JP2009095857A - METHOD FOR FORMING TiAl INTERMETALLIC COMPOUND BASED ALLOY, AND FORMED ARTICLE PRODUCED BY THE METHOD - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming TiAl alloy capable of performing a near-net molding without causing a damage or abrasion due to oxidization and without requiring a removal of an oxidized layer or a base metal modified layer and a heat treatment for softening. <P>SOLUTION: In a method for forming TiAl intermetallic compound based alloy, under a state that a plate shaped TiAl intermetallic compound based alloy including Mn(manganese) or V (vanadium) is held in a vacuum or an inert atmosphere at 1,150°C or higher to 1,250°C or lower for a prescribed time, the alloy is hot-pressed by a die member of a hot press device to mold a recessed shape. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a TiAl intermetallic compound-based alloy molding method and a molded article molded by the molding method, and more particularly, a TiAl intermetallic compound by hot pressing in a vacuum or in an inert atmosphere using a hot pressing apparatus. The present invention relates to a method of molding a base alloy and a molded product molded by the molding method.

TiAl intermetallic compound based alloy (hereinafter referred to as “TiAl alloy”) mainly composed of TiAl (titanium aluminide) intermetallic compound is lightweight and excellent in high-temperature strength. It is promising as a member. These structural member products for aerospace use have various concave shapes such as hollow hemispheres and cones, not flat plates. Therefore, in order to manufacture these products with a TiAl alloy, it is necessary to form a TiAl alloy flat plate by plastic working. However, since the TiAl alloy has very poor ductility in the vicinity of the greenhouse, it is necessary to perform the molding operation by plastic working of the TiAl alloy at a high temperature at which sufficient ductility is exhibited in the TiAl alloy. When a TiAl alloy is applied to an aerospace structural member or the like, the greater the size, thickness, etc. of the target member, the greater the amount of weight reduction when the member is made of a TiAl alloy, resulting in a significant effect. Therefore, it can be said that the need for a TiAl alloy is greater for larger and thicker molded products. Conventionally, as a manufacturing method by plastic processing of a large and thick molded product of TiAl alloy, hot forging, in which a material heated in an atmospheric furnace is taken out of the furnace and forged while being molded, has been proposed. (For example, see Patent Document 1 and Non-Patent Document 1).
JP 2001-316743 A Toshimitsu Tetsui, Kentaro Shindo, Satoshi Kaji, Satoru Kobayashi, Masao Takeyama ”Fabrication of TiAl components by means of hot forging and machining” Intermetallics 13 (2005) 971-987.

  However, in hot forging, it is necessary to heat from about 1300 ° to 1350 ° in the atmosphere, but the TiAl alloy has low oxidation resistance at 1100 ° or more. Therefore, when a TiAl alloy is hot forged, a large amount of an oxide layer is generated, and there is a problem that wear due to oxidation becomes significant. Further, a thick oxide layer and a base material altered layer are formed on the surface of the TiAl alloy product after hot forging. For this reason, an operation of removing the oxide layer and the base material altered layer by machining is necessary, and there is a problem that the material is wasted and the number of work steps is increased. Furthermore, TiAl alloy has a property of hardening when rapidly cooled, but in hot forging, the TiAl alloy is taken out of the furnace and forged so that the cooling rate of the TiAl alloy becomes very fast. Therefore, the molded product of TiAl alloy becomes very hard, and there is a problem that a separate softening heat treatment is required for the subsequent process. In hot forging, the temperature of the TiAl alloy drops rapidly during the operation, so that sufficient ductility is exhibited and the molding operation can be performed for a short time, and a large amount of oxide layer is formed on the outer surface. Adhere to. For this reason, it is difficult to perform near-net molding that fills the mold with material, and it is necessary to make a molded product that is larger than the final shape. There is a problem that the use efficiency of the material is deteriorated because the large part becomes large.

  The present invention has been made in view of such problems, and does not cause wear due to oxidation, and does not require the removal work of the oxide layer and the base material altered layer and the softening heat treatment, and is a TiAl alloy capable of near-net forming. An object is to provide a molding method and a molded product molded by the molding method.

