JPH0196097A - Process for growing single crystal of fe-si-al system alloy - Google Patents

Abstract

PURPOSE:To obtain the satisfactory title single crystal of large crystal size contg. scarcely segregation in the compsn. of the alloy by setting in a heating furnace a polycrystalline rod of a specified Fe-Si-Al system alloy contained in a crucible, melting the rod by heating, then moving the rod slowly in the longitudinal direction of the rod. CONSTITUTION:Each specified amt. of each starting material 8 comprising Fe, Si, and Al having high purity is weighed and charged to an Al2O3 crucible 9 in a vacuum melt casting device, and melted in vacuum or in nonoxidizing atmosphere by heating with an induction coil 10. The crucible 9 is then moved in the directions (a), (b), (c) as shown by arrow marks, and the melt 14 is poured into an iron mold, and a polycrystalline rod 11 of Fe-Si-Al alloy is obtd. The rod 11 is then housed in a Tammann tube 20 serving as an Al2O3 crucible and introduced into a carbon heater 30 tied with Mo wire, and fixed in a pressurizing furnace 40 of an induction heating device 50 interposing an upper chuck 13 and a lower chuck 12. The inside of the furnace 40 is evacuated or replaced with nonoxidizing atmosphere such as Ar, etc., and the content in the crucible is melted by heating (A) with an induction heating coil 21. The crucible is cooled by moving slowly in the direction of arrow mark B while rotating the carbon heater 30, forming thus a single crystal.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to Fe-8 used in magnetic products such as magnetic heads.
The present invention relates to a method for growing an i-Al alloy single crystal, and particularly to a method for growing an Fe-8i-AI alloy single crystal suitable for forming a good single crystal with a large diameter and less segregation of alloy composition.

[Conventional technology]

Fe-8i-Al magnetic alloy (registered trademark Sendust) is an alloy with extremely high magnetic permeability and high hardness, and is used as a material for magnetic heads for audio, VTR, or R-DAT. There is.

[Problem that the invention seeks to solve]

However, the above-mentioned Fe-8i-Al magnetic alloy is a polycrystalline material, and therefore, when used as a magnetic head material, it is difficult to attach to the magnetic tape due to the plane orientation of the crystal grains present during the formation of the gears and plates of the magnetic head. Due to variations in magnetic force or the presence of grain boundaries, mutual bonding strength is weakened and the mechanical strength is weak, resulting in problems such as chipping, chipping, and cracking during grinding and cutting.

On the other hand, the single crystal of the Fe-8i-Al alloy has strong mechanical strength because there are no grain boundaries, and by selecting a fixed plane orientation, the variation in magnetic force to the magnetic tape is reduced. Although it is known to improve wear resistance,
The t11100 growth was not sufficient, the diameter of the single crystal formed was small, and segregation occurred in the alloy composition, so the effect of single crystal property (i) could not be obtained and it was not suitable for production.

For example, in general, when growing using the electron beam belt melting method, if you try to increase the diameter of the sample, the molten material during the growing may flow out, or compositional segregation due to evaporation will increase.
In addition, in general, when growing by the Bridgman method, the sample in the crucible is melted at normal pressure and gradually cooled, so compositional segregation due to evaporation becomes large.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention aims at a method for growing Fe-Si-Aj'-based magnetic alloy crystals having a large diameter and low alloy composition segregation.

[Means and effects for solving the problems] In order to solve the above problems, the present invention uses Fe.

A step of producing a polycrystalline rod of Fe-5t-Al alloy by heating and melting the raw material of S r s Al in a non-oxidizing atmosphere, a step of storing the polycrystalline body in a crucible, and a step of storing the polycrystalline body in a crucible. a step of placing the crystal and the crucible in a pressure furnace; a step of melting the polycrystal with a heating means; and a step of relatively displacing the heating means and the polycrystal along the longitudinal direction of the polycrystal. Gradually move it to Fe-8i-A! This is a method for growing Fe-8t-Al alloy 1j crystals, which comprises a step of growing a single crystal of the alloy.

