JP2018177568A - MANUFACTURING METHOD AND APPARATUS OF HIGH PERFORMANCE HIGH UNIFORM LARGE SCALE SINGLE CRYSTAL OF Fe-Ga BASE ALLOY - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a single crystal of an Fe-Ga based alloy, the manufacturing method being capable of stably manufacturing the single crystal having no crystal defect, no rough surface, no void and no crystallized product of a foreign component in a crystal even in a long-sized form, and an excellent magneto-striction property.SOLUTION: Provided is a manufacturing method of a single crystal of a high performance Fe-Ga base alloy, in which a raw material in a crucible is molten, a melt surface is over-cooled by 200°C or more, and an Fe-Ga base alloy is crystallized and lifted under a seed crystal while the over-cooling is maintained.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method and an apparatus for producing a high-performance, high-profile large Fe-Ga based alloy single crystal.

Since Fe-Ga based alloys exhibit large magnetostriction, they are attracting attention as materials used for actuators, vibration power generation, and the like. In addition, what substituted some Ga for example, for example, Al, Sn, etc. is contained in a Fe-Ga base alloy.
Since the magnetostrictive properties of this alloy largely depend on the chemical composition and crystal orientation, it is necessary to strictly control the chemical composition and crystal orientation.
Crystals with conventional compositions and orientations have been produced mainly by the rapid solidification method (patent document 1), the Bridgman method, and the abnormal grain growth method (non-patent documents 1 and 2).

The conventional methods described in the prior art described above make it difficult to produce inexpensive single crystals in large quantities.
In Patent Document 2, as shown in FIG. 2, the crucible is a double crucible comprising an outer crucible and an inner crucible disposed in the outer crucible, and a seed crystal is brought into contact with the raw material melt in the crucible. After that, there is provided a technique for pulling up the seed crystal to grow a single crystal. According to this technology, it is possible to manufacture large crystals with high precision and low cost in chemical composition and crystal orientation.

JP 2007-214297 A JP, 2016-28831, A

Y. -H. Yoo et al. : J. Applied Physics, 103 (2008), 07B 325, S. -M. et al. Scripta Mater. , 66 (2012), 307.

However, the above-described prior art also has the following problems.
(1) Crystal defects are likely to be introduced as the crystal lengthens. Rough skin occurs on the surface. It is easy for pores and foreign crystals to come into the crystal.
(2) The magnetostrictive characteristics have a variation of 50 to 350 ppmn.
Even when the crystal is blooming, using the automatic diameter control system may suddenly make it difficult to control. That is, there are cases in which stable crystal production is carried out.
Since the Fe—Ga single crystal is a solid solution single crystal, the crystal composition changes by segregation according to the solidification rate, and the magnetostrictive characteristics change.
As the crystal weight increases during crystal growth, the seed expands and the load cell receives an excessive signal, resulting in insufficient crystal diameter control.
There is a correlation between the magnetostrictive properties and the composition, and if the Ga concentration in the crystal is 15 to 17 at%, 250 ppm or more of the magnetostrictive properties can be obtained, but if segregation exceeds 50% due to the occurrence of segregation in the solidification process, the Ga concentration rises It becomes difficult to obtain good magnetostriction characteristics.
The present invention has no crystal defects even if it is long, has no surface roughening, has no pores and heterocrystals in the crystal, is superior in magnetostrictive properties to the prior art, and has variations in composition and hence magnetostrictive properties. It is an object of the present invention to provide a method and an apparatus for producing a high-performance, high-average-size large Fe-Ga based alloy single crystal capable of producing a single crystal with less variation in

