JP5518375B2 - Formed body made of molybdenum alloy having excellent drillability for accelerating electrode and method for producing the same - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a molybdenum alloy molded body excellent in drill workability and a method for producing the same, and in particular, molybdenum alloy molding used as an ion acceleration electrode used in an apparatus such as a focused ion beam apparatus (FIB) or a fusion apparatus. The present invention relates to a body and a manufacturing method thereof.

  Conventionally, a high-melting point is used as an accelerating electrode for accelerating an ion beam in an apparatus such as a focused ion beam apparatus (FIB) or a fusion apparatus that uses an accelerated ion beam and performs fine processing, ion beam irradiation, sputtering, and the like. The material molybdenum plate is used. For example, Japanese Patent Application Laid-Open No. 3-129638 (Patent Document 1) and Japanese Patent Application Laid-Open No. 5-29093 (Patent Document 2) disclose a method of manufacturing an ion acceleration electrode plate, and Japanese Patent Application Laid-Open No. 5-94794. An ion source grid is disclosed in Japanese Patent Publication (Patent Document 3) and Japanese Patent Application Laid-Open No. 5-94795 (Patent Document 4).

  Regarding the shape of the acceleration electrode of molybdenum in the case of the above-mentioned patent documents 1 and 2, as shown in the schematic diagram of the acceleration electrode shown in FIG. 2, a large number of beam holes 2 through which the ion beam passes are formed in the circular molybdenum thin plate 1. Yes. Depending on the size of the accelerating electrode and the type of device, hundreds to thousands of beam holes are drilled in one thin plate. Usually, molybdenum has poor machinability, and there is a problem that the wear of the drill tip is severe, so that the drill life is short and the processing cost is increased. In addition, since the dimensional accuracy of the beam hole in the acceleration electrode causes the spread of the ion beam, polarization, and the like, the dimensional deviation due to wear of the drill blade tip is a serious problem.

JP 2006-299384 A (Patent Document 5), JP 2003-293070 A (Patent Document 6), JP 2007-302981 A (Patent Document 7), JP 2002-327264 A (Patent Document 5). Reference 7), Japanese Patent Application Laid-Open No. 2002-327264 (Patent Document 8), Japanese Patent Application Laid-Open No. 2005-290409 (Patent Document 9), and Japanese Patent Application Laid-Open No. 57-194238 (Patent Document 10) were added with Nb. Examples of Mo alloys are disclosed.
Japanese Patent Laid-Open No. 3-129638 JP-A-5-29093 Japanese Patent Laid-Open No. 5-94794 JP-A-5-94795 JP 2006-299384 A JP 2003-293070 A JP 2007-302981 A JP 2002-327264 A JP 2005-290409 A JP-A-57-194238

  As described above, Patent Documents 5 to 10 disclose examples of Mo alloys to which Nb is added. However, all of them are completely different from the present invention in the intention of Nb addition, the existence form of Nb, or the manufacturing method. Yes. For example, Patent Document 5 and Patent Document 6 are characterized in that, as described in the claims, Nb is dissolved in a solid solution and is nitrided in subsequent processing, and therefore, pure Nb particles are dispersed. Is different.

  Further, as described in paragraph [0007], Patent Document 7 has a description by special melting such as sintered material, melted material, or electron beam melting as a plate material, and the dispersion of pure Nb particles as in the present invention. Therefore, the drilling workability is not improved. Further, Patent Document 8 is a target using an ingot manufactured by a melting method suitable for obtaining a low-oxygen material as described in paragraph [0014], and pure Nb particles are dispersed as in the present invention. Therefore, it does not improve drill workability.

  Furthermore, Patent Document 9 has a microstructure characterized by connecting oxides present around metal element M (Nb, etc.) grains with a network as described in the claims, and the present invention. There is no oxide network around the pure Nb particles. In addition, in Patent Document 10, since there is no description of a constituent phase or a manufacturing method, it is unclear what kind of microstructure it has, but as described in the 11th line on the lower right column of the second page. , Nb addition improves resistance to radiation damage such as void swelling, and Mo alloy excellent in drill workability suitable for accelerating electrode such as drilling thousands of drill holes as in the present invention Is completely different in use, and the intention of adding Nb is also different.

