Tial alloy material, method for producing tial alloy material, and rotor blade for jet engine

Abstract

A TiAl alloy material according to the present disclosure contains: at least one among 0.07-0.25 at% of carbon and 0.30-0.85 at% of silicon; 45.5-47.7 at% of aluminum; 0.5-2.5 at% of chromium; and 0.5-1.0 at% of tungsten, with the remainder consisting of titanium and inevitable impurities. The TiAl alloy material may further contain 0.02-0.06 at% of calcium.

Description

TiAl alloy material, manufacturing method of TiAl alloy material, and jet engine rotor blade

[0001] This disclosure relates to a TiAl alloy material, a method for manufacturing the TiAl alloy material, and a rotor blade for a jet engine. This application claims priority to Japanese Patent Application No. 2024-030480, filed on February 29, 2024, the contents of which are incorporated herein by reference.

[0002] Conventionally, jet engine rotor blades have been made of Ni-based superalloys. In recent years, jet engine rotor blades made of TiAl alloys have been used. The density of TiAl alloys is about half that of Ni-based superalloys. Therefore, jet engine rotor blades made of TiAl alloys contribute significantly to improving engine efficiency and reducing fuel consumption by reducing the weight of the rotor blades.

[0003] Properties required for jet engine rotor blades include high-temperature strength, oxidation resistance, impact resistance, etc. The most important property required for jet engine rotor blades is impact resistance, which is directly linked to the reliability of the jet engine. A clear example that illustrates the importance of impact resistance of TiAl alloys used for jet engine rotor blades can be seen from the operational success or failure of jet engine rotor blades made of two types of TiAl alloys that have actually been put into practical use as materials for jet engine rotor blades.

[0004] Jet engine blades made of TiAl4822 (Ti-48.0Al-2Nb-2Cr (atomic %)), which were first put into practical use, have not encountered any major problems since their practical use. TiAl4822 is currently used in large quantities as a material for the final stage turbine blades of jet engines such as LEAP (Leading Edge Aviation Propulsion).

[0005] The next jet engine rotor blade made of TNM alloy (Ti-43.5Al-4.0Nb-1.0Mo-0.1B (atomic %)) was put to practical use. It was once used as the material for the turbine final stage rotor blades of the PW1100G, a high-bypass geared turbofan engine, but suddenly fell out of use. The reason for this was publicly announced to be that debris flying from inside the engine during flight collided with the turbine final stage rotor blades at high speed, causing the impact and destruction of a considerable number of engine blades.

[0006] The biggest reason for the difference between the two is the difference in engine type. The engine using jet engine blades made of TiAl4822 is a turbofan engine with a relatively low rotational speed. In contrast, the engine using jet engine blades made of TNM alloy is a geared turbofan engine with a relatively high rotational speed. In engines with high rotational speeds, the collision speed between foreign objects and jet engine blades is high. For this reason, it is thought that jet engine blades made of TNM alloy were more susceptible to impact fracture.

[0007] Thus, impact resistance is an important property for TiAl alloys used in practical applications as materials for jet engine blades. In particular, the impact resistance of TiAl alloys used in jet engine blades for engines with high rotational speeds is a crucial property that determines whether the jet engine can be used continuously.

[0008] Patent Document 1 describes an as-cast γ-TiAl alloy preform in which an as-cast γ-TiAl alloy material having a shape suitable for rolling into a thin plate is placed in a cladding material. Patent Document 1 also describes that a suitable γ-TiAl alloy contains titanium and aluminum, as well as appropriate amounts of chromium, niobium, tantalum, tungsten, manganese, boron, carbon, and silicon to impart properties such as improved ductility, creep resistance, oxidation resistance, and impact resistance to the γ-TiAl alloy thin plate.

[0009] Patent Document 2 discloses a TiAl intermetallic compound-based alloy having a volume ratio of non-lamellar structures of 3% or less, a lamellar grain size of 200 μm or less, and a lamellar spacing of 2 μm or less. Patent Document 2 describes a TiAl intermetallic compound-based alloy containing titanium (Ti), aluminum (Al), niobium (Nb), tungsten (W), nickel (Ni), and boron (B).

[0010] Patent Document 3 describes a titanium aluminide intermetallic composition based on a gamma-TiAl intermetallic compound, which is composed of titanium and aluminum in amounts such that a gamma-TiAl intermetallic compound is obtained, chromium, niobium, carbon in an amount of 160 to 470 ppm, and incidental impurities.

[0011] Japanese Unexamined Patent Publication No. 2007-131949 (A) Japanese Unexamined Patent Publication No. 2003-147475 (A) Japanese Unexamined Patent Application No. 2013-209750 (A) Problems to be Solved by the Present Disclosure

[0012] Currently, jet engine blades made of TiAl4822 are used in turbofan engines with low rotational speeds, and there are no practical problems. However, it is expected that next-generation jet engines will have higher rotational speeds. Therefore, jet engine blades made of TiAl4822 may be susceptible to impact fracture, just like jet engine blades made of the TNM alloy.

[0013] Furthermore, it is expected that the operating temperatures of next-generation jet engines will rise, and therefore it is necessary to further improve the high-temperature properties of jet engine rotor blades for next-generation jet engines. For this reason, TiAl alloys used in jet engine rotor blades are required to have even greater improvements in creep strength and oxidation resistance.

[0014] For these reasons, there is a demand for a TiAl alloy having excellent impact resistance, creep strength and oxidation resistance that can be used as a material for jet engine rotor blades in next-generation jet engines.

[0015] Furthermore, methods for manufacturing TiAl alloy materials used for jet engine rotor blades include casting, forging, and additive manufacturing, including technologies under development. From the viewpoint of manufacturing costs, it is preferable to use the currently mainstream casting method for manufacturing TiAl alloy materials used for jet engine rotor blades. Therefore, there is a demand for TiAl alloys that can be manufactured by casting as the material for jet engine rotor blades for next-generation jet engines.

[0016] The present disclosure has been made in view of the above circumstances, and aims to provide a TiAl alloy material that can be produced by a casting method, has excellent impact resistance, creep strength, and oxidation resistance, and is suitable for use as a material for jet engine blades, and a method for producing the same. Another aim of the present disclosure is to provide a jet engine blade made of the TiAl alloy material of the present disclosure, which has excellent impact resistance, high-temperature strength, and oxidation resistance.

[0017] The TiAl alloy material according to the present disclosure is composed of at least one of carbon: 0.07 atomic % to 0.25 atomic % and silicon: 0.30 atomic % to 0.85 atomic %; aluminum: 45.5 atomic % to 47.7 atomic %; chromium: 0.5 atomic % to 2.5 atomic %; tungsten: 0.5 atomic % to 1.0 atomic %; and the balance being titanium and unavoidable impurities.

[0018] The TiAl alloy material of the present disclosure contains at least one of carbon (C) and silicon (Si), aluminum (Al), chromium (Cr), and tungsten (W) in predetermined amounts, with the remainder being titanium (Ti) and unavoidable impurities. Therefore, the TiAl alloy material of the present disclosure can be manufactured using a casting method and has excellent impact resistance, creep strength, and oxidation resistance. Therefore, the TiAl alloy material of the present disclosure can be preferably used as a material for jet engine blades.

