Method for producing target material

Abstract

To provide a method for producing a target material capable of realizing a crystal structure in which the crystal grain size is uniform and fine.SOLUTION: Cold forging, intermediate heat treatment and hot upsetting are applied to a cast block of an aluminum alloy of 99. 99wt% or more to form a crystalline structure of equiaxed grains having a grain size of 5mm or less. Thereafter, cold upsetting using a hammer and final heat treatment are performed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a target material, and more particularly to a method for manufacturing a target material that can obtain a uniform and fine structure by applying plastic processing and heat treatment to an ingot made mainly of aluminum or copper. [Background technology]

[0002] A sputtering target is formed by bonding a target material made of, for example, high-purity aluminum or copper to a backing plate made of a metal different from the target material.

[0003] When manufacturing a target material, an ingot is first produced from raw materials that meet a specified purity. The ingot has coarse crystals with a size of 10 mm or more and an anisotropic crystalline structure that is elongated in the solidification direction, so the crystalline structure needs to be changed.

[0004] In other words, to ensure uniformity in sputtering, the crystalline structure of the target material is required to be uniform, fine, equiaxed grains with a grain size of several hundred microns. In some cases, it is also desirable for the grains to have a random crystal orientation. Therefore, as described above, it is necessary to change the crystalline structure of the ingot by applying plastic processing and heat treatment, and the "first step" and "second step" shown below are carried out.

[0005] (First step) In the first process, a combination of plastic processing (first plastic processing) and heat treatment (first heat treatment) is applied to the ingot. This causes the strain accumulated as lattice defects, including dislocations, during the plastic processing to become mobile as the temperature rises, resulting in recrystallization, which releases internal energy by generating new crystal grains that contain almost no dislocations.

[0006] The crystalline structure of the ingot changes to equiaxed grains of approximately several millimeters or less through recrystallization, eliminating the anisotropy of the cast structure and reducing the crystalline grain size to a certain extent. In the first step, variations in the crystal grain size at each location of the target material are allowed.

[0007] (Second step) In the second process, the work-in-progress that has undergone the first process is subjected to a combination of plastic processing (second plastic processing) and heat treatment (second heat treatment), which recrystallizes the crystalline structure to change it into uniform, fine equiaxed grains with a grain size of several hundred μm or less, forming a crystalline structure that can be used as a target material.

[0008] Here, as the conventional "second step", for example, as described in Patent Document 1, plastic working (second plastic working) is performed using a press. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Special Publication No. 2010-502841 Summary of the Invention [Problem to be solved by the invention]

[0010] However, as the purity of the metal materials (aluminum and copper) that make up the target material increases, it becomes more difficult to homogenize and refine the crystal grains in the second process using a press.

[0011] The present invention has been devised in view of the above points, and has as its object to provide a method for manufacturing a target material that can realize a fine crystal structure with uniform crystal grain size. [Means for solving the problem]

[0012] As a result of various studies by the inventors of the present application, the following findings have been reached.

[0013] That is, metals (hereinafter referred to as "high purity metals") that contain only small amounts of additive elements or impurity elements, such as high purity aluminum with a purity of 99.99 wt% or more, high purity copper with a purity of 99.99 wt% or more, and alloys to which second or subsequent metals are added in a total amount of 1000 ppm or less, tend to have coarse crystal grains in the ingot due to the low frequency of nucleation during solidification.

[0014] Furthermore, when metals are subjected to plastic processing, lattice defects such as dislocations accumulate, causing work hardening. At the same time, however, in an attempt to reduce internal energy, "dynamic recovery" occurs, in which dislocations coalesce and disappear, or rearrange, releasing strain, resulting in softening. In the case of high purity metals, this "dynamic recovery" is likely to occur, making it difficult to refine the crystal grains even if the ingot is subjected to plastic working.

[0015] Furthermore, in the case of high purity metals, since they contain only small amounts of additive elements and impurity elements, there are few elements that inhibit grain growth even during heat treatment, making it difficult to refine the crystal grains.

[0016] Therefore, in the case of high-purity metals, these issues must be taken into consideration and the ingot must be subjected to plastic processing and heat treatment to change the crystalline structure of the ingot, and the aforementioned "first step" and "second step" must be carried out under conditions that can solve these problems.

