KR20090004505A - Manufacturing process for aluminium-lithium alloy target and aluminium-lithium alloy target - Google Patents

Abstract

A manufacturing method of an aluminum-lithium alloy target is provided to suppress the generation of abnormal discharge during film formation of a sputter, stabilize the film formation rate, and uniformize the film thickness distribution by manufacturing an aluminum-lithium alloy target in which impurities and inclusions are less contained, and which has a uniform composition distribution range, and an aluminum-lithium alloy target manufactured by the same is provided. In a manufacturing method of an aluminum-lithium alloy target for sputtering formed in an aluminum single phase, the manufacturing method of the aluminum-lithium alloy target comprises: a first process of melting aluminum in a crucible(12) installed inside a melting furnace(10) maintained to a vacuum atmosphere or an inert gas atmosphere; a second process of coercively dipping a lithium ingot(22) into an aluminum melt in the crucible and stirring the lithium ingot with the aluminum melt; a third process of pouring an aluminum-lithium alloy melt in the crucible into a mold; and a fourth process of performing structure control of the aluminum-lithium alloy ingot.

Description

Manufacturing process for aluminum-lithium alloy target and aluminum-lithium alloy target

The present invention relates to a method for producing an aluminum-lithium alloy target for use in a spattering apparatus and an aluminum-lithium alloy target produced using the method.

Organic electroluminescent (organic EL) devices are required to have high light emission efficiency and high luminance, and high environmental stability. As a material satisfying such a requirement, an Al-Li (aluminum-lithium) -based alloy is known. As described below, Patent Document 1 describes that the electron injection electrode (cathode) of the organic EL device is composed of a spatter film of an Al-Li alloy.

However, uniformity is strongly demanded as a spattering target. Specifically, it is desired that the alloy elements are uniformly dispersed, have few impurities, have few inclusions, have a uniform crystal structure, have a good resistance value distribution, and the like. In an alloy system in which a material (lithium), which is easy to react with oxygen, nitrogen, and moisture, is used as an additive element, such as an Al-Li alloy, a refractory used for suppressing slug formation, suppressing moisture, melting furnace, and jig at the time of alloying It is necessary to suppress the reaction with.

As a conventional Al-Li alloy manufacturing method, Al-Li alloy manufacturing method (refer patent document 2) by air melting, and Al-Li alloy manufacturing method (refer patent document 3) by vacuum melting are known. Further, Patent Documents 4 and 5 disclose methods for producing single crystal targets of aluminum-based alloys for achieving uniform distribution of concentration by performing addition amount of additive elements, casting control or solidification control of molten metal.

Patent Document 1: Japanese Patent Application Laid-Open No. 11-329746

Patent Document 2: Japanese Patent Application Laid-Open No. 6-47697

Patent Document 3: Japanese Patent Application Laid-Open No. 6-330203

Patent Document 4: Japanese Patent Application Laid-Open No. 7-300667

Patent Document 5: Japanese Patent Application Laid-Open No. 11-12727

Conventionally, Al-Li alloys have been mainly developed for aircraft applications, and development of melt casting technologies such as atmosphere control, refractory selection, examination of molten metal cleaning methods, and lithium addition methods have been advanced. Therefore, ingots for the high purity and low inclusion content spattering target required for thin film production were not produced.

It is natural to suppress the formation of compounds with impurities in the dissolving material in order to make a high purity ingot for the spattering target for thin film fabrication, but it is necessary to suppress the reaction of lithium with oxygen, nitrogen and moisture in the atmosphere. Lithium has an extremely low melting point of 180 DEG C and a specific gravity of 0.53 g / cm 3, which is the lightest element in the metal. In addition, lithium easily reacts with oxygen and nitrogen, and forms hydroxide easily by the presence of moisture. For this reason, melting for aluminum and lithium alloying is very difficult.

When melting for aluminum alloying is performed in the air, a method of dispersing the material in a crucible and heating and dissolving the material or dispersing the material in a molten aluminum to increase the contact efficiency between the aluminum and the alloying material. ought. However, the specific gravity is about one fifth of aluminum, and the alloying dissolution of metal lithium and aluminum which is very active in oxygen and moisture is not preferable because lithium oxidation occurs and alloying is inhibited.