[0019] Furthermore, according to the method for producing a TiAl alloy material of the present disclosure, a TiAl alloy material having excellent impact resistance, creep strength, and oxidation resistance can be produced by a casting method. Furthermore, since the jet engine blade of the present disclosure is made of the TiAl alloy material of the present disclosure, it has excellent impact resistance, creep strength, and oxidation resistance.

[0020] FIG. 1 is a perspective view showing a mold used in the examples.

[0021] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described. Note that the numerical ranges in the present disclosure include upper and lower limit values. This also applies to the ranges of absorbed energy in Charpy impact tests, creep rupture time, and weight gain of oxidation test specimens, as well as the composition ranges shown below.

[0022] [1] The TiAl alloy material according to the present disclosure comprises at least one of carbon: 0.07 atomic % to 0.25 atomic % and silicon: 0.30 atomic % to 0.85 atomic %; aluminum: 45.5 atomic % to 47.7 atomic %; chromium: 0.5 atomic % to 2.5 atomic %; tungsten: 0.5 atomic % to 1.0 atomic %; and the balance being titanium and inevitable impurities. Preferably, the titanium content is 48.6 atomic % to 51.8 atomic %.

[0023] [2] The TiAl alloy material according to the above [1] may further contain calcium: 0.02 atomic % to 0.06 atomic %. Preferably, titanium: 48.4 atomic % or more and 51.6 atomic %. [3] The TiAl alloy material according to the above [1] or [2] has an absorbed energy of 3.5 J / cm in a Charpy impact test at room temperature (20°C). ２ or more, the creep rupture time at a temperature of 800°C and a stress of 200 MPa is 200 hours or more, and an oxidation test is carried out in which the specimen is held in air at 900°C for 200 hours, and the weight gain of the oxidation test specimen is 0.03 kg / m ２[4] According to the TiAl alloy material according to the above [3], the Charpy impact test may be performed using a rectangular columnar Charpy impact test piece having no V-notch and measuring 10 mm in length, 10 mm in width, and 55 mm in length, as a test specimen, and using a small hammer with a capacity of 15 J as a hammer for the Charpy impact test.

[0024] [5] According to the TiAl alloy material according to the above [1], the alloy contains at least one of carbon: 0.12 atomic % to 0.22 atomic % and silicon: 0.32 atomic % to 0.82 atomic %, aluminum: 46.5 atomic % to 47.2 atomic %, chromium: 1.0 atomic % to 2.5 atomic %, tungsten: 0.6 atomic % to 1.0 atomic %, and the remainder being titanium and inevitable impurities, and titanium: 48.7 atomic % to 50.6 atomic %.

[0025] [6] The TiAl alloy material according to the above [5] may further contain calcium: 0.02 atomic % to 0.06 atomic %. Preferably, titanium: 48.7 atomic % to 50.4 atomic %. [7] The TiAl alloy material according to the above [5] or [6] has an absorbed energy of 3.5 J / cm in a Charpy impact test at room temperature (20°C). ２ The creep rupture time at a temperature of 800°C and a stress of 200 MPa is 200 hours or more, and an oxidation test is carried out in air at 900°C for 200 hours, and the weight gain of the oxidation test piece due to the oxidation test is 0.03 kg / m ２ The absorbed energy in a Charpy impact test at room temperature (20°C) is 6 J / cm or less. ２ The creep rupture time at a temperature of 800°C and a stress of 200 MPa is 400 hours or more, and an oxidation test is carried out in air at 900°C for 200 hours, and the weight gain of the oxidation test piece due to the oxidation test is 0.02 kg / m ２ At least one of the following conditions may be satisfied.

[0026] [8] A method for producing the TiAl alloy material according to the above [1] or [5] by a casting method, comprising a melting step of melting raw materials including an alloy raw material composed of at least one of carbon and silicon, aluminum, chromium, tungsten, and titanium in a water-cooled copper crucible placed in an inert gas atmosphere to obtain a molten alloy.

[0027] [9] A method for producing the TiAl alloy material according to the above [2] or [6] by a casting method, comprising a melting step of melting an alloy raw material comprising at least one of carbon and silicon, aluminum, chromium, tungsten, and titanium, and a raw material comprising an AlCa alloy in a calcia crucible to obtain a molten alloy.

[0028]

[10] A method for producing the TiAl alloy material according to the above [8] or [9] by a casting method, which may include a casting step of pouring the molten alloy into a mold by gravity casting.

[11] A jet engine rotor blade made of the TiAl alloy material according to any one of [1] to [7].

[0029] [Details of the embodiment of the present disclosure] In order to solve the above-mentioned problems, the present inventors conducted extensive research focusing on the relationship between the composition of a TiAl alloy material and the castability, impact resistance, creep strength, and oxidation resistance, and found that a TiAl alloy material containing at least one of 0.07 atomic % to 0.25 atomic % of carbon (C) and 0.30 atomic % to 0.85 atomic % of silicon (Si), 45.5 atomic % to 47.7 atomic % of aluminum (Al), 0.5 atomic % to 2.5 atomic % of chromium (Cr), 0.5 atomic % to 1.0 atomic % of tungsten (W), and the balance being titanium and unavoidable impurities, is sufficient.

[0030] More specifically, by setting the Al content in the TiAl alloy material within the above-mentioned relatively narrow range, and by adding Cr within the above-mentioned range to effectively improve impact resistance without reducing creep strength, by adding W within the above-mentioned range to improve oxidation resistance without reducing impact resistance and creep strength, and by adding C and / or Si within the above-mentioned range to improve creep strength while ensuring sufficient impact resistance, the present inventors have discovered that all of the properties of impact resistance, creep strength, and oxidation resistance are suitable for use as a material for jet engine blades, and that the material can be manufactured using a casting method, thereby arriving at the present disclosure.

[0031] The TiAl alloy material, the manufacturing method of the TiAl alloy material, and the jet engine blade according to the present disclosure will be described in detail below. In this embodiment, as an example of the TiAl alloy material according to the present disclosure, a case will be described in which the TiAl alloy material is a cast TiAl alloy material manufactured by a casting method.

[0032] [Cast TiAl Alloy] The cast TiAl alloy (TiAl alloy material) of this embodiment is composed of at least one of carbon (C): 0.07 atomic % to 0.25 atomic % and silicon (Si): 0.30 atomic % to 0.85 atomic %; aluminum (Al): 45.5 atomic % to 47.7 atomic %; chromium (Cr): 0.5 atomic % to 2.5 atomic %; tungsten (W): 0.5 atomic % to 1.0 atomic %; and the balance being titanium and inevitable impurities. The inevitable impurities are impurities that are mixed in the raw materials or during the manufacturing process. The cast TiAl alloy of this embodiment is a casting produced by a casting method.

[0033] "Al" Al is a basic element of TiAl alloy together with Ti. Al, together with Ti, forms the TiAl phase in TiAl alloy castings, Ti ３It constitutes an Al phase, etc. If the Al content is less than 45.5 atomic %, the impact resistance becomes insufficient. If the Al content exceeds 47.7 atomic %, the creep strength and impact resistance become insufficient. Therefore, the Al content in the TiAl alloy casting material is set to 45.5 atomic % to 47.7 atomic %. In order to ensure the impact resistance while also ensuring the creep strength and oxidation resistance, the Al content is preferably 46.5 atomic % to 47.2 atomic %.