[0017] The aforementioned "second process" requires uniform and frequent recrystallization of the work-in-progress that has undergone the "first process," making it important to homogenize the distortion.

[0018] When plastic working is applied to metal, there are three main factors that cause the strain imparted to the metal to be non-uniform. These include: (1) the crystal size of the metal being plastically deformed is coarse; (2) the crystal structure of the metal being plastically deformed is anisotropic; and (3) the conditions for plastic processing are inappropriate. These are particularly problematic in the "second step."

[0019] Furthermore, since the factors of "(1) the crystal size of the metal to be plastically deformed is coarse" and "(2) the crystal structure of the metal to be plastically deformed is anisotropic" are resolved by the "first step," it is important to resolve "(3) the conditions for plastic processing are inappropriate." The following explains how to resolve the issue of "(3) inappropriate plastic processing conditions."

[0020] First, when rolling a metal in a certain direction (hereinafter referred to as the "Z direction"), if the amount of reduction is small relative to the thickness of the metal in the Z direction, the strain will not reach deep inside the metal being rolled down, resulting in non-uniform strain. Therefore, in the "second step," it is necessary to set the reduction rate to be sufficiently large.

[0021] Furthermore, when metal is pressed down in the Z direction using free forging, the metal being pressed down will elongate in the Y direction, which is perpendicular to the Z direction, and in the X direction, which is perpendicular to both the Y and Z directions. However, the parts of the metal being pressed down that come into contact with the forging jig and their surrounding areas are hindered from deformation due to friction between the metal and the jig, resulting in uneven distortion.

[0022] This frictional force is proportional to the normal force, which is proportional to the rolling load, and the coefficient of friction between the metal being rolled down and the jig, so by reducing these, it is expected that the strain will be uniform. Generally, in order to reduce the coefficient of friction, a lubricant is applied or laid between the metal being pressed down and the jig, which reduces friction to about one-tenth of the original value.

[0023] Furthermore, when the reduction is performed using an impact machine (for example, an air hammer), unlike a press, the impact machine collides the jig against the metal being reduced at high speed, so even with a small load, a large amount of kinetic energy can be imparted to the metal being reduced, causing plastic deformation. In other words, since an impact machine can deform the metal it is pressing down with a load that is about 1 / 1000 of that of a press, using an impact machine with a small maximum load can significantly reduce friction and make it possible to impart distortion extremely uniformly.

[0024] Furthermore, as mentioned above, when metal is subjected to plastic processing, "dynamic recovery" occurs, resulting in softening. However, if the work-hardening rate exceeds the softening rate due to "dynamic recovery," "dynamic recrystallization" occurs, which releases strain by generating new crystal grains that contain almost no dislocations, resulting in the refinement of the crystal grains.

[0025] In order to refine the crystal grains through this "dynamic recrystallization," it is effective to increase the rate at which strain is applied, and it is therefore important to apply plastic deformation using an impact machine that can apply strain at a high rate instead of a conventional press.

[0026] The "rate of strain application" can be considered as either the "amount of deformation per unit time" or the "reduction rate per unit time (the amount of deformation per unit time divided by the original length)." Here, the explanation will be given assuming the former (amount of deformation per unit time).

[0027] Furthermore, increasing the rate at which strain is applied and resulting in refinement due to behaviors such as "dynamic recovery" and "dynamic recrystallization" that occur when metal undergoes plastic deformation are effective for cold and hot plastic working of high-purity aluminum, in which "dynamic recovery" can easily occur at room temperature or above. Similarly, it is effective for hot plastic working of high purity copper where "dynamic recovery" can occur at high temperatures.

[0028] Furthermore, after plastic deformation using a hammering machine, a final heat treatment is performed to use the remaining strain to induce recrystallization, further refining the grain size. In this case, the temperature of the final heat treatment must be set below the "grain growth temperature" that causes the grain size to coarsen.

[0029] Furthermore, plastic processing by "rolling" may be applied in order to impart uniform strain to the metal being pressed down in the "second step" and to refine the crystal grains, but from the viewpoint of making the crystal orientation even more random, free forging is preferred.

