In-situ synthesized layered Ti-Ti3Al composite material and preparation method thereof

Abstract

The application provides a preparation method of in-situ synthesized Ti-Ti3Al composite material with a layered structure. First, titanium sheets and aluminum sheets are prepared according to a certain titanium-aluminum molar ratio, and the two are alternately stacked to obtain a laminated blank; second, the laminated blank is rolled for several passes at room temperature to obtain an intermediate material; third, the intermediate material is constrained and compacted to obtain a bulk material; then, the bulk material is subjected to pre-rolling, high-temperature annealing and hot rolling to obtain the final Ti-Ti3Al composite material with a layered structure. The application utilizes the rolling composite and in-situ reaction composite synergistic technology, the used equipment is common equipment, the preparation process has good operability, the product has a soft-hard zone layered structure, has high hardness and strong toughness, and has a good application prospect in the field of lightweight high-strength structures.

Description

Technical Field

[0001] This invention belongs to the technical field of composite material preparation, specifically relating to an in-situ synthesized layered Ti-Ti3Al composite material and its preparation method. Background Technology

[0002] Metal matrix composites refer to composite materials prepared using continuous long fibers, short fibers, whiskers, and particles as reinforcing materials, and metals (such as aluminum, magnesium, titanium, nickel, iron, copper, cobalt, etc.) or their alloys as matrix materials through appropriate processes. Composite materials can effectively leverage the advantages of both the matrix and the reinforcing phase, effectively improving the toughness of the material without sacrificing too much strength, and possessing excellent mechanical properties.

[0003] Titanium is an important structural metal with low density, high strength, excellent high-temperature resistance, and corrosion resistance, making it widely used in numerous fields, including aerospace, military equipment, petrochemicals, biomedicine, and automobile manufacturing. However, traditional titanium alloys have reached their performance limits and are unable to meet higher performance requirements. Therefore, introducing reinforcing phases into the titanium matrix to prepare high-performance titanium-based composite materials has become a research hotspot.

[0004] Titanium-based composite materials have higher strength and stiffness, and better wear resistance and heat resistance than titanium alloys. They overcome the shortcomings of traditional titanium alloys, such as low strength and hardness, poor wear resistance, and insufficient elastic modulus. They can also serve normally under harsh conditions such as high temperature, high pressure, strong acid, and strong alkali. They are considered to be a new generation of structural materials that improve the performance of titanium materials and expand the application of titanium materials.

[0005] Currently, the main methods for preparing titanium-based composite materials include casting, powder metallurgy, and 3D printing. However, these processes often face two major challenges: first, how to improve the wettability between the reinforcement and the matrix to enhance their bonding effect; and second, the amount (volume fraction) of reinforcement added to the composite material is limited. Excessive reinforcement can easily lead to problems such as "agglomeration," "interfacial non-wetting," and "defects" in the matrix, resulting in internal defects in the prepared composite material and severely reducing its overall performance.

[0006] Based on this, a novel method for preparing titanium-based composite materials is proposed. By rationally adjusting and optimizing the microstructure, the shortcomings of titanium alloys in tensile plasticity and fracture toughness can be compensated to a certain extent, which is an urgent technical problem to be solved. Summary of the Invention

[0007] One of the objectives of this invention is to provide a method for preparing an in-situ synthesized layered Ti-Ti3Al composite material that exhibits a better balance of strength and toughness, while maintaining high strength and high elongation.

[0008] The second objective of this invention is to provide an in-situ synthesized layered Ti-Ti3Al composite material with better balance of strength and toughness, which maintains high strength while also having a high elongation.

[0009] One of the technical solutions adopted by this invention to achieve its objective is to provide a method for preparing an in-situ synthesized layered Ti-Ti3Al composite material, comprising the following steps:

[0010] S1. Prepare several titanium sheets and aluminum sheets according to a titanium-aluminum molar ratio of (4-8):1. Place the aluminum sheets between the titanium sheets to obtain a laminated blank.

[0011] S2. The laminated billet is rolled several times at room temperature to obtain intermediate material;

[0012] S3. The intermediate material is constrained and compacted to obtain a block material;

[0013] S4. The bulk material is pre-hot rolled, and then subjected to high-temperature annealing and hot rolling cycles several times to obtain the final Ti-Ti3Al composite material with a layered structure.