On the other hand, in the process of cooling solidification, if lithium cannot be dissolved in the aluminum crystal phase, lithium is generated or precipitated as AlLi (β phase) at grain boundaries outside the aluminum crystal phase. In this case, it is difficult to produce the spattering target by processing the ingot because the plastic workability of the ingot is remarkably reduced, forging to a plate shape, or cracking or cracking (cracking near the edges) occurs during rolling. Done. In addition, in the target obtained from the ingot in which the molten Al-Li alloy is poured into the die, when AlLi (β phase) is generated or precipitated outside the aluminum crystal phase, it becomes a two-phase mixed region having a different specific resistance, thereby forming a spatter film ( This can cause abnormal discharge during formation. Therefore, it is necessary to determine the upper limit of the Al-Li alloy lithium content in which AlLi (β phase) generation or precipitation is extremely small.

SUMMARY OF THE INVENTION In view of the above-described problems, an object of the present invention is to provide a method for producing an aluminum-lithium alloy target having a homogeneous compositional distribution with a small content of impurities and inclusions and an aluminum-lithium alloy target.

In solving the above problems, the present invention relates to a method for producing an aluminum-lithium alloy target for spattering, which becomes an aluminum single phase, comprising: an agent for dissolving aluminum in a crucible installed in a melting furnace maintained in a vacuum atmosphere or an inert gas atmosphere. A first step, a second step of forcibly immersing a lithium ingot into the molten aluminum in the crucible, and a third step of injecting an aluminum-lithium alloy melt in the crucible into a mold, and the aluminum-lithium alloy ingot It is characterized by having a 4th process of controlling the organization | tissue.

In the first step, aluminum is dissolved in a crucible in a melting furnace maintained in a vacuum atmosphere or an inert gas atmosphere. Next, in a 2nd process, lithium ingot is forcibly immersed in aluminum molten metal and stirred. By dissolving lithium in the melting furnace, lithium oxidation at the time of alloying is suppressed, and generation of lithium-containing compound slug is prevented. In addition, by forcibly immersing and stirring lithium in the molten aluminum, generation of a concentration difference caused by the specific gravity difference between aluminum and lithium is prevented, and lithium is uniformly dispersed in the molten aluminum.

The second step includes a step of immersing the tip end of the graphite flanger in which the lithium ingot is fixed in the crucible, and a step of rotating the flanger to stir the molten metal. Lithium ingots are housed in a case made of aluminum. This case is melt | dissolved with lithium ingot in aluminum molten metal. The flanger is waiting directly above the crucible, and during the melting of aluminum, a heat shield plate is installed between the crucible and the flanger to prevent dissolution of lithium by radiant heat during the first process. The stirring of the molten metal is performed by the rotational motion around the axis of the flanger.

In order to obtain the Al-Li alloy target for spattering which becomes an aluminum single phase, it is preferable that lithium addition amount is 3 weight% or less. Here, the Al-Li alloy, which becomes a single phase of aluminum, means an Al element and a Li element solid solution. According to the Al-Li equilibrium diagram, the maximum solid solution limit of metal Li to metal Al is 4% by weight at about 600 ° C. However, the maximum solid solubility limit of metal Li decreases with the solubility curve with decreasing temperature. Therefore, at Li addition amount more than the maximum employment limit, AlLi ((beta) phase) crystallization to an aluminum phase at the time of solidification, and precipitation from a supersaturated solid solution cannot be prevented. When such crystallization or precipitation is performed, plastic workability deteriorates and processing precision falls. In addition, from the viewpoint of spattering targets, the presence of a mixed composition of two phases having different specific resistances causes abnormal discharge, resulting in unstable film formation and deterioration in film thickness distribution. For the above reasons, the amount of lithium added is 3% by weight or less.

In the third step, the crucible is tilted and moved in the melting furnace, and molten aluminum-lithium alloy is injected into the mold in a mold provided adjacent to the crucible. In a melting furnace maintained in a vacuum atmosphere or an inert gas atmosphere, aluminum dissolution, lithium addition and dissolution, and mold injection are performed consistently, thereby making it possible to obtain an Al-Li alloy ingot having extremely low foreign substances such as lithium oxide, nitride, or hydroxide. . Moreover, in order to suppress precipitation of the inclusion in an aluminum phase, it is preferable to solidify at an appropriate cooling rate. For example, it is preferable to use a material having high thermal conductivity such as copper as the mold, as well as to inject molten metal while forcibly cooling the mold.

In the fourth step, control of the structure of the produced aluminum-lithium alloy ingot is performed. The ingot texture control corresponds to a forging step including rolling or extrusion for processing into a desired target shape, and a heat treatment step for removing internal stress or adjusting crystal structure. These process temperatures are preferably performed at a temperature lower than the process temperature for the purpose of preventing the deposition of lithium inclusions in the aluminum phase, and are specifically carried out at a temperature condition of 550 ° C. or less.