[0030] [1] Based on this knowledge, in order to achieve the above-mentioned object, the method for manufacturing a target material of the present invention comprises: a first step of applying a first plastic processing and a first heat treatment to an ingot mainly made of aluminum or copper to change the crystalline structure into one having equiaxed grains with a grain size of 5 mm or less; and a second step of applying a second plastic processing and a second heat treatment after the first step to change the crystalline structure into one having a grain size of 300 μm or less, wherein the second plastic processing is carried out at least in part by upsetting using a striking machine, and the second heat treatment is carried out at a temperature of 100°C or more after the second plastic processing.

[0031] Here, by performing the second plastic processing, at least in part, by upsetting using an impact machine, it is possible to impart large kinetic energy to the workpiece even with a small load, and as a result, the rate at which strain is applied can be increased.

[0032] For example, the "press" used to manufacture aluminum target material has a load of several hundred tons to several thousand tons and a strain application rate of several tens of mm / sec, whereas the load of a striking machine (hammer) is several tons or less and a strain application rate of several thousand mm / sec.

[0033] By the way, when a metal into which strain (dislocations) has been introduced is kept at high temperatures, atomic diffusion occurs, dislocations move, and through their coalescence, annihilation, and rearrangement, recovery occurs in which the strain decreases in an attempt to reduce the internal energy.

[0034] If the material is kept at a temperature higher than the temperature at which recovery occurred, it undergoes "primary recrystallization," which generates new crystal grains that contain almost no strain. If the material is kept at an even higher temperature, it undergoes "secondary recrystallization," in which the crystal grains eat away at each other, causing the grain size to coarsen, thereby reducing the strain and the internal energy.

[0035] The grain refinement in the present invention utilizes this "primary recrystallization." In other words, recovery and recrystallization can be induced not only by holding at high temperatures, but also by applying plastic deformation, which is the aforementioned "dynamic recovery" and "dynamic recrystallization." When strain is introduced into a metal, "dynamic recovery" occurs first, releasing the strain, and then, when strain accumulates beyond a certain level, "dynamic recrystallization" occurs.

[0036] However, if the rate at which strain is introduced into the metal is slow (if strain is introduced slowly), the introduced strain continues to be released by "dynamic recovery" and does not reach "dynamic recrystallization."

[0037] On the other hand, when strain is introduced into a metal at a high rate (when strain is introduced quickly), the amount of strain introduced exceeds the amount of strain released by "dynamic recovery," and strain accumulates, causing "dynamic recrystallization" and resulting in the refinement of crystal grains.

[0038] Furthermore, compared to "processing by a press," "processing by a percussion machine" is more likely to introduce strain at a rate that exceeds the threshold (the threshold for dynamic recrystallization), and dynamic recrystallization occurs more frequently than dynamic recovery. Therefore, in the method for manufacturing a target material of the present invention, "processing by an impact machine" is adopted, which causes dynamic recrystallization to occur more frequently, and the "dynamic recrystallization" realizes the refinement of crystal grains.

[0039] In the method for manufacturing a target material of the present invention, it is sufficient that "at least a portion" of the target material is upset by an impact machine, and it is not necessary that the processing be carried out only by an impact machine.

[0040] Furthermore, by carrying out the second heat treatment at a temperature of 100° C. or higher after the second plastic working, the crystal grain size can be further refined by utilizing the remaining strain.

[0041] Furthermore, if the temperature of the second heat treatment is "less than 100°C," even if the workpiece is highly pure or the strain added by the second plastic processing is large, making it easy for recrystallization to occur, only recovery will occur, and it will be difficult to further refine the structure obtained by the second plastic processing (dynamic recrystallization).

[0042] Furthermore, by changing the grain size to "a crystal structure with equiaxed grains and a grain size of 5 mm or less" in the first step, a crystal structure with a uniform and fine grain size is realized. In other words, the new crystal grains generated in the second process (recrystallization) are affected by the orientation and strain direction of the original crystal grains, as well as the anisotropy of the crystal grain shape. Furthermore, the ease with which strain is introduced during the second plastic processing is affected by the orientation of the crystal grains relative to the processing direction. Therefore, unless the grains are relatively fine and equiaxed before the second process (i.e., by the first process), the strain introduced during the second plastic processing will be non-uniform, resulting in unevenness in the final crystal grain size and orientation. Therefore, by changing the crystal structure to one with equiaxed grains and a grain size of 5 mm or less in the first process, the strain introduced in the second plastic processing is made uniform, and the final crystal grain size is made uniform and fine.