[0034] "Cr" Cr improves impact resistance when the Al content in the TiAl alloy cast material is within the above range. If the Cr content is less than 0.5 atomic %, the effect of improving impact resistance is not sufficiently obtained. Furthermore, if the Cr content exceeds 2.5 atomic %, a brittle β phase is formed in the TiAl alloy cast material, resulting in a rapid decrease in impact resistance and creep strength. Therefore, the Cr content in the TiAl alloy cast material is set to 0.5 atomic % to 2.5 atomic %. In order to more effectively improve impact resistance and ensure sufficient creep strength, the Cr content is preferably 1.0 atomic % to 2.5 atomic %, more preferably 1.6 atomic % to 2.2 atomic %.

[0035] "W" W improves oxidation resistance when the Al content in the cast TiAl alloy is within the above range. If the W content is less than 0.5 atomic %, the effect of improving oxidation resistance is not sufficiently obtained. On the other hand, if the W content exceeds 1.0 atomic %, the impact resistance and creep strength become insufficient. Therefore, the W content in the cast TiAl alloy is set to 0.5 atomic % to 1.0 atomic %. In order to further improve oxidation resistance and ensure impact resistance and creep strength, the W content is preferably 0.6 atomic % to 1.0 atomic %.

[0036] "C" C improves creep strength when the Al content in the cast TiAl alloy is within the above range. If the C content is less than 0.07 atomic %, the effect of improving creep strength is not sufficiently obtained. On the other hand, if the C content exceeds 0.2 atomic %, the impact resistance becomes insufficient. Therefore, the C content in the cast TiAl alloy is set to 0.07 atomic % to 0.25 atomic %. In order to further improve creep strength and ensure impact resistance, the C content is preferably 0.12 atomic % to 0.22 atomic %.

[0037] "Si" Si improves creep strength when the Al content in the TiAl alloy cast material is within the above range. If the Si content is less than 0.30 atomic %, the effect of improving creep strength is not sufficiently obtained. On the other hand, if the Si content exceeds 0.85 atomic %, the impact resistance becomes insufficient. Therefore, the Si content in the TiAl alloy cast material is set to 0.30 atomic % to 0.85 atomic %. In order to further improve creep strength and ensure impact resistance, the Si content is preferably 0.32 atomic % to 0.82 atomic %.

[0038] "C+Si" The TiAl alloy cast material of this embodiment contains at least one of carbon (C) and silicon (Si). Therefore, it may contain C but not Si, or it may contain Si but not C, or it may contain both C and Si. When the TiAl alloy cast material of this embodiment contains C and Si, C and Si can be contained in any ratio.

[0039] [Correction based on Rule 91, 22.07.2025] When the cast TiAl alloy material of this embodiment contains Si together with C, the total content of C and Si is preferably 0.37 atomic % or more and 1.10 atomic % or less. Also, when the cast TiAl alloy material of this embodiment contains Si together with C, the total content of C and Si is preferably 0.44 atomic % or more and 1.01 atomic % or less to ensure impact resistance.

[0040] In the TiAl alloy cast material of this embodiment, both C and Si have the function of improving creep strength while ensuring impact resistance. The effect of adding C in improving the creep strength of the TiAl alloy cast material is equivalent to that of adding Si. On the other hand, the effect of adding Si on the impact resistance of the TiAl alloy cast material is smaller than that of adding C. Therefore, a TiAl alloy cast material containing Si but not C, and a TiAl alloy cast material containing Si and C are more likely to produce a TiAl alloy cast material with excellent impact resistance than a TiAl alloy cast material containing C but not Si, and are therefore preferable.

[0041] "Ca" The cast TiAl alloy of this embodiment may further contain 0.02 atomic % to 0.06 atomic % of Ca. When the cast TiAl alloy of this embodiment is produced by a method of removing oxygen from the molten alloy by adding an AlCa alloy to the molten alloy, Ca that has not combined with oxygen and evaporated as fumes during the production process remains in the cast TiAl alloy.

[0042] When the Ca content in the TiAl alloy cast material is 0.02 atomic % or more, the effect of removing oxygen from the molten alloy due to the inclusion of the AlCa alloy is fully exhibited. Therefore, a TiAl alloy cast material with a Ca content of 0.02 atomic % or more is preferable because it has a sufficiently low content of oxygen contained as an unavoidable impurity. The Ca content is more preferably 0.025 atomic % or more. Furthermore, when the Ca content in the TiAl alloy cast material is 0.06 atomic % or less, the castability, impact resistance, creep strength, and oxidation resistance of the TiAl alloy cast material of this embodiment are not impaired. If the Ca content exceeds 0.06 atomic %, impact resistance is slightly reduced. The Ca content is more preferably 0.05 atomic % or less, and an even more preferable Ca content is 0.025 atomic % to 0.05 atomic % or less.

[0043] "Ti" Ti, together with Al, is a fundamental element of TiAl alloys. The elemental composition of the TiAl alloy cast material (TiAl alloy material) of this embodiment is specified as consisting of the balance titanium and unavoidable impurities, but the titanium composition ratio may be specified explicitly. That is, when Ca is not contained, if the Ti content is less than 48.6 atomic %, the creep strength and impact resistance are insufficient. Furthermore, if the Ti content exceeds 51.8 atomic %, the impact resistance is insufficient. Therefore, the Ti content in the TiAl alloy cast material is preferably 48.6 atomic % or more and 51.8 atomic % or less. To ensure creep strength and oxidation resistance while ensuring impact resistance, the Ti content is more preferably 48.7 atomic % to 50.4 atomic %. When Ca is contained in an amount of 0.02 atomic % to 0.06 atomic % or less, if the Ti content is less than 48.6 atomic %, the creep strength and impact resistance are insufficient. Furthermore, if the Ti content exceeds 51.8 atomic percent, the impact resistance becomes insufficient. Therefore, the Ti content in the TiAl alloy casting material is preferably 48.6 atomic percent to 51.8 atomic percent. In order to ensure the impact resistance while also ensuring creep strength and oxidation resistance, the Ti content is more preferably 48.7 atomic percent to 50.6 atomic percent.

[0044] [Method for Manufacturing Cast TiAl Alloy] Next, an example of a method for manufacturing the cast TiAl alloy material of this embodiment will be described. To manufacture the cast TiAl alloy material of this embodiment, raw materials are first prepared. The composition of the alloy raw materials used to manufacture the cast TiAl alloy material is substantially identical to the composition of the cast TiAl alloy material obtained after casting, except for the Al content. Al evaporates during the melting process, resulting in a certain amount of loss during the manufacturing process. However, the amount of Al lost during the manufacturing process is predictable because it is reproducible depending on the melting conditions in the melting process. Therefore, to obtain the desired composition after casting, an alloy raw material having a composition that takes into account the amount of Al lost during the manufacturing process is prepared.

[0045] That is, in this embodiment, the composition of the alloy raw materials is adjusted so that the composition of the TiAl alloy cast material obtained after casting is at least one of carbon (C): 0.07 atomic % to 0.25 atomic % and silicon (Si): 0.30 atomic % to 0.85 atomic %, aluminum (Al): 45.5 atomic % to 47.7 atomic %, chromium (Cr): 0.5 atomic % to 2.5 atomic %, tungsten (W): 0.5 atomic % to 1.0 atomic %, and the remainder being titanium and inevitable impurities.