As described above, the manufactured aluminum-lithium alloy target has a low content of foreign matter and inclusions and a homogeneous aluminum single phase structure in which the composition distribution is within ± 5%. Therefore, occurrence of abnormal discharge is suppressed at the time of spatter deposition, and stabilization of the deposition rate and uniformity of the film thickness distribution can be attained.

As described above, according to the present invention, an aluminum-lithium alloy target having a low content of foreign matter and inclusions and a homogeneous compositional distribution can be obtained.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to drawings.

1 is a schematic cross-sectional view showing the configuration of a melting furnace 10 applied to a method for producing an aluminum-lithium (Al-Li) alloy target according to an embodiment of the present invention. The melting furnace 10 includes a vacuum chamber 11 having an exhaust port 11c connected to a vacuum pump (not shown), a crucible 12 provided inside the vacuum chamber 11 (melting chamber), and the crucible The flanger 13 located just above (12) is provided.

An aluminum block 21 is charged in the crucible 12, and a lithium ingot 22 is supported at the tip of the flanger 13. The inside of the vacuum chamber 11 is adjusted to the predetermined vacuum atmosphere or the atmosphere substituted with inert gas. As will be described later, the melting furnace 10 dissolves the aluminum block 21 in the crucible 12, and then dissolves the lithium ingot 22 by immersing the tip end of the flanger 13 in the molten aluminum.

The crucible 12 is a cylindrical cylinder made of graphite and is housed in the movable container 14. In the movable container 14, the fire resistant holding member 16, in which the coil 15 is recommended at the outer circumferential part, is fixed, and the crucible 12 is housed inside the holding member 16. The holding member 16 is made of, for example, carbon. The movable container 14 is rotatably provided with respect to the base member 17 via the rotation shaft 18. The crucible 12, the holding member 16 and the aluminum block 21 are heated by energizing the coil 15.

The rotation shaft 18 is connected to a rotating mechanism (not shown) provided outside the vacuum chamber 11, and is configured to rotate the movable container 14 with respect to the base member 17. As shown in FIG. Alternatively, the movable container 14 may be pressure-operated to rotate the movable container 14 around the rotating shaft 18.

A lip 12A serving as an oil inlet is formed at the minimum rotational radius position of the crucible 12 opening peripheral portion. In the other area | region of the opening part of the crucible 12, the support rod 12B which has substantially the same projecting height as the lip 12A is attached in multiple lines. The supporting rod 12B is made of a material that can withstand relatively thermal shocks such as graphite and stainless steel.

And the heat shield 19 is mounted on the tip of these lip 12A and the support rod 12B. The heat shield plate 19 is for preventing the lithium ingot 22 from being dissolved by radiant heat when the aluminum block 21 is dissolved. The heat shield plate 19 is made of, for example, graphite, and is configured to selectively obtain a position at which the crucible 12 opening is shielded and a position at which the crucible 12 opening is opened. Specifically, for example, movement control of the shielding plate 19 can be performed using a manipulator (not shown).

The flanger 13 is formed from the compressed graphite material. The flanger 13 is connected to a drive mechanism (not shown) provided outside the vacuum chamber 11, and is configured to enable vertical movement along its axial direction and rotational movement around its axis.

An aluminum case 23 containing the lithium ingot 22 is supported on the tip portion 13A of the flanger 13. The case 23 is formed by, for example, deforming a thin or sheet-like thing into an appropriate shape. Suitably, the lithium ingot 22 is vacuum enclosed inside the case 23. In the present embodiment, the case 23 is supported by the front end portion 13A of the flanger 13 using an aluminum wire 24. In addition, the case 23 and the wire 24 are formed with the same purity as the aluminum block 21.

A mold 25 is provided inside the vacuum chamber 11. The mold 25 is installed adjacent to the movable container 14, and accommodates the Al-Li alloy molten metal which flows out of the crucible 12 through the lip 12A in a rotational motion around the pivot shaft 18. At the same time, it solidifies and forms an Al-Li alloy ingot of a predetermined shape. The mold 25 includes a cooling plate 26 having a cooling water circulation mechanism therein, a formwork 27 installed on the cooling plate 26, and a thin carbon sheet provided between the cooling plate 26 and the formwork 27. (28) is provided. The shape and height of the formwork 27 are not specifically limited, It selects suitably according to the ingot shape to form, such as a circle or a rectangle. The carbon sheet 28 is provided for the purpose of preventing the mold separation of the ingot from falling after the injection of the mold.