[0043] [2] In the method for manufacturing a target material of the present invention, it is preferable that the second plastic processing satisfies the condition L / W ≧ 14, where L (kg) is the load of the impact machine and W (kg) is the weight of the workpiece.

[0044] In upsetting using a striking machine, deformation occurs such that the thickness of the part struck by the striking machine (i.e., the part struck by the striking machine) becomes thinner. When "L / W < 14", there is insufficient force to push aside the "parts around the part struck by the striking machine", which hinders smooth deformation and may result in parts or timing where deformation is restricted, which may prevent uniform refinement of the grain size. In contrast, if the condition "L / W ≧ 14" is satisfied, there is sufficient force to push aside the "areas surrounding the area struck by the striking machine," allowing for smooth deformation and achieving uniform refinement of the crystal grain size.

[0045] [3] In the method for manufacturing a target material of the present invention, it is more preferable that the second plastic processing satisfies the condition L / W ≧ 16, where L (kg) is the load of the impact machine and W (kg) is the weight of the processed material.

[0046] When the condition "L / W ≧ 16" is satisfied, the force for pushing away "the area around the area struck by the striking machine" is more sufficient, and more sufficient uniform refinement of the crystal grains is achieved.

[0047] [4] In the method for manufacturing a target material of the present invention, it is further preferable that the second plastic processing satisfies the condition 16 ≦ L / W ≦ 70, where L (kg) is the load of the impact machine and W (kg) is the weight of the workpiece.

[0048] In upsetting using a striking machine, a larger L / W ratio means a larger amount of deformation per strike. If L / W > 70, the amount of deformation per strike will be excessively large, resulting in uneven deformation in the area struck by the striking machine. In contrast, if the condition "L / W ≦ 70" is satisfied, the amount of deformation per hit will not be too large, there will be no unevenness in the deformation, and even more sufficient uniform refinement of the crystal grains will be achieved.

[0049] [5] In the method for producing a target material of the present invention, the second plastic working is preferably performed at a rolling reduction rate of 25% or more.

[0050] In this case, uniformly fine grain size can be achieved throughout the entire workpiece. On the other hand, if the rolling reduction rate in the second plastic working is less than 25%, the grains near the center of the workpiece thickness may become large.

[0051] [6] In the method for producing a target material of the present invention, when the ingot is mainly made of aluminum, the second heat treatment is preferably carried out at a temperature of 320°C or less.

[0052] In this case, in other words, when the second heat treatment is performed at a temperature of 100° C. or higher and 320° C. or lower, the crystal grains are refined by "primary recrystallization." On the other hand, if the second heat treatment is carried out at a temperature above 320°C, "secondary recrystallization" occurs, resulting in coarsening of the crystal grains.

[0053] [7] In the method for producing a target material of the present invention, when the ingot is mainly made of copper, the second heat treatment is preferably carried out at a temperature of 650°C or less.

[0054] In this case, in other words, when the second heat treatment is performed at a temperature of 100° C. or higher and 650° C. or lower, the crystal grains are refined by "primary recrystallization." On the other hand, if the second heat treatment is carried out at a temperature above 650°C, "secondary recrystallization" occurs, resulting in coarsening of the crystal grains.

[0055] [8] In the method for producing a target material of the present invention, the ingot may be made of aluminum having a purity of 99.99 wt% or more, or copper having a purity of 99.99 wt% or more.

[0056] Even in the case of high-purity aluminum or copper, such as those with a purity of 99.99 wt% or more, the second plastic processing causes "dynamic recrystallization," making it possible to refine the crystal grains. [Effects of the Invention]

[0057] The method for manufacturing a target material of the present invention can realize a fine crystalline structure with uniform grain size. [Brief explanation of the drawings]

