Ti3al-tial laminated composite material and preparation method and application thereof

Abstract

The present application belongs to the technical field of laminated composite materials, and particularly relates to a Ti3Al-TiAl laminated composite material and a preparation method and application thereof. The present application is prepared by a method of vacuum hot pressing and pack hot rolling with forged Ti3Al alloy and forged TiAl alloy as raw materials, improves the plasticity and toughness of the composite material at room temperature, and maintains the high temperature performance (yield strength and tensile strength) of the composite material. The size of the obtained Ti3Al-TiAl laminated composite material is (200-1000) mm*(80-500) mm*(1-5) mm, the tensile strength at room temperature reaches 900-1100 MPa, the plasticity at room temperature is 3%-6%, the fracture toughness is 35 MPa*m 1 / 2 50 MPa*m 1 / 2 , the tensile strength at 800 DEG C. can reach 650-800 MPa, the yield strength at 800 DEG C. can reach 600-700 MPa, and the plasticity at 800 DEG C. is 20%-30%. The present application meets the production requirements of large size and large quantity, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of laminated composite material technology, and specifically relates to a Ti3Al-TiAl laminated composite material, its preparation method and application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] TiAl alloy sheets possess low density, high specific strength, and excellent high-temperature oxidation and creep resistance, making them promising for applications in the aerospace field. However, the inherent brittleness of TiAl alloys results in low plasticity and toughness at room temperature, severely hindering their further development and engineering applications. To address this issue, some researchers have proposed adding soft and tough titanium or titanium alloys to TiAl alloys to prepare titanium alloy-TiAl laminated composites, aiming to improve the room-temperature plasticity and toughness of TiAl alloys, and some research results have been achieved. However, the ultimate operating temperature of high-temperature titanium alloys is typically 650℃, and even some short-term high-temperature titanium alloys struggle to exceed 700℃. Therefore, while this composite material improves the room-temperature plasticity and toughness of TiAl alloys, it significantly reduces the ultimate operating temperature of TiAl alloys (the operating temperature of TiAl alloys is 750℃~850℃), failing to meet the requirements of aerospace applications.

[0004] High-temperature yield strength and high-temperature tensile strength are two important indicators for measuring the ultimate service temperature of high-temperature materials. Tensile strength refers to the strength at which a material fractures during service; while yield strength is the ultimate strength a material can withstand before undergoing significant plastic deformation. In actual service, high-temperature materials undergo significant plastic deformation before fracture, at which point the material has already failed. Therefore, during high-temperature service, the yield strength is more critical than the tensile strength.

[0005] For Ti-TiAl laminated composites, the yield strength at 800℃ is less than 400MPa. Therefore, in order to further improve the ultimate service temperature and high-temperature yield strength of composites, some scholars have prepared Ti3Al-TiAl laminated composites using Ti foil and Al foil as raw materials through hot-pressing diffusion. Compared with titanium alloys, Ti3Al alloys have lower density. At the same time, Ti3Al is an intermetallic compound, and Ti atoms and Al atoms are covalently bonded, resulting in stronger interatomic bonding forces. Therefore, its ultimate service temperature is higher, which can effectively improve the service temperature and strength of composites. However, Ti3Al-TiAl laminated composites prepared by this method have many disadvantages: (1) Due to the Kirkendall effect, the density of the prepared composites is low, which seriously reduces the mechanical properties of the composites; (2) The room temperature and high temperature properties of the composites prepared by this method are not significantly improved. This is mainly because the composite material prepared from Ti foil and Al foil is not alloyed, and the mechanical properties of the matrix material itself are low. Therefore, the room temperature and high temperature performance of the material is not significantly improved; (3) Due to the limitations of hot pressing equipment, it is impossible to prepare large-size composite materials that meet the requirements of industrial production, which hinders the further development and application of the material. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide a Ti3Al-TiAl laminated composite material, its preparation method, and its application. Specifically, the Ti3Al-TiAl laminated composite material is prepared using forged Ti3Al alloy and forged TiAl alloy as raw materials through vacuum hot pressing and cladding hot rolling. This method improves the room temperature plasticity and toughness of the composite material while maintaining its high-temperature performance (yield strength and tensile strength), meeting the needs of large-size and mass production, and has good application prospects.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] In a first aspect, the present invention provides a Ti3Al-TiAl laminated composite material, specifically: using forged Ti3Al alloy and forged TiAl alloy as raw materials, vacuum hot pressing and cladding hot rolling are performed to obtain the Ti3Al-TiAl laminated composite material.