[0046] Furthermore, when the TiAl alloy cast material of this embodiment contains calcium (Ca), the raw materials are composed of an alloy raw material and an AlCa alloy. In this case, the raw materials are prepared so that the composition of the TiAl alloy cast material obtained after casting contains 0.02 atomic % to 0.06 atomic % calcium (Ca). When the raw materials contain an AlCa alloy, most of the Ca content in the raw materials evaporates during the melting process. Therefore, the amount of AlCa alloy used is adjusted taking into account the amount of Ca component that combines with oxygen to form fumes and evaporate during the manufacturing process, and the Al content in the alloy raw material is adjusted corresponding to the amount of AlCa alloy used so that the cast TiAl alloy contains 45.5 atomic % to 47.7 atomic % aluminum (Al).

[0047] The shape of each component contained in the raw material corresponding to the composition after casting is not particularly limited. The shape of each component in the raw material may be partially or completely different. The shape of each component in the raw material may be, for example, pellet-like, flake-like, granular, sponge-like, powder-like, or the like. Furthermore, the raw material may contain raw material in an alloy state. The carbon component in the raw material is preferably in the form of TiC. By using TiC as the carbon component, volatilization of the carbon component during the manufacturing process can be suppressed, and a TiAl alloy cast material having the desired composition can be easily manufactured. In this embodiment, a master alloy ingot prepared by melting raw materials corresponding to the composition after casting may be used as the raw material.

[0048] (Melting Step) Next, raw materials corresponding to the composition after casting are melted to form a molten alloy. When melting the raw materials, it is preferable to use a crucible. For example, a crucible used when melting a TiAl alloy can be used. Specifically, a water-cooled copper crucible, a ceramic crucible, or the like can be used. When a water-cooled copper crucible, which is generally used when melting a TiAl alloy, is used as the crucible, oxygen is not mixed into the molten alloy from the crucible, which is preferable. For example, an yttria crucible, a calcia (calcium oxide) crucible, or the like can be used as the crucible.

[0049] In the manufacturing method of this embodiment, it is preferable to use a calcia crucible as the crucible and melt the raw materials consisting of the alloy raw material and the AlCa alloy in the calcia crucible to produce the molten alloy. The reasons for this are as follows: When the raw materials are melted using a calcia crucible, a general-purpose melting furnace with low power consumption can be used. Furthermore, when the raw materials are melted using a calcia crucible, the temperature of the molten alloy can be increased, so that a TiAl alloy cast material having homogenized alloy components can be produced by a single melting (single melting).

[0050] In contrast, for example, when melting raw materials using a water-cooled copper crucible, a special melting device with high power consumption is required, and since the molten metal temperature cannot be increased when melting raw materials using a water-cooled copper crucible, a TiAl alloy casting material having homogenized alloy components cannot be produced by a single melting, and the melting must be repeated at least two times.

[0051] However, when a calcia crucible is used as the crucible, oxygen is mixed into the molten alloy from the calcia crucible. However, if the raw materials contain a sufficient amount of AlCa alloy, the oxygen mixed into the molten alloy from the crucible reacts with the AlCa alloy to form CaO, which is evaporated and removed from the molten alloy as fumes. As a result, it is possible to produce a TiAl alloy casting material with a sufficiently low content of oxygen contained as an unavoidable impurity.

[0052] The method for melting the raw materials may be any method capable of melting the raw materials to form a molten alloy, and any melting method can be used, such as high-frequency melting.

[0053] When using the high-frequency melting method, for example, a crucible containing raw materials is placed in a chamber of a melting furnace, the chamber is evacuated, and an inert gas such as argon gas is introduced to melt the raw materials in an inert gas atmosphere. In this case, oxygen contamination from the atmosphere can be prevented from being mixed into the molten alloy. Therefore, whether the raw materials are composed only of alloy raw materials or contain an AlCa alloy, a TiAl alloy casting material with a sufficiently low oxygen content as an unavoidable impurity can be produced. In particular, when the raw materials are composed only of alloy raw materials without containing an AlCa alloy, it is preferable to transfer the raw materials from the crucible to a water-cooled copper crucible to prevent oxygen from being mixed into the molten alloy, and melt the raw materials in an inert gas atmosphere to produce a molten alloy, so that a TiAl alloy casting material with a sufficiently low oxygen content as an unavoidable impurity can be obtained.

[0054] In addition, when using a high-frequency melting method, for example, a crucible containing raw materials is placed in a chamber of a melting furnace, and the chamber is evacuated without evacuating or after 10 ５ Pa to 10 ２ Alternatively, a method may be used in which the atmosphere in the chamber is replaced with an inert gas atmosphere by introducing an inert gas such as argon gas into a low vacuum state of 100 Pa, and the raw materials are melted in this state. In this case, oxygen is mixed into the molten alloy from the atmosphere. For this reason, it is preferable to use a raw material consisting of an alloy raw material and an AlCa alloy. This is because the oxygen mixed into the molten alloy from the atmosphere reacts with the AlCa alloy to form CaO, which is evaporated and removed from the molten alloy as fumes.

[0055] (Casting Process) Next, the molten alloy is poured into a mold. The mold can be made of a known material and have a cavity with an inner shape similar to the shape of the TiAl alloy casting product to be produced. Furthermore, when the cast product removed from the mold is machined to the product shape, a mold with a cavity with a simple inner shape can also be used. Examples of the mold that can be used include a zirconia-based ceramic mold used in industrial precision casting of Ti-based alloys, and a cast iron mold used in mold casting.

[0056] Known methods can be used to pour the molten alloy into the mold. For example, a suction casting method, in which the molten alloy is sucked into the mold, may be used. Alternatively, a centrifugal casting method, in which the mold is placed on a rotating table and the rotating table is rotated to apply centrifugal force to the molten alloy, may be used to pour the molten alloy into the mold. The use of suction casting and / or centrifugal casting can prevent the formation of defective shapes due to the formation of regions in the cavity of the mold that are not sufficiently filled with the molten alloy, thereby increasing the yield of non-defective products. In particular, when producing jet engine blades having complex shapes as a product of TiAl alloy casting material, the use of suction casting and / or centrifugal casting is preferred.

[0057] Furthermore, in this embodiment, instead of using a casting method that requires special equipment such as suction casting or centrifugal casting, gravity casting, which is the simplest casting method, may be used as the method for pouring the molten alloy into the mold.

[0058] Furthermore, when the TiAl alloy casting material is to be used as a casting product for a jet engine blade by removing it from a mold and then machining it, gravity casting is preferably used as a method for pouring the molten alloy into the mold. By using gravity casting, it is not necessary to use special equipment as in the case of, for example, suction casting and / or centrifugal casting, and the TiAl alloy casting material can be easily produced using simple equipment.

[0059] Furthermore, when producing TiAl alloy casting materials using gravity casting, it is preferable to use a cast iron mold as the casting mold, because cast iron molds, unlike ceramic molds, can be used for repeated casting, which allows for the production of TiAl alloy casting materials more inexpensively.

[0060] In this embodiment, the molten alloy is poured into a mold, and the mold is allowed to cool using a known method. The cast product is then removed from the mold and machined as necessary. Through these steps, the TiAl alloy cast material of this embodiment is obtained.