[0058] [Figure 1] 1A to 1C are schematic process diagrams illustrating an example of a method for manufacturing a target material. [Figure 2] FIG. 10 is a schematic process diagram for explaining another example of a method for manufacturing a target material. [Figure 3] 1A to 1C are schematic process diagrams illustrating a conventional method for manufacturing a target material. [Figure 4] FIG. 1 is a schematic diagram for explaining upsetting. [Figure 5] FIG. 2 is a diagram showing the state of crystal grains in the in-process target material of Example 1. [Figure 6] FIG. 10 is a diagram showing the state of crystal grains in the in-process target material of Example 2. [Figure 7] FIG. 2 is a diagram showing the state of crystal grains in the target material of Example 1. [Figure 8] FIG. 10 is a diagram showing the state of crystal grains in the target material of Example 2. [Figure 9] FIG. 10 is a diagram showing the state of crystal grains in the target material of Example 3. [Figure 10] FIG. 10 is a diagram showing the state of crystal grains in the target material of Example 4. [Figure 11] FIG. 10 is a diagram showing the state of crystal grains in the target material of Example 8. [Figure 12] FIG. 2 is a diagram showing the state of crystal grains in the target material of Comparative Example 1. [Figure 13] 1 is a diagram showing a cross-sectional state of a work-in-progress target material of Example 1 and Example 2. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0059] Hereinafter, a mode for carrying out the invention (hereinafter referred to as "embodiment") will be described. The explanation will be given in the following order. 1. First embodiment 2. Second embodiment 3. Comparative Example 4. Working Example

[0060] <1. First embodiment> FIG. 1 is a schematic process diagram for explaining an example of a method for producing a target material to which the present invention is applied.

[0061] In the first embodiment, first, an ingot of a predetermined shape is manufactured using aluminum having a purity of 99.9995 wt % or more as a raw material, and this ingot is used as a starting material (see reference symbol S11 in FIG. 1).

[0062] The starting material is a coarse crystal with a crystal size of 10 mm or more, and has an anisotropic crystalline structure elongated in the solidification direction.

[0063] Next, the starting material is subjected to forging and elongation to reduce the cross-sectional area of ​​the material and extend the length of the material (see symbol S12 in FIG. 1). Although upsetting may be used to impart strain to the ingot, in this embodiment, elongation forging is performed in consideration of the dimensions of the starting material, the dimensions of the product, and the amount of strain that needs to be imparted.

[0064] Next, the upper and lower portions of the material are cut (see reference symbol S13 in FIG. 1), and then heat treatment is performed (see reference symbol S14 in FIG. 1). The diagonal lines in FIG. 1 represent areas that have been heated by heat treatment.

[0065] Subsequently, after the heat treatment (intermediate heat treatment), upsetting is carried out before the temperature drops, to compress the material in the length direction and increase the cross-sectional area of ​​the material (see symbol S15 in FIG. 1).

[0066] Note that the reference numerals S12 to S15 correspond to the "first step", and the "first step" changes the grain size to 5 mm or less and changes the crystal structure to equiaxed grains (see FIGS. 13(a) and (b)).

[0067] Here, the typical "first step" involves the following steps: (1) "forging and stretching" to introduce strain in the X and Y directions, (2) "heat treatment (intermediate heat treatment)" to cause recrystallization, (3) "upsetting" to introduce strain in the Z direction, and (4) "heat treatment (intermediate heat treatment)" to cause recrystallization, thereby creating equiaxed grains that are free from anisotropy in all directions.

[0068] In contrast, in this embodiment, the following steps are adopted: (1) "forging and stretching" is performed to introduce strain in the XY directions, (2) "heat treatment (intermediate heat treatment)" is performed to cause recrystallization, and (3') "upsetting using residual heat" is performed to introduce strain in the Z direction and cause dynamic recrystallization. By performing this "upsetting using residual heat," it is possible to omit the second "heat treatment (intermediate heat treatment)." Furthermore, even if the second heat treatment is omitted by using "upsetting using residual heat," the grain size is 5 mm or less, and the crystal structure has changed to equiaxed grains, so this is sufficient as a result of the "first process."

[0069] Next, an air hammer with a load of 0.5 t is used to perform upsetting at room temperature (cold), compressing the material by 67% in the length direction (see symbol S16 in FIG. 1).

[0070] The upsetting process indicated by the symbol S16 has a rolling reduction of 25% or more.

[0071] Thereafter, a heat treatment is carried out at 250° C. for 180 minutes, followed by water cooling to obtain a target material (see symbol S17 in FIG. 1).

[0072] S16 to S17 correspond to the "second step", and the "second step" changes the grain size to a crystalline structure of 300 μm or less.

[0073] <2. Second embodiment> FIG. 2 is a schematic process diagram for explaining another example of the method for producing a target material to which the present invention is applied.