[0009] Preferably, the nominal chemical composition of the forged Ti3Al alloy is Ti-(20~25)Al-(0~20)X-(0.1~2)Z (at%), where X is a β-phase stabilizing element and Z is a microalloying element;

[0010] The nominal chemical composition of the forged TiAl alloy is Ti-(40~45)Al-(0.5~10)X-(0.1~2)Z(at%), where X is the β phase stabilizing element and Z is the microalloying element.

[0011] More preferably, the β-phase stabilizing element is selected from one or more of Cr, Mn, V, Mo, Nb, and Fe; and the microalloying element is selected from one or more of W, B, and Y.

[0012] A second aspect of the present invention provides a method for preparing the Ti3Al-TiAl laminated composite material described in the first aspect, comprising the following steps:

[0013] S1. Cut the forged Ti3Al and forged TiAl alloy to obtain preforms of the two alloys. Then, mechanically grind and polish the preforms to obtain Ti3Al and TiAl alloy slabs.

[0014] S2. Vacuum hot pressing of Ti3Al and TiAl alloy slabs yields composite billet;

[0015] S3. The composite billet is sequentially welded and hot-rolled to obtain a Ti3Al-TiAl laminated composite material with a sheath. After removing the sheath, the Ti3Al-TiAl laminated composite material is obtained.

[0016] Preferably, in step S1, the specific preparation method of the forged Ti3Al and the forged TiAl alloy is as follows: first, the Ti3Al alloy and the TiAl alloy are melted, the ingot obtained by melting is forged, and then annealed, cooled, and the cladding is removed to obtain the alloy.

[0017] The vacuum degree of the smelting process is 10. -2 Pa to 1 Pa, power supply power of 95 to 105 kW; smelting times of 2 to 4 times;

[0018] The forging temperature is 1000–1500℃; the forging rate is 0.2–0.6 m / min;

[0019] The annealing temperature is 700–950°C;

[0020] The cutting method is wire cutting; the polishing method is selected from mechanical polishing or electrolytic polishing.

[0021] Preferably, in step S1, the surface roughness of the Ti3Al and TiAl alloy slabs is Ra6 to Ra8.

[0022] Preferably, in step S1, the length of the Ti3Al and TiAl alloy slab is 50mm to 500mm, the width is 50mm to 500mm, and the thickness is 0.5mm to 20mm.

[0023] Preferably, in step S2, the vacuum hot pressing method involves placing the surface-treated Ti3Al and TiAl alloy slabs in a graphite mold, preferably by alternately stacking the Ti3Al and TiAl alloy slabs, with 2n+1 layers, where n is an integer from 1 to 20 for the Ti3Al alloy slabs.

[0024] More preferably, the two sides of the alternately stacked Ti3Al and TiAl alloy slabs after surface treatment are TiAl alloy.

[0025] Preferably, in step S2, the specific process conditions for vacuum hot pressing are: a vacuum degree of 10... -2 Pa to 1 Pa, heating rate of 5℃ / min to 100℃ / min, hot pressing temperature of 1000℃ to 1200℃, hot pressing time of 0.5h to 3h, and hot pressing pressure of 10MPa to 100MPa.

[0026] Preferably, in step S3, the composite billet is placed in a stainless steel sleeve and welded to obtain a welded part. Then, the welded part is placed in a heating furnace for heat treatment, and then the welded part is placed on a rolling mill for rolling.

[0027] More preferably, the heating treatment involves heating to 1000℃ to 1300℃ at a heating rate of 5℃ / min to 100℃ / min, and holding for 10min to 180min.

[0028] More preferably, the rolling speed is 0.1 m / s to 3 m / s, the deformation per pass is 5% to 25%, the total deformation per pass is 20% to 90%, the reflow temperature per pass is 1000℃ to 1300℃, and the holding time per pass is 2 min to 15 min.

[0029] Further preferred, the rolled material is annealed, specifically by placing the rolled material in a heating furnace at 500℃~800℃ for annealing for 0.5h~24h.

[0030] Preferably, in step S3, the method for removing the casing is a machining method.

[0031] A third aspect of the present invention provides an application of the Ti3Al-TiAl laminated composite material described in the first aspect in the field of aerospace materials.

