Cast peritectic solidified titanium-aluminum alloy with fine lamellar clusters and preparation method thereof

Abstract

The invention provides a casting peritectic solidification titanium-aluminum alloy with fine lamellar clusters and a preparation method thereof, the peritectic solidification titanium-aluminum alloy comprises the following composition elements and atomic percentage: 46-48 at% of Al, 5-7 at% of Nb, 0-2 at% of Zr, 0-1 at% of V, 0-0.5 at% of Mo, 0-0.5 at% of Cr, 0.1-0.3 at% of Si, 0-0.1 at% of B, 0.05-0.1 at% of Y, or 46-48 at% of Al, 5-7 at% of Nb, 0-2 at% of Zr, 0-1 at% of V, 0-0.5 at% of Mo, 0-0.5 at% of Cr, 0.1-0.3 at% of Si, 0.9-1.1 at% of B, and the balance of Ti and inevitable impurities, and alloy chemical elements with different contents are added and then carrying out simple alpha single-phase region annealing treatment or two steps of alpha single-phase region air cooling and two-phase region upper circulating heat treatment to obtain a fine lamellar group structure. The prepared peritectic solidification titanium-aluminum alloy has good casting process performance, the problem that lamellar clusters of the peritectic solidification titanium-aluminum alloy are large in size is solved, and the peritectic solidification titanium-aluminum alloy is excellent in comprehensive performance and has a practical application basis.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium aluminide design and preparation, and particularly relates to a cast peritectic solidification titanium aluminide with fine lamellar clusters and a preparation method thereof. Background Art

[0002] Titanium aluminide has low density, high specific strength, specific stiffness, excellent oxidation resistance and creep resistance. Compared with Ni-based superalloys, the density of titanium aluminide is only about half of theirs, making it a lightweight high-temperature structural material with great development prospects in aerospace materials.

[0003] Titanium aluminide has good prospects in aerospace material applications. The maximum service temperature of the deformed TNM alloy can reach 750°C. However, the difficult-to-eliminate β phase in β-solidification titanium aluminide will reduce the plasticity of the alloy and the stability during long-term service. Moreover, the poor room-temperature plasticity of titanium aluminide also limits its use.

[0004] Alloying and microstructure control are effective methods to improve the properties of titanium aluminide. The different solidification paths of peritectic solidification titanium aluminide and β-solidification titanium aluminide can reduce or even eliminate the precipitation of the β phase. However, the peritectic solidification titanium aluminide also has the problem of coarse microstructure. Obtaining a fine and uniform fully lamellar microstructure is an effective way to endow titanium aluminide with good comprehensive mechanical properties. Some researchers add trace element B to refine the grains, but this method has limited effect on peritectic solidification titanium aluminide; or heat treatment and hot deformation are carried out to obtain a fine-grained microstructure, but this method requires a lot of equipment, takes a long time and has high costs. Therefore, designing a casting peritectic solidification titanium aluminide with good comprehensive properties and fine lamellar clusters by a short process flow is the development direction of this alloy. Summary of the Invention

[0005] The purpose of the present invention is to provide a cast peritectic solidification alloy composition ratio with good comprehensive mechanical properties and a simple method to obtain fine lamellar clusters. This method has a simple process and can obtain fine lamellar tissue with a size of 50-150 μm. The specific implementation is as follows.

[0006] The present invention provides a cast peritectic solidification titanium aluminide with fine lamellar clusters. Its composition elements and atomic percentages are as follows: Al: 46-48 at%, Nb: 5-7 at%, Zr: 0-2 at%, V: 0-1 at%, Mo: 0-0.5 at%, Cr: 0-0.5 at%, Si: 0.1-0.3 at%, B: 0-0.1 at%, Y: 0.05-0.1 at%, and the balance is Ti and unavoidable impurities.

[0007] The present invention provides a cast peritectic solidification titanium aluminide alloy with fine lamellar clusters, and its constituent elements and atomic percentages are as follows: Al: 46-48 at%, Nb: 5-7 at%, Zr: 0-2 at%, V: 0-1 at%, Mo: 0-0.5 at%, Cr: 0-0.5 at%, Si: 0.1-0.3 at%, B: 0.9-1.1 at%, and the balance is Ti and inevitable impurities.

[0008] Preferably, the constituent elements of the peritectic solidification titanium aluminide alloy further include C element, and its atomic percentage is 0-0.1 at%.