[0074] In the second embodiment, the same starting material as in the first embodiment is used, and the same "first step" as in the first embodiment is carried out. That is, the same processing as that of the reference symbols S11 to S15 is carried out for the reference symbols S21 to S25.

[0075] In the second embodiment, following the processing of reference numeral S25, a hydraulic press with a load of 500 t is used to perform upsetting at room temperature (cold), compressing the material by 50% in the length direction (see reference numeral S26-1 in FIG. 2).

[0076] Furthermore, an air hammer with a load of 0.5 t is used to perform upsetting at room temperature (cold), compressing the material by 33% in the length direction (see symbol S26-2 in Figure 2).

[0077] The upsetting process indicated by the symbol S26-2 has a rolling reduction of 25% or more.

[0078] Thereafter, a heat treatment is carried out at 250° C. for 180 minutes, followed by water cooling to obtain a target material (see symbol S27 in FIG. 2).

[0079] S26-1, S26-2, and S27 correspond to the "second step", and the "second step" changes the grain size to a crystalline structure of 300 μm or less.

[0080] <3. Comparative Example> FIG. 3 is a schematic process diagram for explaining a conventional method for manufacturing a target material as a comparative example.

[0081] In the comparative example, the same starting material as in the first and second embodiments is used, and the same "first step" as in the first and second embodiments is carried out. That is, the processing steps S31 to S35 are the same as those S11 to S15.

[0082] In the comparative example, following the processing of reference symbol S35, a hydraulic press with a load of 500 t is used to perform upsetting at room temperature (cold) to compress the material by 67% in the length direction (see reference symbol S36 in FIG. 3).

[0083] Thereafter, a heat treatment is carried out at 250° C. for 180 minutes, followed by water cooling to obtain a target material (see reference numeral S37 in the figure).

[0084] <4. Example> An example will be described below. In the examples, in the above-mentioned "first embodiment," eight types of starting materials (starting materials with the same diameter but different lengths) each having different weights were used to obtain target materials for Examples 1 to 8 shown in Table 1. Table 1 also shows the load L of the air hammer and "(load L of the air hammer) / (weight W of the target material)".

[0085] Here, the air hammer used in this embodiment (air hammer used in cold upsetting of reference symbol S16) has a speed of 4500 mm / sec. Specifically, the speed measured from when the forging height (a specification of the impact device) was reached until just before contacting the material (workpiece) was 4500 mm / sec.

[0086] In addition, in cold upsetting, as shown in Figure 4, material 2 is placed on a base plate 1 and struck (struck) from above with an air hammer 3, compressing the material in the longitudinal direction. However, the striking surface (pressure surface) indicated by symbol a in Figure 4 has a large normal force and a large friction force, making it difficult to deform and difficult to refine the crystal grains. On the other hand, the bottom metal surface (surface in contact with the bottom metal 1) indicated by the symbol b in FIG. 4 distributes pressure during impact (pressure application), making it difficult for deformation to be hindered and facilitating uniform refinement of crystal grains. Therefore, in this embodiment, the sputtering surface, which requires fine and uniform crystal grains, is designated as the bottom metal surface (symbol b), and the backing surface, which does not require fine and uniform crystal grains, is designated as the striking surface (symbol a).

[0087] In the above-mentioned "Comparative Example", the same starting material as in Example 2 was used to obtain a target material for Comparative Example 1. Table 1 also shows the press load L and "(press load L) / (weight W of the comparative material)".

[0088] Here, the press used in the comparative example (the hydraulic press used for cold upsetting indicated by reference numeral S36) has a speed of 39 mm / sec. Specifically, the speed measured from the start of compression of the material (workpiece) until the speed begins to drop sharply is 39 mm / sec.

[0089] [Table 1] JPEG2026003581000002.jpg52167

[0090] Here, the target materials of Examples 1 to 8 have different weights W, namely, "0.98 kg (approximately 1 kg)," "7.25 kg (approximately 7 kg)," "9.91 kg (approximately 10 kg)," "19.91 kg (approximately 20 kg)," "24.78 kg (approximately 25 kg)," "29.86 kg (approximately 30 kg)," "34.69 kg (approximately 35 kg)," and "40.57 kg (approximately 40 kg)," but they all have a common "diameter / thickness" of approximately 21. The "diameter / thickness" of the comparative material is also approximately 21.

