Additive manufacturing method of titanium-based composite material for improving mesh configuration of reinforcement

Abstract

The invention discloses an additive manufacturing method of a titanium-based composite material capable of improving a mesh configuration of a reinforcement body, relates to the field of additive manufacturing, and aims to solve the problem of reinforcement body segregation which is difficult to avoid when the high-reinforcement-body-content mesh-configuration titanium-based composite material is prepared through additive manufacturing. The method comprises the following steps: carrying out low-energy ball milling after carrying out vacuum drying on Ti6Al4V and TiB2; carrying out vacuum drying and screening after ball milling to obtain mixed powder; and carrying out additive manufacturing, and accomplishing additive manufacturing of the titanium-based composite material for improving the mesh configuration of the reinforcement through follow-up ultrasonic assistance. The content of a reinforcing phase TiB in the net-shaped titanium-based composite material is 3.5 vol.%-5.0 vol.%. By means of the method, the net-shaped titanium-based composite material prepared through additive manufacturing can have high yield strength, high tensile strength and high plasticity at the same time at the room temperature. In addition, the technical scheme has the advantages of being short in period, low in cost and stable in process, and further development and application of the net-shaped titanium-based composite material are facilitated.

Description

Technical Field

[0001] The present invention belongs to the field of additive manufacturing, and particularly relates to an additive manufacturing method for a titanium matrix composite material with an improved reticular configuration of reinforcements. Background Art

[0002] Titanium matrix composites use titanium alloys as the matrix and fibers or hard particles, etc. as high-performance second-phase reinforcements, further improving the mechanical properties of the original titanium alloys and expanding the application range of titanium alloys. The reticular configuration titanium matrix composite material wraps the soft phase (alloy matrix) with the hard phase (reinforcement), and its characteristic is that the reinforcement is enriched at the grain boundaries or particle boundaries, presenting a continuous or quasi-continuous reticular structure.

[0003] Additive manufacturing technology, also known as 3D printing, is a new manufacturing technology that uses a high-energy density heat source to melt and stack raw materials layer by layer from bottom to top according to a designed path, ultimately realizing the three-dimensional forming of components. Compared with traditional preparation processes, additive manufacturing technology has advantages such as near-net shape forming and short process cycle, overcoming the problem of difficult subsequent processing in traditional preparation processes. In the additive manufacturing preparation of reticular configuration titanium matrix composites, first, ceramic particles are embedded on the surface of titanium powder through a low-energy ball milling process to obtain a mixed powder. Then, a reticular configuration titanium matrix composite material is prepared in the form of powder spreading or powder feeding for 3D printing. During the additive manufacturing process, ultrasonic vibration is applied, and the ultrasonic wave is used to promote the homogenization of the solidification structure by reducing the temperature gradient, refining grains, inducing equiaxed transformation of grains, suppressing element segregation, etc., solving problems such as large residual stress and uneven stress distribution caused by rapid cooling, and is one of the research hotspots in the field of additive manufacturing.

[0004] However, the quality of the mixed powder prepared by the ball milling process is unstable, and there may be local agglomeration of ceramic particles, which easily leads to the problem of local segregation of reinforcements at the reticular boundaries. When the reinforcement content is relatively high, the scale of reinforcement segregation is further larger, and cracks are more likely to initiate and expand from the reinforcement segregation, seriously reducing the mechanical properties of the additive manufacturing reticular configuration titanium matrix composite material.

[0005] The invention patents CN 117161401 A, CN 117444232 A, and CN 116871530 A respectively disclose a quasi - continuous reticulated titanium - based composite material and its method based on additive manufacturing, a preparation method of a dual - structure titanium - based composite material based on additive manufacturing, and a laminated titanium - based composite material and its method based on direct energy deposition additive manufacturing, aiming to solve the problems of high preparation cost, complex process, and high cost of subsequent processing for additive manufacturing of titanium - based composite materials with a reticulated structure. However, in the three technical solutions, the maximum addition amount of the reinforcement is 2.0 wt.%, corresponding to a TiB content of 3.4 vol.%. As is well known, in titanium - based composites, the segregation ability of the reinforcement at the reticulated boundary increases with the increase of its content (Reference: Invention Patent CN 115044792 B). That is to say, when the TiB reinforcement content exceeds 3.4 vol.%, this technical solution cannot solve the problem of reinforcement segregation in additive - manufactured reticulated - configuration titanium - based composites. In fact, this is indeed the case. For example, when the volume fraction of the reinforcement exceeds 3.5%, the grain boundary positions of the additive - manufactured reticulated - configuration titanium - based composites are almost completely occupied by the reinforcement, and the segregation ability of the reinforcement increases significantly, resulting in a sharp drop in the plasticity of the material.