[0014] The general idea of ​​the in-situ synthesis method for preparing layered Ti-Ti3Al composite materials provided by this invention is as follows:

[0015] This invention addresses the problems of poor wettability between the reinforcement and the matrix and limited reinforcement volume in the preparation of titanium-based composite materials. It provides a method for preparing layered Ti-Ti3Al composite materials through in-situ synthesis. In the preparation process of this composite material: on the one hand, based on the dispersion effect of cumulative rolling and the characteristics of the titanium-aluminum diffusion reaction, the Ti-Ti3Al composite material is prepared in situ, effectively solving the problem of wettability between the reinforcement and the matrix; on the other hand, by controlling the initial titanium and aluminum ratio, the ratio of Ti and Ti3Al in the composite material is controlled, overcoming the problem of limited reinforcement volume in traditional composite material preparation processes, and effectively improving the overall performance of the composite material.

[0016] In this invention, the molar ratio of titanium to aluminum directly affects the ratio of Ti and Ti3Al in the product. In this composite material, Ti3Al acts as a reinforcement, and Ti acts as the matrix. Different ratios of the two lead to differences in the strength and toughness of the composite material. When the amount of titanium is low, there is not enough Ti as a matrix, and the product is mainly a Ti3Al compound, which only retains the brittleness of the Ti3Al compound. When the amount of titanium is high, although the elongation of the composite material can be further improved, the tensile strength will also decrease because the volume ratio of the reinforcement Ti3Al is relatively reduced. In addition, the proportion of Ti3Al reinforcement in the composite material should not be too high. Too high a content of Ti3Al will lead to insufficient toughness of the composite material, resulting in premature fracture during tensile testing. Extensive research has found that controlling the molar ratio of titanium to aluminum to be (4-8):1 in this invention can achieve a balance between the strength and toughness of the composite material, so that the prepared titanium-based composite material has high elongation while maintaining high strength. Preferably, the molar ratio of titanium to aluminum is (5-7):1.

[0017] Furthermore, in step S4, employing appropriate methods to perform high-temperature diffusion and heat treatment on the bulk material is also an important condition to ensure that Al is depleted and the reaction continues to generate the Ti3Al reinforcement product. In this invention, a cycle of pre-hot rolling, high-temperature annealing, and hot rolling is used. Pre-hot rolling can achieve a good pre-compacting effect, giving the bulk material a certain density and effectively preventing oxidation of the material during the subsequent high-temperature diffusion reaction. Then, high-temperature annealing and hot rolling are combined to improve the densification of the bulk material while obtaining the Ti-Ti3Al layered composite material, thereby further optimizing the mechanical properties.

[0018] Preferably, in step S1, the titanium sheet and the aluminum sheet are rectangular, and their length and width are the same.

[0019] Furthermore, in step S1, aluminum sheets are interlaced between titanium sheets, resulting in a laminated blank with titanium sheets as the outer layer and the inner titanium and aluminum sheets placed as alternately as possible.

[0020] Furthermore, before the titanium and aluminum sheets are stacked, they are pretreated, including sanding off the oxide layer on the surface of each metal sheet and cleaning it.

[0021] Furthermore, in step S2, the room temperature rolling passes are 30 to 40, and in each rolling pass, the sample is reduced by 40% to 60% of its thickness.

[0022] Furthermore, in step S2, during the room temperature rolling process, after each rolling pass, the metal sheet is folded in half along the rolling direction before proceeding to the next rolling pass.

[0023] During room temperature rolling, under the immense pressure of the rolling mill, the metal material undergoes intense plastic deformation. As the number of rolling passes increases, the contact area between the titanium and aluminum layers gradually increases, while the interlayer spacing gradually decreases. When the number of rolling passes is sufficiently high, the titanium and aluminum exist in a layered, dispersed state. Preferably, rolling is performed using an industrial rolling mill, with the rolling speed controlled at 100–300 mm / min.