Next, the manufacturing method of the Al-Li alloy target of this embodiment using the melting furnace 10 comprised as mentioned above is demonstrated. 2A to C are schematic diagrams of main steps for explaining a method for producing an Al-Li alloy target of the present embodiment.

(First process)

First, the aluminum block 21 is charged into the crucible 12. The higher the purity of the aluminum block 21 is, the more preferable is, for example, one having a purity of 99.99% (4 nine) or more. As long as a required amount of molten metal is obtained, the shape and number of the aluminum blocks 21 are not particularly limited.

On the other hand, the case 23 which accommodated the lithium ingot 22 inside is supported by 13 A of front end parts of the flanger 13. As shown in FIG. The higher the purity of the lithium ingot 22 is, the better. For example, a purity of 99.9% (3 nine) or more is used. The case 23 is fixed to the tip end portion 13A of the flanger 13 by using an aluminum wire 24. However, the case 23 is not limited to this, and the case 23 is fixed by engaging with the tip end 13A. good.

Next, the inside of the vacuum chamber 11 (dissolution chamber) is evacuated and kept at a predetermined vacuum degree. The melting chamber pressure is not particularly limited, but from the viewpoint of preventing oxidation reaction of aluminum and lithium at the time of melting, the vacuum degree is preferably higher, and is set at a pressure of 1.33 kPa (10 ^-2 Torr) or less, for example. do.

On the other hand, the melting chamber atmosphere is not limited to a vacuum atmosphere, and may be an atmosphere substituted with an inert gas such as argon (Ar). In this case, once the inside of the vacuum chamber 11 is evacuated to a predetermined pressure, argon gas is introduced into the vacuum chamber 11. The pressure of the melting chamber at this time is set to a pressure lower than atmospheric pressure.

After the pressure adjustment of the vacuum chamber 11 is completed, a heat shield plate 19 is installed above the crucible 12, and the coil 15 is energized to control the crucible 12. The crucible 12 heating temperature is set higher than the aluminum melting point (about 660 ° C.). As a result, the aluminum block 21 is dissolved in the crucible 12.

In this embodiment, since the aluminum block 21 is melt | dissolved in the atmosphere cut | disconnected with air | atmosphere, aluminum reaction can be suppressed at the time of melt | dissolution, and aluminum molten metal with few impurities, such as an oxide, can be obtained.

Moreover, since the lithium ingot 22 has a melting point (180 degreeC) lower than aluminum, there exists a possibility that the lithium ingot 22 may melt | dissolve by the radiant heat at the time of aluminum block 21 melt | dissolution. However, in this embodiment, since the upper part of the crucible 12 can be covered by the heat shielding plate 10 when the aluminum block 21 is dissolved, the radiant heat from the crucible 12 does not reach the case 23, and thus the lithium ingot ( 22) Dissolution can be avoided.

(Second process)

Subsequently, dissolution for alloying aluminum with lithium is performed (FIG. 2A). In this step, first, the heat shield plate 19 covering the upper portion of the crucible 12 is removed. Then, the flanger 13 is lowered by a predetermined amount, and the tip portion 13A is immersed in the molten aluminum to dissolve the lithium ingot 22. In this case, the aluminum case 23 and the wire 24 are also dissolved together.

Subsequently, the flanger 13 is rotated about its axis to stir the molten metal 20 in the crucible 12 (FIG. 2B). The stirring action can be mainly obtained by the shape effect of the flanger tip portion 13A. In this embodiment, 13 A of flanger tip parts are formed in the shape which protruded the protrusion (wing | blade) in the several places of the outer peripheral part, and large stirring action can be obtained only by the rotation of the flanger 13. As shown in FIG.

In this embodiment, since the addition of the lithium ingot 22 to the molten aluminum is performed in the vacuum chamber 11 adjusted to atmosphere, lithium oxidation etc. at the time of alloying are suppressed, and generation | occurrence | production of lithium containing compound slug is suppressed. I can prevent it. In addition, since the lithium ingot 22 is forcibly immersed in the aluminum molten metal and stirred in the same manner as described above, occurrence of a concentration difference caused by the difference in specific gravity between aluminum and lithium is prevented, and lithium is contained in the aluminum molten metal. It can disperse | distribute uniformly. Furthermore, since the crucible 12 is made of graphite, it is possible to prevent intrusion into the crucible 12 from the molten aluminum surface containing lithium, thereby suppressing the production of a lithium-containing compound.

