Method for processing quasi-continuous net-shaped reinforced titanium-based composite material thin-wall structure through cold spraying additive-hot pressing equal material

Abstract

The invention belongs to the technical field of titanium-based thin-wall component machining, and discloses a method for machining a high-temperature-resistant titanium-based thin-wall component through cold spraying additive-hot pressing and the like. A titanium-based layered gradient structure prefabricated blank is prepared mainly through a cold spraying method, and machining of the high-performance and high-temperature-resistant titanium-based thin-wall component is achieved in combination with a subsequent equal material technology. The processing and preparing process comprises the steps that the component content of the titanium-based composite powder is determined; preparing composite powder; carrying out cold spraying additive printing to obtain a layered gradient preformed thin-wall blank; and carrying out reaction hot pressing to form the high-temperature-resistant thin-wall component. By means of the method, high-production-efficiency, low-cost and high-performance manufacturing of the high-temperature-resistant layered gradient titanium-based composite material or the titanium-aluminum intermetallic compound thin-wall component can be achieved; the high-temperature-resistant thin-wall component with the maximum service temperature of 800 DEG C can be machined and prepared according to the target service temperature requirement, and customization of the service performance can be achieved according to the mechanical property requirement of the component.

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 and other materials. Background Art

[0002] With the rapid development of aerospace technology, the cruising speed of aircraft is constantly increasing, which also puts 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℃. The performance of traditional titanium alloys (service temperature <600℃) based on the addition of alloying elements 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℃. 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, and are 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, the room temperature elongation is generally required to be >5%. However, the intrinsic brittleness of titanium-based composite materials 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 composite materials, Chinese patent number CN200810136852.8 discloses a method for manufacturing a mesh-structured TiB-reinforced titanium-based composite material, in which the mesh-structured titanium-based composite material prepared by a powder metallurgy method exhibits higher strength and toughness than the composite material with uniform distribution of the reinforcing phase, and improves the problem of brittle fracture of titanium-based composite materials. However, the powder metallurgy method is difficult to process and realize 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 element ratio of the main elements Ti and Al, or adding other trace elements such as Nb and Mn to regulate the organization 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 hot 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, but due to the obvious difference in the deposition efficiency of titanium and aluminum powders, it is difficult to accurately control the proportion of elements in the titanium-aluminum alloy, and the control of element content relies on a lot of empirical trial and error, which makes it difficult to truly apply. Chinese Patent No. CN200510010168.1 discloses a method for preparing titanium-aluminum alloys by hot pressing of element foils. This method can control the proportion of elements more accurately, but due to the presence of titanium and aluminum foils and cotton, it is easy to introduce impurities into the material. At the same time, this method is difficult to add other elements other than titanium and aluminum elements to the material. In addition, for the processing of gradient titanium-based composites, it is difficult to prepare thin-walled slabs using traditional methods because the titanium-based composites 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-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 are gradient differences in the content of ceramic phases 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 can not only ensure the heat resistance of the parts but also achieve 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 view of 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 the high-efficiency additive-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 realizing 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-hot pressing, comprising the following steps:

[0008] S1. ball-milling raw materials of titanium-based composite materials or titanium-aluminum intermetallic compounds to mix powders, and then cold spraying them by alternately feeding powders to obtain a cold spray preform with an alternating layer structure;

[0009] S2, hot pressing and sintering the obtained cold sprayed prefabricated blank 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, the titanium-based powder is respectively mixed with different amounts of ceramic particles by ball milling to obtain mixed powder 1 and mixed powder 2 with different ceramic particle contents; during the cold spraying process, the mixed powder 1 and the mixed powder 2 are alternately fed, and the obtained cold spray preform is a structure of alternating layers of the mixed powder 1 and the mixed powder 2;

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

[0012] The present invention is based on a double-powder feeder cold spraying device, and different powders are respectively placed in a first and a second powder carrying tank; 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 ceramic particles in the ceramic particle mixed powder of the titanium-based composite material is 1%-6%. Different ceramic particle contents can be 1%, 2%, 3%, 4%, 5%, 6%. When alternately feeding the powder, 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, in the titanium-aluminum intermetallic compound, other added elements include one or more of Cr, Nb, and Mn. The element content ratio of Ti:Al: other added elements is 45-50:45-50:2-10. For the titanium-aluminum intermetallic compound, the element content added to the titanium matrix is ​​consistent with the element content in the target titanium-aluminum alloy. Taking Ti-48Al-2Cr-2Nb titanium-aluminum alloy as an example, the element content 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 other added element powders is 3-10 μm.