[0032] The beneficial effects achieved by one or more technical solutions of the present invention are as follows:

[0033] (1) The present invention uses forged Ti3Al alloy and TiAl alloy as raw materials. The matrix material has undergone alloying treatment, which can effectively improve the mechanical properties of the composite material. At the same time, after replacing pure Ti foil or titanium alloy with Ti3Al alloy, the concentration gradient of Al atoms can be effectively reduced, the diffusion rate of Al atoms in TiAl alloy to Ti3Al alloy can be slowed down, thereby suppressing the Kirkendall effect, effectively improving the density of the composite material, and thus improving the mechanical properties of the composite material.

[0034] (2) Vacuum hot pressing can effectively remove oxygen between layers, preventing oxidation or oxide inclusions at the interface of the composite material and improving the interfacial bonding strength. Simultaneously, during the cladding hot rolling process, the rheological stress of Ti3Al alloy is closer to that of TiAl alloy than that of Ti foil or titanium alloy, which is beneficial for coordinated deformation, thereby reducing residual stress in the material, preventing cracking, and improving the mechanical properties of the material. On the other hand, the recrystallization temperature of Ti3Al is higher than that of pure titanium or titanium alloy, resulting in a more stable microstructure. Therefore, during high-temperature rolling, the recrystallization grain growth rate in Ti3Al alloy is lower, resulting in finer grains after rolling, which can effectively improve the strength of the composite material. Finally, the preparation process of this invention is simple, the prepared material has high performance, and it can realize large-scale industrial production of the material.

[0035] (3) The Ti3Al-TiAl laminated composite material obtained by the present invention has dimensions of (200~1000)mm*(80~500)mm*(1~5)mm, a room temperature tensile strength of 900~1100MPa, a room temperature plasticity of 3%~6%, and a fracture toughness of 35MPa·m. 1 / 2 ~50MPa·m 1 / 2 At 800℃, the tensile strength can reach 650-800MPa, the yield strength at 800℃ can reach 600-700MPa, and the plasticity at 800℃ is 20%-30%. Attached Figure Description

[0036] Figure 1 This is a flowchart illustrating the preparation process of the composite material of the present invention;

[0037] Figure 2 The tensile stress-strain curves for Example 1 and Comparative Example 1 at 800℃ are shown, where points A and a represent tensile strength, and points B and b represent yield strength. Detailed Implementation

[0038] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0039] As mentioned above, the currently prepared composite materials have many drawbacks: (1) Due to the Kirkendall effect, the prepared composite materials have low density, which seriously reduces the mechanical properties of the composite materials; (2) The room temperature and high temperature properties of the composite materials prepared by this method are not significantly improved. This is mainly because the composite materials prepared using Ti foil and Al foil as raw materials have not undergone alloying treatment, and the mechanical properties of the matrix material itself are low, so the room temperature and high temperature properties of the material are not significantly improved; (3) Due to the limitations of hot pressing equipment, it is impossible to prepare large-size composite materials that meet the requirements of industrial production, which hinders the further development and application of the material. Therefore, those skilled in the art urgently need to design a composite material with good room temperature plasticity and toughness and high high temperature properties (tensile strength, yield strength, etc.) that can meet the requirements of large-size and mass production.

[0040] The first typical embodiment of the present invention provides a Ti3Al-TiAl laminated composite material, specifically: using forged Ti3Al alloy and forged TiAl alloy as raw materials, vacuum hot pressing and cladding hot rolling are performed to obtain the Ti3Al-TiAl laminated composite material.

[0041] In one or more embodiments of this implementation, the nominal chemical composition of the forged Ti3Al alloy is Ti-(20~25)Al-(0~20)X-(0.1~2)Z(at%), where X is a β-phase stabilizing element and Z is a microalloying element;

[0042] The nominal chemical composition of the forged TiAl alloy is Ti-(40~45)Al-(0.5~10)X-(0.1~2)Z(at%), where X is the β phase stabilizing element and Z is the microalloying element.

[0043] In one or more embodiments of this implementation, the β-phase stabilizing element is selected from one or more of Cr, Mn, V, Mo, Nb, and Fe; the microalloying element is selected from one or more of W, B, and Y.

[0044] A second typical embodiment of the present invention provides a method for preparing the above-mentioned Ti3Al-TiAl laminated composite material, comprising the following steps:

[0045] S1. Cut the forged Ti3Al and forged TiAl alloy to obtain preforms of the two alloys. Then, mechanically grind and polish the preforms to obtain Ti3Al and TiAl alloy slabs.