[0024] Furthermore, in step S3, the intermediate material is constrained and fixed using a copper tube. Copper has excellent ductility and will not crack during compaction. Titanium foil is used to isolate the inner wall of the copper tube from the intermediate material. This step uses titanium foil to isolate the intermediate material from the copper tube, preventing the edge copper from diffusing inward and avoiding a reaction between the titanium in the intermediate material and the copper tube at high temperatures. Preferably, the compaction operation in step S3 is performed using a hydraulic press.

[0025] Further, in step S4, the pre-hot rolling temperature is 550–650°C, and the deformation is 20%–40%. The deformation refers to the amount of reduction of the block material along the rolling direction during the pre-hot rolling process. In this invention, the block material is pre-rolled at 550–650°C, and the pre-rolling temperature is close to the melting point of aluminum, which can achieve a good pre-compacting effect.

[0026] Furthermore, in step S4, the conditions of the high-temperature annealing treatment are crucial factors in ensuring sufficient reaction of Ti-Al, depletion of Al, and generation of adequate Ti3Al reinforcement. Preferably, the high-temperature annealing temperature is 850–950°C. Furthermore, the high-temperature annealing time should not be too long to avoid increasing the diffusion distance of Al, causing the sample to become homogenized, and thus failing to maintain the layered structure. Preferably, the high-temperature annealing time is 1–1.5 hours.

[0027] In this invention, the preparation method of pre-hot rolling, high-temperature annealing and hot rolling in step S4 does not require limiting the protective atmosphere conditions. The heating treatment can be completed using a muffle furnace. The preparation process is simple and the required time is shorter.

[0028] Furthermore, in step S4, the number of cycles of high-temperature annealing and hot rolling is 2 to 3, and the total deformation is 60% to 65%. The total deformation refers to the total reduction of the block material along the rolling direction during the cycle of high-temperature annealing and hot rolling.

[0029] In steps S3 and S4 of the present invention, the intermediate material constrained and fixed by the copper tube is first compacted to obtain a bulk material. After a period of high-temperature diffusion reaction and hot rolling deformation densification, the bulk material is completely consumed and forms a Ti3Al intermetallic compound. At this time, the alloy still retains an excess of Ti, and then the Ti-Ti3Al composite material with a layered structure is synthesized in situ.

[0030] The second objective of this invention is to provide an in-situ synthesized layered Ti-Ti3Al composite material prepared by the preparation method described in the first objective of this invention.

[0031] Furthermore, in the layered Ti-Ti3Al composite material, Ti is the matrix and Ti3Al is the reinforcement; the volume fraction of Ti3Al in the layered Ti-Ti3Al composite material is 43% to 79%, preferably 50% to 67%.

[0032] In some preferred embodiments, the layered Ti-Ti3Al composite material has a tensile strength of 1058–1077 MPa, an elongation of 11.8%–12.5%, and a hardness of 356.4–359.3 HV0.5 at room temperature.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] (1) The present invention provides a method for preparing an in-situ synthesized layered Ti-Ti3Al composite material. Based on the characteristics of Ti-Al diffusion reaction, the method controls the formation of alloy products by adjusting the ratio of titanium and aluminum raw materials, reaction temperature and reaction time, so as to realize the in-situ synthesis of Ti-Ti3Al layered composite material.

[0035] (2) The present invention provides a method for preparing an in-situ synthesized layered Ti-Ti3Al composite material. The initial titanium and aluminum sheets are thinned and dispersed by a cumulative rolling process, so that Ti and Al exist in a layered dispersion form under room temperature rolling conditions. This is beneficial to the formation of non-uniform layered structure materials. The presence of a large number of phase interfaces in this structure can improve the strength of the composite material. Moreover, under stress, it can give full play to the advantages of its two-phase materials and achieve the coordination of strength and toughness.