[0006] The invention patent CN 111151746 B discloses a method for additive manufacturing of a titanium - based composite material with in - situ embedded ultra - fine reticulated structure reinforcements, aiming to solve the problems of defects such as agglomeration and pores of the reinforcement caused by conventional powder mixing. This technical solution avoids the problem of reinforcement segregation caused by uneven composition of the mixed powder through pre - alloying the original powder. However, although using composite powder instead of mixed powder can solve the problem of reinforcement segregation, obviously, the production cycle of the composite powder is too long, weakening the rapid manufacturing advantage of additive manufacturing. Moreover, the powder particle size required for the additive manufacturing method is usually small, and the yield of qualified fine powder is usually low when preparing composite powder by gas atomization or plasma rotating electrode method, which will also lead to a several - fold increase in powder cost.

[0007] The invention patent CN 119282403 A discloses a method for homogenizing the reinforcing phase in laser welding of aluminum - matrix composites assisted by insert - type ultrasonic vibration, aiming to solve the problem that the reinforcing phase particles cannot be completely homogenously distributed during the laser welding of silicon carbide - reinforced aluminum - matrix composites. The insert - type ultrasonic vibration can play a role in strengthening the stirring of the molten pool and homogenizing the distribution of the reinforcing phase. However, if high - intensity ultrasonic waves are directly inserted into the liquid, it is easy to cause strong turbulence in the molten pool, deteriorate the molten pool spatter, and make the interaction process between the laser and the material more difficult to control. Therefore, there are problems of poor practicability and unstable process to be solved.

[0008] The invention patent CN 111112619 B discloses a method for ultrasonic-assisted laser additive manufacturing of two-dimensional titanium-based functionally graded materials. First, the patent discloses a macroscopically layered and microscopically uniform titanium-based composite material. As is well known, for different configurations of titanium-based composite materials prepared by additive manufacturing, the mechanisms for suppressing the segregation of reinforcements are different. When the reinforcements are uniformly distributed in the alloy matrix, the nucleation sites of the reinforcements are random during the solidification of the molten pool, and the superimposed ultrasonic energy field is more likely to promote the uniform distribution of the reinforcements in the matrix. When the reinforcements are distributed in a network structure in the alloy matrix, the limited network interfaces restrict the nucleation positions of the reinforcements, resulting in the segregation behavior of the reinforcements nucleating at the network structure interfaces being more likely to occur. Secondly, the substrate vibration type ultrasonic-assisted process adopted in this technical solution forms an ultrasonic energy field that is only effective within a certain building height, which has technical defects. That is to say, when the building height of additive manufacturing exceeds this threshold, this process will lose its effectiveness in the dispersion distribution of the reinforcements, and the newly formed reinforcements will significantly segregate again. Therefore, this process cannot fully utilize the technical advantages of additive manufacturing to prepare titanium-based composite materials.

[0009] Combined with the above analysis, it can be known that the feasibility of the existing technology to solve the problem of reinforcement segregation in titanium-based composite materials with a network configuration is relatively low. This is because the segregation behavior of the reinforcements at the network boundaries belongs to the intrinsic property of the solidification path of the molten pool of titanium-based composite materials, and the agglomeration scale will also increase significantly with the increase in the addition amount of the reinforcements. Therefore, in the existing technologies for improving the room temperature mechanical properties of titanium-based composite materials with a network configuration prepared by additive manufacturing, the addition amount of the reinforcements is generally at a relatively low level, which cannot meet the further development needs of titanium-based composite materials with a network configuration. Follow-up ultrasonic vibration has been applied to the direct laser deposition of ceramic-reinforced metal matrix composite materials (reference: invention patent CN 110484914 B). However, it must be noted that the materials targeted by this technical solution are metal matrix composite materials with a uniform configuration, and its purpose is to reduce the internal pores of the sample, evenly distribute the stress, and ensure the uniformity of the solidification structure, so that the reinforcements can fully play the role of dispersion strengthening. Considering that the matrix structure of titanium-based composite materials with a network configuration is inherently non-uniform, the distribution of the reinforcements is also non-uniform, and the actual role of the reinforcements is load transfer strengthening. That is to say, invention patent CN 110484914 B cannot provide a technical inspiration for a solution targeting the regulation of non-uniform microstructure. To sum up, the existing technology cannot solve the problem of reinforcement segregation in titanium-based composite materials with a network configuration prepared by additive manufacturing, which hinders the application and development of titanium-based composite materials with a network configuration. Summary of the Invention