[0046] S2. Vacuum hot pressing of Ti3Al and TiAl alloy slabs yields composite billet;

[0047] S3. The composite billet is sequentially welded and hot-rolled to obtain a Ti3Al-TiAl laminated composite material with a sheath. After removing the sheath, the Ti3Al-TiAl laminated composite material is obtained.

[0048] In one or more embodiments of this implementation, in step S1, the cutting method is wire cutting; the polishing method is selected from mechanical polishing or electrolytic polishing.

[0049] In one or more embodiments of this implementation, in step S1, the surface roughness of the Ti3Al and TiAl alloy slabs is Ra6 to Ra8.

[0050] In one or more embodiments of this implementation, in step S1, the length of the Ti3Al and TiAl alloy slab is 50mm to 500mm, the width is 50mm to 500mm, and the thickness is 0.5mm to 20mm.

[0051] In one or more embodiments of this implementation, in step S2, the vacuum hot pressing method involves placing the surface-treated Ti3Al and TiAl alloy blanks in a graphite mold, preferably by alternately stacking the Ti3Al and TiAl alloy blanks, with 2n+1 layers, where n is an integer from 1 to 20 for the Ti3Al alloy blanks.

[0052] In one or more embodiments of this implementation, the two sides of the alternately stacked Ti3Al and TiAl alloy slabs after surface treatment are TiAl alloy.

[0053] In one or more embodiments of this implementation, in step S2, the specific process conditions for vacuum hot pressing are: a vacuum degree of 10... -2 Pa to 1 Pa, heating rate of 5℃ / min to 100℃ / min, hot pressing temperature of 1000℃ to 1200℃, hot pressing time of 0.5h to 3h, and hot pressing pressure of 10MPa to 100MPa.

[0054] In one or more embodiments of this implementation, in step S3, the composite billet is placed in a stainless steel sleeve and a welding operation is performed to obtain a welded part. Then, the welded part is placed in a heating furnace for heat treatment, and then the welded part is placed on a rolling mill for rolling.

[0055] In one or more embodiments of this implementation, the heating treatment involves heating to 1000℃ to 1300℃ at a heating rate of 5℃ / min to 100℃ / min, and holding for 10min to 180min.

[0056] In one or more embodiments of this implementation, the rolling speed is 0.1 m / s to 3 m / s, the deformation per pass is 5% to 20%, the total rolling deformation is 20% to 90%, the reflow temperature per pass is 1000℃ to 1300℃, and the holding time per pass is 2 min to 10 min.

[0057] In one or more embodiments of this implementation, the rolled material is annealed, specifically by placing the rolled material in a heating furnace at 500°C to 800°C for annealing for 0.5 to 24 hours.

[0058] In one or more embodiments of this implementation, in step S3, the method for removing the casing is a machining method.

[0059] A third typical embodiment of the present invention provides an application of the above-mentioned Ti3Al-TiAl laminated composite material in the field of aerospace materials.

[0060] This invention proposes a method for preparing Ti3Al-TiAl laminated composite materials using forged Ti3Al alloy and forged TiAl alloy as raw materials via vacuum hot pressing and cladding hot rolling. The main objective is to improve the room temperature ductility and toughness of the TiAl alloy while maintaining its high-temperature performance. During the preparation process, both Ti3Al alloy and TiAl alloy are obtained through melting and forging methods. This alloying treatment of the matrix material effectively improves the mechanical properties of the composite material. Secondly, using Ti3Al and TiAl alloy as raw materials effectively reduces the Al atom concentration gradient, thereby mitigating the Kirkendall effect to some extent and improving the mechanical properties of the composite material. Finally, the vacuum hot pressing and cladding hot rolling methods are suitable for industrial production, meeting the needs of large-size and high-volume production. Simultaneously, the larger rolling force during rolling enhances the bonding strength between the Ti3Al alloy and the TiAl alloy. The dynamic recovery recrystallization process during rolling effectively refines the grains, resulting in fine-grain strengthening and improving the ductility, toughness, and strength of the composite material.

[0061] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are explanations of the present invention and not limitations thereof.

[0062] Example 1 This embodiment provides a Ti3Al-TiAl laminated composite material and its preparation method.