  In order to achieve the above object, the TiAl intermetallic compound-based alloy molding method according to claim 1 is a TiAl intermetallic compound-based alloy molding method comprising a plate-like TiAl metal-containing alloy containing Mn or V. The compound base alloy is molded into a concave shape by hot pressing with a carbon mold material in a state where the compound base alloy is held at 1150 ° C. or more and 1250 ° C. or less for 0.5 hour or more in a vacuum or an inert atmosphere. It is a feature.

  The method for forming a TiAl intermetallic compound-based alloy according to claim 2 is the method for forming a TiAl intermetallic compound-based alloy according to claim 1, wherein the TiAl intermetallic compound-based alloy before molding is sized. 500 × 500 × t30 mm or more and 1300 × 1300 × t80 mm or less.

  The method for molding a TiAl intermetallic compound-based alloy according to claim 3 is the method for molding a TiAl intermetallic compound-based alloy according to claim 1 or 2, wherein the press stroke in the hot press by the hot press apparatus is It is characterized by being 50 mm or more and 800 mm or less.

  A method for molding a TiAl intermetallic compound-based alloy according to claim 4 is a method for molding a TiAl intermetallic compound-based alloy according to any one of claims 1 to 3, wherein hot pressing by the hot press device is performed by: It is characterized by pressing at a speed of 5 mm / min to 10 mm / min.

  A method for forming a TiAl intermetallic compound-based alloy according to claim 5 is a method for forming a TiAl intermetallic compound-based alloy according to any one of claims 1 to 4, wherein the TiAl intermetallic compound-based alloy is formed by hot pressing using the hot press device. The TiAl intermetallic compound base alloy is pressed so that the thickness is 10 mm or more and 60 mm or less at the thinnest part.

  The method for forming a TiAl intermetallic compound-based alloy according to claim 6 is the method for forming a TiAl intermetallic compound-based alloy according to any one of claims 1 to 5, wherein the mold material is a carbon having a concave shape. It is characterized by comprising a lower mold made of carbon and an upper mold made of carbon having a convex shape corresponding to the concave shape of the lower mold.

  The TiAl intermetallic compound-based alloy molding method according to claim 7 is the TiAl intermetallic compound-based alloy molding method according to any one of claims 1 to 6, wherein the size of the lower mold made of carbon is The maximum size is about 1500 × 1500 × 1000 mm.

  A method for molding a TiAl intermetallic compound-based alloy according to claim 8 is a method for molding a TiAl intermetallic compound-based alloy according to any one of claims 6 or 7, wherein the TiAl intermetallic compound-based alloy is molded. Through a through hole provided in a portion to be removed without forming a molded product later, a rod-like hole is provided in a hollow hole provided in a portion corresponding to the through hole of the TiAl intermetallic compound based alloy of the lower mold. The TiAl intermetallic compound base alloy is fixed to the lower mold by inserting a pin, and hot pressing is performed by the hot pressing apparatus.

  The method for forming a TiAl intermetallic compound based alloy according to claim 9 is the method for forming a TiAl intermetallic compound based alloy according to claim 8, wherein the pin is TZM (a molybdenum alloy to which titanium and zirconium are added). It is made of an alloy.

  A method for forming a TiAl intermetallic compound-based alloy according to claim 10 is a method for forming a TiAl intermetallic compound-based alloy according to any one of claims 1 to 9, wherein the TiAl intermetallic compound group before forming is formed. The alloy is oxidized at 900 ° C. or more and less than 1050 ° C. in the atmosphere for 0.5 hour or more and less than 5.0 hour to form an oxide film on the surface of the TiAl intermetallic compound base alloy, and then the carbon-made alloy is used. The mold material is hot-pressed by the hot press apparatus and molded.

  A molded article of the TiAl intermetallic compound base alloy according to claim 11 is characterized by being molded by the method of molding a TiAl intermetallic compound base alloy according to any one of claims 1 to 10.