  Although there are many patent documents as described above, however, Mo is usually poor in machinability, and there is a problem that drill life is shortened because the wear of the drill tip is severe, and there is a problem of increasing the processing cost. Since the dimensional accuracy of the beam hole causes the spread of the ion beam, polarized light, and the like, the dimensional deviation due to wear of the drill tip is a big problem. In order to solve these problems, the inventors have intensively studied. As a result, the inventors found that drilling workability is extremely improved by adding Nb to Mo and dispersing a pure Nb phase, leading to the invention. Is.

The gist of the invention is that
(1) Atomic%, Nb: 1 to 50%, balance Mo and inevitable impurities, and pure Nb is dispersed in a matrix made of pure Mo. The average particle diameter of the pure Nb is 3 to 3 A molded body made of a molybdenum alloy excellent in drilling workability for an acceleration electrode , characterized by being 100 μm and an area ratio of 3 to 40%.
(2) In order to obtain the average particle diameter of pure Nb in the molded article described in (1), the raw material Nb average particle diameter is set to 25 to 80 μm, which is excellent in accelerating electrode drill workability A compact made of molybdenum alloy.
( 3 ) A method for producing a molded body made of a molybdenum alloy excellent in drilling workability for an acceleration electrode , characterized in that a mixed powder of Mo powder and Nb powder is formed by hot isostatic pressing.
( 4 ) The method for producing a molded body made of a molybdenum alloy having excellent drilling workability for an acceleration electrode according to ( 3 ), wherein hot isostatic pressing is performed at 1100 to 1500 ° C.

  As described above, a Mo alloy molded body excellent in drill workability suitable for an accelerating electrode of various apparatuses and a method for producing the same by dispersing as pure Nb particles in a matrix made of pure Mo according to the present invention. It is to provide.

Hereinafter, the reasons for limiting the component composition of the present invention will be described.
Nb: 1-50%
Nb contributes to drilling workability improvement with the addition amount, but if less than 1%, the effect cannot be obtained, and if it exceeds 50%, the effect is saturated and the cost is increased, so the range. Was 1 to 50%. Also, commercially available Nb powders often have higher oxygen values than Mo powders. For this reason, considering drill workability and oxygen value, it is more preferably 5 to 30%. This is because if the oxygen value is too high, there may be a problem that gas is generated during use as an acceleration electrode.

Dispersion of pure Nb in pure Mo matrix The present invention is a Mo alloy, and the matrix is based on Mo. However, since drill workability deteriorates when Nb dissolves in Mo of the matrix, the matrix is pure Mo. . It is inferred that the cause of deterioration in drill workability due to the solid solution of Nb in the Mo of the matrix is that the matrix is hardened by the solid solution of Nb. On the other hand, as the form of Nb, drill workability is improved by dispersing it as pure Nb particles in the matrix Mo.

Average particle size of pure Nb in the molded product: 3 to 100 μm
The reason why the average particle size of pure Nb in the molded body is 3 to 100 μm is that the Nb phase dispersed in Mo is softer than Mo, so in the above range, the drill workability is improved by the notch effect, This is because the wear amount of the end mill edge becomes small. However, in the case of less than 3 μm, the notch effect does not appear because it is small, the end mill edge wear increases, and drill workability deteriorates. On the other hand, even when it exceeds 100 μm, it is too large to exhibit the notch effect, so that the effect of improving the drill workability is lowered, so the range is set to 3 to 100 μm. Preferably it is 5-50 micrometers.

Area ratio of pure Nb in the molded product: 3 to 40%
The reason why the area ratio of pure Nb in the molded body is 3 to 40% is within the above range, and the end mill edge wear amount is small. However, when the Nb area ratio in the molded body is less than 3%, the details are unknown, but the notch effect cannot be obtained, so that the amount of end mill edge wear increases. On the other hand, if it exceeds 40%, the time for cutting only Nb increases, and the effect of increasing the cutting resistance by cutting Nb softer than Mo becomes larger than the effect of improving drill workability by the notch effect. This is because the effect does not appear. Therefore, the range was made 3 to 40%. Preferably it is 5 to 30%.

  As described above, the particle size of pure Nb is about 100 μm or less. In addition, a diffusion phase (solid solution of Mo and Nb) of about 10 μm is usually present at the interface between the pure Mo in the matrix and the dispersed pure Nb particles. FIG. 1 is a diagram showing an example of a microstructure of a Mo alloy according to the present invention.