[0036] (3) The in-situ synthesized layered Ti-Ti3Al composite material obtained by the present invention can overcome the problems of low volume fraction of reinforcement, poor dispersion, poor wettability and weak bonding interface strength in conventional titanium-based composite materials. The present invention utilizes the synergistic technology of rolling composite and in-situ reaction composite, and the equipment used is common equipment. The preparation process is easy to operate, and the product has a layered structure with soft and hard regions. It has high hardness and toughness and has good application prospects in the field of lightweight and high-strength structures. Attached Figure Description

[0037] Figure 1 This is an optical micrograph of the layered Ti-Ti3Al composite material obtained in Example 1 of this invention;

[0038] Figure 2 This is an optical micrograph of the layered Ti-Ti3Al composite material obtained in Example 2 of the present invention. Detailed Implementation

[0039] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0041] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0042] Example 1

[0043] (1) Cut aluminum and titanium sheets to size 100×50×0.2mm, sand the oxide layer on the surface and clean them. Take two aluminum sheets and weigh them. Then take titanium sheets according to a titanium-aluminum ratio of 7:1 molar mass. Stack the titanium and aluminum sheets as staggered as possible and place the aluminum sheets between the titanium sheets to obtain a laminated blank.

[0044] (2) Wrap the laminated billet obtained in step (1) in a steel sheet and roll it using an industrial rolling mill. After each rolling pass, fold the metal sheet in half along the rolling direction and then roll it again. Repeat the folding-rolling process until 40 passes. The thickness reduction of the sample in each rolling pass is about 50%, generally maintained at 40% to 60%, to obtain intermediate material.

[0045] (3) Take a small section of copper tube and attach a small piece of titanium foil to the inner wall of the copper tube to separate the material to be filled from the copper tube. Fill the copper tube with the intermediate material obtained in step (2) and press it under a hydraulic press to obtain a block material.

[0046] (4) The bulk material obtained in step (3) is placed in a muffle furnace and kept at 600°C for 10 minutes. It is then taken out and hot rolled immediately to obtain a relatively dense material that has not completed the diffusion reaction. During the pre-hot rolling process, the reduction along the rolling direction of the bulk material is about 30%.

[0047] (5) The material obtained in step (4) is placed in a muffle furnace and kept at 900°C for 1 hour. Then it is taken out and hot rolled immediately. The high-temperature diffusion reaction and hot rolling are repeated once, keeping the material at 900°C for 1 hour. The cumulative reduction of the composite material is about 65%.

[0048] Figure 1 The image shown is a light microscope photograph of the material in Embodiment 1 of the present invention, such as... Figure 1 As shown, after undergoing 40 passes of room temperature rolling, 600℃ rolling densification, and 900℃ high-temperature diffusion reaction and densification, the material maintains its non-uniform layered structure. At the same time, the composite material contains two phases of Ti and Ti3Al, and the volume fraction of the reinforcement Ti3Al in the layered material is about 50%.

[0049] According to the test results, the Ti-Ti3Al composite material with layered structure prepared in this embodiment has a tensile strength of 1058 MPa, an elongation of 12.5%, and a hardness of 356.4 HV0.5 at room temperature.

[0050] Example 2

[0051] (1) Cut aluminum and titanium sheets to size 100×50×0.2mm, sand the oxide layer on the surface and clean them. Take two aluminum sheets and weigh them. Then take titanium sheets according to a titanium-aluminum ratio of 7:1 molar mass. Stack the titanium and aluminum sheets as staggered as possible and place the aluminum sheets between the titanium sheets to obtain a laminated blank.

[0052] (2) Wrap the laminated billet obtained in step (1) in a steel sheet and roll it using an industrial rolling mill. After each rolling pass, fold the metal sheet in half along the rolling direction and then roll it again. Repeat the folding-rolling process until 30 passes. The thickness reduction of the sample rolled in each pass is about 50%, generally maintained at 40% to 60%. An intermediate material is obtained.

[0053] (3) Take a small section of copper tube and attach a small piece of titanium foil to the inner wall of the copper tube to separate the material to be filled from the copper tube. Fill the copper tube with the intermediate material obtained in step (2) and press it under a hydraulic press to obtain a block material.

[0054] (4) The bulk material obtained in step (3) is placed in a muffle furnace and kept at 600°C for 10 minutes. It is then taken out and hot rolled immediately to obtain a relatively dense material that has not completed the diffusion reaction. During the pre-hot rolling process, the reduction along the rolling direction of the bulk material is about 30%.