  According to the invention described in claim 1, a plate-like TiAl intermetallic compound containing Mn or V at a temperature of 1150 ° C. or more and 1250 ° C. or less in a vacuum or an inert atmosphere by hot pressing using a hot pressing apparatus. Mold the base alloy. Therefore, since a thick oxide layer or base material altered layer is not formed on the surface of the TiAl intermetallic compound base alloy, wear due to oxidation does not occur, and processing for removing the thick oxide layer or base material altered layer is not caused. A large number of man-hours are not required for the work, and a near net can be formed. Further, in the hot press, the cooling rate is slowed because cooling is performed inside the hot press apparatus after the molding is completed, the degree of hardening of the TiAl intermetallic compound base alloy is low, and no softening heat treatment is required.

  According to the invention described in claim 2, since the size of the TiAl intermetallic compound base alloy before molding is 500 × 500 × t30 mm or more and 1300 × 1300 × t80 mm or less, a large and thick TiAl intermetallic compound base alloy Can be molded by hot pressing.

  According to the invention described in claim 3, since the press stroke in the hot press, that is, the amount of movement of the ram is 50 mm or more and 800 mm or less, a large and deep molded product can be molded by the hot press.

  According to the fourth aspect of the present invention, since pressing is performed by moving the ram at a speed of 5 mm / min or more and 10 mm / min or less, the TiAl intermetallic compound base alloy can be suitably molded.

  According to the fifth aspect of the present invention, since the TiAl intermetallic compound base alloy is pressed so that the thickness is 10 mm or more and 60 mm or less at the thinnest portion, the thick TiAl intermetallic compound base alloy is molded. Can be molded.

  According to the invention of claim 6, the mold material is composed of a carbon lower mold having a concave shape and a carbon upper mold having a convex shape corresponding to the concave shape of the lower mold. A TiAl intermetallic compound base alloy can be suitably formed into a concave shape by disposing a plate-like TiAl intermetallic compound base alloy between the upper mold and the upper mold into the lower mold by hot pressing.

  According to the seventh aspect of the present invention, since the carbon material that is lightweight, has high strength at high temperatures, and can provide a large material at a relatively low cost is used as the material of the mold material, the size of the lower mold is about 1500 × 1500 × 1000 mm at maximum. The TiAl intermetallic compound base alloy can be molded into a large molded product by hot pressing. In addition, in the conventional Mo alloy (for example, TZM alloy) which is a mold material used at a high temperature of 1200 ° C. or higher, there is no large-size material as described above. Therefore, it cannot be used for molding large TiAl intermetallic compound base alloys.

  According to the invention of claim 8, since the TiAl intermetallic compound base alloy is fixed to the lower die using the rod-shaped pin, the outer peripheral portion of the TiAl intermetallic compound base alloy is a lower concave shape during hot pressing. Since it can be prevented from being drawn toward the part, a molding operation of a predetermined shape is possible.

  According to the ninth aspect of the present invention, since the pin is made of a TZM alloy and has high strength even at 1150 ° C. or higher and 1250 ° C. or lower, the size of the pin can be reduced. Therefore, the size of the through hole provided in the TiAl intermetallic compound base alloy can be reduced, and the portion having the through hole to be removed after molding of the TiAl intermetallic compound base alloy can be reduced. It is efficient without waste.

  According to the invention described in claim 10, since an oxide film is formed in advance on the surface of the TiAl intermetallic compound base alloy material, when the hot press is performed by a hot press apparatus, the oxide film is formed with a carbon mold. It functions as a mold release agent and can prevent the reaction between the TiAl intermetallic compound base alloy and the carbon mold.

  Since the molded product of the TiAl intermetallic compound base alloy according to claim 11 is molded by the method of molding the TiAl intermetallic compound based alloy according to any one of claims 1 to 10, the oxide layer or the base material alteration A large number of man-hours is not required for the layer removal operation, and a near net can be formed. Further, since a soft heat treatment is not required, the manufacturing cost can be kept low. Further, since the TiAl intermetallic compound base alloy does not react with the carbon mold, the yield is good, and the carbon mold can be used repeatedly, so that the manufacturing cost can be kept low. Furthermore, a large and thick molded product can be molded under suitable conditions by hot pressing using a TiAl intermetallic compound-based alloy.