[0091] Furthermore, when manufacturing the target materials of Examples 1 to 8, in order to obtain work-in-process items (work-in-process items that have undergone the first step) of different dimensions from starting materials of the same diameter, the conditions for the forging and stretching process (reference symbol S12) and cutting (reference symbol S13) were different, but the conditions for the intermediate heat treatment (reference symbol S14) and upsetting process (reference symbol S15) were the same.

[0092] In addition, the cold upsetting (reference numeral 16) is performed by using a 0.5 ton air hammer at room temperature (cold) to compress the material by 67% in the longitudinal direction, and the final heat treatment (reference numeral S17) is performed by performing heat treatment at 250°C for 180 minutes and then water cooling, which are common to Examples 1 to 8.

[0093] Here, the state of crystal grains in the in-process target material of Example 1 (which has undergone only the first step of the steps for obtaining the target material of Example 1) is shown in FIG. 5 and FIG. 13(a). Specifically, Fig. 5(a) shows the state of "crystal grains at a depth of 4.5 mm from the sputtering surface," Fig. 5(b) shows the state of "crystal grains at a depth of 7.5 mm from the sputtering surface," and Fig. 5(c) shows the state of "crystal grains at a depth of 10.5 mm from the sputtering surface." Also, Fig. 13(a) shows the cross-sectional state (macrophotograph of the cross section) of a work-in-progress of the target material of Example 1. As shown in FIGS. 5(a) to 5(c) and FIG. 13(a), it was confirmed that the grain size of the in-process target material of Example 1 was 5 mm or less and had an equiaxed grain structure.

[0094] The state of crystal grains in the in-process target material of Example 2 (which has undergone only the first step of the steps for obtaining the target material of Example 2) is shown in FIG. 6 and FIG. 13(b). Specifically, Fig. 6(a) shows the state of "crystal grains at a depth of 9 mm from the sputtering surface," Fig. 6(b) shows the state of "crystal grains at a depth of 15 mm from the sputtering surface," and Fig. 6(c) shows the state of "crystal grains at a depth of 21 mm from the sputtering surface." Also, Fig. 13(b) shows the cross-sectional state (macrophotograph of the cross section) of a work-in-progress target material of Example 2. As shown in FIGS. 6(a) to 6(c) and FIG. 13(b), it was confirmed that the grain size of the in-process target material of Example 2 was 5 mm or less and had an equiaxed grain structure.

[0095] Furthermore, although the illustration of the crystal grain phase diagram is omitted, it was confirmed that the grain size of the in-process target materials of Examples 3 to 8 (those for which only the first step of the process for obtaining the target materials of Examples 3 to 8 had been performed) was 5 mm or less and had an equiaxed grain crystal structure.

[0096] In addition, taking into consideration that the surface of the cast material is cut when manufacturing the target material, the state of the crystal grains on the "face 25% deep from the sputtering surface" (hereinafter referred to as the "25% face") of the target materials of Examples 1 to 4 and 8 described above (Figures 7(a) to 11(a)) and the state of the crystal grains on the "face 35% deep from the sputtering surface" (hereinafter referred to as the "35% face") of the target materials of Examples 1 to 4 and 8 (Figures 7(b) to 11(b)) are shown.

[0097] Also shown are the state of the crystal grains on the "25% surface" of the target material of Comparative Example 1 (Figure 12(a)) and the state of the crystal grains on the "35% surface" of the target material of Comparative Example 1 (Figure 12(b)).

[0098] Furthermore, for the target materials of Examples 1 to 8 and Comparative Example 1 described above, three points were randomly selected from each of the following locations (1) to (6), and the average values ​​of the crystal grain sizes (μm) measured at these three points are shown in Table 2. (1) Near the center (25% of the faces) (2) Near the center (35% of the faces) (3) Midway between the center and the surface (25% of the surface) (4) Midway between the center and the surface (35% of the surface) (5) Near the epidermis (25% of the surface) (6) Near the epidermis (35% of the surface)

[0099] [Table 2] JPEG2026003581000003.jpg98167

[0100] Furthermore, for each of the target materials of Examples 1 to 8 and Comparative Example 1, the "maximum crystal grain size," "minimum crystal grain size," and "average crystal grain size" were calculated for the "near the center," "middle position," and "near the surface" of the "25% surface," and the "near the center," "middle position," and "near the surface" of the "35% surface."