[0061] The TiAl alloy cast material of this embodiment contains at least one of carbon (C) and silicon (Si), aluminum (Al), chromium (Cr), and tungsten (W) in predetermined amounts, with the remainder being titanium (Ti) and unavoidable impurities. Therefore, the TiAl alloy cast material of this embodiment can be manufactured using a casting method. Furthermore, because of the above composition, the TiAl alloy cast material of this embodiment has excellent impact resistance, creep strength, and oxidation resistance. Therefore, the TiAl alloy cast material of this embodiment is suitable as a material for jet engine blades.

[0062] Furthermore, according to the method for producing the TiAl alloy material of this embodiment, the TiAl alloy material of this embodiment, which is excellent in impact resistance, creep strength, and oxidation resistance, can be produced by casting.

[0063] [Jet Engine Blade] The jet engine blade of this embodiment is made of the cast TiAl alloy material of this embodiment, and therefore has excellent impact resistance, creep strength, and oxidation resistance.

[0064] The shape of the jet engine blade of this embodiment is not particularly limited. The jet engine blade of this embodiment can be manufactured, for example, by using the TiAl alloy cast material of this embodiment as a raw material and machining it using a known method as necessary. Therefore, the jet engine blade of this embodiment may be manufactured by machining a TiAl alloy cast material that is close to the shape of the product, which is cast into a ceramic mold using, for example, a suction casting method and / or a centrifugal casting method, or by extensive machining of a TiAl alloy cast material of a simple shape that is cast into a cast iron mold using a gravity casting method.

[0065] The above describes in detail the embodiments of the present disclosure, but the above embodiment is an example of the present disclosure, and additions, omissions, substitutions, and other modifications to the configuration are possible within the scope that does not deviate from the spirit of the present disclosure.

[0066] [Alloy No. 1 to Alloy No. 42] Using the casting method described below, cast TiAl alloys (Alloy No. 1 to Alloy No. 42) having the compositions shown in Tables 1 to 3 were produced.

[0067] First, raw materials composed of an alloy raw material and an AlCa alloy and having compositions corresponding to those shown in Tables 1 to 3 were prepared. Specifically, the alloy raw materials were sponge Ti, Al pellets, a Cr granular raw material, a W powder raw material, a TiC alloy powder, and a Si granular raw material, which were weighed and mixed so that the contents of each component in the TiAl alloy cast material obtained after casting would be in the proportions shown in Tables 1 to 3. Furthermore, an AlCa alloy containing 90% by mass of Al and 10% by mass of Ca was used as the AlCa alloy, and was weighed so that the proportion of AlCa alloy in the raw material was 0.14% by mass. The total mass of the alloy raw material and the AlCa alloy was then adjusted to approximately 800 g. The amount of Al pellets in the alloy raw material was adjusted to the target composition of the TiAl alloy cast material shown in Tables 1 to 3, after subtracting the amount corresponding to the amount of Al contained in the AlCa alloy in the raw material and taking into account evaporation during melting.

[0068]

[0069]

[0070]

[0071] Next, the raw materials were placed in a calcia (calcium oxide) crucible and melted using a high-frequency melting method to obtain a molten alloy. Specifically, a calcia crucible containing approximately 800 g of raw materials was placed in a chamber of a melting furnace, and evacuation of the chamber was initiated. After evacuating to a predetermined vacuum level, an inert gas was introduced, and the pressure of the inert gas reached a predetermined value to create an inert gas atmosphere. The raw materials were then heated and melted using a high-frequency power source. After all the raw materials were melted, heating using the high-frequency power source was continued until the molten metal was sufficiently homogenized, thereby obtaining a molten alloy with a homogeneous composition.

[0072] The molten alloy was then poured into the mold shown in Figure 1. Figure 1 is a perspective view of the mold 1 used in the examples. The mold 1 shown in Figure 1 is made of cast iron. As shown in Figure 1, the mold 1 has an external shape that is approximately rectangular, e.g., 90 mm in length, 90 mm in width, and 130 mm in height, but is not limited to this. The mold 1 consists of a first mold 10a and a second mold 10b arranged opposite the first mold 10a. The first mold 10a and the second mold 10b are approximately the same shape. The first mold 10a and the second mold 10b are made of cast iron.

[0073] When pouring the molten alloy into the mold 1, the first and second molds 10a and 10b are clamped together from the outside with a clamp (not shown) to form a single unit. After the molten alloy is cooled to produce the TiAl alloy castings (Alloy No. 1 to Alloy No. 42), the clamp is removed to separate the first and second molds 10a and 10b. This allows the cast TiAl alloy castings (Alloy No. 1 to Alloy No. 42) to be removed from the mold 1.

[0074] 1, a first mold 10a and a second mold 10b are arranged opposite each other to form a cavity 11. The cavity 11 has an inner surface shape similar to that of the TiAl alloy casting material produced in the examples.

[0075] 1, the cavity 11 is made up of a first region 11a to a third region 11c stacked in order from the bottom up. More specifically, the first region 11a has a flat plate-like outer shape with a length of 16 mm in a first direction substantially perpendicular to the opposing surfaces of the first mold 10a and the second mold 10b, a bottom length of 60 mm in a second direction substantially perpendicular to the first direction, and a height of 90 mm, for example, but is not limited to this.

[0076] The second region 11b has a length in the second direction that is the same as that of the first region 11a. The second region 11b has a trapezoidal side shape when viewed from the first direction, with a lower base length of 16 mm, an upper base length of 30 mm, and a height of 15 mm, for example, but not limited to, the third region 11c having a substantially rectangular parallelepiped shape with a length in the second direction that is the same as that of the first region 11a, a length in the first direction that is the same as that of the upper base of the second region 11b, and a height of 25 mm, for example, but not limited to, the third region 11c.

[0077] An alumina funnel 2 having a generally cylindrical outer shape with a diameter of 80 mm and a height of 50 mm, for example, is disposed on the upper surface of the mold 1 shown in Fig. 1, but the outer shape of the alumina funnel 2 is not limited to this. The alumina funnel 2 prevents the molten alloy from spilling outside the mold 1 when the molten alloy is poured into the mold 1. As shown in Fig. 1, the alumina funnel 2 is split into two parts, and by arranging a first member and a second member of generally the same shape opposite each other, a flow path is formed inside the funnel 2, consisting of a generally cylindrical connecting portion 11d and a generally conical main body 11e.

[0078] The connection portion 11d of the flow path of the alumina funnel 2 is connected to the third region 11c of the cavity 11 of the mold 1. The connection portion 11d has a cylindrical outer shape with a diameter of 40 mm, for example, but is not limited to this. The center of the connection portion 11d when viewed from above is the same as the centers of the first region 11a to the third region 11c of the cavity 11 of the mold 1, but is not limited to this.

[0079] The main body 11e of the flow path of the alumina funnel 2 has a center that is the same as the center of the connection part 11d when viewed from above, and has an approximately conical outer shape with a bottom diameter of 40 mm and a top diameter of 60 mm, for example, but is not limited to this.

[0080] When pouring the molten alloy into the mold 1, an alumina funnel 2 was placed on the top surface of the mold 1, as shown in Figure 1. Gravity casting was used as a method for pouring the molten alloy into the mold 1. The molten alloy was supplied into the cavity 11 through the flow path of the alumina funnel 2. The molten alloy was supplied until the liquid level of the poured molten alloy reached a position near the top surface of the main body 11e on the inner wall of the alumina funnel 2.