[0055] (5) The material obtained in step (4) is placed in a muffle furnace and kept at 900°C for 1 hour. Then it is taken out and hot rolled immediately. The high-temperature diffusion reaction and hot rolling are repeated once, keeping the material at 900°C for 1 hour. The cumulative reduction of the composite material is about 60%.

[0056] Figure 2 The image shown is a light micrograph of the material in Example 2 of this invention. The composite material prepared in this example maintains its non-uniform layered structure and contains two phases of Ti and Ti3Al. The volume fraction of the reinforcing Ti3Al in the layered material is about 50%.

[0057] According to the test results, the Ti-Ti3Al composite material with layered structure prepared in this embodiment has a tensile strength of 1077 MPa, an elongation of 11.8%, and a hardness of 359.3 HV0.5 at room temperature.

[0058] Example 3

[0059] (1) Cut aluminum and titanium sheets to size 100×50×0.2mm, sand the oxide layer on the surface and clean them. Take two aluminum sheets and weigh them. Then take titanium sheets according to a titanium-aluminum ratio of 4:1 molar mass. Stack the titanium and aluminum sheets as staggered as possible and place the aluminum sheets between the titanium sheets to obtain a laminated blank.

[0060] (2) Wrap the laminated billet obtained in step (1) in a steel sheet and roll it using an industrial rolling mill. After each rolling pass, fold the metal sheet in half along the rolling direction and then roll it again. Repeat the folding-rolling process until 40 passes. The thickness reduction of the sample rolled in each pass is about 50%, generally maintained at 40% to 60%. An intermediate material is obtained.

[0061] (3) Take a small section of copper tube and attach a small piece of titanium foil to the inner wall of the copper tube to separate the material to be filled from the copper tube. Fill the copper tube with the intermediate material obtained in step (2) and press it under a hydraulic press to obtain a block material.

[0062] (4) The bulk material obtained in step (3) is placed in a muffle furnace and kept at 550°C for 10 minutes. It is then taken out and hot rolled immediately to obtain a relatively dense material that has not completed the diffusion reaction. During the pre-hot rolling process, the reduction along the rolling direction of the bulk material is about 25%.

[0063] (5) The material obtained in step (4) is placed in a muffle furnace and kept at 850°C for 1.5 hours. It is then taken out and hot rolled immediately. It is then placed in a muffle furnace and kept at 850°C for 1 hour to carry out a high-temperature diffusion reaction. It is then taken out and hot rolled once to make the cumulative reduction of the composite material about 60%.

[0064] The composite material prepared in this embodiment maintains its non-uniform layered structure, and contains a two-phase structure of Ti and Ti3Al, with the volume fraction of the reinforcing Ti3Al in the layered material being approximately 79%.

[0065] Example 4

[0066] (1) Cut aluminum and titanium sheets to size 100×50×0.2mm, sand the oxide layer on the surface and clean them. Take two aluminum sheets and weigh them. Then take titanium sheets according to a titanium-aluminum ratio of 8:1 molar mass. Stack the titanium and aluminum sheets as staggered as possible and place the aluminum sheets between the titanium sheets to obtain a laminated blank.

[0067] (2) Wrap the laminated billet obtained in step (1) in a steel sheet and roll it using an industrial rolling mill. After each rolling pass, fold the metal sheet in half along the rolling direction and then roll it again. Repeat the folding-rolling process until 35 passes. The thickness reduction of the sample in each rolling pass is about 50%, generally maintained at 40% to 60%, to obtain intermediate material.

[0068] (3) Take a small section of copper tube and attach a small piece of titanium foil to the inner wall of the copper tube to separate the material to be filled from the copper tube. Fill the copper tube with the intermediate material obtained in step (2) and press it under a hydraulic press to obtain a block material.

[0069] (4) The bulk material obtained in step (3) is placed in a muffle furnace and kept at 650°C for 10 minutes. It is then taken out and hot rolled immediately to obtain a relatively dense material that has not completed the diffusion reaction. During the pre-hot rolling process, the reduction along the rolling direction of the bulk material is about 35%.

