JPS59145760A - Free cutting alloy with high magnetic permeability - Google Patents

Abstract

PURPOSE:To obtain an alloy with high magnetic permealloy and superior grindability for the core of a magnetic head by adding specified amounts of Si, Al and Sn to Fe. CONSTITUTION:An Fe-Si-Al alloy consisting of 4-12wt% Si, 3-8wt% Al and the balance Fe is put in an alumina crucible after adding 0.05-6wt% Sn, and the alloy is melted in vacuum or a nonoxidizing atmosphere in a high-frequency induction furnace to manufacture an alloy with high magnetic permeability. The grindability of the alloy is considerably improved without deteriorating the magnetic characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a Fe-8i-AA magnetic alloy, and particularly to a high magnetic permeability alloy for magnetic and core applications that have poor grindability.

In general, the characteristics that magnetic materials for cores should have include good abrasion resistance against sliding of magnetic recording media;
The saturation magnetic flux density is high to completely magnetize the recording medium.
It has high magnetic permeability, which is related to magnetic sensitivity, low coercive force to prevent magnetization by the recording medium, and high corrosion resistance so that it can be used in any environment.

Conventionally, .zo-malloy, nftoferrite, etc. have been used as magnetic materials for magnetic helad cores, but .zo-malloy has poor wear resistance, and nftoferrite has the disadvantages of low saturation magnetic flux density. ing.

Recently, in the audio and VTR fields.

Metal chips are used as magnetic recording media with high recording density.

As vapor-deposited tapes and the like are becoming more widespread, and in the VTR field narrower tracks and narrower Gannog lengths are progressing, a magnetic head core phase with high saturation magnetic flux density and wear resistance is required. ing.

Therefore, magnetic alloys such as Fe-3i-p have recently been attracting attention as a magnetic material that compensates for the drawbacks of malloy and ferrite and also satisfies the above requirements. Although the Fe-8t-At magnetic alloy has excellent magnetic properties as a herad core material, it has a problem of poor grindability due to the inherent brittleness of the material.

In view of the above points, this invention has developed Fe-8i, which has good magnetic properties as a core phase and excellent grindability.
-The aim is to provide A7 alloy.

In this invention, Sn is added to Fe-81-A1 alloy consisting of 4 to 12% Si, 3 to 8% At, and the balance Fe.
It is characterized by the addition of 5 to 6 moles, which significantly improves free machinability without deteriorating magnetic properties.

Here, Sn improves the fluidity of the Fe-81-kL gold alloy molten metal and significantly reduces pinholes in the ingot. Furthermore, + Sn is + 'ri, Zr + Nb
+ Even if P, which is different from other elements such as platinum group elements, is added at 0.05 to 6%, the hardness hardly changes + Fe -SI
-Improves the inherent brittleness of At alloys.

The reason for setting the Sn amount to 0.05 to 6% is that if the Sn content is less than 0.005, the grindability is not improved, but if it is still more than 6%.

This is because Sn precipitates at grain boundaries, forming a two-phase mixed structure of soft grain boundary portions and hard matrix, which causes chipping and chipping, which impairs machinability and further deteriorates magnetic properties. The reason for setting Si to 4 to 12% and At to 3 to 8% is because magnetic properties deteriorate outside this range.

Next, embodiments of the present invention will be described.

To prepare a sample, first, Fe and Si of industrial purity are used.

Raw materials of Al, Sn, and other elements as necessary were mixed, and this was melted in an alumina crucible in a high frequency induction furnace in a vacuum or in a non-oxidizing atmosphere to obtain a sound ingot. From this ingot, there are 8 external diameter gates.

A ring-shaped sample with an inner diameter of 4 wrl and a thickness of 0.2 mm was fabricated by electrical discharge machining, and was subjected to magnetic property measurements. Furthermore, in order to evaluate the grindability, the width was 7 mm, the length was 100 mm,
One-pass creep molding of 5 mm x 2 ru was performed on a block-shaped sample with a thickness of 4 m++ as shown in FIG. A diameter of 30 mm was also used as a test piece for corrosion resistance testing.

A sample with a thickness of 5 mm was prepared and a corrosion resistance test was conducted. The evaluation method for each test is as follows.

1) Magnetic properties Effective relative permeability at 0, 3 kHz (tte (0,
3kHz)).

2) Load current value (A) applied to the surface grinder when forming one pack leaf 0 of 5 cabinets x 2 pans using grindable GCM stone.

The current value during idle operation (no load state) is 4A. As the load current value increases, the grinding resistance also increases, which impairs the grindability. Therefore, the smaller the load current value, the better the grindability.

3) Corrosion resistance An acid resistance test was carried out by immersing the test piece in a 20% hydrochloric acid aqueous solution (30°C) for 1 minute, and evaluation was made by the number of pitting corrosion occurring per 1 cm2 of the test piece. For various compositions,
Table 1 shows the results of the above test.

As a comparative example, a Fe 5i-At alloy containing no Sn and Nb, Ti, Co, W, and Sb were used.
The case where . From Table 1, Nb +
Ti+'Co, W.

The load current value when sb is added is high in both cases with no additive (flat 1) and υ, which impairs grindability, and in the case of Ti addition (flat 3), it even reaches IOA.

Margin below Table 1 On the other hand, the load current values of plates 7 to 13 to which Sn is added are as follows.

In all cases, it is less than 6 A of flat plate 1, and in particular flat plate 10 with 2 pieces of Sn added has good magnetic properties and a load current value of 4.5 A, which indicates that the grinding process is good. FIG. 2 shows the relationship between the amount of Sn added, the load current value, and the effective magnetic permeability. In the case where Sn was added by more than 6%, it was difficult to prepare a test piece due to the severe cracking and chipping described above, so it could not be used for testing.

From Table 1 and Figure 2, when +3% or more of Sn is added, the load current value does not change and only the effective magnetic permeability decreases.

It can be seen that the most preferable upper limit of the amount of Sn added in the alloy of the present invention is 3%.

When 2% Sn is added to an alloy containing 1% and 2% TI, which significantly increases the load current value, the load current value is halved (see Comparative Example 3 and Example 14.15).

From this, it can be seen that S
It can be seen that the addition of ni significantly improves grindability.

As described above, according to the present invention, it is possible to obtain an alloy having a high magnetic permeability without being concerned about grinding processability and corrosion resistance since it is configured as described above. Therefore, the alloy according to the present invention is suitable for use in parts that undergo precision processing, such as magnetic head materials.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a sample that has been subjected to grinding processing.

Claims (1)

[Claims] 1. Si 4-12%, A23-8% by weight. A free-machining high permeability alloy characterized by comprising 0.05 to 6% Sn and the remainder substantially Fe.