[0018] Preferably, in step S1, the ball milling speed of the ball milling mixed powder is 250-270r / min, and the ball milling time is 6-8h. The ball-to-material ratio during ball milling is 5:1, and the ball milling atmosphere is argon. A high speed will cause the powder to break and result in poor sphericity, and a low speed will cause the ceramic powder to be unable to adhere to the surface of the titanium powder.

[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, thereby achieving synchronous deposition of titanium powder and reinforcement phase. The present invention can ensure that titanium alloy matrix powders or titanium pure titanium matrix powders have good sphericity by controlling the particle size and ball milling parameters of the powders, while small-sized ceramic particles or other added element powder particles can be embedded and attached to the surface of the matrix powders.

[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 layers.

[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 parameters of the cold spraying process 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 as follows: gas pressure of 5-6MPa, gas heating temperature of 700-800°C, powder feeding distance of 15-20mm, powder feeding rate of 15-20g / min, lateral movement speed of the spray gun of 100-150mm / s, and spraying angle of 90°; the parameters for cold spraying the aluminum layer are set as follows: gas pressure of 5-6MPa, gas heating temperature of 450-500°C, powder feeding distance of 15-20mm, powder feeding rate of 15-20g / min, lateral movement speed of the spray gun of 100-150mm / 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 preferably selects a material with lower hardness, such as pure aluminum or other types of aluminum alloys in annealed state; 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 the hot pressing of the titanium-based composite material, the hot pressing temperature is set to 1050-1150°C, the hot pressing pressure is set to 20-30MPa, the heat preservation and pressure holding time is 1-2h, 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, and TiB with better bonding with the matrix and stronger strengthening effect is generated in situ.

[0029] Preferably, in step S2, for the hot pressing of titanium-aluminum intermetallic compound, firstly, the temperature is kept at 500-550°C for 2-3h to make titanium and aluminum react to generate TiAl3 with a better melting point: Ti+3Al→TiAl3; after the 500°C heat preservation is completed, the temperature is raised to 1250-1300°C, 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°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 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 titanium-aluminum intermetallic compound high-temperature resistant thin-walled component raw material 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 requirements of titanium-aluminum alloys.

[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 collision, 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 layer 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 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 from the detailed description of non-limiting embodiments made with reference to the following drawings:

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

[0039] Figure 2 In Example 1, 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 and mixing of titanium powder and 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 preform prepared by cold spray additive in Example 1. DETAILED DESCRIPTION

[0044] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments 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 of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0045] A method for cold spraying additive-hot pressing and other material processing of high temperature resistant titanium-based thin-walled components, the method mainly comprises: 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, titanium alloy powder and ceramic particles are ball-milled and mixed; for titanium-aluminum intermetallic compounds, pure titanium powder and other additive element powders except aluminum are ball-milled and mixed, and under the premise of ensuring good sphericity of titanium powder, small-sized other additive element powder particles are embedded and attached to the surface of titanium matrix powder; S3: based on a double powder feeder cold spraying device, different powders are respectively placed in a first and a second powder carrier tank; cold spraying parameters are set according to material properties, the powder feeding speeds of two powder feed 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, and the cold spraying processing and manufacturing of the preformed blank is completed; S4: the cold sprayed preformed blank obtained in S3 is placed in a final hot pressing forming mold for hot pressing sintering, and the forming and forming purposes are completed simultaneously 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 component content of the powder raw material. For layered gradient titanium-based composite materials, the content of ceramic phase raw materials such as TiB2 or B4C added to the titanium alloy matrix includes 2%, 4%, 6%, etc. For titanium-aluminum intermetallic compounds, the content of elements added to the titanium matrix is ​​consistent with the content of elements in the target titanium-aluminum alloy. Taking Ti-48Al-2Cr-2Nb titanium-aluminum alloy as an example, the element 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 powders. 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 select 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 constituent materials, and for trace amounts of other element powders such as Nb, Mn or Cr, a limited particle size of 3-10 microns is selected.