[0081] After the molten alloy was poured into the mold 1 in this manner, the mold 1 was allowed to cool, thereby producing the target TiAl alloy casting material. Thereafter, the two-piece alumina funnel 2 was separated into a first member and a second member, and the clamp was removed to separate the first mold 10a and the second mold 10b, thereby removing the cast TiAl alloy casting materials (Alloy No. 1 to Alloy No. 42) from the mold 1.

[0082] The compositions of Alloy No. 1 to Alloy No. 42 thus obtained were analyzed using inductively coupled plasma (ICP) atomic emission spectroscopy and combustion-infrared absorption spectroscopy, respectively. As a result, it was confirmed that Alloy No. 1 to Alloy No. 42 all had the compositions shown in Tables 1 to 3.

[0083] Next, Alloys No. 1 to No. 42 obtained in this manner were evaluated for "(1) impact resistance," "(2) creep strength," and "(3) oxidation resistance" using the methods described below. The results are shown in Tables 4 and 5. Tables 1 to 5 also show the classification of Alloys No. 1 to No. 42 as "Disclosed Alloys," which are examples of the present disclosure, and "Comparative Alloys," which are comparative examples.

[0084] (1) Impact Resistance Normally, when manufacturing jet engine blades made of cast TiAl alloys, the cast TiAl alloys obtained after casting are subjected to HIP (hot isostatic pressing) treatment. Therefore, (1) Alloy No. 1 to Alloy No. 42 before evaluating impact resistance were subjected to a heat treatment corresponding to typical HIP conditions, in which they were held at 1200°C for 4 hours and then cooled at a cooling rate of 10°C / min.

[0085] Furthermore, TiAl alloy cast materials are brittle materials. Therefore, if a 2 mm V-notch is typically made in a Charpy impact test specimen made of a TiAl alloy cast material, the absorbed energy measurement results will be smaller. As a result, the difference in absorbed energy measurement results between each test specimen will be reduced, potentially making it impossible to evaluate the differences between each test specimen. For this reason, the shape of the test specimen in the Charpy impact test method disclosed herein is modified based on JIS Z2242-2018 "Method for Charpy Impact Testing of Metallic Materials" (ISO 148-1:2016, Metallic materials - Charpy pendulum impact test - Part 1: Test method). That is, for (1) Impact Resistance in this Example, a prismatic Charpy impact test specimen with a length of 10 mm, a width of 10 mm, and a length of 55 mm, without a V-notch, was prepared as the test specimen. Furthermore, since a normal hammer with a capacity of 300 J was used as the hammer for the Charpy impact test, which would result in a large measurement error, a small hammer with a capacity of 15 J was used to reduce the measurement error.

[0086] Specifically, Charpy impact test specimens were taken from Alloy No. 1 to Alloy No. 42, which had been subjected to heat treatment equivalent to HIP conditions, at a position corresponding to the first region 11a in the cavity 11 of the mold 1 shown in FIG. 1 . The Charpy impact test specimens were prepared as rectangular columns measuring 10 mm in length, 10 mm in width, and 55 mm in length. Each Charpy impact test specimen was then subjected to a Charpy impact test at room temperature (20°C), and the absorbed energy was measured. The results were evaluated based on the following evaluation criteria.

[0087] [Evaluation Criteria] A (better impact resistance): Absorbed energy of 6 J / cm in a Charpy impact test at room temperature (20°C) ２ B (Excellent impact resistance): The absorbed energy in a Charpy impact test at room temperature (20°C) is 3.5 J / cm ２ 6J / cm or more ２ C (poor impact resistance): The absorbed energy in a Charpy impact test at room temperature (20°C) is less than 3.5 J / cm ２ is less than.

[0088] (2) Creep Strength After Charpy impact test specimens were obtained for Alloy No. 1 to Alloy No. 42 in (1) Impact Resistance, creep test specimens were taken from a position corresponding to the first region 11a of the cavity 11 of the mold 1 shown in FIG. 1 . Creep test specimens were prepared with a circular cross section, with shoulders between the parallel portion and the gripping portions at both ends of the parallel portion. Specifically, creep test specimens were prepared with a total length of 60 mm, with the parallel portion being cylindrical with a diameter of 4 mm and a length of 20 mm, and the gripping portion being a thread with an outer diameter of 8 mm and a pitch of 1.25 mm (M8 x P1.25). A creep test was conducted on each creep test specimen obtained in this manner at a temperature of 800°C and a stress of 200 MPa, and the time to rupture was measured. Evaluation was then performed based on the following evaluation criteria.

[0089] [Evaluation criteria] A (superior creep strength): The time to rupture at a temperature of 800°C and a stress of 200 MPa is 400 hours or more. B (superior creep strength): The time to rupture at a temperature of 800°C and a stress of 200 MPa is 200 hours or more but less than 400 hours. C (poor creep strength): The time to rupture at a temperature of 800°C and a stress of 200 MPa is less than 200 hours.

[0090] (3) Oxidation Resistance (2) Creep Strength After tensile test specimens were taken from Alloy No. 1 to Alloy No. 42, oxidation test specimens were taken from positions corresponding to the first region 11a in the cavity 11 of the mold 1 shown in FIG. 1. The oxidation test specimens were flat plates measuring 10 mm in length, 20 mm in width, and 2 mm in thickness. Each oxidation test specimen was subjected to an oxidation test in which it was held in air at 900°C for 200 hours, and the weight gain of the oxidation test specimens due to the oxidation test was measured. Evaluation was then conducted based on the following evaluation criteria.

[0091] [Evaluation Criteria] A (better oxidation resistance): Weight increase after oxidation test is 0.02 kg / m ２ B (Excellent oxidation resistance): Weight increase after oxidation test is 0.02 kg / m or less ２ Super 0.03kg / m ２ C (poor oxidation resistance): Weight increase after oxidation test is 0.03 kg / m or less. ２ It's super.

[0092]

[0093]

[0094] As shown in Tables 1 and 4, Alloy Nos. 1 to 4, 6 to 9, 12 to 14, and 17 to 20, which are "disclosed alloys" containing 45.5 atomic % to 47.7 atomic % of aluminum (Al), 0.5 atomic % to 2.5 atomic % of chromium (Cr), 0.5 atomic % to 1.0 atomic % of tungsten (W), 0.07 atomic % to 0.25 atomic % of carbon (C), and 0.02 atomic % to 0.06 atomic % of calcium (Ca), with the balance being titanium and unavoidable impurities, were all confirmed to have excellent impact resistance, creep strength, and oxidation resistance.

[0095] This is described in further detail below. [1] Regarding the Suitable Al Concentration Alloys No. 1 to 5 are a group in which the Al content was varied. In this group, the contents of Al and all other components excluding Ti and irreversible impurities were within the appropriate range. When the Al content was 45.6 atomic % (Alloy No. 1), 46.2 atomic % (Alloy No. 2), 46.7 atomic % (Alloy No. 3), and 47.4 atomic % (Alloy No. 4), the impact resistance, creep strength, and oxidation resistance were all good. On the other hand, when the Al content was as high as 48.0 atomic % (Alloy No. 5 (Comparative Alloy)), the impact resistance and creep strength were poor.