In the invention according to claim 1, after melting the Fe-Ga based alloy raw material in the crucible, the Fe raw material is put into the melt according to the crystallization solidification rate, and the Ga concentration in the melt is controlled within a certain range. A method for producing a high-performance, high-average-size large Fe-Ga-based alloy single crystal characterized by performing pulling while.
The invention according to claim 2 separates the growth interface from the raw material supply surface, and the method for producing a high-performance, high-profile large Fe-Ga based alloy single crystal according to claim 1.
It is preferable to separate the growth interface and the material supply surface from the viewpoint of the influence on the growth interface, the liquefaction and diffusion of Fe, and the like when supplying the material.
The invention according to claim 3 is characterized in that the crucible is a double crucible of an outer crucible and an inner crucible, the growth interface is enclosed in the inner crucible, and the raw material supply surface is in the outer crucible. Method of manufacturing large Fe-Ga based alloy single crystal.
The double crucible also has the effect of blocking radiation to the seed and the grown crystal. This makes it possible to suppress the growth of the seed, to increase the thermal diffusion from the crystal, and to facilitate the growth of large diameter crystals.
The invention according to claim 4 is characterized in that the outer crucible is rotated, and the method for producing a high performance / high average large Fe-Ga based alloy single crystal according to claim 2 or 3.
It is preferable to rotate the outer crucible because liquefaction and diffusion of the Fe raw material that has been dropped quickly is performed.
The invention according to claim 5 is characterized in that the Ga raw material is simultaneously charged together with the Fe raw material, and the production of the high-performance high-profile large Fe-Ga based alloy single crystal according to any one of claims 1 to 4 Method.
By simultaneously introducing the Ga raw material, it is possible to reduce costs such as preparation of a long single crystal exceeding 300 mm in length and reduction of the initial raw material (reduction of the remaining raw material).
In addition, it also becomes easy to grow large-diameter crystals, which conventionally had to increase the amount of initial input material.
The invention according to claim 6 is
A heating chamber,
An outer crucible provided in the heating chamber;
It has a hole provided in the outer crucible and in communication with the melt in the outer crucible,
An inner crucible arranged to surround the growth interface,
A raw material continuous feeding device having a raw material inlet between the outer crucible inner wall and the inner crucible outer wall;
High-performance, high-average large Fe-Ga-based alloy single crystal manufacturing apparatus having a.

  According to the present invention, there is no crystal defect even if it is long, there is no surface roughening on the surface, there are no vacancies and heterocrystals in the crystal, magnetostriction characteristics are better than before, and composition variation It becomes possible to provide a method and an apparatus for producing a high-performance, high-average-size large Fe-Ga based alloy single crystal capable of producing a single crystal with less variation in magnetostriction characteristics.

It is a conceptual diagram which shows the example of the single crystal growth apparatus which concerns on the Example of this invention. It is a conceptual diagram of the conventional single crystal growth apparatus.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.
[Form of breeding apparatus]
FIG. 1 is a view for explaining a single crystal pulling apparatus according to a first embodiment of the present invention.
In this example, a heating chamber, and an outer crucible provided in the heating chamber,
An inner crucible provided in the outer crucible, having a hole communicating with the melt in the outer crucible, and arranged to surround the growth interface, and a raw material between the inner wall of the outer crucible and the inner wall of the inner crucible And a raw material continuous feeding device having an inlet.
In the present example, an alumina crucible is used as the outer crucible.
The inner crucible also uses an alumina crucible.

The present embodiment will be described in detail.
The inner crucible is disposed inside the outer crucible, and the inner wall of the inner crucible surrounds the growth surface. In addition, the bottom surface of the inner crucible is an inclined surface, and the bottom surface is provided with a hole communicating with the melt held in the outer crucible. When the bottom of the inner crucible is immersed in the melt of the outer crucible, the melt is introduced into the inside of the inner crucible. The inside of the inner wall of the inner crucible is the growth surface.
In the present example, the heating chamber is formed of a carbon heat insulating material 400. An outer crucible and an inner crucible are disposed in the heating chamber.
The heating chamber is further provided with an Fe (Ga) supply device.

The present embodiment will be described in more detail below.
(Inner crucible)
The inner inner crucible 18 is made of a high melting point material. Alumina is preferred.
In addition, magnesia or titanium nitride boron (BN) may be used.
The bottom surface of the inner crucible is an inclined surface, and the bottom surface is provided with a hole communicating with the melt held in the outer crucible. The inside of the inner wall of the inner crucible is the growth surface.

(Outside crucible)
The outer outer crucible 19 is made of a high melting point material. Alumina is preferred.
In addition, magnesia or titanium nitride boron (BN) may be used.
The outer crucible 19 has a bottom (bottomed) and has a side wall rising upward from the periphery of the bottom.