  Hereinafter, a method for forming a TiAl intermetallic compound-based alloy (hereinafter referred to as “TiAl alloy”) according to the present invention will be described with reference to the drawings. The TiAl alloy molding method according to the present invention molds a TiAl alloy by hot pressing using a hot press apparatus. As shown in FIG. 5, the conventional hot press apparatus 100 has a specimen 200 in a planar state in a high-temperature furnace 102 that is heated by a heater 101 or filled with an inert gas. It is a device that pushes the specimen 200 into the jig 103b uniaxially by sandwiching it with the jigs 103a and 103b and pressing down the ram 104 from above the upper jig 103a. Conventionally, the hot press apparatus 100 has been used for pressure sintering of metal powder and brazing of metal members, and the movement amount (stroke) of the ram at that time can be made with a flat jig at most. It was about several tens of mm. However, the hot press apparatus has a stroke of several hundred mm in terms of performance. The inventor of the present application can move a ram of several hundred mm by using a mold having a three-dimensional uneven structure instead of a flat jig, and by using the amount of movement, I came up with the idea that a flat plate can be formed into a concave shape using a press.

In order to mold a TiAl alloy by hot pressing, it is necessary to select a TiAl alloy having sufficient plastic deformability for molding at a temperature of 1150 ° C. or higher and 1250 ° C. or lower, which is a temperature when molding with a hot press apparatus. . Further, the structure of the TiAl alloy is preferably a three-phase structure of β phase, γ phase and α ₂ phase in order to ensure plastic deformability at high temperature and strength and ductility from room temperature to high temperature. TiAl alloys that meet these conditions include TiAl alloys containing Mn (manganese) or V (vanadium), such as Ti-42Al-5Mn (at%: atomic concentration) and Ti-42Al-10V (at %: Atomic concentration). The condition that the temperature at the time of molding by the hot press apparatus is 1150 ° C. or higher and 1250 ° C. or lower is determined from the viewpoint of durability of the mold material used for hot pressing, prevention of reaction between the TiAl alloy and the mold material, and plastic deformability of the TiAl alloy. Is. The TiAl alloy is not limited to the above-described specific example, and any TiAl alloy may be used as long as it has a sufficient plastic deformability for molding at a temperature of 1150 ° C. or higher and 1250 ° C. or lower, which is a temperature at the time of molding with a hot press apparatus. It may be a thing.

  As the mold material, a carbon material is used from the viewpoint of weight reduction and cost reduction. The carbon mold material has a low durability at 1250 ° C. or higher, and is greatly damaged when used in a hot press, and cannot be used repeatedly. Further, at 1250 ° C. or higher, even if a reaction prevention measure is taken, the mold material and the TiAl alloy react with each other and are bonded to each other when hot pressing is performed. Furthermore, various alloys exist as the TiAl alloy, and since it is 1150 ° C. or more that any alloy exhibits a sufficient plastic deformability for molding, heating at 1150 ° C. or more is necessary.

  The molded product formed by hot pressing is obtained by pressing the center of a plate-like TiAl alloy with a mold material, and the shape is symmetrical and pressed as shown in FIGS. 1 (a) and (b). The center portion thus formed has a curved surface, and a flat plate shape before molding is maintained around the pushed-in portion. The flat plate of TiAl alloy before molding is, for example, large and thick with a size of 500 × 500 × t30 mm or more and 1300 × 1300 × t80 mm or less and a weight of 30 kg or more and 540 kg or less. Such a flat plate of TiAl alloy is molded by being pressed by a mold material by 50 to 800 mm by hot pressing, and the thickness after molding is 10 to 60 mm in the thinnest part. Such a large and thick TiAl alloy cannot be molded by existing gas pressure molding or isothermal forging. This is because gas pressure molding has a limit in pressure because gas is pressurized using a pressure medium. Therefore, it is only possible to mold a product having a thickness of several millimeters at most. Also, constant temperature forging usually uses a Mo alloy mold, but as described above, there is no Mo alloy mold that can mold such a large molded product, and even if it exists, it is very expensive. Therefore, it is not suitable for industrial use.