[0063] (1) Sponge titanium, aluminum briquettes, Al-V, Al-Nb, and Al-Y master alloys were selected and used to melt TiAl alloy with a nominal composition of Ti-43Al-9V-0.3Y (at.%) and Ti3Al alloy with a nominal composition of Ti-24Al-15Nb-0.2Y (at.%), respectively, in a vacuum induction levitation melting furnace. The melting vacuum degree was 10. -2 The melting power was 100 kW (2500–2600 °C), and each ingot was melted three times. Two ingots were then sealed with stainless steel for forging. The forging temperature was 1200 °C, the deformation was 80%, and the forging rate was 0.5 m / min. The forged material was annealed at 900 °C for 12 h, followed by furnace cooling to room temperature. The cladding was removed by wire cutting to obtain forged TiAl alloy and forged Ti3Al alloy.

[0064] (2) The forged TiAl alloy and Ti3Al alloy were wire cut, rounded, and polished to obtain a slab with dimensions of 120mm×80mm×2mm, a corner radius of 2mm, and a surface finish of Ra8.

[0065] (3) Three TiAl alloy slabs and two Ti3Al alloy slabs were alternately placed into a graphite mold, with TiAl alloy on both sides. The vacuum furnace was evacuated to 0.1 Pa, and then the furnace temperature was raised to 1100 °C at a heating rate of 50 °C / min. Then, a pressure of 30 MPa was applied to the sample and held for 1 h. After hot pressing, the sample was cooled to room temperature with the furnace to obtain the composite billet.

[0066] (4) The composite blank is welded with 304 stainless steel.

[0067] (5) Place the welded billet into a heating furnace, and then heat the furnace chamber to 1150℃ at a heating rate of 20℃ / min. After holding at this temperature for 30 minutes, place the composite billet onto a rolling mill for rolling. The rolling speed is 0.5 m / min, the deformation per pass is 20%, the total deformation is 80%, the return temperature per pass is 1150℃, and the holding time per pass is 8 minutes. Place the rolled material into a heating furnace at 750℃ and hold for 6 hours, and then cool it to room temperature with the furnace.

[0068] (6) The cladding was removed by machining to obtain a Ti3Al-TiAl laminated composite material with dimensions of 480mm×100mm×2mm.

[0069] Example 2 This embodiment provides a Ti3Al-TiAl laminated composite material and its preparation method.

[0070] (1) Sponge titanium, aluminum briquettes, B4C, Al-Nb, Al-Y, and Al-W master alloys were selected to melt TiAl alloys with nominal compositions of Ti-44Al-8.5Nb-0.2W-0.1B-0.1Y (at.%) and Ti3Al alloys with nominal compositions of Ti-22Al-12Nb-0.2Y (at.%), respectively, in a vacuum induction levitation melting furnace. The melting vacuum degree was 10. -2 The melting power was 100 kW (2500–2600 °C), and each ingot was melted three times. Two ingots were then sealed with stainless steel for forging. The forging temperature for the TiAl alloy was 1250 °C, and for the Ti3Al alloy was 1200 °C. The deformation of both alloys was 80%, and the forging rate was 0.5 m / min. The forged materials were annealed at 900 °C for 12 h, followed by furnace cooling to room temperature. The cladding was removed by wire cutting to obtain forged TiAl and forged Ti3Al alloys.

[0071] (2) The forged TiAl alloy and Ti3Al alloy were wire cut, rounded, and polished to obtain a slab with dimensions of 80mm×60mm×2mm, a corner radius of 2mm, and a surface finish of Ra8.

[0072] (3) Four TiAl alloy slabs and three Ti3Al alloy slabs were alternately placed into a graphite mold, with TiAl alloy on both sides. The vacuum furnace was evacuated to 0.1 Pa, and then the furnace temperature was raised to 1050 °C at a heating rate of 50 °C / min. Then, a pressure of 30 MPa was applied to the sample and held for 1 h. After hot pressing, the sample was cooled to room temperature with the furnace to obtain the composite billet.

[0073] (4) The composite blank is welded with 304 stainless steel.

[0074] (5) Place the welded billet into a heating furnace, and then heat the furnace chamber to 1200℃ at a heating rate of 20℃ / min. After holding at this temperature for 30 minutes, place the composite billet onto a rolling mill for rolling. The rolling speed is 0.5 m / min, the deformation per pass is 15%, the total deformation is 80%, the return temperature per pass is 1200℃, and the holding time per pass is 10 minutes. Place the rolled material into a heating furnace at 800℃ and hold for 6 hours, and then cool it to room temperature with the furnace.

[0075] (6) The cladding was removed by machining to obtain a Ti3Al-TiAl laminated composite material with dimensions of 320mm×80mm×2.5mm.

