A method for cold spray additive- hot press isometric machining quasi-continuous net-shaped reinforced titanium matrix composite thin-walled structure

Abstract

The application belongs to the technical field of titanium-based thin-walled component processing, and discloses a method for processing high-temperature-resistant titanium-based thin-walled components by cold spraying additive-thermal pressing equal-material processing. The method mainly utilizes a cold spraying method to prepare a titanium-based layered gradient structure preform blank, and combines a subsequent equal-material process to realize the processing of high-performance and high-temperature-resistant titanium-based thin-walled components. The processing and preparation process comprises the following steps: determining the component content of titanium-based composite powder; preparing the composite powder; cold spraying additive printing out a layered gradient preformed thin-walled blank; and reaction hot pressing forming-a high-temperature-resistant thin-walled component. The method can realize the high production efficiency, low cost and high performance of the manufacturing of high-temperature-resistant layered gradient titanium-based composite materials or titanium-aluminum intermetallic compound thin-walled components; can realize the processing and preparation of high-temperature-resistant thin-walled components with a service temperature of up to 800 DEG C according to the target service temperature requirement, and can realize the customization of service performance according to the required mechanical performance requirement of the components.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium-based thin-walled component processing, and discloses a method for processing high-temperature resistant titanium-based thin-walled components by cold spraying, material addition, hot pressing, etc. Background Art

[0002] With the rapid development of aerospace technology, the cruising speed of aircraft has been continuously improved, which has also put forward higher requirements on the service temperature of thin-walled components in high-speed aircraft. Due to the heat caused by friction or heat transfer, the surface temperature can reach 800°C. The performance of traditional titanium alloys (service temperature <600°C) based on the addition of alloying elements to achieve strengthening can no longer meet the higher performance requirements of materials in the aerospace field. The use of titanium-based composite materials or titanium-aluminum intermetallic compounds to process these thin-walled parts can achieve a service temperature of 800°C. In addition to excellent high-temperature resistance, titanium-based composite materials and titanium-aluminum intermetallic compounds have higher specific stiffness, specific strength and oxidation resistance than titanium alloys, making them more ideal high-temperature structural materials.

[0003] In addition to high temperature resistance, in order to ensure the assembly and load-bearing capacity between parts, its room temperature elongation is generally required to be greater than 5%. However, the intrinsic brittleness of titanium-based composites and titanium-aluminum intermetallic compounds causes their room temperature plastic elongation to be often less than 3%. In order to solve this problem, researchers have proposed some solutions. For titanium-based composites, Chinese patent number CN200810136852.8 discloses a method for manufacturing a network structure TiB reinforced titanium-based composite material. The network titanium-based composite material prepared by the powder metallurgy method exhibits higher strength and toughness than the composite material with uniform distribution of the reinforcing phase, improving the problem of brittle fracture of titanium-based composite materials. However, the powder metallurgy method is difficult to process and achieve near-net forming of complex-shaped parts, and the material utilization efficiency is not high. For titanium-aluminum intermetallic compounds, the room temperature toughness is improved by optimizing the elemental ratio of the main elements Ti and Al, or adding other trace elements such as Nb and Mn to regulate the structure of the titanium-aluminum intermetallic compound. Chinese Patent No. CN201410273532.2 discloses a casting preparation process for high-niobium titanium-aluminum alloy, which achieves the refinement of titanium-aluminum alloy lamellae and the homogenization of the structure. However, the process flow is complicated, the cost is high, and thermal cracking is prone to occur when cooling to the ductile-brittle transition temperature. Chinese Patent No. 202311519350.4 discloses a method for preparing titanium-aluminum alloy preforms by cold spraying titanium and aluminum mixed powders. However, due to the obvious difference in the deposition efficiency of titanium and aluminum powders, it is difficult to accurately control the ratio of elements in the titanium-aluminum alloy. The control of element content relies on a lot of trial and error, which makes it difficult to actually apply it. Chinese Patent No. CN200510010168.1 discloses a method for preparing titanium-aluminum alloys by hot pressing of element foils. This method can more accurately control the ratio of elements, but due to the presence of titanium and aluminum foils and cotton, impurities are easily introduced into the material. At the same time, this method makes it difficult to add elements other than titanium and aluminum to the material. In addition, for the processing of gradient titanium-based composite materials, it is difficult to prepare thin-walled slabs using traditional methods because the titanium-based composite materials themselves are extremely brittle and have a very high risk of cracking during deformation.