By using the above rr formation method for the Fe-5i-Al alloy t-1 crystal, the diameter of the formed single crystal can be increased,
Further, a Fe-Si-Al alloy single crystal having a uniform composition with little compositional segregation is formed.

〔Example〕

“Next, an example of the t1 formation method of Fe-5i-Al alloy single crystal according to the present invention will be explained. Fig. 1 is a flow chart from raw material to growth. This example will be described according to this flow chart. First, , high purity raw materials such as Fe 99.98%, Si 99, 999%, Al
Use 99.999%.

Next, the above raw materials were mixed with F e 83.5%, Si 9.5%, A
These weighed Fe were weighed at a rate of l6.0%.

The S s % Al raw material is placed in an alumina crucible 9 of a vacuum melting and casting apparatus shown in FIG. 2, and heated and melted (molten metal 14) using a high frequency filter 10 in a vacuum state (1) or in a non-oxidizing atmosphere in an inert gas. Next, the molten metal 14 in the alumina crucible 9 is cast into an iron mold to create a polycrystalline round bar sample 11 as shown by arrows A, C, and C in FIG. As shown in FIG. The carbon heater 30 containing 11 is placed before high-pressure high-frequency induction, which is a single crystal growth device!!A
Set it in the device 50. The high-pressure, high-frequency induction heating device 50 includes an upper chuck 13 and a lower chuck 12 that fix the carbon heater 30 within the casing 40, and a high-frequency heating coil 21 disposed around the carbon heater 30. The above device 50 further includes an upper sample rotation vertical drive section 24 and an upper sample rotation vertical drive section 25 that rotate the carbon heater 30 externally.
1 Ar gas cylinder 41 that supplies Ar (argon) gas into the class 40, a rotary pump 42 that makes the interior of the class 40 a vacuum, a pressure gauge 43 that measures the pressure inside the class 40, an electric LfX 44 of the high-frequency heating coil 21, and a furnace. A copper pipe 4 arranged around the outer circumference of the furnace 40 and cooling the outside of the furnace 40 with a water flow.
5. In addition, for the sake of explanation, the carbon heater 30,
The diagrams of the crucible 20, sample t111, and high-frequency heating coil 21 are enlarged compared to the furnace 40.

After setting the carbon heater 30 containing the round bar sample 11 and the crucible 2° in the device 50 mentioned above, the inside of the furnace 40 is emptied to an appropriate atmosphere using the rotary pump 42, and then heated with an Ar gas cylinder 41. Ar gas is supplied into the furnace 40, and the inside of the furnace is pressurized to, for example, 1 atm, 5 atm, or 10 atm. Next, a high frequency current is passed through the high frequency heating coil 21, and the carbon heater 30 near the high frequency heated coil 21 is heated.
The temperature of the round bar sample 11 is increased, and the heat is transmitted through the crucible 20 and melts a part of the round bar sample 11 to form a melted part A.

At this time, the upper sample rotating vertical drive unit 24 is driven to rotate the carbon heater 30, and at the same time the crucible 20 and the round bar sample 11 are rotated to make the temperature distribution uniform. Next, the fourth
In the state shown in the figure, the upper sample rotating vertical drive section 24 is driven to rotate the carbon heater 30 and gradually move it downward as shown by arrow B, thereby cooling the melted part A and forming a single crystal. Here, a part of the round bar sample corresponding to the high frequency heating coil 21 forms a new melted part, but the carbon heater 3
When 0 moves further in the B direction, the molten part is cooled and a single crystal is formed. In this way, the carbon heater 30 is moved by the drive unit 24 until the high-frequency heating coil corresponds to the upper part of the round bar sample 11, and then the Ar gas in the tilt 40 is removed, and the rotary pump 42 is used to evacuate the carbon heater 30, which is then evacuated to normal pressure. , take out the single crystallized round bar from the furnace 40,
The Y1 formation of the t11 crystal is completed.