Therefore, it is preferable that the Al-Li alloy used as the spattering target is an aluminum single phase from the viewpoint of plastic workability and film formation characteristics in use. Al-Li alloy which is a single phase of aluminum means a solid solution of Al element and Li element. When the alloy structure becomes polyphase, the compositional distribution (concentration distribution) of the additional elements is increased, and the plastic workability is lowered. In addition, due to the presence of a mixed composition of two phases having different specific resistances, resistance distribution occurs on the target surface, resulting in abnormal discharge, and stabilization of film deposition rate and uniform film thickness distribution cannot be achieved.

In order to obtain the Al-Li alloy target for spattering which becomes an aluminum single phase, it is preferable that lithium addition amount is 3 weight% or less on the basis of the alloy whole component. In this embodiment, the lithium ingot 22 addition amount becomes 3% or less of the total weight of the aluminum block 21, the case 23, the wire 24, and the said lithium ingot 22. As shown in FIG.

Fig. 3 schematically shows an Al-Li-based equilibrium diagram (Source: "BINARY ALLOY PHASE DIAGRAM" Second Edition, T. B Massalski, ASM INTERNATIONAL ISBN: 0-87170-404-8). The maximum employment limit of lithium for aluminum is 496% at 596 ° C. However, the maximum employment limit of lithium decreases with the solubility curve (SC) with decreasing temperature. Therefore, at the amount of lithium added above the maximum employment limit, it becomes impossible to prevent AlLi (β phase) crystallization into the aluminum phase at the time of solidification. In the present embodiment, the amount of lithium added is suppressed to 3% by weight or less, and as described later, the molten metal is cast at a constant or higher cooling rate to produce an Al-Li alloy target that becomes an aluminum single phase. have.

(Third process)

Next, a step of injecting the molten Al-Li alloy 20 in the crucible 12 into the mold 25 is performed (FIG. 2C). In this step, the crucible 12 is tilted and moved by rotating the movable container 14 counterclockwise with respect to FIG. 1 around the rotation shaft 18, and the molten metal 20 is injected into the mold 25. Cooling water is circulated in the cooling plate 26 constituting the mold 25. Therefore, the molten Al-Li alloy 20 flowing out of the crucible 12 is solidified at a constant cooling rate with respect to the mold 25. As a result, precipitation of AlLi (β phase) into the aluminum phase due to supersaturation of lithium can be prevented and the aluminum single phase can be maintained even after solidification.

In the present embodiment, in the melting furnace maintained in a vacuum atmosphere, aluminum dissolution, lithium addition and dissolution and mold injection are made to be consistent. Therefore, it is desirable to obtain an Al-Li alloy ingot having extremely few foreign substances such as lithium oxide, nitride or hydroxide. It becomes possible.

(Fourth process)

Next, the structure control of the obtained Al-Li alloy ingot is performed. The ingot texture control includes a forging step including a rolling process or an extrusion process for processing into a desired target shape, and a heat treatment process for removing internal stress or adjusting crystal structure.

The process temperature here becomes 550 degreeC or less. This is because even when the lithium content is below the maximum employment limit, even when the alloy structure is in a single phase, depending on the process temperature, the β phase precipitation may occur due to the subsequent plastic working and heat treatment. For example, even at a process temperature below the process point, there may be a case where the process line (process temperature) is locally exceeded due to the uniformity of the heating furnace or the overheating of the processing part. Precipitation of the β phase causes abnormal discharge such as voltage rise and arc generation when used as a target, resulting in an imbalance in film deposition rate. Therefore, in this embodiment, the upper limit of process temperature is set to 550 degreeC or less in consideration of the temperature change of several tens degree at the time of a process, and the polyphase of the alloy structure of a target is avoided.

As mentioned above, the Al-Li alloy target which concerns on this invention is manufactured. According to the Al-Li alloy target of the present embodiment, it is possible to obtain an aluminum single phase structure in which the amount of foreign matter and inclusions is small and the composition distribution is homogeneous (for example, within ± 5%). Therefore, occurrence of abnormal discharge can be suppressed at the time of spatter deposition, and stabilization of the deposition rate and uniformity of the film thickness distribution can be achieved.

EXAMPLE

(Example 1)

An Al-Li alloy ingot was manufactured using the melting furnace 10 described with reference to FIG. 1. For the aluminum block 21, rod-shaped high-purity aluminum (purity 99.99%) of about 300 mm was used. As the case 23 for accommodating the lithium ingot 22, the high-purity aluminum was rolled to prepare a 0.2 mm thick foil. A rod-shaped lithium (manufactured by Toyo Metal Co., Ltd., purity 99.9%) having a diameter of 100 mmφ was used for the lithium ingot 22.

