 1 are evaluated with respect to the 450 ° C. heat treatment with respect to the durability time with respect to the soft magnetic characteristic criterion of μ _i ≧ 500, all of the examples of A to G are obtained at this temperature. Can withstand heat treatment and has B _S = 80
It can be used as an amorphous film that can be used even in a composition range having a saturation magnetic flux density of 0 to 11000 Gauss and higher. Therefore, when glass or the like having a low melting point around 450 ° C. is used, the application effect to the magnetic head processing is great.

Similarly, the composition range in this case is such that when the element ratio of the quaternary alloy is expressed as Co _X Nb _Y Ta _Z Zr _W , 0.5 at% ≤ Y ≤ 12 at% Ta and 1.5 at% ≤ Ta. Z ≦ 8.5 at%, both of the above conditions are satisfied at the same time, and Y and Z
Corresponds to the case where the sum of the above is within the range of 8.0 at% ≦ Y + Z ≦ 13.5 at%.

Similarly, for Co, Zr is X ≧ 82 at% W <5 at%, and X + Y + Z + W = 100 at% is satisfied between X, Y, Z, and W.

Table 2 shows CoN as a comparative example with the present invention.
The saturation magnetic flux density of the sputtered film of each alloy composition of the ternary alloy system of bZr and the initial permeability characteristic value after the heat treatment at 450 ° C. are summarized. As shown in the example of Table 2 in the ternary alloy film of CoNbZr without Ta, for example, even if only one element of Ta is removed from the CoNbTaZr system of the present invention, a high saturation magnetic flux having a stable initial magnetic permeability even after heat treatment. It can be seen that it becomes difficult to obtain a density alloy. This is clear from comparison with the characteristic values of the CoNbTaZr alloy film in Table 1 after heat treatment at 450 ° C. That is, the combination of the four elements of the present invention is 8000.
It can be seen that this 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.

[0024]

[Table 2]

As described above, the thermal stability of the present invention is that the soft magnetic characteristics (physical property values), mainly the initial magnetic permeability of the amorphous alloy film, are constant with respect to processing by heat treatment of the head such as glass bonding. It means the holding time stability of heat treatment at a temperature, which is distinguished from the heat resistance of a structure showing a high amorphous crystallization temperature. Further, the alloy composition range in the present invention from the above examples is based on the retention time stability of a physical property value called initial permeability at a constant heat treatment temperature of μi ≧ 500, and other practical saturation magnetic flux density values (Bs). And saturation magnetostriction (λs) and other magnetic characteristic values are specified.

[0026]

According to the Co _X Nb _Y Ta _Z Zr _W alloy of the present invention, in various magnetic heads using a conventional high magnetic flux density material, soft magnetic properties are deteriorated due to heat treatment at a high temperature such as low melting point glass processing. In contrast to the large restriction on the lower side, thermal stability that can maintain good soft magnetic characteristics even when subjected to heat treatment for a long time (several hours or longer) at a high heat treatment temperature of 450 ° C. or even 500 ° C. A high magnetic flux density soft magnetic alloy with excellent properties can be realized.

Therefore, according to the magnetic head using this material, the head processing yield is improved, and 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 Co-Nb-Ta-Z in an example of the present invention.
FIG. 4 is a time-temperature-transformation phase diagram (TTT phase diagram) obtained from a change in initial magnetic permeability when the r-based alloy is held at various temperatures.

FIG. 2 is a conventionally known Co—Fe—S film.
It is a TTT phase diagram (Bs> = 8000G) of an i-B type alloy.

FIG. 3 is a graph showing Co in an embodiment of the present invention._84.9Nb_5.6Zr
_3.7Ta_5.8And Co_82.9Nb _10.9Zr_4.0Ta_2.2To
About μ by isothermal heat treatment at 500 ℃_iThe subordinates of
It is the graph shown.

Claims (2)

[Claims] 1. A composition represented by Co _X Nb _Y Ta _Z Zr _W , wherein X + Y + Z + W = 1 in terms of atomic composition percentage.
00, X ≧ 82, 0.5 ≦ Y ≦ 12, 1.5 ≦ Z ≦ 8.5, W
<5 and within the range of 8.0 ≦ Y + Z ≦ 13.5, 450
A thermal stable high magnetic flux density amorphous alloy having a soft magnetic property of 500 or more as initial magnetic permeability and a saturation magnetic flux density of 8000 Gauss or more even after being subjected to heat treatment at ℃. 2. The heat stable high magnetic flux density amorphous alloy according to claim 1, wherein 9.5 ≦ Y + Z ≦ 13.5.