  Next, manufacture of the raw material shape | molded by the hot press using a hot press apparatus is demonstrated. First, an ingot of a TiAl alloy is hot forged to produce an amorphous thick flat plate. Alternatively, a TiAl alloy powder is sintered by HIP (Hot Isostatic Press) or the like to produce an amorphous thick flat plate. The amorphous thick flat plate thus obtained is cut into a predetermined shape such as a disk by water jet cutting or wire cutting. Then, the upper and lower surfaces of the thick flat TiAl alloy obtained by cutting are cut into a predetermined thickness by a milling machine or the like.

  When the TiAl alloy manufactured in this way is hot-pressed as it is in a vacuum or under an inert atmosphere by a hot press apparatus, the TiAl alloy and the carbon mold material react to be bonded to each other. Therefore, it is necessary to take measures to prevent bonding due to reaction. Conventionally, there is a release agent such as BN (boron nitride) spray, and it is conceivable to prevent the reaction by applying this release agent to the surface of the TiAl alloy and the carbon mold. However, in the molding operation by the hot press according to the present invention, in the molding process, the TiAl alloy is stretched while rubbing the surface of the side surface of the carbon mold. For this reason, the release agent applied to both surfaces easily peels off due to friction, so that the effectiveness of the release agent is not sufficiently exhibited.

  Thus, a normal release agent such as BN spray cannot be expected to be effective. Therefore, the TiAl alloy before molding is subjected to atmospheric oxidation treatment to form a dense oxide film mainly composed of an alumina film on the surface of the TiAl alloy. Then, the reaction between the TiAl alloy and the carbon mold is prevented by using this oxide film as a release agent. Since this oxide film is an oxide stable to carbon, it does not react with carbon and is suitable as a release agent. In addition, since this oxide film is naturally formed on the entire surface of the TiAl alloy when the TiAl alloy is oxidized in the air, it has good adhesion and followability to the TiAl alloy. Even if it is stretched while rubbing, it functions as a release agent. This oxide film is formed by oxidizing the TiAl alloy at 900 ° C. or more and 1050 ° C. or less for 0.5 hours or more and 5.0 hours or less in the air. When the temperature for the oxidation treatment is 900 ° C. or lower, a dense oxide film is not formed. When the temperature is 1050 ° C. or higher, the oxide film becomes too thick and the oxide film is easily separated from the TiAl alloy. Further, when the oxidation treatment time is 0.5 hours or less, a dense oxide film is not formed, and when it is 5.0 hours or more, the oxide film becomes too thick and easily peels off.

  The present invention also solves problems such as wear due to oxidation of a TiAl alloy in hot forging. Oxidation should therefore be avoided. In hot forging, before and after being molded into the final product shape, the furnace is repeatedly put in and out of the furnace at 1300 ° C. or more several tens of times, and is reheated each time, so that it is heated for a total of about 10 hours. As a result, the amount of material that is worn away as an oxide layer that is peeled off during the molding operation increases, and the amount of oxide layer and base material altered layer that must be finally fixed to the material to be removed becomes very large, which requires the removal operation. Man-hours also increase. On the other hand, the above-described oxide film as a release agent in the present invention is formed by oxidation at about 1000 ° C. for only about 2.0 hours, and therefore hardly peels off and must be fixed to the material and removed. The amount of oxide film and base material altered layer that must be reduced is also reduced. In addition, since the oxide film is a very thin film, it does not hinder near-net molding.