[0101] Graph 1 shows the relationship between the "maximum crystal grain size," "average crystal grain size," and "difference between the maximum and minimum crystal grain size" and L / W for the target materials of Examples 1 to 8. In addition, for Comparative Example 1, since L / W is too large, for convenience of illustration, the values ​​of "maximum crystal grain size," "average crystal grain size," and "difference between maximum and minimum crystal grain size" are shown instead of the relationship with L / W.

[0102] [Graph 1] JPEG2026003581000004.jpg86131

[0103] (Consideration) In the method for manufacturing a target material to which the present invention is applied, an air hammer is used in the cold upsetting process, thereby making it possible to achieve uniform and refined crystal grains in an ingot of aluminum alloy with a purity of 99.9995 wt% with small differences in crystal grain size between the center, middle, and near the surface.

[0104] Furthermore, the "maximum crystal grain size," "average crystal grain size," and "difference between the maximum and minimum crystal grain sizes" of the target materials of Examples 1 to 8 are smaller than the "maximum crystal grain size," "average crystal grain size," and "difference between the maximum and minimum crystal grain sizes" of the target material of Comparative Example 1, which indicates that uniform refinement of the crystal grains has been achieved.

[0105] This can be easily understood by comparing Example 2 (see FIG. 7) and Comparative Example 1 (see FIG. 12), which have the same target material weight and dimensions. Specifically, the target material of Comparative Example 1 (see FIG. 12) has an "average crystal grain size" of 253 μm and a "difference between the maximum and minimum crystal grain sizes" of 163 μm, whereas the target material of Example 2 has an "average crystal grain size" of 169 μm and a "difference between the maximum and minimum crystal grain sizes" of 36 μm, which shows that uniform refinement of the crystal grains has been achieved, as described above.

[0106] Furthermore, from Graph 1, it can be seen that when the condition "L / W ≧ 14" is satisfied (specifically, in the cases of Examples 1 to 7), the "average crystal grain size" is below 230 μm, and a sufficient refinement effect can be achieved.

[0107] Furthermore, from Graph 1, it can be seen that when the condition "L / W ≧ 16" is satisfied (specifically, in the cases of Examples 1 to 6), the "average crystal grain size" is below 200 μm, and an even more sufficient effect of refinement can be achieved.

[0108] Furthermore, from Graph 1, it can be seen that when the condition "16 ≦ L / W ≦ 70" is satisfied (specifically, in the cases of Examples 2 to 6), the "average crystal grain size" is below 200 μm and the "difference between the maximum and minimum crystal grain size" is below 40 μm, and a sufficient homogenization effect is achieved.

Claims

1. a first step of subjecting an ingot made mainly of aluminum or copper to a first plastic working process and a first heat treatment to change the crystalline structure into one having equiaxed grains with a grain size of 5 mm or less; a second step of applying a second plastic working and a second heat treatment after the first step to change the crystal structure into one having a grain size of 300 μm or less, The second plastic working is performed at least in part by upsetting using a striking machine, The second heat treatment is carried out at a temperature of 100° C. or higher after the second plastic working. Method for manufacturing target material.

2. The second plastic working includes: When the load of the impact machine is L (kg) and the weight of the workpiece is W (kg), Satisfy the condition L / W≧14 The method for manufacturing the target material according to claim 1 .

3. The second plastic working includes: Satisfy the condition L / W≧16 The method for producing a target material according to claim 2 .

4. The second plastic working includes: Satisfy the condition L / W≦70 The method for producing a target material according to claim 3 .

5. The second plastic working has a rolling reduction of 25% or more. The method for producing a target material according to claim 1 or 2.

6. the ingot is composed primarily of aluminum, The second heat treatment is carried out at a temperature of 320° C. or less. The method for producing a target material according to claim 1 or 2.

7. The ingot is composed mainly of copper, The second heat treatment is performed at a temperature of 650° C. or less. The method for producing a target material according to claim 1 or 2.

8. The ingot is made of aluminum having a purity of 99.99 wt% or more, or copper having a purity of 99.99 wt% or more. The method for producing a target material according to claim 1 or 2.

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