[0096] [2] Regarding the Suitable Cr Concentration Alloys No. 6 to 10 are a group in which the Cr content was varied. In this group, the contents of all components except Cr were within the appropriate range. When the Cr content was 1.3 atomic % (Alloy No. 6), 1.7 atomic % (Alloy No. 7), 2.1 atomic % (Alloy No. 8), and 2.3 atomic % (Alloy No. 9), the impact resistance, creep strength, and oxidation resistance were all good. In particular, Alloy No. 8 and Alloy No. 9 had excellent impact resistance. On the other hand, when the Cr content was as high as 2.7 atomic % (Alloy No. 10 (comparison alloy)), the impact resistance and creep strength were poor.

[0097] [3] Regarding the Suitable W Concentration Alloys Nos. 11 to 15 are a group in which the W content was varied. In this group, the contents of all components except W were within the appropriate range. When the W content was 0.62 atomic % (Alloy No. 12), 0.82 atomic % (Alloy No. 13), and 0.94 atomic % (Alloy No. 14), the impact resistance, creep strength, and oxidation resistance were all good. In particular, Alloy No. 14 had excellent oxidation resistance. On the other hand, when the W content was low at 0.43 atomic % (Alloy No. 11 (Comparative Alloy)), the oxidation resistance was poor. Furthermore, when the W content was high at 1.06 atomic % (Alloy No. 15 (Comparative Alloy)), the oxidation resistance was particularly excellent, but the impact resistance and creep strength were poor.

[0098] [4] Regarding the Suitable Carbon Concentration: Alloys No. 16 to 20 are a group in which the carbon content was varied. In this group, the contents of all components except carbon were within the appropriate range. When the carbon content was 0.08 atomic percent (Alloy No. 17), 0.14 atomic percent (Alloy No. 18), 0.18 atomic percent (Alloy No. 19), and 0.22 atomic percent (Alloy No. 20), the impact resistance, creep strength, and oxidation resistance were all good. In particular, Alloy No. 19 had excellent creep strength. On the other hand, when the carbon content was relatively low, at 0.05 atomic percent (Alloy No. 16), the creep strength was poor.

[0099] Furthermore, as shown in Tables 2 and 5, Alloy Nos. 21 to 24, 26 to 29, 32 to 34, and 37 to 40, which are "disclosed alloys" containing 45.5 atomic % to 47.7 atomic % of aluminum (Al), 0.5 atomic % to 2.5 atomic % of chromium (Cr), 0.5 atomic % to 1.0 atomic % of tungsten (W), 0.3 atomic % to 0.85 atomic % of silicon (Si), and 0.02 atomic % to 0.06 atomic % of calcium (Ca), with the balance being titanium and inevitable impurities, were all confirmed to have excellent impact resistance, creep strength, and oxidation resistance.

[0100] Among the compositions that were evaluated as (B, B, B) or higher in impact resistance, creep strength, and oxidation resistance, alloys having a composition range (A, B, B) that provides good impact resistance when creep strength is comparable include alloy Nos. 3, 8, and 9 shown in Table 4, and alloy Nos. 23, 27-29, 32-33, and 38 shown in Table 5. Furthermore, alloys having a composition range (B, A, B) that provides good creep strength when impact resistance is comparable include alloy Nos. 19 and 20 shown in Table 4, and alloy Nos. 39 and 40 shown in Table 5. Furthermore, alloys having a composition range (B, B, A) that provides good oxidation resistance when impact resistance and creep strength are comparable include alloy No. 14 shown in Table 4 and alloy No. 34 shown in Table 5.

[0101] This is described in more detail below.

[11] Regarding the Suitable Al Concentration: Alloys No. 21 to 25 are a group in which the Al content was varied. In this group, the contents of Al and all other components excluding Ti and irreversible impurities were within the appropriate range. When the Al content was 45.6 atomic % (Alloy No. 21), 46.2 atomic % (Alloy No. 22), 46.7 atomic % (Alloy No. 23), and 47.4 atomic % (Alloy No. 24), the impact resistance, creep strength, and oxidation resistance were all good. In particular, Alloy No. 23 had excellent impact resistance. On the other hand, when the Al content was as high as 48.0 atomic % (Alloy No. 25 (comparison alloy)), the impact resistance and creep strength were poor.

[0102]

[12] Regarding the Suitable Cr Concentration Alloys No. 26 to 30 are a group in which the Cr content was varied. In this group, the contents of all components except Cr were within the appropriate range. When the Cr content was 1.3 atomic % (Alloy No. 26), 1.7 atomic % (Alloy No. 27), 2.1 atomic % (Alloy No. 28), and 2.3 atomic % (Alloy No. 29), the impact resistance, creep strength, and oxidation resistance were all good. In particular, Alloy No. 27, Alloy No. 28, and Alloy No. 29 exhibited excellent impact resistance. On the other hand, when the Cr content was as high as 2.7 atomic % (Alloy No. 30 (comparison alloy)), the impact resistance and creep strength were poor.

[0103]

[13] Regarding the Suitable W Concentration Alloys No. 31 to 35 are a group in which the W content was varied. In this group, the contents of all components except W were within the appropriate range. When the W content was 0.62 atomic % (Alloy No. 32), 0.82 atomic % (Alloy No. 33), and 0.94 atomic % (Alloy No. 34), the impact resistance, creep strength, and oxidation resistance were all good. In particular, Alloy No. 32 and Alloy No. 33 had excellent impact resistance. Alloy No. 34 had excellent oxidation resistance. On the other hand, when the W content was low at 0.43 atomic % (Alloy No. 31 (Comparative Alloy)), the oxidation resistance was poor. When the W content was high at 1.06 atomic % (Alloy No. 35 (Comparative Alloy)), the oxidation resistance was particularly excellent, but the impact resistance and creep strength were poor.

[0104]

[14] Regarding the Preferred Si Concentration Alloys No. 36 to 40 represent a group in which the Si content was varied. In this group, the contents of all components except Si were within the appropriate range. When the Si content was 0.35 atomic % (Alloy No. 37), 0.54 atomic % (Alloy No. 38), 0.72 atomic % (Alloy No. 39), and 0.82 atomic % (Alloy No. 40 (Comparative Alloy)), the impact resistance, creep strength, and oxidation resistance were all good. In particular, Alloy No. 37 and Alloy No. 38 had excellent impact resistance. Furthermore, Alloy No. 39 had excellent creep resistance. On the other hand, when the Si content was relatively low, at 0.26 atomic % (Alloy No. 36), the impact resistance was particularly good, but the creep strength was poor.

[0105]

[15] Cases in which Si is Contained Along with C: Alloys No. 41 and No. 42 are from the group containing both C and Si. When the total content of C and Si was 0.51 atomic % (Alloy No. 41) and when the total content of C and Si was 0.80 atomic % (Alloy No. 42), the impact resistance, creep strength, and oxidation resistance were all good. That is, as shown in Tables 3 and 5, Alloy No. 41 and Alloy No. 42 are "disclosed alloys" containing 0.07 atomic % to 0.25 atomic % carbon (C), 0.3 atomic % to 0.85 atomic % silicon (Si), 45.5 atomic % to 47.7 atomic % aluminum (Al), 0.5 atomic % to 2.5 atomic % chromium (Cr), 0.5 atomic % to 1.0 atomic % tungsten (W), and 0.02 atomic % to 0.06 atomic % calcium (Ca), with the balance consisting of titanium and unavoidable impurities. It was confirmed that No. 42 has excellent impact resistance, creep strength, and oxidation resistance.