[0009] The present invention provides a preparation method of a cast peritectic solidification titanium aluminide alloy with fine lamellar clusters. The preparation method includes, Step 1: Weigh sponge titanium, high-purity aluminum, high-purity zirconium, AlNb alloy, TiSi alloy, AlMo alloy, high-purity chromium, AlB alloy, AlV alloy, and yttrium powder according to the ratio. Step 2: The raw materials weighed in Step 1 are melted once in a vacuum consumable arc melting furnace, and after melting, they are cooled with the furnace to obtain a primary ingot. Step 3: Take out the primary ingot obtained in Step 2 and place it in a cold crucible vacuum induction melting furnace for secondary melting. Before melting, fill the furnace with argon, the vacuum degree < 1 Pa, and at the same time pour it into a mold to obtain a as-cast peritectic solidification titanium aluminide alloy. Step 4: Place the as-cast peritectic solidification titanium aluminide alloy obtained in Step 3 in a hot isostatic pressing furnace, heat it to 1240-1330 °C under argon protection, the gas pressure is 150-190 MPa, hold the pressure for 2-6 h for hot isostatic pressing, and then take it out after cooling with the furnace to room temperature. Step 5: Place the hot isostatically pressed as-cast peritectic solidification titanium aluminide alloy in a heat treatment furnace, hold it at (T 1 ~(T 1 +25) °C for 10 min and then take it out and air-cool it to room temperature. Among them, T 1 is the α transformation temperature of the as-cast peritectic solidification titanium aluminide alloy. Step 6: Place the as-cast peritectic solidification titanium aluminide alloy air-cooled to room temperature in a heat treatment furnace, hold it at (T 1 -35)~(T 1 -5) °C for 5 min and then take it out and air-cool it to room temperature. Step 7: Repeat the heat treatment and air-cooling in Step 6 for 5-7 times to obtain a peritectic solidification titanium aluminide alloy with fine lamellar clusters.

[0010] Preferably, the microstructure of the as-cast peritectic solidification titanium aluminide alloy in Step 3 is composed of α 2The fully lamellar structure composed of α and γ phases, with a small amount of β phase and yttrium oxide phase distributed within the lamellar clusters and at the interfaces of the lamellar clusters, and the average lamellar cluster size being 200 - 400 μm.

[0011] Preferably, the temperature of the hot isostatic pressing in step four is below the α transformation temperature of the as-cast peritectic solidification titanium aluminide alloy and within the upper range of its two-phase region, so that the microstructure of the as-cast peritectic solidification titanium aluminide alloy after hot isostatic pressing is a near-γ structure composed of a small amount of β phase, yttrium oxide phase, and equiaxed γ grains.

[0012] The microstructure of the peritectic solidification titanium aluminide alloy with fine lamellar clusters in step seven is a small amount of yttrium oxide phase and fine lamellar clusters, and the lamellar cluster size is 50 - 150 μm.

[0013] The present invention also provides a preparation method of a cast peritectic solidification titanium aluminide alloy with fine lamellar clusters, and the preparation method includes, Step one: Weigh sponge titanium, high-purity aluminum, high-purity zirconium, AlNb alloy, TiSi alloy, AlMo alloy, AlV alloy, high-purity chromium, titanium carbide, TiB 2 powders according to the ratio. Step two: The raw materials obtained in step one are melted once in a vacuum consumable arc melting furnace, and after the melting is completed, they are cooled with the furnace to obtain a primary ingot. Step three: Take out the primary ingot obtained in step two, place it in a cold crucible vacuum induction melting furnace for secondary melting. Before melting, argon gas is filled into the furnace, and the vacuum degree is < 1 Pa. At the same time, it is poured into a mold to obtain an as-cast peritectic solidification titanium aluminide alloy. Step four: Place the as-cast peritectic solidification titanium aluminide alloy in step three in a hot isostatic pressing furnace and heat it to 1240 - 1330 °C under argon protection, with a gas pressure of 150 - 190 MPa, and hold the pressure for 2 - 6 h for hot isostatic pressing. After cooling with the furnace to room temperature, take it out. Step five: Place the as-cast peritectic solidification titanium aluminide alloy obtained in step four in a heat treatment furnace, and keep it at (T 1 ~(T 1 + 40) °C for 5 min and then cool it with the furnace to room temperature to obtain a peritectic solidification titanium aluminide alloy with fine lamellar clusters, where T 1 is the α transformation temperature of the as-cast peritectic solidification titanium aluminide alloy.

[0014] Preferably, the microstructure of the as-cast peritectic solidification titanium aluminide alloy in step three is mainly a fully lamellar structure composed of α 2 and γ phases, with a small amount of TiB 2 phase and bright white strip segregation distributed in the structure, and the lamellar cluster size is 70 - 100 μm.