As a crucible 12, a compressed graphite crucible was used. The shape of the crucible 12 was a cylindrical with a bottom, and the thing of inner diameter 175mm (phi) and depth 300mm was used as shown in FIG. After setting 7,750 g of high-purity aluminum in this crucible and reducing the pressure in a melting furnace to 1.33x10 <^-2> Pa, The crucible was heated to 750 degreeC by induction heating (40 kPa), and high purity aluminum was melt | dissolved.

Here, as shown in FIG. 4, the temperature monitoring of the molten aluminum used a CA sheath thermocouple inserted in the thermocouple protective tube 30 made of high purity graphite installed in the crucible 12. The outer shape of the protective tube 30 was 15 mm long, 15 mm wide, and 310 mm high, the inner diameter was 4 mmφ, and the depth was 300 mm.

3% by weight of lithium was double wrapped in 0.2 mm thick high-purity aluminum foil, and fixed with a high-purity aluminum wire (99.99%) tied to the tip portion 13A of the flanger 13 located above the crucible. The heat exchanger plate 19 made of graphite was installed in the crucible opening, and the crucible opening was opened before the lithium addition value.

The furnace pressure was maintained at 1.33 × 10 ⁻² Pa even when the concentration of the molten aluminum was 750 ° C. Next, after removing the heat shield plate at this temperature and opening the crucible opening part, the flanger was moved quickly and the lithium ingot supported on the tip part was forcibly immersed in the molten aluminum and stirred for 1 minute. After that, the induction heating of the crucible was stopped and poured into a mold (inner diameter 260 mmφ, height 60 mm) in the crucible at about 700 ° C to obtain a disc-shaped aluminum-lithium alloy molten metal.

As shown in Fig. 5, the samples were each 20 mm inside portions (a point, b point) from the centers of the top and bottom portions of the obtained ingot, and 5 mm inside portions (c points) from the central portion in the lateral height direction of the ingot. The sample was collected and analyzed for lithium composition by ICP-AES (High Frequency Plasma Emission Spectroscopy). The analytical results were 3.08% by weight at point a, 2.90% by weight at point b, 3.02% by weight at point c, and 3.0% by weight ± 5%.

The ingot after sampling was subjected to press forging and rolling, and could be processed without cracking to a thickness of 15 mm, thereby obtaining a spattering target having a thickness of 12 mm and a diameter of 200 mm φ. The process temperature of press forging was 550 degreeC, it rolled after heat processing, and performed the last heat processing at 450 degreeC. It was bonded to a copper cold plate (backing plate) by indium solder, and this was set in a spatter device, and spatter treatment was performed for 1 hour under a DC spatter condition of 0.9 kPa and 1 kPa under a reduced pressure argon gas atmosphere. . At spattering, no abnormal discharge phenomenon appeared and was stable.

Then, the target was removed from the apparatus, and the surface observation of the target, the cross-sectional observation in which the target was cut crosswise, and the composition analysis of the cross section were performed. Surface observation and cross-sectional observation used a CCD magnifier with a magnification of 50 times. The target surface after the spatter test was smooth with no puddles, bumps, bulges, etc. observed across the front. No voids or the like were observed throughout the cross section cut crosswise. In the thickness center part of a cross section, the sample was extract | collected from the target outer peripheral part, the intermediate part, and the center part substantial part as follows, and the composition composition of lithium was analyzed by ICP-AES method.

Measurement results,

4 outer peripheries: 3.08 wt%, 2.98 wt%, 2.88 wt%, 2.86 wt%

4 middle parts: 3.02% by weight, 2.96% by weight, 3.00% by weight, 2.86% by weight

1 center: 2.88% by weight

It was within 3.0 weight% +/- 5% with respect to 9 places of systems.

In addition, for histological observation, sampling was carried out from two outer peripheral parts, two intermediate parts, and one central part near the sampling position of the composition analysis sample of the cross section. As a result of the structure observation of the Al-Li alloy, it was confirmed that aluminum is a single phase in which lithium is dissolved in aluminum.

(Example 2)

An Al-Li alloy target was produced in the same manner as in Example 1 except that the Al-Li alloying was dissolved in an argon gas atmosphere.