FIG. 5 shows a second embodiment of the method for growing a Fe5i-Al alloy single crystal according to the present invention. In this embodiment, the carbon heater 30 is fixed and the high frequency heating coil 21 is moved. In the figure, 44 is a power source for the high frequency heating coil 21, and 45 is a vertical drive unit that moves the high frequency heating coil up and down.

In the above-mentioned growth, the inside of the furnace 40 is pressurized with Ar gas as described above, and this prevents the molten material in the molten part of the round bar sample 11, especially Al, from evaporating and prevents compositional segregation. It is decreasing. Furthermore, the existence of the crucible 20 prevents the melted portion of the round bar sample 11 from flowing out, and by appropriately selecting the diameter of the crucible 20, a large diameter single crystal can be formed.

In addition, the lower chuck 12 and the lower sample rotating vertical drive unit 2
5 is used when the carbon heater 30 is fixed or rotated together with the upper chuck part 13, etc., or when it is fixed or rotated only at the lower part, and is unnecessary when it is fixed or rotated only at the upper part as in the embodiment. becomes.

The carbon heater 30 is used to prevent the crucible 20 from cracking due to the round bar sample 11 being heated and melted by the high-frequency heating coil 21 and the melt coming into contact with the low temperature crucible 20. It can be omitted depending on the material selection. Moreover, the round bar sample 1 is heated by the high frequency heating coil 21.
Although a part of 1 is melted, the composition segregation due to gravity is less than when the whole is melted, but the composition segregation due to evaporation is also reduced, and the case where the whole is melted is also included in the present invention. It is.

〔Effect of the invention〕

As mentioned above, the method for growing the Fe-8i-Al alloy single crystal according to the present invention involves heating and melting the raw material of F'e1S 11Al in a non-oxidizing atmosphere to produce a polycrystalline rod of the Fe-8i-Al alloy. a step of storing the polycrystalline rod in a crucible; a step of installing the polycrystalline rod and the crucible in a pressure furnace; a step of melting the polycrystalline rod with heating means; and a step of melting the polycrystalline rod with heating means. The method consists of the step of growing a single crystal of Fe-8i-Al alloy by gradually moving the means and the polycrystalline rod relatively along the longitudinal direction of the polycrystalline rod, so that the diameter of the crucible can be adjusted at an appropriate time. By selecting Fe-8i-Al, it has a large diameter, and since it is grown under pressure, it can produce good Fe-8i-Al with less segregation of alloy composition.
This produces effects such as the ability to grow single crystals of the system alloy.

[Brief explanation of the drawing]

Fig. 1 to Fig. 4 are all Fe-8i-A according to the present invention.
The first example of the method for growing single crystals of I-series alloys is shown. Figure 1 is a flowchart from raw materials to growth, Figure 2 is a schematic diagram of a vacuum melting and casting apparatus, and Figure 3 is a polycrystalline round bar sample. Fig. 4 is a schematic diagram of a high-pressure high-frequency heating device, and Fig. 5 shows a second embodiment of a single crystal of Fe-8t-Al alloy according to the present invention. FIG. 1 is a schematic diagram of a high-pressure high-frequency heating device. 11... Round bar sample 20... Crucible 21
...High frequency heating coil 50.51...High pressure high frequency induction heating device Fig. 1 Fig. 2 Fig. 3 Fig. 4

Claims (1)

[Claims] A step of heating and melting raw materials of Fe, Si, and Al in a non-oxidizing atmosphere to produce a polycrystalline rod of Fe-Si-Al alloy, and a step of storing the polycrystalline rod in a crucible. a step of installing a polycrystalline rod and a crucible in a pressure furnace; a step of melting the polycrystalline rod with a heating means; and a step of moving the heating means and the polycrystalline rod relative to each other along the longitudinal direction of the polycrystalline rod. A method for growing a single crystal of an Fe-Si-Al alloy, which comprises a step of growing a single crystal of an Fe-Si-Al alloy by gradually moving the crystal to a single crystal.