[0015] Preferably, the microstructure of the peritectic solidification titanium aluminide alloy in step five is mainly composed of α2 The fully lamellar structure composed of α and γ phases, with a small amount of TiB phases distributed in the structure, segregation eliminated, and the lamellar colony size being 70 - 120 μm. 2

[0016] Compared with the prior art, the present invention has the following beneficial effects: Through the design and optimization of the composition of titanium aluminide alloy, followed by heat treatment, the present invention obtains a cast peritectic solidification alloy with excellent comprehensive properties and fine lamellar colonies; by adding different contents of alloying elements and then performing a simple α single-phase region annealing treatment or two-step α single-phase region air cooling and upper cycle heat treatment in the two-phase region, a fine lamellar structure can be obtained. The peritectic solidification titanium aluminide alloy with this composition has good casting process performance and can overcome the problem of coarse lamellar colony size in cast peritectic solidification titanium aluminide alloy. At the same time, the preparation method of the present invention has low requirements for equipment and a simple heat treatment process, and has great application value in the industrial field. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the SEM image of the as-cast structure of the peritectic solidification titanium aluminide alloy in Example 1 of the present invention.

[0018] Figure 2 It is the SEM image of the hot isostatic pressing structure of the peritectic solidification titanium aluminide alloy in Example 1 of the present invention.

[0019] Figure 3 It is the SEM image of the peritectic solidification titanium aluminide alloy with a fine lamellar structure obtained in Example 1 of the present invention.

[0020] Figure 4 It is the SEM image of the peritectic solidification titanium aluminide alloy with a fine lamellar structure obtained in Example 2 of the present invention.

[0021] Figure 5 It is the SEM image of the peritectic solidification titanium aluminide alloy after heat treatment in Comparative Example 1 of the present invention.

[0022] Figure 6 It is the SEM image of the as-cast structure of the peritectic solidification titanium aluminide alloy in Example 3 of the present invention.

[0023] Figure 7 It is the SEM image of the peritectic solidification titanium aluminide alloy with a fine lamellar structure obtained in Example 3 of the present invention.

[0024] Figure 8 It is the SEM image of the as-cast structure of the peritectic solidification titanium aluminide alloy in Comparative Example 2 of the present invention.

[0025] Figure 9 It is the SEM image of the peritectic solidification titanium aluminide alloy after heat treatment in Comparative Example 2 of the present invention. DETAILED IMPLEMENTATION METHODS

[0026] ​To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Apparently, the described embodiments are part of the embodiments of the present disclosure, rather than all of them. Based on the described embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative efforts also fall within the scope of protection of the present disclosure.

[0027] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the subject matter of the present disclosure pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and the relevant art, and will not be interpreted in an idealized or overly formal manner unless expressly so defined herein.

[0028] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase "embodiments" appearing in various places in the specification does not necessarily refer to the same embodiment, nor are they independent or alternative embodiments mutually exclusive of other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0029] A cast peritectic solidifying titanium-aluminum alloy with fine lamellar clusters provided by the present invention preferably has the following composition elements and atomic percentages: Al: 46 - 48 at%; Nb: 5 - 7 at%; Zr: 0 - 2 at%; V: 0 - 1 at%; Mo: 0 - 0.5 at%; Cr: 0 - 0.5 at%; Si: 0.1 - 0.3 at%, for example, Si can be 0.1 at%, 0.2 at%, 0.3 at%; B: 0 - 0.1 at%, for example, B can be 0 at%, 0.05 at%, 0.1 at%; Y: 0.05 - 0.1 at%, for example, Y can be 0.05 at%, 0.075 at%, 0.085 at%, 0.1 at%, and the balance is Ti and unavoidable impurities; Or preferably, the composition elements and atomic percentages are: Al: 46 - 48 at%; Nb: 5 - 7 at%; Zr: 0 - 2 at%; V: 0 - 1 at%; Mo: 0 - 0.5 at%; Cr: 0 - 0.5 at%; Si: 0.1 - 0.3 at%, for example, Si can be 0.1 at%, 0.2 at%, 0.3 at%; B: 0.9 - 1.1 at%, for example, B can be 0.9 at%, 1.0 at%, 1.1 at%; C: 0 - 0.1 at%; and the balance is Ti and unavoidable impurities; In some embodiments of the present invention, the compositional elements and atomic percentages of the peritectic solidified titanium aluminide are different in terms of the content of element B. When the content of element B is low, element Y is added to the compositional elements of the peritectic solidified titanium aluminide. When the content of element B is high, element Y is not contained in the compositional elements of the peritectic solidified titanium aluminide; for different contents of element B and element Y, the preparation methods of the above-mentioned peritectic solidified titanium aluminide are also different.