[0076] Comparative Example 1 This comparative example provides a Ti-TiAl laminated composite material and its preparation method.

[0077] (1) Sponge titanium, aluminum briquettes, Al-V, and Al-Y master alloys were selected to melt TiAl alloys with a nominal composition of Ti-43Al-9V-0.3Y (at.%) and titanium alloys with a nominal composition of Ti-6Al-4V (wt.%), respectively, in a vacuum induction levitation melting furnace. The melting vacuum degree was 10. -2 The melting power was 100 kW (2500–2600 °C), and each ingot was melted three times. Subsequently, the TiAl alloy was forged using a stainless steel cladding. The forging temperature for the TiAl alloy was 1200 °C, and for the titanium alloy was 960 °C. The deformation of both alloys was 80%, and the forging rate was 0.5 m / min. The forged TiAl was annealed at 900 °C for 12 h, and the titanium alloy was annealed at 600 °C for 12 h. After annealing, both materials were cooled to room temperature in the furnace. The cladding was removed using wire cutting to obtain the forged TiAl alloy and the forged titanium alloy.

[0078] (2) The forged TiAl alloy and titanium alloy were wire cut, rounded, and polished to obtain a slab with dimensions of 120mm×80mm×2mm, a corner radius of 2mm, and a surface finish of Ra8.

[0079] (3) Three TiAl alloy slabs and two titanium alloy slabs were alternately placed into a graphite mold, with TiAl alloy on both sides. The vacuum furnace was evacuated to 0.1 Pa, and then the furnace temperature was raised to 1100 °C at a heating rate of 50 °C / min. Then, a pressure of 30 MPa was applied to the sample and held for 1 h. After hot pressing, the sample was cooled to room temperature with the furnace to obtain the composite billet.

[0080] (4) The composite blank is welded with 304 stainless steel.

[0081] (5) Place the welded billet into a heating furnace, and then heat the furnace chamber to 1200℃ at a heating rate of 20℃ / min. After holding at this temperature for 30 minutes, place the composite billet onto a rolling mill for rolling. The rolling speed is 0.5 m / min, the deformation per pass is 20%, the total deformation is 80%, the return temperature per pass is 1200℃, and the holding time per pass is 8 minutes. Place the rolled material into a heating furnace at 700℃ and hold for 6 hours, and then cool it to room temperature with the furnace.

[0082] (6) The cladding was removed by machining to obtain a Ti-TiAl laminated composite material with dimensions of 480mm×100mm×2mm.

[0083] Comparative Example 2 This comparative example provides a Ti-TiAl laminated composite material and its preparation method.

[0084] (1) Sponge titanium, aluminum briquettes, B4C, Al-Nb, Al-V, Al-Y, Al-W, and Al-Y master alloys were selected to melt TiAl alloys with a nominal composition of Ti-44Al-8.5Nb-0.2W-0.1B-0.1Y (at.%) and titanium alloys with a nominal composition of Ti-6Al-4V (wt.%) in a vacuum induction levitation melting furnace. The melting vacuum degree was 10. -2 The melting power was 100 kW (2500–2600 °C), and each ingot was melted three times. Subsequently, the TiAl alloy was forged using a stainless steel cladding. The forging temperature for the TiAl alloy was 1250 °C, and for the titanium alloy was 960 °C. The deformation of both alloys was 80%, and the forging rate was 0.5 m / min. The forged TiAl was annealed at 960 °C for 12 h, and the titanium alloy was annealed at 600 °C for 12 h. After annealing, both materials were cooled to room temperature in the furnace. The cladding was removed using wire cutting to obtain the forged TiAl alloy and the forged titanium alloy.

[0085] (2) The forged TiAl alloy and titanium alloy were wire cut, rounded, and polished to obtain a slab with dimensions of 80mm×60mm×2mm, a corner radius of 2mm, and a surface finish of Ra8.

[0086] (3) Four TiAl alloy slabs and three titanium alloy slabs were alternately placed into a graphite mold, with TiAl alloy on both sides. The vacuum furnace was evacuated to 0.1 Pa, and then the furnace temperature was raised to 1100 °C at a heating rate of 50 °C / min. Then, a pressure of 30 MPa was applied to the sample and held for 1 h. After hot pressing, the sample was cooled to room temperature with the furnace to obtain the composite billet.

[0087] (4) The composite blank is welded with 304 stainless steel.