The pressure in the furnace was 1.33 × 10 ⁻² Pa to melt the aluminum in the crucible. When the temperature of the aluminum molten metal was 750 ° C, the pressure in the furnace was once reduced to 2.66 kPa, and then high-purity aluminum argon gas (purity of 99.999%, dew point temperature of -70 ° C or lower) was introduced into the furnace, and the pressure was 6.66 in an argon gas atmosphere. It was set as the reduced pressure of x10 <^4> Pa. Next, at this temperature, the lid (heat shield plate) of the crucible was opened, the flanger was lowered, and the lithium ingot was forcibly immersed in the molten aluminum and stirred for 1 minute. After the induction heating stop of the crucible, the mold was poured into a mold having an internal diameter of 260 mm phi and a height of 60 mm to be solidified by cooling to obtain an Al-Li alloy ingot. Subsequent processes were the same as Example 1, and the spattering target of thickness 12mm and diameter 200mmphi was obtained.

About the obtained spattering target, the same spatter test and composition analysis as in Example 1 were performed. Spatter was produced without abnormal discharge, and the composition analysis of lithium was also within 3.0 wt% ± 5%. Further, as a result of histological observation by sampling from two outer peripheral parts, two intermediate parts, and one central part near the sampling position of the composition analysis sample of the cross section, aluminum in the state in which lithium was dissolved in aluminum as in Example 1 It was confirmed that it was a single phase.

(Example 3)

An Al-Li alloy ingot was produced in the same manner as in Example 2 except that the shape of the mold was 220 mm in width, 500 mm in length, and 25 mm in depth. Thereafter, the surface was cut, press forged, and rolled to fabricate an ingot of 10 mm in thickness and 1000 mm in length without causing cracking. Moreover, shape processing was carried out with the spattering target of thickness 8mm and diameter 200mmphi, and the same spatter test and composition analysis as Example 1 were performed. Spatter was made without abnormal discharge, and the composition analysis result of lithium was also within 3.0 weight% +/- 5.

Also, as a result of histological observation by sampling from two outer peripheral parts, two intermediate parts, and one central part near the sampling position of the compositional analysis sample of the cross section, as in Example 1, lithium was dissolved in aluminum. It was confirmed that it was an aluminum single phase.

(Comparative Example 1)

7,000 grams of high-purity aluminum was set in the crucible (inner diameter 175 mmφ, depth 300 mm) made from magnesia using the 1000 degreeC atmospheric air heating furnace (electric furnace), and it melt | dissolved by overheating in air | atmosphere. The aluminum oxide which generate | occur | produced on the surface was removed with the alumina plate, and similarly to Example 1, the predetermined amount of lithium wrapped with aluminum foil was quickly thrown in the molten aluminum. The input was partly suspended as an oxide on the melt surface. Oxides (slugs) suspended on the surface of the molten metal were removed with an alumina plate.

The molten Al-Li alloy in the crucible was poured into a mold having an internal diameter of 260 mm phi and a height of 60 mm to cool to obtain an Al-Li alloy ingot. Samples were taken at 20 mm inside portions (points a and b in FIG. 5) from the center of the height direction top and bottom portions of the ingot, and 5 mm inside portions (point c in FIG. 5) from the central portion in the lateral height direction of the ingot. The sample was collected and analyzed for lithium composition by ICP-AES (High Frequency Plasma Emission Spectroscopy). The analysis result was 2.82% by weight at point a, 2.56% by weight at point b, 2.98% by weight at point c, and a maximum of 3.0% by weight -15%.

The ingot after sampling performed press forging and rolling, and processed it to thickness 15mm. A spattering target having a thickness of 12 mm and a diameter of 200 mm phi was used. However, when the surface was observed, foreign matter and voids were observed. The spatter target was cut crosswise and cross-sectional observation was carried out, but foreign substances and voids were also observed in the cross section, and thus it could not be used as a spattering target for film formation.

(Comparative Example 2)

The Al-Li alloy was dissolved in an argon gas atmosphere by a vacuum induction heating furnace. 4% by weight of lithium was double wrapped in 0.2 mm thick high-purity aluminum foil, lightly fixed with aluminum wire so as to fall straight to the tip of the flanger (see FIG. 1) by vibration, and suspended on the top of the crucible. The conditions until lithium alloying were performed similarly to Example 2, but lithium addition opened the lid of the crucible, vibrated the flanger lightly, and dropped the lithium ingot wrapped in aluminum foil on the molten aluminum surface.

