JPS607017B2 - magnetic alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nickel-iron magnetic alloy that is suitable for application to, for example, magnetic heads that require wear resistance and high magnetic flux density. This invention relates to a magnetic alloy that has improved hot workability without causing any damage.

Conventionally, as magnetic alloys for recording/reproducing magnetic heads, JIS
．． Mo permalloy, which is a PC grade permalloy, is often used.

Although it has excellent magnetic permeability, it has a hardness (
The disadvantage is that the magnetic tape has a low Hv of 120, and therefore the wear caused by the magnetic tape is extremely high and the service life is short. When the magnetic head wears out, the adhesion between the tape as a magnetic recording medium and the magnetic head decreases, and the gap depth of the magnetic head changes, causing a significant deterioration in recording and reproduction characteristics. In addition to the Mo permalloy mentioned above, there are also high hardness materials such as 16AI-Fe alloy as magnetic alloys for magnetic heads, but they generally have low magnetic permeability and
Moreover, it has the disadvantage of poor workability.

By the way, audio magnetic tapes have traditionally been made mainly of metal oxides, but with advances in performance, metal tapes (also called alloy tapes) made of new materials containing pure iron as a main component have been developed.

Although this metal tape has a high-density recording capacity, it has a large coercive force of about 1000 oersteds, so with conventional head materials, the head becomes saturated before the metal tape saturation level with a large input signal, making it difficult to produce sound. There is a problem that the image becomes distorted. Therefore, it cannot be expected to improve the maximum output level, which is an advantage of metal tape. For this reason, conventional magnetic heads with low saturation magnetic flux density cannot take advantage of the advantages of metal tape, and in order to be compatible with metal tape, saturation magnetic flux density B
A magnetic head with o of 7500 Gauss or more is required.

Conventional JIS. PC grade permalloy has a saturation magnetic flux density of 6
Since it is as low as 500 to 7000 Gauss, it is inappropriate as a recording/reproducing magnetic head alloy for metal tape. In view of this, the main object of the present invention is to provide a nickel-iron magnetic alloy having excellent magnetic properties, high hardness, and high magnetic flux density.

The alloy of the present invention has a weight ratio of 75 to 84.9% Nj and Ti.
o. 5-5%, CO. 0.03% or less and Mg0.001~
This magnetic alloy is characterized in that the remaining S content is 0.020% and the balance is Fe and impurities, and the amount of S remaining in the alloy is 0.003% or less.

Further, it is permissible for Si and M, which are used as deoxidizing agents, and Mn, which is used as a deoxidizing and desulfurizing agent, to be contained in a total amount of 2% or less.

In addition, the following percentages represent weight %. Among the above components, Ni exhibits excellent magnetic permeability within the range of 75 to 84.9%, but when Ni is less than 75%, the magnetic permeability decreases and 84.9% is less than 75%.
．． When it exceeds 9%, magnetic permeability and saturation magnetic flux density decrease.

Ti is effective for increasing hardness, and the effect appears when it is added in an amount of 0.5% or more.

If the amount of Ti is less than 0.5%, it is difficult to increase the hardness. As the amount of Ti increases, the hardness increases, but when it exceeds 5%, the saturation magnetic flux density decreases and the magnetic permeability also decreases. 1st
The figure is a characteristic curve diagram showing the relationship between the amount of carbon C added and the initial magnetic permeability. C is added as a dehydrogenation agent, and as the C content increases, the initial magnetic permeability i decreases. When the amount of C is 0.03% or more, the initial magnetic permeability is low and it cannot be put to practical use. Mg is added as a desulfurization agent to improve the hot workability of the present alloy, and must be added after sufficient desulfurization has been performed.