[0030] In some embodiments of the present invention, when the content of element B is low and element Y is contained, the preparation method of the cast peritectic solidified titanium aluminide with fine lamellar clusters includes, Step 1: Weigh sponge titanium, high-purity aluminum, high-purity zirconium, AlNb alloy, TiSi alloy, AlMo alloy, high-purity chromium, AlB alloy, AlV alloy, and yttrium powder according to the ratio; Step 2: The raw materials weighed in Step 1 are melted once in a vacuum consumable arc melting furnace, and after the melting is completed, they are cooled with the furnace to obtain a primary ingot; Step 3: Take out the primary ingot obtained in Step 2 and place it in a cold crucible vacuum induction melting furnace for secondary melting. Before melting, argon is filled into the furnace, and the vacuum degree is <1 Pa. At the same time, it is poured into a mold to obtain a as-cast peritectic solidified titanium aluminide; the microstructure of the obtained as-cast peritectic solidified titanium aluminide is a fully lamellar structure composed of α 2 and γ phases. A small amount of β phase and yttrium oxide phase are distributed in the lamellar clusters and at the interfaces of the lamellar clusters. The average lamellar cluster size is preferably 200 - 400 μm. For example, it can be 200 μm, 230 μm, 260 μm, 290 μm, 300 μm, 330 μm, 360 μm, 400 μm, etc.

[0031] Step 4: Place the as-cast peritectic solidified titanium aluminide obtained in Step 3 in a hot isostatic pressing furnace, heat it to 1240 - 1330 °C under argon protection, with a gas pressure of 150 - 190 MPa, hold the pressure for 2 - 6 h for hot isostatic pressing, and then take it out after cooling to room temperature with the furnace; Step 5: Place the hot isostatically pressed as-cast peritectic solidified titanium aluminide in a heat treatment furnace, at a temperature preferably T 1 ~(T 1 +25) °C. For example, the temperature can be T 1 °C, T 1 +5 °C, T 1 +10 °C, T 1 +15 °C, T 1 +20 °C, T 1 +25 °C. After holding for 10 min, take it out and air-cool it to room temperature. Among them, T 1 is the α transformation temperature of the as-cast peritectic solidified titanium aluminide; Step 6: Place the as-cast peritectic solidified titanium aluminum alloy that has been air-cooled to room temperature in a heat treatment furnace. At a temperature of (T 1 - 35)~(T 1 - 5) °C, for example, the temperature can be T 1 - 35 °C, T 1 - 25 °C, T 1 - 20 °C, T 1 - 15 °C, T 1 - 10 °C, T 1 - 5 °C. After holding for 5 min, take it out and air-cool to room temperature; Step 7: Repeat the heat treatment and air cooling in Step 6 preferably 5 - 7 times. For example, it can be 5 times, 6 times, or 7 times to obtain a cast peritectic solidified titanium aluminum alloy with fine lamellar clusters. Its microstructure is a small amount of yttrium oxide phase and fine lamellar clusters. The size of the lamellar clusters is preferably 50 - 150 μm. For example, it can be 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm.

[0032] In some embodiments of the present invention, when the content of element B is relatively high and element Y is not contained, the preparation method of the cast peritectic solidified titanium aluminum alloy with fine lamellar clusters includes, Step 1: Weigh sponge titanium, high-purity aluminum, high-purity zirconium, AlNb alloy, TiSi alloy, AlMo alloy, AlV alloy, high-purity chromium, titanium carbide, TiB 2 powder according to the ratio; Step 2: The raw materials obtained in Step 1 are melted once in a vacuum consumable arc melting furnace, and after melting is completed, it is cooled with the furnace to obtain a primary ingot; Step 3: Take out the primary ingot obtained in Step 2 and place it in a cold crucible vacuum induction melting furnace for secondary melting. Before melting, fill the furnace with argon, the vacuum degree < 1 Pa, and at the same time pour it into a mold to obtain an as-cast peritectic solidified titanium aluminum alloy; the microstructure of the obtained as-cast peritectic solidified titanium aluminum alloy mainly consists of a fully lamellar structure composed of α 2 and γ phases, with a small amount of TiB 2 phases and bright white strip segregations distributed in the structure. The size of the lamellar clusters is preferably 70 - 100 μm. For example, it can be 70 μm, 80 μm, 90 μm, 100 μm, etc.