[0070] (5) The material obtained in step (4) is placed in a muffle furnace and kept at 900°C for 1 hour. It is then taken out and hot rolled immediately. It is then placed in a muffle furnace and kept at 850°C for 1 hour to carry out a high-temperature diffusion reaction. It is then taken out and hot rolled once to make the cumulative reduction of the composite material about 60%.

[0071] The composite material prepared in this embodiment maintains its non-uniform layered structure, and contains a two-phase structure of Ti and Ti3Al, with the volume fraction of the reinforcing Ti3Al in the layered material being approximately 43%.

[0072] Comparative Example 1

[0073] (1) Cut aluminum and titanium sheets to size 100×50×0.2mm, sand the oxide layer on the surface and clean them. Take two aluminum sheets and weigh them. Then take titanium sheets according to a titanium-aluminum ratio of 3:1 molar mass. Stack the titanium and aluminum sheets as staggered as possible and place the aluminum sheets between the titanium sheets to obtain a laminated blank.

[0074] (2) Wrap the laminated billet obtained in step (1) in a steel sheet and roll it using an industrial rolling mill. After each rolling pass, fold the metal sheet in half along the rolling direction and then roll it again. Repeat the folding-rolling process until 30 passes. The thickness reduction of the sample in each rolling pass is about 50%, generally maintained at 40% to 60%, to obtain intermediate material.

[0075] (3) Take a small section of copper tube and attach a small piece of titanium foil to the inner wall of the copper tube to separate the material to be filled from the copper tube. Fill the copper tube with the intermediate material obtained in step (2) and press it under a hydraulic press to obtain a block material.

[0076] (4) Place the block material obtained in step (3) into a muffle furnace, keep it at 700°C for 30 minutes, and immediately take it out for hot rolling. Repeat the hot rolling step 3-4 times.

[0077] The material broke during the wire cutting process, meaning the resulting material was almost entirely a Ti-Al compound, making the sample extremely brittle and unable to be shaped.

[0078] Comparative Example 2

[0079] (1) Cut aluminum and titanium sheets to size 100×50×0.2mm, sand the oxide layer on the surface and clean them. Take two aluminum sheets and weigh them. Then take titanium sheets according to the molar mass ratio of 11:1. Stack the titanium and aluminum sheets as staggered as possible, and place the aluminum sheets between the titanium sheets to obtain the laminated blank.

[0080] (2) Wrap the laminated billet obtained in step (1) in a steel sheet and roll it using an industrial rolling mill. After each rolling pass, fold the metal sheet in half along the rolling direction and then roll it again. Repeat the folding-rolling process until 30 passes. The thickness reduction of the sample in each rolling pass is about 50%, generally maintained at 40% to 60%, to obtain intermediate material.

[0081] (3) Take a small section of copper tube and attach a small piece of titanium foil to the inner wall of the copper tube to separate the material to be filled from the copper tube. Fill the copper tube with the intermediate material obtained in step (2) and press it under a hydraulic press to obtain a block material.

[0082] (4) The bulk material obtained in step (3) is placed in a muffle furnace and kept at 600°C for 10 minutes. It is then taken out and hot rolled immediately to obtain a relatively dense material that has not completed the diffusion reaction.

[0083] (5) Place the material obtained in step (4) into a muffle furnace, keep it at 900°C for 1 hour, and immediately take it out for hot rolling. Then repeat the process of keeping it at 900°C for 1 hour and hot rolling once, so that the cumulative reduction of the composite material is about 60%.

[0084] Light micrographs show that the composite material prepared in this comparative example has lost its layered structure, and the degree of heterogeneity has been greatly reduced, so it can no longer achieve the design concept of a layered structure.

[0085] Comparative Example 3

[0086] (1) Cut aluminum and titanium sheets to size 100×50×0.2mm, sand the oxide layer on the surface and clean them. Take two aluminum sheets and weigh them. Then take titanium sheets according to a titanium-aluminum ratio of 7:1 molar mass. Stack the titanium and aluminum sheets as staggered as possible and place the aluminum sheets between the titanium sheets to obtain a laminated blank.