(Crucible support shaft)
The crucible support shaft 500 having a pedestal on which the outer crucible is placed is rotatable and can move up and down, and stirring of the melt by rotation and control of the depth of the melt in the inner crucible by moving up and down can be controlled.

(Automatic material supply device)
A predetermined amount of Fe raw material or Fe raw material and Ga raw material can be automatically dropped and supplied into the outer crucible, so that the raw material composition ratio in the melt can be controlled within a certain range, and for lengthening and enlargement It can also be used as a raw material additional supply device.

FIG. 2 is a view for explaining a conventional single crystal pulling apparatus.
The crucible was a double crucible consisting of an outer crucible (carbon susceptor) 19 and an inner crucible (alumina crucible) 18 disposed in the outer crucible 19, and the seed crystal 210 was brought into contact with the raw material melt 300 in the crucible. This is a single crystal growth apparatus for growing the single crystal 200 by pulling up the seed crystal 210 later.
The side surface of the inner crucible 18 and the side surface of the outer crucible 19 may be disposed in contact with each other or may be spaced apart. When separated, a single crystal with less variation in composition and crystal orientation can be obtained. From this viewpoint, the separation distance is preferably 1 mm to 10 mm, and more preferably 2 mm to 5 mm. Preferably, a spacer is provided between the bottom of the inner crucible 18 and the bottom inner surface of the outer crucible 19.

The conventional form will be described in detail.
A heating chamber 15 formed of a heat insulating material (refractory material) provided in the chamber 11, a crucible provided inside the heating chamber 15, and a heating coil 20 disposed on the outer periphery of the heating chamber 15; After bringing the seed crystal 210 into contact with the raw material melt 300 obtained by heating the crucible, the seed crystal 210 is pulled up to grow the single crystal 200.
After bringing the seed crystal 210 into contact with the raw material melt 300 in the crucible, the seed crystal 210 is pulled up to grow the single crystal 200.
The crucible is a single crystal growth apparatus comprising an inner crucible 18 for holding a raw material, and an outer crucible 19 arranged at a distance or not from the outside of the inner crucible 18.

The conventional form will be described in more detail below.
(Inner crucible)
The inner inner crucible 18 is made of a high melting point material. Alumina is preferred.
In addition, magnesia or titanium nitride boron (BN) may be used.

(Outside crucible)
The outer crucible 19 is made of graphite. Graphite is much cheaper than Ir. In addition, the heat generation efficiency for radio frequency (RF) is extremely good.
The outer crucible 19 has a bottom (bottomed) and has a side wall rising upward from the periphery of the bottom.

The height of the upper end (the top of the side wall) of the outer crucible 19 is set not higher than the upper end of the inner crucible 18 so that carbon gas or carbon particles generated when graphite generates heat are not mixed into the melt. . In the example shown in FIG. 2, the upper ends of the two are flush.
The inside diameter of the outer crucible 19 is preferably set as appropriate so that the entire outer surface of the inner crucible 18 and the entire inner surface of the outer crucible 19 are in contact with each other. Also in the bottom portion, it is preferable that the bottom inner surface of the outer crucible 19 be in contact with the bottom outer surface of the inner crucible 18 to slide the inner crucible 18 into the outer crucible 19 so as to be fittable.
If the inner surface of the outer crucible 19 and the outer surface of the inner crucible 18 are mirror finished, the inner crucible 18 can be easily slid into the outer crucible 19 and stored.
Although FIG. 2 shows an example in which the inner crucible 18 and the outer crucible 19 are disposed in contact with each other, the amount of Fe is more than Fe _0.80 Ga _0.20, or the required temperature is high due to the Ga substitution body. In this case, since the carbon and alumina react with each other, it is better to dispose the side wall of the inner crucible 18 and the side wall of the outer crucible 19 apart from each other.