[0033] Step 4: Place the as-cast peritectic solidified titanium aluminum alloy in Step 3 in a hot isostatic pressing furnace and heat it to 1240 - 1330 °C under argon protection, with a gas pressure of 150 - 190 MPa, hold the pressure for 2 - 6 h for hot isostatic pressing, and take it out after cooling to room temperature with the furnace; Step 5: Place the as-cast peritectic solidified titanium aluminum alloy obtained in Step 4 in a heat treatment furnace. At a temperature of T 1 ~(T1 +40) °C, for example, it can be T 1 °C, T 1 +5 °C, T 1 +10 °C, T 1 +15 °C, T 1 +20 °C, T 1 +25 °C, T 1 +30 °C, T 1 +35 °C, T 1 +40 °C, where T 1 is the α transformation temperature of the as-cast peritectic solidified titanium aluminide alloy. After holding for 5 min, it is cooled to room temperature with the furnace, and a cast peritectic solidified titanium aluminide alloy with fine lamellar clusters is obtained. Its microstructure is mainly a fully lamellar structure composed of α 2 and γ phases, with a small amount of TiB 2 phases distributed in the structure. The segregation is eliminated, and the size of the lamellar clusters is preferably 70 - 120 μm. For example, it can be 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, etc.

[0034] The present invention will be further described below through specific embodiments.

[0035] Example 1

[0036] The chemical composition of the peritectic solidified titanium aluminide alloy used in this example is, by atomic percentage, Al: 47 at%, Nb: 6 at%, Zr: 1 at%, V: 1 at%, Mo: 0.5 at%, Cr: 0.5 at%, Si: 0.2 at%, B: 0.1 at%, Y: 0.05 at%, and the balance is Ti and inevitable impurity elements. Its α transformation temperature is about 1335 °C. The specific preparation method is as follows: Step 1: Weigh sponge titanium, high-purity aluminum, high-purity zirconium, AlNb alloy, TiSi alloy, AlMo alloy, high-purity chromium, AlB alloy, AlV alloy, and yttrium powder according to the ratio of Ti-47A1-6Nb-0.5Mo-0.5Cr-1Zr-1V-0.2Si-0.1B-0.05Y; Step 2: The raw materials obtained in Step 1 are melted once in a vacuum consumable arc melting furnace, and after melting, they are cooled with the furnace to obtain an ingot; Step 3: Take out the ingot obtained in Step 2 and place it in a cold crucible vacuum induction melting furnace for secondary melting. Before melting, argon is filled into the furnace, and the vacuum degree < 1 Pa. At the same time, it is poured into a mold to obtain an alloy ingot. At this time, the as-cast structure of the alloy is as Figure 1 shown, which is a lamellar cluster composed of α 2 and γ, a small amount of fine strip-shaped β phases distributed at the lamellar cluster boundaries and between the lamellae, and circular yttrium oxide phases, where α 2The volume fraction is 9.6%, the volume fraction of the γ phase is 83.9%, the volume fraction of the β phase is 5.5%, and the average lamellar colony size is 300 μm; Step 4: Place the alloy ingot obtained in Step 3 in a hot isostatic pressing furnace and heat it to 1290 °C under argon protection, with a gas pressure of 170 MPa, hold the pressure for 4 h for hot isostatic pressing, and take it out after cooling to room temperature with the furnace. At this time, the microstructure of the alloy in the hot isostatic pressing state is as Figure 2 shown, which is composed of massive β phase, equiaxed γ grains and a small amount of yttrium oxide phase. Among them, the volume fraction of the equiaxed γ grains is 93.9%, and the volume fraction of the β phase is 6.1%; Step 5: Place the hot isostatic pressed titanium aluminide obtained in Step 4 in a heat treatment furnace, hold it at 1350 °C for 10 min, and then take it out and air-cool it to room temperature; Step 6: Place the titanium aluminide air-cooled to room temperature in Step 5 in a heat treatment furnace, hold it at 1320 °C for 5 min, and then take it out and air-cool it to room temperature; Step 7: Repeat the heat treatment and air-cooling of the titanium aluminide air-cooled to room temperature in Step 6 for 5 times according to the method of Step 6 to obtain a cast peritectic solidified titanium aluminide with fine lamellar colonies. Its microstructure is as Figure 3 shown, which is a fully lamellar structure composed of lamellar colonies and a small amount of yttrium oxide phase. The lamellar colonies intersect with each other to form interlocking grain boundaries, and the average lamellar colony size is 60 μm.