[0088] (5) Place the welded billet into a heating furnace, and then heat the furnace chamber to 1250℃ at a heating rate of 20℃ / min. After holding at this temperature for 30 minutes, place the composite billet onto a rolling mill for rolling. The rolling speed is 0.5 m / min, the deformation per pass is 15%, the total deformation is 80%, the return temperature per pass is 1250℃, and the holding time per pass is 10 minutes. Place the rolled material into a heating furnace at 750℃ and hold for 6 hours, and then cool it to room temperature with the furnace.

[0089] (6) The cladding was removed by machining to obtain a Ti-TiAl laminated composite material with dimensions of 320mm×80mm×2.5mm.

[0090] Comparative Example 3This comparative example provides a Ti3Al-TiAl laminated composite material and its preparation method.

[0091] (1) Six industrial Ti foils with dimensions of 50mm*50mm*220μm and five industrial Al foils with dimensions of 50mm*50mm*200μm were cleaned with a mixed solution of 10% NaOH and 15% HF to remove oxide scale. Then the oxide scale-removed foils were placed in anhydrous ethanol, ultrasonically cleaned and dried.

[0092] (2) The cleaned Ti foil and Al foil were alternately placed into a hot press furnace for hot pressing composite to obtain the Ti-Al composite material. The hot pressing process parameters were: 500℃ / 60min / 10 -2 Pa.

[0093] (3) The Ti-Al composite material was placed in a hot press furnace for further hot pressing to obtain the Ti-Al3Ti composite material. The hot pressing process parameters were: 1200℃ / 30min / 10 -2 Pa.

[0094] (4) The Ti-Al3Ti composite material was placed in a hot press furnace for densification treatment to obtain a Ti-Al3Ti composite material with high density. The densification process parameters were: 1300℃ / 40MPa / 2h / 10 -2 Pa.

[0095] (5) The densification-treated Ti-Al3Ti composite material was placed in a hot press furnace for a two-step heat treatment, and then cooled to room temperature with the furnace to obtain a Ti3Al-TiAl laminated composite material with dimensions of 50mm*50mm*2.2mm. The process parameters for the two-step heat treatment were: ①1300℃ / 12h / 10 -2 Pa;②1350℃ / 10min / 10 -2 Pa.

[0096] Test Example 1 :

[0097] This experiment tested the relevant properties of the composite materials obtained in Examples 1-2 and Comparative Examples 1-3, as shown in Table 1:

[0098] Table 1

[0099]

[0100] As shown in Table 1, the Ti3Al-TiAl laminated composite material prepared in this invention has a room temperature tensile strength of 900–1100 MPa, a room temperature plasticity of 3%–6%, and a fracture toughness of 35 MPa·m. 1 / 2 ~50MPa·m 1 / 2At 800℃, the tensile strength can reach 650-800MPa, the yield strength at 800℃ can reach 600-700MPa, and the plasticity at 800℃ is 20%-30%.

[0101] Compared to Comparative Examples 1-2, the room temperature tensile strength of Examples 1-2 is close to that of the Comparative Examples, while the room temperature plasticity, fracture toughness, and 800℃ plasticity are slightly lower than those of Comparative Examples 1-2. However, the 800℃ tensile strength and yield strength of Examples 1-2 are much higher than those of Comparative Examples 1-2 (230-300 MPa higher). This shows that after replacing the titanium alloy with the Ti3Al alloy, the bonding mode of Ti atoms and Al atoms changes from solid solution strengthening to covalent bonding, which can effectively improve the interatomic bonding force and elastic modulus, thereby improving the service temperature and strength of the composite material.

[0102] Compared to Comparative Example 3, the performance indicators of Examples 1 and 2 are significantly higher than those of Comparative Example 3. This is because the raw materials in Comparative Example 3 are Ti foil and Al foil, which have not undergone alloying treatment; at the same time, during the hot pressing process, the atomic diffusion rate of Al is relatively fast, and the concentration gradient is relatively large, which easily leads to the formation of pores (Kirkendall effect), reducing the mechanical properties of the composite material. In terms of preparation method, the composite material prepared by encasing hot rolling will improve its interfacial bonding strength under the action of huge rolling force; the matrix material will also undergo dynamic recovery recrystallization during the rolling process, refining the microstructure and improving the mechanical properties of the composite material.