[0048] 3. Low-energy ball milling of metal and reinforcing phase powders. For layered gradient titanium-based composite materials, taking TiB ceramic particles as the reinforcing phase as an example, a certain weight of TA1 metal powder ( Figure 1 ) is mixed with TiB2 powder and low-energy ball milling is performed to mix the powders. Under the premise of ensuring that the powders have good sphericity and integrity, the TiB2 particles are relatively evenly inlaid 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 powders are 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 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 powder mixing process of titanium-aluminum intermetallic compound, small-sized trace element powder and large-sized pure titanium powder are mixed to prepare composite powder, the content of which is the same as the target titanium-aluminum intermetallic compound composition, and the powder mixing parameters are also set to 250-270 revolutions per minute, ball milling time 8h, and ball milling atmosphere is argon atmosphere.

[0049] 3. Cold spray additive printing. The mixed powder must always be kept in a vacuum environment before spraying to avoid oxidation of the titanium alloy powder. Cold spray substrate materials should preferably be materials with lower hardness, such as pure aluminum or other types of annealed aluminum alloys; before spraying, the substrate material should be ground, polished and sandblasted to achieve a roughness of about 15μm.

[0050] For layered gradient titanium-based composite materials, the cold spraying 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, lateral movement speed of the spray gun of 100mm / s, and spraying angle of 90°. Titanium-based composite powders with different ceramic phase contents are fed alternately in two powder feeding tanks, and 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.

[0051] For the spraying method of titanium-aluminum intermetallic compounds, the titanium-based composite powder prepared in step S2 and the pure aluminum powder are placed in two powder feeding tanks respectively, and the two powders are sprayed alternately. The thickness is accurately measured using a laser confocal microscope, and the thickness ratio of each layer is completely consistent with the ratio of titanium and aluminum 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, lateral movement speed of the spray gun of 100mm / s, and spraying 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, lateral movement speed of the spray gun of 100mm / s, and spraying angle of 90°.

[0052] 4. Reaction hot pressing 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 generate TiAl3 with a better melting point: Ti+3Al→TiAl3; after the 500℃ heat preservation, 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 gradient titanium-based composite material or titanium-aluminum intermetallic compound thin-walled component with high strength, toughness and high temperature resistance is obtained.

[0055] Example 1

[0056] This embodiment prepares a layered gradient titanium-based composite material 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) TA1 metal powder and 2g (4g) TiB2 ceramic powder respectively, select 500g of stainless steel grinding balls with particle sizes of 6mm and 10mm, mix 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. The microscopic photo of the composite powder after ball milling is shown in the figure below. Figure 3 shown.

[0059] 3. The cold spray substrate material is pure aluminum; before spraying, the substrate material is ground, polished and sandblasted to make its roughness reach about 15μm. The cold spray parameters used are set as follows: gas pressure of 5MPa, gas heating temperature of 800℃, powder feeding distance of 20mm, powder feeding rate of 20g / min, lateral movement speed of spray gun of 100mm / s, and spraying angle of 90°. Two titanium-based composite material powders with different ceramic contents are placed in powder feeding tank 1 and powder feeding tank 2 respectively. During the spraying process, titanium-based composite material powders with different TiB2 contents in the two powder feeding tanks are alternately fed. The spraying ratio of different powders is set to 1:1, and the spraying thickness of each layer is set to 300μm. During the spraying process, a laser confocal microscope is used intermittently to measure the spraying thickness until the target requirements are accurately met. The two titanium-based composite material powders are sprayed alternately twice, and the final overall thickness of the flat plate is 1.2mm.

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

[0061] In this example, a 1.2 mm thick titanium-based composite material with equal thickness was prepared by cold spray additive manufacturing. The macroscopically, it has a layered gradient structure with different ceramic phases, and the microscopically, the layers have a structural feature of a network distribution of ceramic phases, forming a heterogeneous structure distribution on both scales. The schematic diagram of cold spraying 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 the high-temperature service performance by 200°C compared with 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, which increases the strength by more than 150MPa, and at the same time can make the elongation not significantly reduced compared with the matrix titanium alloy.