On the slowly rotating molten aluminum surface, an oxide-like float could be seen. After induction heating stop, it poured in the mold of internal diameter 260mm (phi) and height 60mm, and cooled, and obtained the Al-Li alloy ingot. Samples were each 20 mm inside (in point a and b of FIG. 5) from the center of the top and bottom portions in the height direction of the ingot, and 5 mm inside of the middle in the lateral height direction of the ingot (point c in FIG. 5). The sample was collected and analyzed for lithium composition by ICP-AES (High Frequency Plasma Emission Spectroscopy). The analytical results were 3.02% by weight at point a, 2.88% by weight at point b, 2.90% by weight at point c, and within 3.0% by weight ± 5%.

Subsequent processes were the same as Example 1, and the spattering target of thickness 12mm and diameter 200mmphi was obtained. And the same spatter test and composition analysis as in Example 1 were carried out. Five abnormal discharges occurred in the 1 hour spatter test. The target surface observation after the spatter test, the cross-sectional observation cut | disconnected on the cross, and the composition analysis were performed. On the surface, projections thought to have occurred at the time of abnormal discharge were confirmed, and further, holes or recesses of about 1 mm were detected at 13 locations from the front surface. In cross-sectional observation, there were also numerous cavities that were thought to be obtained by solidifying some oxides. Furthermore, as a result of histological observation by sampling from two outer peripheral parts, two intermediate parts, and one central part near the sampling position of the composition analysis sample, the aluminum phase and the AlLi phase (β phase) in which lithium was dissolved in aluminum were observed. It was confirmed that it became two phases.

As mentioned above, although embodiment and Example of this invention were described, of course, this invention is not limited to these, A various deformation | transformation is possible for it based on the technical idea of this invention.

For example, although the above embodiments and examples were made to dissolve aluminum in a crucible under a vacuum atmosphere, the aluminum dissolution may be performed under an inert gas atmosphere such as argon gas.

Moreover, in the above embodiment, although the mold 25 was comprised combining the die 27 with the cooling plate 26, you may use the mold which integrally formed the cooling plate 26 and the die 27. .

BRIEF DESCRIPTION OF THE DRAWINGS It is a side cross-sectional view which shows schematic structure of the melting furnace used in embodiment of this invention.

FIG. 2 is a sectional view of principal parts schematically illustrating a lithium alloying step and a casting step for explaining an embodiment of the present invention. FIG.

3 is an Al-Li equilibrium diagram.

4 is a plan view and a side cross-sectional view showing the configuration of a graphite crucible used in an embodiment of the present invention.

5 is a view showing a sampling position for composition analysis of the Al-Li alloy ingot in the embodiment of the present invention.

* Description of the sign *

10: melting furnace 11: vacuum chamber

12: Crucible 13: Flanger

14: movable container 18: rotating shaft

19: heat shield 20: molten Al-Li alloy

21: aluminum block 22: lithium ingot

25: mold

Claims (8)

In the manufacturing method of the aluminum-lithium alloy target for spattering which becomes an aluminum single phase, A first step of dissolving aluminum in a crucible installed in a melting furnace maintained in a vacuum atmosphere or an inert gas atmosphere, A second step of forcibly immersing and stirring a lithium ingot in the molten aluminum in the crucible; A third step of injecting an aluminum-lithium alloy molten metal in the crucible into a mold; A fourth step of performing structure control of the aluminum-lithium alloy ingot; Method for producing an aluminum-lithium alloy target, characterized in that it has a. The method of claim 1, wherein the second step, A step of immersing a graphite flanger tip portion having a lithium ingot fixed in the crucible; Rotating the flanger to stir the molten metal; Method for producing an aluminum-lithium alloy target, characterized in that it has a. The method of manufacturing an aluminum-lithium alloy target according to claim 2, wherein the lithium ingot is accommodated in an aluminum case, and the case is dissolved together with the lithium ingot. The method of claim 3, wherein in the second process, the flanger is located directly above the crucible, The method of manufacturing an aluminum-lithium alloy target, characterized in that the heat shield plate is provided between the crucible and the flanger during aluminum melting. The method of manufacturing an aluminum-lithium alloy target according to claim 4, wherein the amount of lithium ingot added is 3% by weight. The method of manufacturing the aluminum-lithium alloy target according to claim 1, wherein in the third step, the crucible is tilted and the aluminum-lithium alloy molten metal is injected into a mold provided adjacent to the crucible. The method of claim 1, wherein the fourth process includes a forging process and a heat treatment process, and the process temperature is 550 ° C. or less. In the aluminum-lithium alloy target produced by the method for producing an aluminum-lithium alloy target according to claim 1, An aluminum-lithium alloy target, wherein the lithium content is at most 3% by weight and the composition distribution is at most ± 5%.

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