  Next, the shaping | molding by the hot press apparatus 1 of the TiAl alloy 1000 in which the oxide film was formed is demonstrated using FIG. As shown in FIG. 2, the hot press apparatus 1 used for hot pressing the TiAl alloy 1000 includes a furnace 2, a plurality of heaters 3 for heating the inside of the furnace 2, and a ram 4 for pressing. The hot press apparatus 1 has the same configuration as the conventional hot press apparatus 100 described above. When the TiAl alloy 1000 is molded using the hot press apparatus 1, for example, a carbon lower mold (mold material) 10 having a conical recess whose tip is substantially hemispherical is formed inside the furnace 2. Installed. The size of the lower mold 10 is about 1500 × 1500 × 1000 mm at the maximum. A disc-shaped TiAl alloy 1000 is disposed in the opening of the recess of the lower mold 10 so that the TiAl alloy 1000 is supported by the peripheral portion 10a of the opening. Further, on the upper part of the lower mold 10, a carbon upper mold 11 for pushing the TiAl alloy 1000 arranged in the opening of the depression of the lower mold 10 into the depression of the lower mold 10 is arranged via the TiAl alloy 1000. The The upper mold 11 has a conical shape whose tip is substantially hemispherical. The cone of the upper mold 11 is substantially similar to the cone of the depression of the lower mold 10, and the cone of the upper mold 11 is smaller than the cone of the lower mold 10 by a predetermined amount.

  In addition, a cylindrical guide 12 that supports the shaft of the upper die 11 pushed down by the ram 4 so as not to move is provided on the upper portion of the lower die 10. Most of the inner diameter of the guide 12 is substantially the same as the maximum diameter of the upper mold 11, but the inner diameter of the lower end portion is substantially the same as the outer diameter of the TiAl alloy 1000. Therefore, a step-shaped portion 12 a is formed at the boundary between the large diameter portion and the small diameter portion of the guide 12. The position of the disc-shaped TiAl alloy 1000 is fixed by the step-shaped portion 12 a below the guide 12, the small-diameter portion of the lower end portion of the guide 12, and the peripheral portion 10 a of the opening of the recess of the lower mold 10. The

  When the arrangement inside the furnace 2 is thus prepared, the inside of the furnace 2 is evacuated to a vacuum state. Alternatively, the inside of the furnace 2 may be filled with an inert gas after the inside of the furnace 2 is evacuated. Then, the interior of the furnace 2 is heated by the heater 3 to 1150 ° C. or higher and 1250 ° C. or lower, preferably 1175 ° C. or higher and 1225 ° C. or lower, for example, 1200 ° C. When the TiAl alloy 1000 reaches approximately 1200 ° C., the temperature is maintained for approximately 0.5 hours to make the temperature of the TiAl alloy 1000 uniform. At this time, since the inside of the furnace 2 is in a vacuum state or filled with an inert gas, there is no possibility that the TiAl alloy 1000 is oxidized by heating. Thereafter, the ram 4 of the hot press apparatus 1 is lowered, and the upper die 11 is pushed into the depression of the lower die 10 through the TiAl alloy 1000. The lowering speed of the ram is optimally about 5 mm / min or more and 10 mm / min or less. If it is 5 mm / min or less, the working time for holding at a high temperature becomes too long, and the characteristics of the TiAl alloy are deteriorated and the working efficiency is poor. Moreover, if it is 10 mm / min or more, the deformation speed is too high, and wrinkles or the like may occur, which may prevent molding into a near net. The flat plate of the TiAl alloy 1000 is not only bent but also plastically deformed by being pushed into the depression of the lower mold 10 of the upper mold 11, so that the thickness is reduced. The TiAl alloy 1000 is molded into a predetermined shape by pushing the upper mold 11 completely into the recess of the lower mold 10.

  The shape of the TiAl alloy 1000 after molding is the shape of the space between the lower mold 10 and the upper mold 11. The load of the hot press using the hot press apparatus 1 becomes the largest at the final stage of molding, and is about 300 tons at the maximum. After completion of molding, the ram 4 is raised to remove the press load, and the entire temperature of the hot press apparatus 1 is lowered at a low speed by natural cooling. When the temperature inside the furnace 2 reaches about 200 ° C. or lower, the TiAl alloy 1000 is taken out of the hot press apparatus 1 together with the lower mold 10, the upper mold 11, and the guide 12, and the TiAl alloy 1000 is removed from the lower mold 10 and the upper mold. Release from the mold 11. In this way, a hollow, substantially conical TiAl alloy molded product 1000 as shown in FIG. 3 is obtained.