[0004] In order to solve the above problems, the present invention proposes a cold spray additive manufacturing-hot pressing composite processing technology. By utilizing the characteristics of cold spray additive manufacturing layer by layer stacking, efficient and precise element content control and low-cost layered gradient preform preparation can be achieved. The performance enhancement and final shape forming of the gradient preform are completed by hot pressing. For layered gradient titanium-based composite materials, there is a gradient difference in the content of ceramic phase between different layers, and the structural characteristics of the ceramic phase network distribution within the layer form a heterogeneous structure distribution on both scales, ensuring that the layered gradient structure not only ensures the heat resistance of the parts but also achieves a synergistic improvement in the strength and toughness of the material. For the processing of titanium-aluminum alloy parts, the same processing method of alternating layered spraying of titanium and aluminum powders is adopted. This method can achieve precise control of the ratio of titanium and aluminum elements, and can also meet the addition of other elements such as Nb and Mn to achieve a wide range of strength-toughness regulation of titanium-aluminum intermetallic compounds. Summary of the Invention

[0005] In response to the problems existing in the prior art, the purpose of the present invention is to provide a method for cold spraying additive-hot pressing and other material processing of high-temperature resistant titanium-based thin-walled components. The present invention can not only realize high-efficiency additive-and other material composite manufacturing of titanium-based composite materials and titanium-aluminum intermetallic compound thin-walled parts, but also can flexibly control the content of different phases and customize the required material performance, ultimately achieving high-efficiency, low-cost and high-performance processing and manufacturing of high-temperature resistant parts.

[0006] In order to achieve the above-mentioned object of the present invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for processing high-temperature resistant titanium-based thin-walled components by cold spraying additive manufacturing and hot pressing, comprising the following steps:

[0008] S1. Ball-milling raw materials of a titanium-based composite material or a titanium-aluminum intermetallic compound to mix the powders, and then cold spraying the raw materials by alternating powder feeding to obtain a cold sprayed preform having an alternating layer structure;

[0009] S2. hot pressing and sintering the obtained cold sprayed preform to obtain a high temperature resistant titanium-based thin-walled component (layered gradient titanium-based composite material);

[0010] In step S1, when preparing the titanium-based composite material, titanium-based powder is respectively ball-milled with different amounts of ceramic particles to obtain mixed powder 1 and mixed powder 2 with different ceramic particle contents; during the cold spraying process, mixed powder 1 and mixed powder 2 are alternately fed, and the resulting cold spray preform has a structure of alternating layers of mixed powder 1 and mixed powder 2;

[0011] In step S1, when preparing titanium-aluminum intermetallic compound, pure titanium matrix powder is mixed with powders of other additive elements except aluminum by ball milling to obtain a mixed powder containing other additive elements; during cold spraying, the mixed powder and aluminum powder are fed alternately, and the obtained cold spray preform is a structure of alternating mixed powder layers and aluminum powder layers.

[0012] The present invention is based on a dual-powder feeder cold spraying device. Different powders are placed in a first and a second powder-carrying tank, respectively. Cold spraying parameters are set according to material properties, and the powder feeding speeds of the two powder-feeding tanks are set according to the powder spraying ratio requirements. The cold spraying path is planned in combination with the specific size and shape of the component to complete the cold spray processing and manufacturing of the preformed blank.

[0013] Preferably, in step S1, the ceramic particles include one or more of TiB2 and B4C. The titanium alloy includes one or more of TC4, TA15, and Ti65.

[0014] Preferably, in step S1, the volume content of the ceramic particles in the mixed powder of the titanium-based composite material is 1%-6%. Different ceramic particle contents can be 1%, 2%, 3%, 4%, 5%, and 6%. When alternately feeding the two powders, the ceramic particle contents of the two powders can be 1% and 2%, 1% and 2%, 1% and 3%, 2% and 4%, 4% and 6%, 2% and 6%, etc.

[0015] Preferably, in step S1, the titanium-aluminum intermetallic compound includes one or more of Cr, Nb, and Mn. The ratio of Ti:Al:other added elements is 45-50:45-50:2-10. For the titanium-aluminum intermetallic compound, the content of the elements added to the titanium matrix is ​​consistent with the content of the target titanium-aluminum alloy. For example, in the case of Ti-48Al-2Cr-2Nb titanium-aluminum alloy, the ratio of Ti:Al:Cr:Nb is 48:48:2:2.

[0016] Preferably, in step S1, when preparing the titanium-based composite material, the particle size of the titanium alloy matrix powder is 75-105 μm, and the particle size of the ceramic particles is 1-3 μm. The titanium-based powder includes titanium or titanium alloy.

[0017] Preferably, in step S1, when preparing the aluminum intermetallic compound, the particle size of the pure titanium matrix powder is 75-105 μm, and the particle size of the other added element powders is 3-10 μm.