[0037] Example 2

[0038] Using the same component ratio as in Example 1, the specific preparation method is as follows: Step 1: Weigh sponge titanium, high-purity aluminum, high-purity zirconium, AlNb alloy, TiSi alloy, AlMo alloy, high-purity chromium, AlB alloy, AlV alloy, and yttrium powder according to the ratio of Ti-47Al-6Nb-0.5Mo-0.5Cr-1Zr-1V-0.2Si-0.1B-0.05Y; Step 2: The raw materials obtained in Step 1 are melted once in a vacuum consumable arc melting furnace, and after melting is completed, they are cooled with the furnace to obtain a primary ingot; Step 3: Take out the primary ingot obtained in Step 2, place it in a cold crucible vacuum induction melting furnace for secondary melting. Before melting, argon is filled into the furnace, the vacuum degree is <1 Pa, and at the same time, it is poured into a mold to obtain an alloy ingot; Step 4: Place the alloy ingot obtained in Step 3 in a hot isostatic pressing furnace and heat it to 1290 °C under argon protection, with a gas pressure of 170 MPa, hold the pressure for 4 h for hot isostatic pressing, and take it out after cooling to room temperature with the furnace; Step 5: Place the hot isostatic pressed titanium aluminide obtained in Step 4 in a heat treatment furnace, hold it at 1350 °C for 10 min, and then take it out and air-cool it to room temperature; Step 6: Place the titanium aluminum alloy that has been air-cooled to room temperature in Step 5 into a heat treatment furnace, hold it at 1330 °C for 5 minutes, then take it out and air-cool it to room temperature; Step 7: Repeat the heat treatment and air-cooling of the titanium aluminum alloy that has been air-cooled to room temperature in Step 6 five times according to the method in Step 6 to obtain a cast peritectic solidified titanium aluminum alloy with fine lamellar clusters. Its microstructure is as Figure 4 shown, a fully lamellar microstructure composed of lamellar clusters and a small amount of yttrium oxide phase. The lamellar clusters intersect with each other to form interlocking grain boundaries, and the average lamellar cluster size is 80 μm.

[0039] Example 3

[0040] The chemical composition of the peritectic solidified titanium aluminum alloy used in this example is, by atomic percentage: Al: 47 at%, Nb: 6 at%, Zr: 1 at%, V: 1 at%, Mo: 0.5 at%, Cr: 0.5 at%, Si: 0.2 at%, C: 0.1 at%, B: 1.1 at%, and the balance is Ti and inevitable impurity elements. Its α transformation temperature is about 1330 °C. The specific preparation method is as follows: Step 1: Weigh sponge titanium, high-purity aluminum, high-purity zirconium, AlNb alloy, TiSi alloy, AlMo alloy, high-purity chromium, AlV alloy, titanium carbide, and TiB 2 powder according to the ratio of Ti-47Al-6Nb-0.5Mo-0.5Cr-1Zr-1V-0.2Si-0.1C-1.1B; Step 2: The raw materials obtained in Step 1 are melted once in a vacuum consumable arc melting furnace, and after melting, they are cooled with the furnace to obtain a primary ingot; Step 3: Take out the primary ingot obtained in Step 2, place it in a cold crucible vacuum induction melting furnace for secondary melting. Before melting, argon gas is filled into the furnace, and the vacuum degree is <1 Pa. At the same time, it is poured into a mold to obtain an alloy ingot. The as-cast microstructure of the alloy is as Figure 6 shown, a fully lamellar microstructure composed of α 2 and γ phases, with a small amount of TiB 2 phases and bright white strip segregation distributed in the microstructure, and the average lamellar cluster size is 80 μm; Step 4: Place the alloy ingot obtained in Step 3 in a hot isostatic pressing furnace, heat it to 1290 °C under argon protection, with a gas pressure of 170 MPa, hold the pressure for 4 h for hot isostatic pressing, and then take it out after cooling with the furnace to room temperature; Step 5: Place the hot isostatically pressed titanium aluminum alloy obtained in Step 4 in a heat treatment furnace, hold it at 1350 °C for 5 minutes, and then cool it with the furnace to room temperature to obtain a cast peritectic solidified titanium aluminum alloy with fine lamellar clusters as Figure 7 shown, a fully lamellar microstructure composed of α 2 and γ phases, with a small amount of TiB 2The phase segregation is eliminated, and the average lamellar colony size is 100 μm.

[0041] Comparative Example 1 The hot isostatic pressing state titanium aluminum alloy obtained in Step 4 of Example 1 was placed in a heat treatment furnace, heated to 1350 °C, held for 5 min, and then cooled to room temperature with the furnace.

[0042] Figure 5 SEM micrograph of the microstructure of the titanium aluminum alloy after being heated to 1350 °C, held for 5 min, and cooled to room temperature with the furnace in Comparative Example 1. Its microstructure is a fully lamellar structure with an average lamellar colony size of 200 μm. Comparing Figure 3 、 Figure 4 、 Figure 5 It can be clearly seen that treating the titanium aluminum alloy with this composition by the methods of Example 1 and Example 2 can obtain a fine fully lamellar structure, and improve the strength and plasticity of the alloy by fine grain strengthening.