Using a mixed powder of Mo powder and Nb powder as raw material powder and molding by hot isostatic pressing (HIP) at 1100 to 1500 ° C. As described above, obtaining a microstructure having pure Nb particle dispersion in a pure Mo matrix This is not possible with the dissolution method. That is, since Mo and Nb form a complete solid solution, when dissolved and cast, the constituent phase becomes a Mo—Nb solid solution, and a pure Mo phase or a pure Nb phase cannot be generated. Therefore, a pure Mo powder and a pure Nb powder are mixed and subjected to hot isostatic pressing (HIP) at 1100 to 1500 ° C. to obtain a microstructure having pure Nb particle dispersion in a pure Mo matrix.

  At this time, if the HIP molding is performed at a temperature lower than 1100 ° C., the relative density is low and chipping occurs when drilling a drill hole. If the HIP molding is performed at a temperature exceeding 1500 ° C., the mutual diffusion of Mo and Nb becomes remarkable. Nb phase disappears and drill workability deteriorates. In addition, when performing normal HIP molding, carbon steel or stainless steel metal cans (melting point: about 1400 to 1500 ° C.) are filled with raw material powder and molded, so that the melting of the metal cans is suppressed and HIP molding is performed at 1400 ° C. or lower. It is preferable to do.

  The molded body thus obtained is obtained by removing a metal can such as carbon steel with a lathe, for example, to obtain a molded body of MoNb alloy. Thereafter, the formed body is finished as a member by drilling as necessary for machining, lathe or polishing as necessary. Prior to machining, hot rolling or hot forging may be performed, or after correction or punching with a cold press, the workpiece may be subjected to machining with drilling.

Example 1
Hereinafter, the present invention will be described specifically by way of examples.
Commercially available Mo powder (average particle size 10 μm) and commercially available Nb powder (average particle size 30 μm) were mixed so as to have the composition shown in Table 1, and an outer cylinder can made of carbon steel having a diameter of 200 mm × length of 80 mm. After filling and degassing and enclosing, it was held at the temperature shown in Table 1 for 5 hours to perform HIP molding. A disk-shaped test piece having a diameter of 100 mm × 3 t was collected from this molded body by wire cutting, lathe and polishing. In addition, about what carried out HIP at 1400 degreeC or more, the outer cylinder can of the billet which carried out HIP shaping | molding at 1350 degreeC by the said method was removed by cutting, and this was HIP-molded again at the temperature of 1400 degreeC or more. The relative density evaluation at that time, the confirmation of the remaining pure Nb phase, and the results of the drill workability test are shown.

  In the relative density evaluation, a 10 mm × 10 mm × 10 mm test piece was cut out from the end material of the produced molded body, the density was measured by the Archimedes method, and the value divided by the theoretical calculation density was evaluated in%. Further, the remaining Nb phase was confirmed by mirror-polishing the end material of the produced molded body and analyzing the Nb particle portion by EDX. The case where there was a site where only Nb was detected was marked with ◯, and the case where there was only a site where Mo was detected simultaneously with Nb was marked with x.

  Furthermore, in the drilling workability test, 10 temporary holes were drilled with a 4.3 mm diameter drill using the collected disk-shaped test piece, and then the main hole was rotated with an 8 mm diameter end mill (carbide, TiAlN coating). Drilling was performed from above the temporary hole at several 800 rpm and a feed rate of 10 mm / min. Use a new 4.3 mm diameter drill and 8 mm diameter end mill for each test material, and evaluate the wear width of the inner part 1.5 mm from the end of the 8 mm diameter end mill edge after drilling 10 holes. I did it. The results are also shown in Table 1.

表１に示すように、Ｎｏ．１〜６は本発明例であり、Ｎｏ．７〜１２は比較例である。

As shown in Table 1, no. Nos. 1 to 6 are examples of the present invention. 7 to 12 are comparative examples.

  Comparative Example No. 7 is the case of Mo alone, and the end mill edge wear is large. Comparative Example No. No. 8 has a low Nb content. As with No. 7, the end mill edge wear is large. Comparative Example No. In contrast, No. 9 has a high Nb content and the effect of improving the end mill edge wear is saturated. Comparative Example No. No. 10 has a low relative density because the HIP molding temperature is low.