[0018] Preferably, in step S1, the mixed powder is milled at a speed of 250-270 rpm for 6-8 hours. The ball-to-powder ratio is 5:1, and the milling atmosphere is argon. High speeds can cause powder breakage and poor sphericity, while low speeds prevent the ceramic powder from adhering to the titanium powder surface.

[0019] For titanium-based composite materials or titanium-aluminum intermetallic compounds, mechanical ball milling allows small-sized TiB2 or other element powders to be embedded or tightly wrapped in large-sized Ti matrix powders, achieving simultaneous deposition of titanium powder and reinforcement phases. By controlling the powder particle size and ball milling parameters, the present invention can ensure that the titanium alloy matrix powder or pure titanium matrix powder has good sphericity, while small-sized ceramic particles or other additive element powder particles can be embedded and attached to the surface of the matrix powder.

[0020] Preferably, in step S1, when preparing the titanium-based composite material, the spraying thickness of the mixed powder 1 and the mixed powder 2 is 200-600 μm (the thickness ratio of the two powder layers is 1-3:1-3). The number of powder layers is not less than 4.

[0021] For the spraying method of layered gradient titanium-based composite materials, titanium-based composite material powders with different TiB2 contents are fed alternately from two powder feeding tanks. The spraying ratios of different powders are set to 1:1, 1:2 and 1:3. The spraying thickness of each layer is set in the range of 200-600μm. The thickness is accurately measured using a laser confocal microscope. The two powders are sprayed alternately until the target requirements are met.

[0022] When preparing titanium-based composite materials, the cold spray processing parameters are set as follows: gas pressure of 5-6 MPa, gas heating temperature of 700-800°C, powder feeding distance of 15-20 mm, powder feeding rate of 15-20 g / min, lateral movement speed of the spray gun of 100-150 mm / s, and spraying angle of 90°.

[0023] Preferably, in step S1, when preparing the aluminum intermetallic compound, the thickness ratio of the mixed powder layer and the aluminum powder layer is controlled to ensure the titanium and aluminum content in the target titanium-aluminum intermetallic compound. The number of powder layers is not less than 4 layers.

[0024] The titanium-based composite powder prepared in step S2 and the pure aluminum powder are placed in two powder feeding tanks respectively. The two powders are sprayed alternately. The thickness ratio of each layer is completely consistent with the titanium-aluminum ratio in the target titanium-aluminum intermetallic compound. The thickness is also accurately measured using a laser confocal microscope.

[0025] Preferably, in step S1, for the spraying method of titanium-aluminum intermetallic compound, the parameters for cold spraying the titanium layer are set to: gas pressure of 5-6 MPa, gas heating temperature of 700-800°C, powder feeding distance of 15-20 mm, powder feeding rate of 15-20 g / min, lateral movement speed of the spray gun of 100-150 mm / s, and spraying angle of 90°; the parameters for cold spraying the aluminum layer are set to: gas pressure of 5-6 MPa, gas heating temperature of 450-500°C, powder feeding distance of 15-20 mm, powder feeding rate of 15-20 g / min, lateral movement speed of the spray gun of 100-150 mm / s, and spraying angle of 90°.

[0026] Preferably, in step S1, for titanium-based composite materials or titanium-aluminum intermetallic compounds, the cold spraying substrate material is preferably a material with lower hardness, such as pure aluminum or other types of annealed aluminum alloys; before spraying, the substrate material is ground, polished and sandblasted to achieve an optimal roughness of about 15 μm.

[0027] Preferably, in step S2, for hot pressing of titanium-based composite materials, the hot pressing temperature is set to 1050-1150°C, the hot pressing pressure is set to 20-30 MPa, the holding time is 1-2 hours, the heating rate is set to 10-15°C / min, and the vacuum degree is <10 -2 Pa, the shape and size of the hot pressing graphite mold are processed according to the shape of the target part.

[0028] Preferably, in step S2, for the hot pressing of the layered gradient titanium-based composite material, TiB2 reacts with the titanium matrix during the heat preservation and pressure holding process: TiB2+Ti→2TiB, in situ generating TiB with better bonding with the matrix and stronger strengthening effect.

[0029] Preferably, in step S2, for the hot pressing of the titanium-aluminum intermetallic compound, first, the temperature is kept at 500-550°C for 2-3 hours to allow titanium and aluminum to react to form TiAl3 with a better melting point: Ti+3Al→TiAl3; after the 500°C temperature is completed, the temperature is raised to 1250-1300°C, the pressure is set to 20-30 MPa, the temperature and pressure are kept for 1-2 hours, the temperature rise rate of the whole process is set to 10-15°C / min, and the vacuum degree is <10 -2 Pa, the shape and size of the hot pressing graphite mold are processed according to the shape of the target part.