[0010] The present invention aims to provide an additive manufacturing method for a titanium matrix composite material with an improved reinforcement network configuration, so as to solve the inevitable reinforcement segregation problem when preparing a titanium matrix composite material with a high reinforcement content and a network configuration by additive manufacturing. The present invention enables the titanium matrix composite material with a network configuration prepared by additive manufacturing to have high yield strength, high tensile strength and high plasticity at room temperature. Moreover, the technical solution of the present invention also has the advantages of short cycle, low cost and stable process, which is helpful for the further development and application of the titanium matrix composite material with a network configuration.

[0011] An additive manufacturing method for a titanium matrix composite material with an improved reinforcement network configuration provided by the present invention is carried out according to the following method:

[0012] Step 1: After vacuum drying Ti6Al4V and TiB2, perform low-energy ball milling. After ball milling, perform vacuum drying and screening to obtain a mixed powder.

[0013] Step 2: Perform additive manufacturing on the ball-milled material and complete the additive manufacturing of the titanium matrix composite material with an improved reinforcement network configuration through follow-up ultrasonic assistance; the content of the reinforcing phase TiB in the titanium matrix composite material with a network configuration is 3.5 vol.% to 5.0 vol.%.

[0014] Furthermore, the content of the reinforcing phase TiB in the titanium matrix composite material with a network configuration is 4.0 vol.%.

[0015] Furthermore, the nominal particle size of the Ti6Al4V powder is 45 - 106 μm and the purity is 99.99%. The nominal particle size of the TiB2 powder is 1 - 10 μm and the purity is 99.99%.

[0016] Furthermore, the process conditions of the low-energy ball milling in Step 1: rotation speed 200 - 220 rpm, time 5 - 6 h, ball-to-material ratio 4:1 - 5:1, and use argon protection.

[0017] Furthermore, the vacuum drying treatment conditions in Step 1: working temperature 110 - 120 °C, heat preservation time 3 - 4 h, heating rate 2 - 4 °C / min, cooling rate 1 - 3 °C / min, and take it out after cooling to room temperature.

[0018] Furthermore, the particle size of the mixed powder obtained by screening in Step 1 is 150 - 325 mesh.

[0019] Further, the additive manufacturing process described in Step 2: spot size 2 - 3 mm, powder spot size 0.8 - 2.0 mm, powder spot focal length 16 - 18 mm, layer thickness 0.5 - 0.6 mm, first layer thickness 70% - 90%, track pitch 1.0 - 1.5 mm, zigzag filling, starting angle 0°, alternating angle 45° - 90°, filling speed 400 - 800 mm / min, idle running speed 2400 mm / min, filling power 600 - 1500 W, external continuous light output, powder feeding rate 3.0 - 8.0 g / min, powder cylinder temperature 60 - 65 °C, powder feeding carrier gas flow rate 6.0 - 9.0 L / min, protective mirror argon gas flow rate 10.0 - 12.0 L / min, high-temperature circulating water temperature 25 - 26 °C, low-temperature circulating water temperature 22 - 23 °C.

[0020] Further, before performing additive manufacturing on the ball-milled material in Step 2, the forming space of the additive manufacturing equipment is purged and recycled with high-purity argon gas:

[0021] The purity of the high-purity argon gas is 99.999%. The argon gas flow rate during the purging process is 0.6 - 1.0 MPa. After the oxygen content in the forming space is lower than 100 ppm, the purging is turned off and the recycling and purification are started. In the recycling and purification process, copper catalyst is used to absorb oxygen, molecular sieve for water is used to absorb water, and the flow rate of the circulating fan is 90 m 3 / h. After the purging and recycling and purification treatment, the water and oxygen contents in the forming space are both reduced to below 10 ppm, and the gas pressure in the chamber is 0.6 - 0.9 mbar.