[0043] Comparative Example 2 The chemical composition of the peritectic solidification titanium aluminum alloy used in this comparative example is Al: 47 at%, Nb: 6 at%, Mo: 0.5 at%, Cr: 0.5 at%, Zr: 1 at%, Si: 0.2 at%, C: 0.1 at%, B: 0.1 at% in atomic percentage, and the balance is Ti and inevitable impurity elements. Its α transformation temperature is about 1330 °C. The preparation method is as follows: Step 1: Weigh sponge titanium, high-purity aluminum, high-purity zirconium, AlNb alloy, TiSi alloy, AlMo alloy, high-purity chromium, titanium carbide, and AlB alloy according to the ratio of Ti-47Al-6Nb-0.5Mo-0.5Cr-1Zr-0.2Si-0.1C-0.1B. Step 2: The raw materials obtained in Step 1 were melted once in a vacuum consumable arc melting furnace, and after melting, they were cooled with the furnace to obtain a primary ingot. Step 3: The primary ingot obtained in Step 2 was taken out and placed in a cold crucible vacuum induction melting furnace for secondary melting. Before melting, argon was filled into the furnace, and the vacuum degree was <1 Pa. At the same time, it was poured into a mold to obtain an alloy ingot. Step 4: The alloy ingot obtained in Step 3 was placed in a hot isostatic pressing furnace, heated to 1290 °C under argon protection, with a gas pressure of 170 MPa, and hot isostatic pressing was carried out for 4 h, and then taken out after cooling to room temperature with the furnace. Step 5: The hot isostatic pressing titanium aluminum alloy obtained in Step 4 was placed in a heat treatment furnace, held at 1350 °C for 5 min, and then cooled to room temperature with the furnace. Figure 8 Micrograph of the as-cast microstructure of the titanium aluminum alloy in Comparative Example 2 Figure 9 SEM micrograph of the microstructure of the heat-treated titanium aluminum alloy in Comparative Example 2.Figure 1 , Figure 6 and Figure 8 are compared with Figure 7 and Figure 9 respectively. It can be clearly seen that the as-cast structure of peritectic solidification titanium aluminide alloy and the structure after heat treatment at temperatures above the α-transformation point can be significantly refined by adopting the component designs of Example 1 and Example 3.

[0044] The above-given examples are the preferred examples for implementing the present invention, and the present invention is not limited to the above examples. Any non-essential addition or replacement made by those skilled in the art according to the technical features of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A cast peritectic solidified titanium-aluminum alloy having fine lamellar clusters, characterized in that: The constituent elements and atomic percentages of the peritectic solidifying titanium aluminum alloy are: Al: 46-48at%, Nb: 5-7at%, Zr: 0-2at%, V: 0-1at%, Mo: 0-0.5at%, Cr: 0-0.5at%, Si: 0.1-0.3at%, B: 0-0.1at%, Y: 0.05-0.1at%, and the remainder is Ti and unavoidable impurities.

2. A cast peritectic solidified titanium-aluminum alloy having fine lamellar clusters, characterized in that: The constituent elements and atomic percentages of the peritectic solidifying titanium aluminum alloy are: Al: 46-48at%, Nb: 5-7at%, Zr: 0-2at%, V: 0-1at%, Mo: 0-0.5at%, Cr: 0-0.5at%, Si: 0.1-0.3at%, B: 0.9-1.1at%, and the remainder is Ti and unavoidable impurities.

3. The cast peritectic solidified titanium-aluminum alloy with fine lamellar clusters according to claim 2, characterized in that: The constituent elements of the peritectic solidifying titanium aluminum alloy also include C element, and its atomic percentage is 0-0.1at%.

4. The method for preparing a cast peritectic solidified titanium aluminum alloy having fine lamellar clusters according to claim 1, characterized in that: The preparation method comprises: Step 1: Weigh titanium sponge, high purity aluminum, high purity zirconium, AlNb alloy, TiSi alloy, AlMo alloy, high purity chromium, AlB alloy, AlV alloy, and yttrium powder according to the proportion; Step 2: The raw materials weighed in step 1 are melted once in a vacuum consumable arc melting furnace, and cooled with the furnace after the melting is completed to obtain a primary ingot; Step 3: taking out the primary ingot obtained in step 2, placing it in a cold crucible vacuum induction melting furnace for secondary melting, filling the furnace with argon gas before melting, with a vacuum degree of <1 Pa, and pouring it into a mold to obtain a cast peritectic solidified titanium aluminum alloy; Step 4: placing the cast peritectic solidified titanium-aluminum alloy obtained in step 3 in a hot isostatic pressing furnace, heating to 1240-1330° C. under argon protection conditions, gas pressure of 150-190 MPa, maintaining the pressure for 2-6 h for hot isostatic pressing, and taking out after cooling to room temperature with the furnace; Step 5: placing the cast peritectic solidified titanium-aluminum alloy after hot isostatic pressing in a heat treatment furnace, keeping it at T1~(T1+25)℃ for 10min, and then taking it out and air cooling it to room temperature, wherein T1 is the α transformation temperature of the cast peritectic solidified titanium-aluminum alloy; Step 6: placing the cast peritectic solidified titanium-aluminum alloy cooled to room temperature in a heat treatment furnace, keeping it at (T1-35)~(T1-5)℃ for 5 minutes, and then taking it out and cooling it to room temperature in air; Step 7: The heat treatment and air cooling of step 6 are cycled for 5-7 times to obtain a peritectic solidified titanium aluminum alloy with fine lamellar clusters.