[0063] It should be noted that the above examples only specifically illustrate the flat plate parts prepared by the combination of pure titanium + TiB2 as the titanium matrix and the reinforcement phase. The same is true for other similar titanium-based composite materials in the field, including titanium matrices such as TC4, TA15, Ti65, and ceramic phases such as B4C and TiC. At the same time, the shape of the final parts is not limited to flat plate parts, and can be spherical, cylindrical, etc. The post-processing process can also use hot rolling, hot isostatic pressing and other similar hot pressing processing 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 75-105μm ( Figure 4 a) and pure aluminum spheres ( Figure 4 b) Metal powder particles, pure Cr powder and pure Nb powder particles with a particle size distribution of 3-10 μm are selected as powder raw materials. For Ti-48Al-2Cr-2Nb titanium aluminum intermetallic compound, the atomic percentages of the four elements are 48:48:2:2 for Ti:Al:Cr:Nb, and the weight percentages are 59:33:3:5.

[0067] 2. Weigh 100g of TA1 metal powder, 4.5g of pure Cr powder and 8.05g of pure Nb powder, select 500g of stainless steel grinding balls with particle sizes of 6mm and 10mm, mix them and then ball mill the mixed powder. The ball milling speed is 260 revolutions per minute, the ball milling time is 8h, and the ball milling atmosphere is argon atmosphere to obtain Ti-Cr-Nb mixed powder.

[0068] 3. The cold spray substrate material is pure aluminum; before spraying, the substrate material is ground, polished and sandblasted to a roughness of about 15μm. The parameters for cold spraying the Ti-Cr-Nb mixed powder layer are: 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, spray angle of 90°; the parameters for cold spraying the pure aluminum layer are: 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, 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 alternately fed. 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 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 powders are sprayed alternately three times, and the final overall thickness of the flat plate is 1.2mm.

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

[0071] In this embodiment, a 1.2 mm thick Ti4822 titanium aluminum alloy sheet was prepared by a cold spray additive manufacturing + hot pressing method. This method can achieve a titanium aluminum alloy sheet with high flatness and no cracks on the edge, solving the problem that the traditional method is difficult to prepare titanium aluminum alloy sheets.

[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 preparation method is also applicable to other titanium aluminum alloys that have been developed or developed by researchers themselves, such as Ti-45Al-2Nb-2Mn-0.8vol.%TiB2(45XD), Ti45Al(5-10)Nb, etc. At the same time, the shape of the final part is not limited to flat parts, but can be spherical, cylindrical, etc. The post-processing process can also use hot isostatic pressing and other similar hot pressing processing methods.

[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 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 obtained titanium-based composite material mixed powders with different volume ratio gradients are evenly stacked and laid in a gradient sequence of cold spraying to obtain a laminated structure powder; and then subjected to true hot pressing treatment.

[0086] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

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 titanium-based composite materials or titanium-aluminum intermetallic compounds to mix powders, and then cold spraying them by alternately feeding powders to obtain a cold spray preform with 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, the titanium-based powder is respectively mixed with different amounts of ceramic particles by ball milling to obtain mixed powder 1 and mixed powder 2 with different ceramic particle contents; during the cold spraying process, the mixed powder 1 and the mixed powder 2 are alternately fed, and the obtained cold spray preform is a structure of alternating layers of the mixed powder 1 and the mixed powder 2; In step S1, when preparing titanium-aluminum intermetallic compound, pure titanium matrix powder and powders of other additive elements except aluminum are ball-milled to obtain mixed powder containing other additive elements; during cold spraying, the mixed powder and aluminum powder are fed alternately, and the obtained cold spray preform has 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-hot pressing according to claim 1 is 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-hot pressing according to claim 1 is characterized in that: In step S1, the volume content of 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-hot pressing according to claim 1 is 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 other added element powders is 3-10 μm.

5. The method for processing high temperature resistant titanium-based thin-walled components by cold spraying additive-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-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-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-hot pressing according to claim 1, characterized in that: In step S2, for hot pressing sintering of the titanium-based composite material, the hot pressing temperature is set to 1050-1150°C, the hot pressing pressure is set to 20-30MPa, the heat preservation and pressure holding time is 1-2h, 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-hot pressing according to claim 1, characterized in that: In step S2, for the hot pressing sintering of titanium-aluminum intermetallic compounds, first, the temperature is kept at 500-550°C for 2-3 hours. After the heat preservation is completed, the temperature is raised to 1250-1300°C, the pressure is set to 20-30MPa, the heat preservation and pressure holding time is 1-2 hours, the heating rate of the whole process is set to 10-15°C / 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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