[0103] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A Ti3Al-TiAl laminated composite material, characterized in that, Specifically, using forged Ti3Al alloy and forged TiAl alloy as raw materials, vacuum hot pressing and cladding hot rolling are performed to obtain Ti3Al-TiAl laminated composite material; The nominal chemical composition of the forged Ti3Al alloy is Ti-(20~25)Al-(0~20)X-(0.1~2)Z (at%), and the nominal chemical composition of the forged TiAl alloy is Ti-(40~45)Al-(0.5~10)X-(0.1~2)Z (at%), wherein X is a β-phase stabilizing element and Z is a microalloying element; The β-phase stabilizing element is selected from one or more of Cr, Mn, V, Mo, Nb, and Fe; the microalloying element is selected from one or more of W, B, and Y.

2. A method for preparing the Ti3Al-TiAl laminated composite material according to claim 1, characterized in that, Includes the following steps: S1. Cut the forged Ti3Al and forged TiAl alloy to obtain preforms of the two alloys. Then, mechanically grind and polish the preforms to obtain Ti3Al and TiAl alloy slabs. S2. Vacuum hot pressing of Ti3Al and TiAl alloy slabs yields composite billet; S3. The composite billet is sequentially welded and hot-rolled to obtain a Ti3Al-TiAl laminated composite material with a sheath. After removing the sheath, the Ti3Al-TiAl laminated composite material is obtained.

3. The preparation method according to claim 2, characterized in that, In step S1, the specific preparation method of the forged Ti3Al and forged TiAl alloy is as follows: first, the Ti3Al alloy and TiAl alloy are melted, the ingot obtained by melting is subjected to cladding forging treatment, and then annealed, cooled and the cladding is removed to obtain the alloy. The vacuum degree of the smelting process is 10. -2 Pa~1 Pa, power supply power of 95~105 kW; number of smelting times of 2~4; The forging temperature is 1000~1500℃; the forging speed is 0.2~0.6 m / min; The annealing temperature is 700~950℃; The cutting method is wire cutting; the polishing method is selected from mechanical polishing or electrolytic polishing.

4. The preparation method according to claim 2, characterized in that, In step S1, the surface roughness of the Ti3Al and TiAl alloy slabs is Ra6~Ra8; The Ti3Al and TiAl alloy slabs have a length of 50 mm to 500 mm, a width of 50 mm to 500 mm, and a thickness of 0.5 mm to 20 mm.

5. The preparation method according to claim 2, characterized in that, In step S2, the vacuum hot pressing method involves placing the surface-treated Ti3Al and TiAl alloy slabs in a graphite mold.

6. The preparation method according to claim 5, characterized in that, In step S2, the vacuum hot pressing method involves alternately stacking Ti3Al and TiAl alloy slabs in a graphite mold, with 2n+1 layers, where n is the number of Ti3Al alloy slab layers and is an integer from 1 to 20.

7. The preparation method according to claim 5, characterized in that, The Ti3Al and TiAl alloy slabs after surface treatment are stacked alternately on both sides, with TiAl alloy on both sides.

8. The preparation method according to claim 2, characterized in that, In step S2, the specific process conditions for vacuum hot pressing are: a vacuum degree of 10... -2 Pa~1 Pa, heating rate of 5℃ / min~100℃ / min, hot pressing temperature of 1000℃~1200℃, hot pressing time of 0.5 h~3 h, and hot pressing pressure of 10 MPa~100 MPa.

9. The preparation method according to claim 2, characterized in that, In step S3, the composite billet is placed in a stainless steel sleeve and welded to obtain a welded part. The welded part is then placed in a heating furnace for heat treatment, and subsequently placed on a rolling mill for rolling.

10. The preparation method according to claim 9, characterized in that, The heating treatment involves heating to 1000℃~1300℃ at a heating rate of 5℃ / min~100℃ / min, and holding for 10 min~180 min.

11. The preparation method according to claim 9, characterized in that, The rolling speed is 0.1 m / s to 3 m / s, the deformation per pass is 5% to 25%, the total deformation per pass is 20% to 90%, the reflow temperature per pass is 1000℃ to 1300℃, and the holding time per pass is 2 min to 15 min.

12. The preparation method according to claim 9, characterized in that, The rolled material is then annealed, specifically by placing it in a heating furnace at 500℃~800℃ for 0.5 h~24 h.

13. The preparation method according to claim 2, characterized in that, In step S3, the method for removing the casing is a machining method.

14. The application of the Ti3Al-TiAl laminated composite material according to claim 1 in the field of aerospace materials.

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