[0106]

[16] When the titanium composition ratio is explicitly specified, when the titanium composition ratio is explicitly specified and the Ca content is 0.02 atomic % to 0.06 atomic % or less, when the Ti content is 48.6 atomic % to 51.6 atomic % or less, the impact resistance, creep strength, and oxidation resistance are evaluated as BBB, as shown in Tables 4 and 5. When the Ti content is 48.7 atomic % to 50.4 atomic % or less, the impact resistance, creep strength, and oxidation resistance are evaluated as ABB, BAB, or BBA, as shown in Tables 4 and 5, and the properties are superior to those in the case of BBB. Note that when calcium (Ca) is not contained in the TiAl alloy material disclosed herein, the calcium (Ca) content of the disclosed alloys and comparative alloys of Alloy Nos. 1 to 42 is deducted, resulting in a titanium content of 48.6 atomic % to 51.8 atomic %. When the impact resistance, creep strength, and oxidation resistance are evaluated as ABB, BAB, or BBA, the calcium (Ca) content of the disclosed alloys and comparative alloys of Alloy Nos. 1 to 42 is subtracted to determine the titanium content: 48.7 atomic % to 50.6 atomic %.

[0107] [Summary] As described above, the "disclosed alloys" shown in Tables 1 to 5 have been shown to exhibit superior properties compared to the "comparative alloys" that do not satisfy the composition of the TiAl alloy cast materials of the present application. Note that, although the above embodiment shows a casting method as a method for producing the TiAl alloy material according to the present disclosure, the method for producing the TiAl alloy material according to the present disclosure is not limited to this, and the TiAl alloy material may also be produced by a forging method, a powder metallurgy method, or an additive manufacturing method.

[0108] <Additional Notes> The TiAl alloy material, the method for manufacturing the TiAl alloy material, and the jet engine rotor blade described in each embodiment can be understood, for example, as follows.

[0109] [1] A TiAl alloy material comprising at least one of carbon: 0.07 atomic % to 0.2 atomic % and silicon: 0.30 atomic % to 0.75 atomic %, aluminum: 46.0 atomic % to 47.7 atomic %, chromium: 1.5 atomic % to 2.5 atomic %, tungsten: 0.5 atomic % to 1.0 atomic %, and the balance being titanium and inevitable impurities.

[0110] [2] The TiAl alloy material according to [1], further containing calcium: 0.02 atomic % to 0.06 atomic %.

[0111] [3] A method for producing the TiAl alloy material according to [1] by a casting method, comprising a melting step of melting raw materials containing an alloy raw material composed of at least one of carbon and silicon, aluminum, chromium, tungsten, and titanium in a water-cooled copper crucible placed in an inert gas atmosphere to obtain a molten alloy.

[0112] [4] A method for producing the TiAl alloy material according to [2] by a casting method, comprising a melting step of melting an alloy raw material comprising at least one of carbon and silicon, aluminum, chromium, tungsten, and titanium, and an AlCa alloy raw material in a calcia crucible to obtain a molten alloy.

[0113] [5] A method for producing a TiAl alloy material according to [3] or [4], comprising a casting step of pouring the molten alloy into a mold by gravity casting. [6] A moving blade for a jet engine, comprising the TiAl alloy material according to [1] or [2].

[0114] The TiAl alloy cast material of the present disclosure has good impact resistance. Therefore, even when used in components that are subject to impacts from foreign objects during use, such as jet engine blades, impact fracture is unlikely to occur. Furthermore, the TiAl alloy cast material of the present disclosure has excellent creep strength and oxidation resistance. Therefore, the TiAl alloy cast material of the present disclosure is suitable for use in components that are used at high temperatures, such as jet engine blades. Specifically, jet engine blades made from the TiAl alloy cast material of the present disclosure are more effective at higher temperatures than jet engine blades made from current TiAl4822, and are suitable for use in jet engine blades of next-generation jet engines that require higher reliability and higher operating temperatures.

[0115] 1 Mold 10a First mold 10b Second mold 11 Cavity

Claims

1. A TiAl alloy material comprising at least one of carbon: 0.07 atomic % to 0.25 atomic % and silicon: 0.30 atomic % to 0.85 atomic %, aluminum: 45.5 atomic % to 47.7 atomic %, chromium: 0.5 atomic % to 2.5 atomic %, tungsten: 0.5 atomic % to 1.0 atomic %, and the balance being titanium and unavoidable impurities.

2. The TiAl alloy material according to claim 1, further containing calcium: 0.02 atomic % to 0.06 atomic %.

3. The absorbed energy in the Charpy impact test at room temperature (20°C) is 3.5 J / cm ２ or more, the creep rupture time at a temperature of 800°C and a stress of 200 MPa is 200 hours or more, and an oxidation test is carried out in which the specimen is held in air at 900°C for 200 hours, and the weight gain of the oxidation test specimen is 0.03 kg / m ２ The TiAl alloy material according to claim 1 or 2, wherein:

4. The TiAl alloy material according to claim 3, wherein the Charpy impact test uses as a test specimen a rectangular columnar Charpy impact test piece having no V-notch and measuring 10 mm in length, 10 mm in width and 55 mm in length, and the hammer used in the Charpy impact test is a small hammer with a capacity of 15 J.

5. The TiAl alloy material according to claim 1, comprising at least one of carbon: 0.12 atomic % to 0.22 atomic % and silicon: 0.32 atomic % to 0.82 atomic %, aluminum: 46.5 atomic % to 47.2 atomic %, chromium: 1.0 atomic % to 2.5 atomic %, tungsten: 0.6 atomic % to 1.0 atomic %, and the balance consisting of titanium and unavoidable impurities, with titanium: 48.7 atomic % to 50.6 atomic %.

6. The TiAl alloy material according to claim 5, further containing calcium: 0.02 atomic % to 0.06 atomic % and titanium: 48.7 atomic % to 50.4 atomic %.

7. The absorbed energy in the Charpy impact test at room temperature (20°C) is 3.5 J / cm ２ The creep rupture time at a temperature of 800°C and a stress of 200 MPa is 200 hours or more, and an oxidation test is carried out in air at 900°C for 200 hours, and the weight gain of the oxidation test piece due to the oxidation test is 0.03 kg / m ２ The absorbed energy in a Charpy impact test at room temperature (20°C) is 6 J / cm or less. ２ The creep rupture time at a temperature of 800°C and a stress of 200 MPa is 400 hours or more, and an oxidation test is carried out in air at 900°C for 200 hours, and the weight gain of the oxidation test piece due to the oxidation test is 0.02 kg / m ２ The TiAl alloy material according to claim 5 or 6, which satisfies at least one of the following conditions:

8. A method for producing the TiAl alloy material according to claim 1 or 5 by a casting method, comprising a melting step of melting raw materials containing alloy raw materials consisting of at least one of carbon and silicon, aluminum, chromium, tungsten, and titanium in a water-cooled copper crucible placed in an inert gas atmosphere to produce a molten alloy.

9. A method for producing the TiAl alloy material according to claim 2 or 6 by a casting method, comprising a melting step of melting an alloy raw material consisting of at least one of carbon and silicon, aluminum, chromium, tungsten, and titanium, and an AlCa alloy raw material in a calcia crucible to produce a molten alloy.

10. A method for producing a TiAl alloy material according to claim 8 or claim 9, comprising a casting step of pouring the molten alloy into a mold by gravity casting.

11. A jet engine rotor blade or turbine wheel made of the TiAl alloy material according to any one of claims 1 to 7.

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