  Comparative Example No. In contrast, since No. 11 has a high HIP molding temperature, no pure Nb phase remains and the end mill edge wear is large. Comparative Example No. No. 12 is a melting method, not HIP treatment, and no pure Nb phase remains and the end mill edge wear is large. On the other hand, No. which is an example of the present invention. Since all of Nos. 1 to 6 satisfy the conditions of the present invention, it can be seen that the relative density is high, the pure Nb phase remains, and the end mill edge wear is small.

(Example 2)
Next, a test piece having a cross section of 15 mm × 15 mm and a thickness of 5 mm was produced from the disk-shaped test piece produced by the method of Example 1 by wire cutting. In order to see in more detail the effect of the residual form of pure Nb phase on drilling workability, this test piece was embedded in a resin, and the cross section was analyzed by EDX while observing the shape of Nb particles with an electron microscope. A site containing 95% or more and 100% Nb at several concentrations was determined as the Nb phase. Further, the size of the Nb phase was determined by the diameter of the corresponding unit area circle by image analysis, and the average particle size and area ratio were calculated. These samples were subjected to a drill workability test. The drill workability test was evaluated by the method described in Example 1. The results are shown in Tables 2 and 3.

表２に示す、一般に市販されているＮｂ原料粉末の平均粒径は、１００μｍ以下であることから、Ｎｏ．１９の原料Ｎｂは市販のＮｂ原料粉末を分級し、微粉末を除去することで、平均２００μｍになるように調整した。

The average particle size of Nb raw material powders shown in Table 2 that are generally commercially available is 100 μm or less. Nineteen raw materials Nb were adjusted to an average of 200 μm by classifying commercially available Nb raw material powder and removing fine powder.

  As shown in Table 2, no. Nos. 13 to 17 are examples of the present invention. Reference numerals 18 and 19 are comparative examples. Comparative Example No. No. 18 has a large end mill edge wear because the average particle size of pure Nb in the compact is small. Comparative Example No. No. 19 has a large end mill edge wear because the average particle size of pure Nb in the compact is large. On the other hand, No. which is an example of the present invention. Since all of Nos. 13 to 17 satisfy the conditions of the present invention, it is understood that the end mill edge wear amount is small.

表３に示す、いずれの試作例も、使用したＮｂ原料粉末の平均粒径は３０μｍである。

In any of the prototypes shown in Table 3, the average particle diameter of the used Nb raw material powder is 30 μm.

  As shown in Table 3, no. Nos. 20 to 23 are examples of the present invention. 24 and 25 are comparative examples. Comparative Example No. No. 24 has a large end mill edge wear because the area ratio of pure Nb in the compact is small. Comparative Example No. No. 25 has a large end mill edge wear because the area ratio of pure Nb in the compact is large. On the other hand, No. which is an example of the present invention. Since all of Nos. 20 to 23 satisfy the conditions of the present invention, it is understood that the end mill edge wear amount is small.

  As described above, Nb: 1 to 50%, balance Mo and unavoidable impurities, pure Nb is dispersed in a matrix made of pure Mo, and the average particle diameter of pure Nb in the molded body is 3 to 100 μm. A microstructure having pure Nb particles in a pure Mo matrix is obtained by molding by hot isostatic pressing at 1100-1500 ° C. so that the area ratio of pure Nb in the molded product is 3-40%. The compact can obtain a Mo alloy compact excellent in drill workability particularly suitable for an accelerating electrode of various apparatuses.

It is a figure which shows the microstructure example of Mo alloy which concerns on this invention. It is a schematic diagram of an acceleration electrode.

1 Molybdenum sheet 2 Beam hole


Patent Applicant Sanyo Special Steel Co., Ltd.
Attorney: Attorney Shiina

Claims (4)

Atomic%, Nb: 1 to 50%, balance Mo and inevitable impurities, and pure Nb is dispersed in a matrix made of pure Mo. Average particle diameter of the pure Nb: 3 to 100 μm, area Ratio: 3 to 40%, a molded body made of a molybdenum alloy having excellent drilling workability for acceleration electrodes . In order to obtain the average particle diameter of pure Nb in the molded product according to claim 1, the raw material Nb average particle diameter is 25 to 80 μm. Molded body. A method for producing a molded body made of a molybdenum alloy excellent in drilling workability for an acceleration electrode , characterized in that a mixed powder of Mo powder and Nb powder is formed by hot isostatic pressing. The method for producing a molded body made of a molybdenum alloy having excellent drilling workability for an acceleration electrode according to claim 2, wherein hot isostatic pressing is performed at 1100 to 1500 ° C.

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