An Fe—Ga single crystal was grown using a resistance heating type Czochralski furnace (CZ method) having an internal structure as shown in FIG.
Into an alumina crucible having an inner diameter of 130 mm, 5000 g of a raw material blended with 79 at% of Fe and 21 at% of Ga as a starting raw material was charged. The crucible made of alumina into which the raw material was charged was introduced into the growth furnace, the pressure in the furnace was set to a reduced pressure atmosphere, and argon gas was flowed at a flow rate of 1.0 L / min. Thereafter, the crucible was heated and gradually heated over 16 hours until the melting point of Fe—Ga was reached. Thereafter, the single crystal cut out in the (100) orientation was used as a seed crystal, and the seed crystal was lowered close to the melt. The seed crystal is gradually lowered while rotating this seed crystal at a speed of 4.0 rotations per minute, and the seed crystal is raised at a speed of 2.0 mm / h while bringing the tip of the seed crystal into contact with the melt and gradually lowering the temperature. While rotating the crucible at a speed of 2.0 rotations per minute, crystal growth was carried out while raising the crucible at a maximum speed of 0.39 mm / h so that the liquid surface position was always constant. In addition, Fe raw material was dropped into the crucible so as to be a total of 6.6 g per hour.
As a result, a single crystal with a diameter of 50 mm and a length of 200 mm in the straight body portion was obtained. The obtained crystals were free of surface irregularities and internal voids in all parts, and the magnetostrictive properties also exceeded 250 ppm.

(Conventional example)
Fe—Ga single crystals were grown using a high-frequency induction heating Czochralski furnace (CZ method) having an internal structure as shown in FIG.
Into an alumina crucible having an inner diameter of 130 mm, 5000 g of a raw material in which 80 at% of Fe and 20 at% of Ga were blended as a starting material was charged. The crucible made of alumina into which the raw material was charged was introduced into the growth furnace, the pressure in the furnace was set to a reduced pressure atmosphere, and argon gas was flowed at a flow rate of 1.0 L / min. Thereafter, the crucible was heated and gradually heated over 16 hours until the melting point of Fe—Ga was reached. Thereafter, the single crystal cut out in the (100) orientation was used as a seed crystal, and the seed crystal was lowered close to the melt. While rotating this seed crystal at a speed of 4.0 revolutions per minute, the seed crystal is dropped at a speed of 2.0 mm / h of actual growth while gradually lowering to bring the tip of the seed crystal into contact with the melt and gradually lowering the temperature. Crystal growth was performed.
As a result, a single crystal having a diameter of 50 mm and a length of 125 mm in a straight barrel portion was obtained. The obtained crystals had surface irregularities and internal voids in the range of 50 mm from the bottom, and the magnetostrictive properties were also less than 250 ppm in those places.

15 heating chamber 18 inner crucible 19 outer crucible 20 heating means (heating coil)
200 ingot (single crystal)
Reference numeral 210 seed crystal 300 raw material melt 400 carbon heat insulating material 500 crucible support shaft 600 carbon heater 700 automatic raw material supply device

Claims (6)

After melting the Fe-Ga based alloy raw material in the crucible, the Fe raw material is put into the melt according to the crystallization solidification rate, and pulling is performed while controlling the Ga concentration in the melt within a certain range. Of producing high-performance, high-quality large Fe-Ga based alloy single crystals. The method for producing a high-performance, high-average-size large Fe-Ga-based alloy single crystal according to claim 1, characterized in that the growth interface and the raw material supply surface are separated. The high-performance, high-average-size large Fe-Ga-based alloy single crystal according to claim 2, wherein the crucible is a double crucible of an outer crucible and an inner crucible, the growth interface is enclosed in the inner crucible, and the raw material supply surface is in the outer crucible. Manufacturing method. The method for producing a high performance / high profile large Fe-Ga based alloy single crystal according to claim 2 or 3, wherein the outer crucible is rotated. 5. The method for producing a high-performance, high-uniform, large Fe-Ga based alloy single crystal according to any one of claims 1 to 4, wherein Ga raw material is simultaneously charged together with Fe raw material. A heating chamber,
An outer crucible provided in the heating chamber;
It has a hole provided in the outer crucible and in communication with the melt in the outer crucible,
An inner crucible arranged to surround the growth interface,
A raw material continuous feeding device having a raw material inlet between the outer crucible inner wall and the inner crucible outer wall;
High-performance, high-average large Fe-Ga-based alloy single crystal manufacturing apparatus having a.

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