[0087] (2) Wrap the laminated billet obtained in step (1) in a steel sheet and roll it using an industrial rolling mill. After each rolling pass, fold the metal sheet in half along the rolling direction and then roll it again. Repeat the folding-rolling process until 20 passes. The thickness reduction of the sample in each rolling pass is about 50%, generally maintained at 40% to 60%, to obtain intermediate material.

[0088] (3) Take a small section of copper tube and attach a small piece of titanium foil to the inner wall of the copper tube to separate the material to be filled from the copper tube. Fill the copper tube with the intermediate material obtained in step (2) and press it under a hydraulic press to obtain a block material.

[0089] (4) The bulk material obtained in step (3) is placed in a muffle furnace and kept at 600°C for 10 minutes. It is then taken out and hot rolled immediately to obtain a relatively dense material that has not completed the diffusion reaction. During the pre-hot rolling process, the reduction along the rolling direction of the bulk material is about 30%.

[0090] (5) The material obtained in step (4) is placed in a muffle furnace and kept at 900°C for 1 hour. Then, it is immediately taken out and hot rolled. The high-temperature diffusion reaction process is repeated once to make the cumulative reduction of the composite material about 55%.

[0091] Light micrographs show that the composite material prepared in this comparative example does not exhibit a layered structure, and the sample has many defects such as pores and cracks, with a tensile strength of less than 100 MPa.

[0092] Comparative Example 4

[0093] (1) Cut aluminum and titanium sheets to size 100×50×0.2mm, sand the oxide layer on the surface and clean them. Take two aluminum sheets and weigh them. Then take titanium sheets according to a titanium-aluminum ratio of 5:1 molar mass. Stack the titanium and aluminum sheets as staggered as possible and place the aluminum sheets between the titanium sheets to obtain a laminated blank.

[0094] (2) Wrap the laminated billet obtained in step (1) in a steel sheet and roll it using an industrial rolling mill. After each rolling pass, fold the metal sheet in half along the rolling direction and then roll it again. Repeat the folding-rolling process until 30 passes. The thickness reduction of the sample in each rolling pass is about 50%, generally maintained at 40% to 60%, to obtain intermediate material.

[0095] (3) Take a small section of copper tube and attach a small piece of titanium foil to the inner wall of the copper tube to separate the material to be filled from the copper tube. Fill the copper tube with the intermediate material obtained in step (2) and press it under a hydraulic press to obtain a block material.

[0096] (4) The bulk material obtained in step (3) is placed in a tube furnace, and the temperature is increased from room temperature to 900°C at a rate of 5°C / min and held for 2 hours to allow the Ti and Al, which have been dispersed by room temperature rolling, to undergo a full diffusion reaction. Then, the material is cooled to room temperature with the furnace to generate a Ti-Ti3Al composite material with Ti3Al intermetallic compound as the reinforcement and excess Ti as the matrix. At this point, due to the Ti-Al diffusion reaction, there are a large number of pores and gaps in the material. This step is carried out in an argon atmosphere throughout to protect it from oxidation.

[0097] (5) The material obtained in step (4) after high temperature diffusion reaction is placed in a muffle furnace at 900°C and kept for 10 minutes. Then it is immediately taken out and hot rolled to eliminate defects such as pores in the alloy. Repeat the holding-rolling cycle 3 times and the cumulative thickness reduction is about 65%.

[0098] Tests showed that the Ti-Ti3Al composite material with a layered structure prepared in this comparative example had a tensile strength of 497 MPa, an elongation of 5.4%, and a hardness of 418.8 HV0.5 at room temperature.

[0099] Based on the above embodiments and comparative examples, it can be seen that:

[0100] In Examples 1 and 2, the molar ratio of titanium to aluminum in the raw materials was controlled to be 7:1 (the volume ratio of Ti to Ti3Al in the composite material was approximately 1:1), and a preparation scheme of pre-hot rolling, high-temperature annealing, and hot rolling was adopted. The resulting composite material had a tensile strength of 1058–1077 MPa, an elongation of 11.8%–12.5%, and a hardness of 356.4–359.3 HV0.5. The product exhibited a layered structure with soft and hard zones, and possessed high hardness and toughness.