[0030] The present invention also provides a high-temperature resistant titanium-based thin-walled component prepared by the method.

[0031] The present invention also provides an application of the high-temperature resistant titanium-based thin-walled component in aerospace.

[0032] Compared with the existing manufacturing technology, the present invention has at least the following beneficial effects:

[0033] (1) The present invention provides a method for preparing a gradient titanium-based composite material high-temperature resistant thin-walled component raw blank by a cold spraying method, using titanium-based composite powder as the raw material, thereby solving the problem that titanium-based composite material thin-walled plates or foils are difficult to prepare, greatly reducing costs, and avoiding defects such as interfaces or impurities introduced by foil plates.

[0034] (2) The present invention provides a method for preparing a raw material for a high-temperature resistant thin-walled component of a titanium-aluminum intermetallic compound by a cold spraying method, forming a lamellar structure material by alternately spraying titanium powder and aluminum powder, and controlling the element content by precise thickness measurement to ensure that the accuracy of the element content can reach within 1%, thereby meeting the high-precision element content requirement of titanium-aluminum alloy.

[0035] (3) The present invention uses a cold spraying method to prepare titanium-based composite materials and titanium-aluminum intermetallic compound layered gradient preforms. During the powder deposition process, the oxide layer on the surface of the powder particles will be sputtered out during high-speed collisions, thereby greatly reducing the oxygen content in the overall material, which is beneficial to improving the toughness of the material.

[0036] (4) The present invention performs hot pressing and other material processing on the cold sprayed layered preform, and realizes the in-situ generation of ceramic phases such as TiB and TiC (layered gradient composite materials) and the in-situ generation of TiAl alloy (titanium-aluminum intermetallic compound) of titanium and aluminum to simultaneously realize the forming of the final shape of the part and significantly improve the performance of the part. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0038] Figure 1 It is a schematic diagram of the overall processing flow of preparing high-temperature resistant thin-walled components of layered gradient titanium-based composite materials and high-temperature resistant thin-walled components of titanium-aluminum intermetallic compounds according to the present invention.

[0039] Figure 2 The pure titanium powder ( Figure 2 a), TiB2 ceramic powder ( Figure 2 b) Microscopic photograph.

[0040] Figure 3 This is a microscopic photograph of the composite powder after ball-milling the titanium powder and the ceramic powder in Example 1.

[0041] Figure 4 In Example 2, pure titanium powder ( Figure 4a), pure aluminum powder ( Figure 4 b) Microscopic photograph.

[0042] Figure 5 Schematic diagram of the cold spray additive process for layer-by-layer processing of prefabricated blanks.

[0043] Figure 6 This is a photo of the layered gradient titanium-based composite material prefabricated by cold spray additive manufacturing in Example 1. DETAILED DESCRIPTION

[0044] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0045] A method for cold spraying additive manufacturing and hot pressing of high-temperature resistant titanium-based thin-walled components, the method mainly comprising: S1: calculating the content of different components in the required sprayed titanium-based composite material or titanium-aluminum intermetallic compound; S2: for layered gradient titanium-based composite materials, ball-milling titanium alloy powder and ceramic particles; for titanium-aluminum intermetallic compounds, ball-milling pure titanium powder and powders of other additive elements other than aluminum, and while ensuring good sphericity of the titanium powder, small-sized particles of the powder of other additive elements are embedded and attached to the surface of the titanium matrix powder; S3: based on a dual-powder feeder cold spraying device, different powders are respectively placed in a first and a second powder-carrying tank; cold spraying parameters are set according to material properties, the powder feeding speeds of the two powder-feeding tanks are set according to the powder spraying ratio requirements, and the cold spraying path is planned in combination with the specific size and shape of the component to complete the cold spray processing and manufacturing of the preformed blank; S4: placing the cold sprayed preformed blank obtained in S3 into a final hot pressing forming die for hot pressing and sintering, thereby simultaneously completing the forming and finishing purposes to obtain the final high-temperature resistant titanium-based thin-walled component. The preparation method is carried out according to the following steps:

[0046] 1. Determine the composition of the powder raw materials. For layered gradient titanium-based composites, the content of ceramic phases such as TiB2 or B4C added to the titanium alloy matrix ranges from 2%, 4%, to 6%. For titanium-aluminum intermetallic compounds, the element content of the added elements in the titanium matrix should be consistent with that of the target titanium-aluminum alloy. For example, for Ti-48Al-2Cr-2Nb titanium-aluminum alloy, the elemental content ratio of Ti:Al:Cr:Nb is 48:48:2:2.