As for deoxidation, C deoxidation is the most effective in terms of improving magnetic properties. FIG. 2 is a diagram showing the relationship between test temperature and cross-sectional shrinkage rate in a tensile test for the alloy of the present invention. As shown in the figure, the cross-sectional shrinkage ratio of the Mg-added material is greater than that of the Mg-free material. The larger the cross-sectional shrinkage rate, the better the hot workability. This shows that hot workability is significantly improved by adding Mg. FIG. 3 shows the relationship between the Mg content, the initial magnetic permeability (i), and the cross-sectional shrinkage rate (test temperature: 1200° C.). As shown in the figure, the initial magnetic permeability ratio i decreases as the Mg content increases, and if the Mg content exceeds 0.02%, the ratio i becomes too low to be put to practical use. Further, the cross-sectional shrinkage rate increases as the M weight increases, and reaches a saturation value when the Mg amount is 0.02%. From the above, hot workability is significantly improved by adding Mg, and if the Mg amount is less than 0.001%, the effect of improving hot workability is small, and if it exceeds 0.020%, hot workability is significantly improved. The amount of Mg should be between 0.001 and 0.000, since it not only does not contribute to improvement but also lowers the magnetic properties, especially the initial permeability Buddha i.
A range of 0.020% is valid. Next, an example of the method for producing the alloy of the present invention will be explained.

Appropriate amounts of Ni, Fe, and Ti were melted in a vacuum using an appropriate melting furnace to create a compositionally uniform molten metal, and first an appropriate amount of C was added as a deoxidizing agent to perform sufficient deoxidation. After that, it is most effective to desulfurize by adding Mg in an amount of 10 to 3 ph to the amount of S in the molten metal. Since the purpose of desulfurization using Mg is to form MgS, it is sufficient to add Mg in an amount approximately equal to the amount of S in the molten metal, but Mg has a melting point of 6.
Since it is as low as 54oo, only 1/1 of the amount of Mg added remains in the melt wound and most of it evaporates, so as mentioned above, it is necessary to add Mg in an amount of 10 to 3 times the amount of S in the melt wound. be. The obtained molten metal is poured into a suitable mold to produce a sound ingot, which is then subjected to normal hot working and cold working to a thickness of 0.09 mm.
Rolled to 9 legs. In hot working, no selvage, cracks, etc. were produced, and hot workability was good. Then, a ring from the plate material on the 1st outer diameter side and 6th inner diameter side was punched out and used as a sample. These samples were held in a hydrogen atmosphere at 1100 oo for 3 hours and then cooled at a cooling rate of 2000 C'Hr. The saturation magnetic flux density B,o of each sample obtained in this way
Table 1 shows the results of measuring the coercive force Hc, initial permeability i, and hardness Hv. Table 1: As a result of analyzing the S content, the S content was 0.003% or less in all samples.

Next, in order to investigate the existence form of Mg in the alloy, line analysis was performed using an X-ray microanalyzer. The results are shown in Figure 4. As can be seen from FIG. 4, the positions where Mg-KQ and S-KQ reach their maximum coincide, and almost no fluctuation was observed in 0-KQ, confirming that MgS was formed. As described above, according to the present invention, since it is configured as described above, it has the effect of having excellent hot workability and hardness of Hv=150 or more, and high saturation magnetic flux density and excellent magnetic properties. . Therefore, by applying the alloy of the present invention to a recording/reproducing magnetic head for metal tape, the recording/reproducing characteristics are improved. It is also suitable for application to magnetic heads for high-speed repulsion such as electronic computers and VTRs.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between the amount of carbon added and the initial magnetic permeability i, Figure 2 is a diagram showing the relationship between the test temperature of the alloy of the present invention and the cross-sectional shrinkage rate in the tensile test, and Figure 3 is FIG. 4 is a diagram showing the relationship between the amount of magnesium, the initial magnetic permeability i, and the cross-sectional shrinkage rate. FIG. 4 is a diagram for explaining the existence form of Mg. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1 Nickel 75-84.9% by weight, titanium 0.5-5
An alloy containing 0.03% by weight or less (not including zero) of carbon and 0.001 to 0.020% by weight of magnesium, with the balance consisting of iron and impurities, and the amount of S remaining in the alloy is A magnetic alloy characterized in that the content is 0.003% by weight or less.