  In particular, when a product having a shape whose entire outer periphery does not remain on the lower die as shown in FIG. 1 is formed, the periphery of the TiAl alloy 1000 that is plastically deformed when the upper die 11 is pushed into the recess of the lower die 10. There is a possibility that the portion is drawn in the direction of the depression of the lower mold 10. In order to prevent this pull-in, as shown in FIG. 4, several through holes 1000a are provided in the peripheral portion of the TiAl alloy 1000 that is not a product after the TiAl alloy 1000 is molded, and the through holes of the lower mold 10 are also provided. A hole (recess) 10b is provided in a portion corresponding to 1000a, and as shown in FIG. 4, the hole (recess) 10b is made of a TZM (molybdenum alloy added with titanium and zirconium) alloy through the through-hole 1000a and is rod-shaped. The TiAl alloy 1000 may be fixed to the lower mold 10 by inserting the pin 300. Since the strength of the TZM alloy is very high even at 1150 ° C. or more and 1250 ° C. or less, the pin 300 made of the TZM alloy can be made small. Therefore, since the size of the through hole 1000a of the TiAl alloy 1000 into which the pin 300 is inserted can be small, the size of the peripheral portion that does not become a product after the molding of the TiAl alloy 1000 can be small, and the TiAl alloy 1000 is not wasted.

<Example>
A TiAl alloy ingot having a diameter of 380 mm and a length of 800 mm made of 42 atomic% Al, 5 atomic% Mn, the remainder Ti and inevitable impurities is hot forged to form a thick flat plate having a diameter of about 1050 mm to 1250 mm and a thickness of about 75 mm to 85 mm. Formed. The amorphous thick flat TiAl alloy 1000 thus obtained was cut into a disk shape having a diameter of 1000 mm by water jet cutting, and the upper and lower surfaces of the disk-shaped TiAl alloy 1000 were cut by a milling machine to obtain a thickness of 60 mm. did.

  Next, the obtained TiAl alloy 1000 disk is heated to 1000 ° C. in the atmosphere and oxidized in the atmosphere for 1 hour, whereby an oxide film mainly made of an alumina film having a thickness of about 50 μm is formed on the surface of the TiAl alloy disk. Formed.

  Using such a TiAl alloy 1000, as shown in FIG. 2, after the lower mold 10, the TiAl alloy 1000, the upper mold 11, and the guide 12 are installed in the furnace 2 of the hot press apparatus 1, the furnace 2 The inside of was vacuum-evacuated and filled with an inert gas, Ar gas. Next, the TiAl alloy 1000 inside the furnace 2 was heated to about 1200 ° C. by the heater 3 and this temperature was maintained for 0.5 hour. Then, the ram 4 was lowered by about 500 mm at a speed of 8 mm / min at a temperature of about 1200 ° C., and the upper die 11 was pushed into the lower die 10 through the TiAl alloy 1000.

  Thereafter, after the temperature of the entire furnace 2 reaches around 200 ° C., the TiAl alloy 1000 is taken out of the furnace 2 together with the lower mold 10, the upper mold 11, and the guide 12, and the lower mold 10 and the upper mold 11 of the TiAl alloy 1000 are taken out. I tried to release from. The TiAl alloy 1000 was easily released from the lower mold 10 and the upper mold 11 to obtain a molded product 1000 as shown in FIG. Although the molded product 1000 after the mold release was visually confirmed, the surface of the molded product 1000 was not damaged as a result of separating the bonding caused by the reaction that occurred between the lower mold 10 and the upper mold 11. . Since the molded product 1000 obtained in this way has a structure in which three phases of β phase, γ phase, and α2 phase coexist, the molded product 1000 has high strength and high toughness.

  The embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the technical idea of the present invention. For example, in the above-described embodiment, before performing hot pressing by the hot press apparatus 1 for the TiAl alloy 1000, atmospheric oxidation treatment is performed to form an oxide film as a release agent on the surface of the TiAl alloy 1000. However, when the mold release effect can be ensured by other methods, the oxide film is not necessarily formed, and the TiAl alloy 1000 may be hot pressed as it is.