[0047] 2. Screening of the particle size and type of powder raw materials. Cold spray additive manufacturing has certain requirements for the particle size and shape of the powder. In the present invention, for layered gradient titanium-based composite materials, it is preferred to select titanium alloy spherical metal powder particles with a particle size distribution of 75-105μm, and TiB2 or B4C particles with a particle size distribution of 1-3μm as reactants for generating titanium boride whiskers (TiBw) reinforcement phase. For titanium-aluminum intermetallic compounds, it is preferred to select pure titanium spherical metal powder particles with a particle size distribution of 75-105μm and pure aluminum powder of 75-105μm as basic components. For trace added Nb, Mn or Cr and other element powders, a limited particle size of 3-10 microns is selected.

[0048] 3. Low-energy ball milling of metal and reinforcement phase powders. For layered gradient titanium-based composite materials, taking TiB ceramic particles as reinforcement phase, a certain weight of TA1 metal powder ( Figure 1 ) is mixed with TiB2 powder and low-energy ball milling is performed to mix the powder. Under the premise of ensuring that the powder has good sphericity and integrity, the TiB2 particles are relatively evenly embedded and attached to the TA1 metal powder particles. In the present invention, 98g (or 96g, or 94g) of TA1 metal powder and 2g (or 4g, or 6g) of TiB2 ceramic powder are weighed, and a total of 500g of stainless steel grinding balls with particle sizes of 6mm and 10mm are selected. After mixing, the powder is ball milled and mixed. The ball milling speed is 250-270 revolutions per minute. As the ceramic phase content increases, the ball milling speed can be appropriately increased. The ball milling time is 8h, and the ball milling atmosphere is an argon atmosphere. Finally, on the basis of ensuring good sphericity and integrity, a good and uniform inlaying and attachment effect is obtained ( Figure 1 For the titanium-aluminum intermetallic compound powder mixing process, small-sized trace element powders are mixed with large-sized pure titanium powders to prepare composite powders with the same content as the target titanium-aluminum intermetallic compound. The powder mixing parameters are also set to 250-270 revolutions per minute, the ball milling time is 8 hours, and the ball milling atmosphere is argon atmosphere.

[0049] 3. Cold spray additive printing. The mixed powder must be kept in a vacuum environment before spraying to prevent oxidation of the titanium alloy powder. Cold spray substrates are preferably made of relatively low-hardness materials, such as pure aluminum or other annealed aluminum alloys. Before spraying, the substrate should be ground, polished, and sandblasted to achieve an optimal roughness of approximately 15μm.

[0050] For layered gradient titanium-based composites, the cold spraying parameters were set as follows: gas pressure of 5 MPa, gas heating temperature of 800°C, powder feeding distance of 20 mm, powder feeding rate of 20 g / min, lateral movement speed of the spray gun of 100 mm / s, and spray angle of 90°. Titanium-based composite powders with different ceramic phase contents were fed alternately from two powder feeding tanks. The spray ratios of the different powders were set at 1:1, 1:2, and 1:3. The spray thickness of each layer was set in the range of 200-600 μm. The thickness was accurately measured using a laser confocal microscope. The two powders were sprayed alternately until the target requirements were achieved.

[0051] For the spraying method of titanium-aluminum intermetallic compounds, the titanium-based composite powder prepared in step S2 and pure aluminum powder are placed in two powder feeding tanks respectively. The two powders are sprayed alternately, and the thickness is accurately measured using a laser confocal microscope. The thickness ratio of each layer is completely consistent with the titanium-aluminum ratio in the target titanium-aluminum intermetallic compound. When cold spraying the titanium layer, the parameters are set as follows: gas pressure of 5MPa, gas heating temperature of 800℃, powder feeding distance of 20mm, powder feeding rate of 20g / min, spray gun lateral movement speed of 100mm / s, and spray angle of 90°; when cold spraying the aluminum layer, the parameters are set as follows: gas pressure of 5MPa, gas heating temperature of 500℃, powder feeding distance of 20mm, powder feeding rate of 20g / min, spray gun lateral movement speed of 100mm / s, and spray angle of 90°.

[0052] 4. Reaction hot pressing and sintering of cold sprayed preforms. For hot pressing of titanium-based composite materials, the cold sprayed preforms are placed in a graphite mold for reaction hot pressing to eliminate the defects of the cold sprayed bulk material and allow the ceramic particles to react with the titanium matrix in situ to generate TiBw whiskers with better strengthening effect. The hot pressing temperature is set to 1100°C, the hot pressing pressure is set to 20MPa, the holding time is 2h, the heating rate is set to 10°C / min, and the vacuum degree is <10 -2 Pa, the shape and size of the hot pressing graphite mold are processed according to the shape of the target part to complete the forming of the final thin-walled part.