5. The method for preparing a cast peritectic solidified titanium aluminum alloy having fine lamellar clusters according to claim 4, characterized in that: The microstructure of the cast peritectic solidified titanium aluminum alloy in step 3 is a full lamellar structure composed of α2 and γ phases, with a small amount of thin strip-shaped β phase and circular yttrium oxide phase distributed in the lamellar clusters and at the lamellar cluster interfaces, and the average lamellar cluster size is 200-400μm.

6. The method for preparing a cast peritectic solidified titanium aluminum alloy having fine lamellar clusters according to claim 4, characterized in that: The temperature of the hot isostatic pressing in step 4 is below the α transformation temperature of the cast peritectic solidifying titanium aluminum alloy and in the upper range of its two-phase region, so that the microstructure of the cast peritectic solidifying titanium aluminum alloy after hot isostatic pressing is a near-γ structure composed of a small amount of blocky β phase and yttrium oxide phase and equiaxed γ grains.

7. The method for preparing a cast peritectic solidified titanium aluminum alloy having fine lamellar clusters according to claim 4, characterized in that: The microstructure of the peritectic solidified titanium aluminum alloy with fine lamellar clusters in step 7 is a small amount of yttrium oxide phase and fine lamellar clusters, the lamellar clusters are interlaced to form interlocking grain boundaries, and the size of the lamellar clusters is 50-150 μm.

8. The method for preparing a cast peritectic solidified titanium aluminum alloy having fine lamellar clusters according to claim 3, characterized in that: The preparation method comprises: Step 1: Weigh titanium sponge, high purity aluminum, high purity zirconium, AlNb alloy, TiSi alloy, AlMo alloy, AlV alloy, high purity chromium, titanium carbide, and TiB2 powder according to the proportion; Step 2: The raw material obtained in step 1 is melted once in a vacuum consumable arc melting furnace, and after the melting is completed, it is cooled along with the furnace to obtain a primary ingot; Step 3: taking out the primary ingot obtained in step 2, placing it in a cold crucible vacuum induction melting furnace for secondary melting, filling the furnace with argon gas before melting, with a vacuum degree of <1 Pa, and pouring it into a mold to obtain a cast peritectic solidified titanium aluminum alloy; Step 4: placing the cast peritectic solidified titanium-aluminum alloy in step 3 in a hot isostatic pressing furnace and heating it to 1240-1330° C. under argon protection conditions, with a gas pressure of 150-190 MPa, maintaining the pressure for 2-6 hours for hot isostatic pressing, and taking it out after cooling it to room temperature with the furnace; Step 5: Place the cast peritectic solidifying titanium-aluminum alloy obtained in step 4 in a heat treatment furnace, keep it at T1~(T1+40)℃ for 5 minutes, and then cool it to room temperature with the furnace to obtain a peritectic solidifying titanium-aluminum alloy with fine lamellar clusters, wherein T1 is the α transformation temperature of the cast peritectic solidifying titanium-aluminum alloy.

9. The method for preparing a cast peritectic solidified titanium aluminum alloy having fine lamellar clusters according to claim 8, characterized in that: The microstructure of the cast peritectic solidified titanium aluminum alloy in step 3 is mainly a full lamellar structure composed of α2 and γ phases, with a small amount of TiB2 phase and bright white strip segregation distributed in the structure, and the lamellar cluster size is 70-100μm.

10. The method for preparing a cast peritectic solidified titanium aluminum alloy having fine lamellar clusters according to claim 8, characterized in that: The microstructure of the peritectic solidified titanium aluminum alloy described in step 5 is a full lamellar structure mainly composed of α2 and γ phases, with a small amount of TiB2 phase distributed in the structure, segregation is eliminated, and the lamellar cluster size is 70-120μm.

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