  Also, the molded product 1000 shown in FIG. 3 is merely an example, and the molded product molded by the TiAl intermetallic compound-based alloy molding method of the present invention is a concave shape that can be molded using the hot press apparatus 1. Needless to say, any shape may be used.

  The present invention is applicable to a method of molding a large and thick TiAl intermetallic compound base alloy using a hot press apparatus, and a molded product molded by the molding method.

It is explanatory drawing which shows the example of the molded article shape | molded by the shaping | molding method of the TiAl alloy of this invention. It is explanatory drawing which shows the mode of the hot press by the hot press apparatus. It is explanatory drawing which shows an example of the molded article shape | molded by the shaping | molding method of the TiAl alloy of this invention using the hot press apparatus. It is explanatory drawing which shows a mode that the TiAl alloy 1000 was fixed to the lower mold | type 10 with the pin 300 made from a TZM alloy. It is explanatory drawing which shows the mode of the hot press by the conventional hot press apparatus 100. FIG.

Explanation of symbols

1 Hot press device 2 Furnace 3 Heater 4 Ram 10 Lower mold (carbon mold)
11 Upper mold (carbon mold)
12 Guide 300 Pin 1000 TiAl alloy (molded product)

Claims (11)

A method for forming a TiAl intermetallic compound-based alloy,
A carbon mold material is used by a hot press apparatus in a state where a plate-like TiAl intermetallic compound-based alloy containing Mn or V is held at 1150 ° C. or more and 1250 ° C. or less for 0.5 hour or more in a vacuum or an inert atmosphere. A method of forming a TiAl intermetallic compound-based alloy, which is hot-pressed and formed into a concave shape.   The method for molding a TiAl intermetallic compound-based alloy according to claim 1, wherein the TiAl intermetallic compound-based alloy before molding has a size of 500 x 500 x t30 mm or more and 1300 x 1300 x t80 mm or less.   The method for forming a TiAl intermetallic compound-based alloy according to claim 1 or 2, wherein a press stroke in the hot press by the hot press apparatus is 50 mm or more and 800 mm or less.   The method for forming a TiAl intermetallic compound-based alloy according to any one of claims 1 to 3, wherein in the hot pressing by the hot pressing apparatus, pressing is performed at a speed of 5 mm / min to 10 mm / min.   The TiAl according to any one of claims 1 to 4, wherein the TiAl intermetallic compound base alloy is pressed by hot pressing with the hot pressing device so that the thickness is 10 mm or more and 60 mm or less at the thinnest portion. A method for forming an intermetallic compound-based alloy.   The said mold material consists of a carbon lower mold | type which has a concave shape, and a carbon upper mold | type which has a convex shape corresponding to the concave shape of the said lower mold | type. Of forming a TiAl intermetallic compound-based alloy.   The method for molding a TiAl intermetallic compound-based alloy according to claim 6, wherein the size of the lower mold made of carbon is about 1500 x 1500 x 1000 mm at the maximum.   Provided in the portion corresponding to the through hole of the TiAl intermetallic compound-based alloy of the lower mold through the through-hole provided in the portion that is removed without forming the molded product after molding of the TiAl intermetallic compound-based alloy The hot press is performed by the hot press apparatus by fixing the TiAl intermetallic compound base alloy to the lower mold by inserting a rod-like pin into the hollow hole formed. The forming method of the TiAl intermetallic compound base alloy as described.   The method of forming a TiAl intermetallic compound-based alloy according to claim 8, wherein the pin is made of a TZM (titanium, molybdenum alloy added with zirconium) alloy.   The TiAl intermetallic compound base alloy before molding is oxidized in the atmosphere at 900 ° C. or higher and lower than 1050 ° C. for 0.5 hour or more and less than 5.0 hours to form an oxide film on the surface of the TiAl intermetallic compound base alloy. The method for forming a TiAl intermetallic compound-based alloy according to any one of claims 1 to 9, wherein, after forming, the hot-pressing device is used to form the carbon-made mold material.   A molded product of a TiAl intermetallic compound-based alloy, which is molded by the method for molding a TiAl intermetallic compound-based alloy according to any one of claims 1 to 10.

Images