[0053] For the hot pressing of titanium-aluminum intermetallic compounds, first keep the temperature at 550℃ for 2h to make titanium and aluminum react to form TiAl3 with a better melting point: Ti+3Al→TiAl3; after the 500℃ heat preservation is completed, the temperature is raised to 1300℃, the pressure is set to 20MPa, the heat and pressure holding time is 2h, the heating rate of the whole process is set to 10℃ / min, and the vacuum degree is <10 -2 Pa, the shape and size of the hot pressing graphite mold are processed according to the shape of the target part.

[0054] 5. Using the above parameters for processing, a high-strength, toughness, and high-temperature-resistant gradient titanium-based composite material or titanium-aluminum intermetallic compound thin-walled component is obtained.

[0055] Example 1

[0056] This embodiment prepares a layered gradient titanium-based composite flat plate part, including the following steps:

[0057] 1. Select TA1 spherical metal powder particles with a particle size distribution of 75-105μm ( Figure 2 a), select TiB2 particles with a particle size distribution of 1-3 μm ( Figure 2 b), as a catalyst for the formation of titanium boride whiskers (TiB w ) reactants of the reinforcing phase.

[0058] 2. Preparation of two titanium-based mixed powders with ceramic phase contents of 1% and 2% respectively: Weigh 98g (96g) of TA1 metal powder and 2g (4g) of TiB2 ceramic powder respectively, select 500g of stainless steel grinding balls with particle sizes of 6mm and 10mm, mix them and then ball mill the mixed powders. The ball milling speed is 270 rpm, the ball milling time is 8h, and the ball milling atmosphere is argon atmosphere. Microscopic photos of the composite powder after ball milling are shown as follows: Figure 3 shown.

[0059] Third, the cold spray substrate material was pure aluminum. Before spraying, the substrate material was ground, polished, and sandblasted to a roughness of approximately 15μm. The cold spray parameters used were: gas pressure of 5MPa, gas heating temperature of 800°C, powder feed distance of 20mm, powder feed rate of 20g / min, spray gun traverse speed of 100mm / s, and spray angle of 90°. Two titanium-based composite powders with different ceramic contents were placed in powder feed tanks 1 and 2, respectively. During the spraying process, the titanium-based composite powders with different TiB2 contents were alternately fed from the two powder feed tanks. The spray ratio of the different powders was set at 1:1, and the spray thickness of each layer was set at 300μm. Laser confocal microscopy was used intermittently during the spraying process to measure the spray thickness until the target thickness was accurately achieved. The two titanium-based composite powders were sprayed alternately twice, resulting in a final overall thickness of 1.2mm for the flat plate.

[0060] 4. Place the cold spray preform into the graphite mold for reaction hot pressing. The hot pressing temperature is set to 1100℃, the hot pressing pressure is set to 20MPa, the holding time is 2h, the heating rate is set to 10℃ / min, and the vacuum degree is <10 -2 Pa.

[0061] In this example, a 1.2mm thick titanium-based composite material with uniform thickness was prepared by cold spray additive manufacturing. The macroscopically, it has a layered gradient structure with different ceramic phases, and the microscopically, it has a network-like distribution of ceramic phases within the layer, forming a heterogeneous structure distribution at both scales. The cold spray schematic and the actual morphology after spraying are shown in Figure 2. Figure 5、 6 shown.

[0062] The layered gradient titanium-based composite material prepared by this method can improve its high-temperature service performance by 200°C compared to the matrix titanium alloy. At the same time, the alternating distribution of soft and hard materials in the thickness direction induces geometric dislocations to accumulate at the interface during deformation, forming the effects of heterogeneous induced strengthening and heterogeneous induced plasticity improvement, increasing the strength by more than 150MPa while maintaining a significant decrease in elongation compared to the matrix titanium alloy.

[0063] It should be noted that the above examples only specifically address flat-plate parts made from a combination of pure titanium and TiB2 as the titanium matrix and reinforcement phase. The same applies to other similar titanium-based composite materials in the field, including titanium matrices such as TC4, TA15, and Ti65, and ceramic phases such as B4C and TiC. Furthermore, the shape of the final part is not limited to flat-plate parts and can be spherical, cylindrical, or other shapes. Post-processing methods can also include hot rolling, hot isostatic pressing, and similar hot pressing methods.

[0064] Example 2

[0065] This embodiment prepares a Ti-48Al-2Cr-2Nb titanium aluminum intermetallic compound flat plate part, including the following steps:

[0066] 1. Select TA1 with a particle size distribution of 75-105 μm ( Figure 4 a) and pure aluminum spheres ( Figure 4 b) Metal powder particles: Pure Cr powder and pure Nb powder with a particle size distribution of 3-10 μm were selected as the powder raw materials. For the Ti-48Al-2Cr-2Nb titanium-aluminum intermetallic compound, the atomic percentages of the four elements Ti:Al:Cr:Nb were 48:48:2:2, respectively, and the weight percentages were 59:33:3:5.