[0101] Compared with the examples, Comparative Examples 1 and 2 adjusted the molar ratio of titanium to aluminum to 3:1 and 11:1, respectively, to prepare composite materials. The experimental results show that when the titanium content is low, the resulting material is almost a Ti-Al compound, the sample is extremely brittle and cannot be formed; while when the titanium content is high, the composite material loses its layered structure, the degree of heterogeneity is greatly reduced, and the expected layered structure cannot be obtained.

[0102] Comparative Example 3 reduced the number of rolling passes during room temperature rolling, and the resulting composite material did not exhibit a layered structure, and the sample contained defects such as pores and cracks. This indicates that in this invention, sufficient rolling passes can ensure that titanium and aluminum exist in a layered dispersion state, and partial solid solution and reaction occur in the formed intermediate material, ultimately resulting in an improvement in the overall mechanical properties of the composite layered material.

[0103] In Comparative Example 4, steps (4) and (5) employed a different preparation method than those in Examples 1 and 2. This comparative example first placed the bulk material in a tube furnace for diffusion reaction, then maintained it at a high temperature in a muffle furnace to eliminate defects before hot rolling. This preparation method is more complex and time-consuming than the examples, and requires a protective atmosphere. The final composite material had a tensile strength of 497 MPa and an elongation of 5.4%, significantly lower than the samples obtained in Examples 1 and 2. This indicates that the pre-rolling + high-temperature annealing + hot rolling scheme in this invention not only has advantages such as simple process, easy operation, and short time, but also plays a crucial role in generating sufficient Ti3Al reinforcement, reducing internal defects in the product, and improving the overall performance of the composite material.

[0104] In summary, by optimizing and adjusting the ratio of titanium and aluminum in the raw materials and selecting appropriate high-temperature diffusion reaction and hot rolling densification treatment methods, the strength and toughness of the composite material can be further coordinated, so that the prepared layered composite material can maintain high strength while also having higher elongation.

[0105] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the content of this specification should be included within the protection scope of the present invention.

Claims

1. An in-situ synthesized layered Ti-Ti3AI composite material, characterized in that, In the layered Ti-Ti3Al composite material, Ti is the matrix and Ti3Al is the reinforcement; the volume fraction of the reinforcement Ti3Al in the layered Ti-Ti3Al composite material is 43%~79%. The preparation method of the layered Ti-Ti3Al composite material includes the following steps: S1. Prepare several titanium sheets and aluminum sheets according to a titanium-aluminum molar ratio of (4~8):

1. Place the aluminum sheets between the titanium sheets to obtain a laminated blank. S2. The laminated billet is rolled at room temperature for 30 to 40 passes to obtain intermediate material; in each rolling pass, the reduction of the sample is 40% to 60% of its thickness; S3. The intermediate material is constrained and compacted to obtain a block material; S4. The block material is pre-hot rolled at a temperature of 550~650℃ and the deformation is 20%~40%; then it is subjected to high-temperature annealing and hot rolling cycles 2~3 times, with a total deformation of 60%~65%, to obtain the final Ti-Ti3Al composite material with a layered structure.

2. The laminated Ti-Ti3Al composite material according to claim 1, characterized by In step S1, the titanium sheet and the aluminum sheet are rectangular, and their length and width are the same.

3. The laminated Ti-Ti3Al composite material of claim 1, wherein In step S2, during room temperature rolling, after each rolling pass, the metal sheet is folded in half along the rolling direction before the next rolling pass is performed.

4. The layered Ti-Ti3Al composite material according to claim 1, characterized in that, In step S3, the intermediate material is constrained and fixed using a copper tube, and titanium foil is used to isolate the inner wall of the copper tube from the intermediate material.

5. The layered Ti-Ti3Al composite material according to claim 1, characterized in that, In step S4, the high-temperature annealing treatment is performed at a temperature of 850~950℃ for 1~1.5h; the hot rolling treatment is performed at a temperature of 700~900℃.

6. The layered Ti-Ti3Al composite material according to claim 1, characterized in that, The layered Ti-Ti3Al composite material has a tensile strength of 1058~1077MPa, an elongation of 11.8%~12.5%, and a hardness of 356.4~359.3HV0.5 at room temperature.

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