[0067] Second, 100g of TA1 metal powder, 4.5g of pure Cr powder, and 8.05g of pure Nb powder were weighed, mixed, and ball-milled using 500g of 6mm and 10mm stainless steel grinding balls. The milling speed was 260 rpm for 8 hours in an argon atmosphere to obtain a Ti-Cr-Nb mixed powder.

[0068] 3. The cold spray substrate material was pure aluminum; before spraying, the substrate material was ground, polished, and sandblasted to a roughness of approximately 15μm. The parameters for cold spraying the Ti-Cr-Nb mixed powder layer were: gas pressure of 5MPa, gas heating temperature of 800°C, powder feeding distance of 20mm, powder feeding rate of 20g / min, spray gun lateral movement speed of 100mm / s, and spray angle of 90°; the parameters for cold spraying the pure aluminum layer were: gas pressure of 5MPa, gas heating temperature of 500°C, powder feeding distance of 20mm, powder feeding rate of 20g / min, spray gun lateral movement speed of 100mm / s, and spray angle of 90°.

[0069] 4. Layered spraying of mixed powders; Ti-Cr-Nb mixed powder and pure Al powder are placed in powder feeding tank 1 and powder feeding tank 2 respectively. During the spraying process, the two powders in the two powder feeding tanks are fed alternately. The thickness ratio of each layer is completely consistent with the ratio of titanium to aluminum in the target titanium-aluminum intermetallic compound. According to the weight percentage and density of the mixed powder, the thickness ratio of the Ti-Cr-Nb mixed powder layer to the pure aluminum layer is calculated to be 53:47. The spraying thickness of the two layers of powder is set to 212μm and 188μm respectively. During the spraying process, a laser confocal microscope is used intermittently to measure the spraying thickness until the target requirement is accurately reached. The two titanium-based composite material powders are sprayed alternately three times, and the final overall thickness of the flat plate is 1.2mm.

[0070] Fourth, the cold spray preform is placed in a graphite mold for reactive hot pressing. First, it is kept at 550℃ for 2h without applying pressure to make titanium and aluminum react to generate TiAl3 with a better melting point: Ti+3Al→TiAl3; after the 550℃ holding is completed, the temperature is raised to 1300℃, the pressure is set to 20MPa, the holding time is 2h, the heating rate of the whole process is set to 10℃ / min, and the vacuum degree is <10 -2 Pa

[0071] This example uses a cold spray additive manufacturing (AM) and hot pressing method to produce a 1.2mm thick Ti4822 titanium-aluminum alloy sheet. This method produces a highly flat, crack-free titanium-aluminum alloy sheet, resolving the difficulty of producing titanium-aluminum alloy sheets using traditional methods.

[0072] It should be noted that the above examples only specifically describe the flat plate parts made of Ti4822 titanium aluminum alloy as a representative.

[0073] This method is also applicable to other titanium-aluminum alloys, either already developed or developed by researchers, such as Ti-45Al-2Nb-2Mn-0.8 vol.% TiB2 (45XD) and Ti45Al(5-10)Nb. The final part shape is not limited to flat plates and can also be spherical, cylindrical, and other shapes. Post-processing methods such as hot isostatic pressing (HIP) can also be used.

[0074] Comparative Example 1

[0075] This comparative example is basically the same as Example 1, except that a titanium-based mixed powder with a ceramic phase content of 1.5% is prepared for subsequent cold spraying.

[0076] Comparative Example 2

[0077] This comparative example is basically the same as Example 2, except that TA1 metal powder, pure Cr powder, pure Nb powder, and pure Al powder are directly mixed and ball-milled for subsequent cold spraying.

[0078] Comparative Example 3

[0079] This comparative example is basically the same as Example 1, with the only difference being that titanium-based mixed powders with ceramic phase contents of 1%, 1.3%, 1.7%, and 2% were prepared, and subsequent cold spraying was carried out in the order of increasing ceramic phase content (1%-1.3%-1.7%-2%), and the spraying thickness of each layer was set at 300 μm.

[0080] Comparative Example 4

[0081] This comparative example is basically the same as Example 1, with the only difference being that the prepared titanium-based mixed powder is cold sprayed in the order of increasing and then decreasing the ceramic phase content (1%-2%-2%-1%), and the spraying thickness of each layer is set at 300 μm.

[0082] Comparative Example 5

[0083] This comparative example is basically the same as Example 1, except that the ball milling parameter is 400 r / min.

[0084] Comparative Example 6

[0085] This comparative example is basically the same as Example 1, except that the prepared titanium-based composite material mixed powders with different volume ratio gradients are stacked and evenly laid in a gradient order of cold spraying to obtain a laminated structure powder; and then subjected to true hot pressing treatment.

[0086] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A method for processing high-temperature resistant titanium-based thin-walled components by cold spraying additive-hot pressing, characterized in that: The steps include: S1. Ball-milling raw materials of a titanium-based composite material or a titanium-aluminum intermetallic compound to mix the powders, and then cold spraying the raw materials by alternating powder feeding to obtain a cold sprayed preform having an alternating layer structure; S2, hot pressing and sintering the cold sprayed prefabricated blank to obtain a high temperature resistant titanium-based thin-walled component; In step S1, when preparing the titanium-based composite material, titanium-based powder is respectively ball-milled with different amounts of ceramic particles to obtain mixed powder 1 and mixed powder 2 with different ceramic particle contents; during the cold spraying process, mixed powder 1 and mixed powder 2 are alternately fed, and the resulting cold spray preform has a structure of alternating layers of mixed powder 1 and mixed powder 2; In step S1, when preparing titanium-aluminum intermetallic compound, pure titanium matrix powder is mixed with powders of other additive elements except aluminum by ball milling to obtain a mixed powder containing other additive elements; during cold spraying, the mixed powder and aluminum powder are fed alternately, and the obtained cold spray preform is a structure of alternating mixed powder layers and aluminum powder layers.

2. The method for processing high-temperature resistant titanium-based thin-walled components by cold spraying additive manufacturing and hot pressing according to claim 1, characterized in that: In step S1, the ceramic particles include one or more of TiB2 and B4C; And / or, in step S1, the titanium alloy includes one or more of TC4, TA15, and Ti65.

3. The method for processing high-temperature resistant titanium-based thin-walled components by cold spraying additive manufacturing and hot pressing according to claim 1, characterized in that: In step S1, the volume content of the ceramic particles in the ceramic particle mixed powder of the titanium-based composite material is 1%-6%; And / or, in step S1, other added elements in the titanium-aluminum intermetallic compound include one or more of Cr, Nb, and Mn.

4. The method for processing high-temperature resistant titanium-based thin-walled components by cold spraying additive manufacturing and hot pressing according to claim 1, characterized in that: In step S1, when preparing the titanium-based composite material, the particle size of the titanium alloy matrix powder is 75-105 μm, and the particle size of the ceramic particles is 1-3 μm; And / or, in step S1, when preparing the aluminum intermetallic compound, the particle size of the pure titanium matrix powder is 75-105 μm, and the particle size of the other added element powder is 3-10 μm.

5. The method for processing high-temperature resistant titanium-based thin-walled components by cold spraying additive manufacturing and hot pressing according to claim 1, characterized in that: In step S1, the ball milling speed of the mixed powder is 250-270 r / min, and the ball milling time is 6-8 h.

6. The method for processing high-temperature resistant titanium-based thin-walled components by cold spraying additive manufacturing and hot pressing according to claim 1, characterized in that: In step S1, when preparing the titanium-based composite material, the spraying thickness of the mixed powder 1 and the mixed powder 2 is 200-600 μm.

7. The method for processing high-temperature resistant titanium-based thin-walled components by cold spraying additive manufacturing and hot pressing according to claim 1, characterized in that: In step S1, when preparing the aluminum intermetallic compound, the thickness ratio of the mixed powder layer and the aluminum powder layer is controlled to ensure the titanium and aluminum content in the target titanium-aluminum intermetallic compound.

8. The method for processing high-temperature resistant titanium-based thin-walled components by cold spraying additive manufacturing and hot pressing according to claim 1, characterized in that: For the hot pressing sintering of cold sprayed preforms prepared from titanium-based composite materials, the hot pressing temperature is set to 1050-1150°C, the hot pressing pressure is set to 20-30 MPa, the holding time is 1-2 h, the heating rate is set to 10-15°C / min, and the vacuum degree is <10 -2 Pa.

9. The method for processing high-temperature resistant titanium-based thin-walled components by cold spraying additive manufacturing and hot pressing according to claim 1, characterized in that: For the hot pressing sintering of the cold sprayed preform prepared by titanium aluminum intermetallic compound, the temperature is first kept at 500-550℃ for 2-3h. After the end of the heat preservation, the temperature is raised to 1250-1300℃, the pressure is set to 20-30MPa, the heat preservation and pressure holding time is 1-2h, the heating rate of the whole process is set to 10-15℃ / min, and the vacuum degree is <10 -2 Pa.

10. A high-temperature resistant titanium-based thin-walled component prepared by the method according to claim 1.

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