[0022] Further, the follow-up ultrasonic-assisted process in Step 2 has an ultrasonic amplitude of 20 - 25 μm, a vibration frequency of 20 kHz, an action spacing of 10 - 15 mm, and a pre-pressure of 120 - 200 N.

[0023] The titanium matrix composite material with an improved reinforcing body network configuration is prepared by using the method of the present invention.

[0024] The present invention has the following beneficial effects:

[0025] On the one hand, the present invention provides an additive manufacturing method for titanium matrix composites that improves the reticular configuration of reinforcements. The present invention innovatively introduces a follow-up ultrasonic assistance into the additive manufacturing process of reticular configuration titanium matrix composites, so that the reticular configuration titanium matrix composites can still obtain a microstructure without reinforcement segregation at a relatively high reinforcement content. At the same time, the material obtains higher room temperature yield strength, tensile strength and higher room temperature plasticity (for example, the room temperature yield strength of the 3.5 vol.% TiB / Ti6Al4V composite prepared by the present invention reaches 1223 MPa, the tensile strength reaches 1316 MPa, and the elongation rate reaches 6.4%). On the other hand, the present invention also provides an additive manufacturing method for this material, which has the advantages of simple operation, short process, stable process, low cost, suitable for mass production, etc., and helps to promote the development and application of reticular configuration titanium matrix composites. Description of the Drawings

[0026] Figure 1 Macroscopic photograph of the 3.5 vol.% TiB / Ti6Al4V composite sample with ultrasonic assistance;

[0027] Figure 2 Macroscopic reticular structure of the 3.5 vol.% TiB / Ti6Al4V composite with ultrasonic assistance;

[0028] Figure 3 SEM photograph of the microstructure of the 3.5 vol.% TiB / Ti6Al4V composite with ultrasonic assistance;

[0029] Figure 4 Room temperature mechanical properties of the 3.5 vol.% TiB / Ti6Al4V composite with ultrasonic assistance;

[0030] Figure 5 SEM photograph of the microstructure of the 5.0 vol.% TiB / Ti6Al4V composite with ultrasonic assistance;

[0031] Figure 6 SEM photograph of the microstructure of the 3.5 vol.% TiB / Ti6Al4V composite without ultrasonic assistance;

[0032] Figure 7 Room temperature mechanical properties of the 3.5 vol.% TiB / Ti6Al4V composite without ultrasonic assistance;

[0033] Figure 8 SEM photograph of the microstructure of the 5.0 vol.% TiB / Ti6Al4V composite without ultrasonic assistance. Detailed Description of the Invention

[0034] To make the objectives, technical solutions and advantages of the embodiments of the present invention more clearly understood, the spirit of the disclosure of the present invention will be described in detail below. After any person skilled in the relevant technical field understands the embodiments of the content of the present invention, the techniques taught by the content of the present invention can be changed and modified without departing from the spirit and scope of the content of the present invention.

[0035] The illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but not to limit the present invention.

[0036] 1. Raw material mixing:

[0037] First, the spherical Ti6Al4V powder treated by vacuum drying and the irregular TiB2 powder are mechanically mixed by low-energy ball milling to obtain an intermediate material. The process parameters of the vacuum drying treatment are as follows: the working temperature is 110 - 120 °C, preferably, including but not limited to any point value among 113 °C, 116 °C, 119 °C or the range value between any two of them; the heat preservation time is 3 - 4 h, preferably, including but not limited to any point value among 3.3 h, 3.6 h, 3.9 h or the range value between any two of them; the heating rate is 2 - 4 °C / min, preferably, including but not limited to any point value among 2.5 °C / min, 3.0 °C / min, 3.5 °C / min or the range value between any two of them; the cooling rate is 1 - 3 °C / min, preferably, including but not limited to any point value among 1.5 °C / min, 2.0 °C / min, 2.5 °C / min or the range value between any two of them. The nominal particle size of the Ti6Al4V powder is 45 - 106 μm, and the purity is 99.99%. The nominal particle size of the TiB2 powder is 1 - 10 μm, and the purity is 99.99%. The mass fraction of the TiB2 powder is 0.05 - 3.00 wt.%, preferably, including but not limited to any point value among 0.50 wt.%, 1.00 wt.%, 1.50 wt.%, 2.00 wt.%, 2.50 wt.% or the range value between any two of them. The process parameters of the low-energy ball milling are as follows: the rotation speed is 200 - 220 rpm, preferably, including but not limited to any point value among 205 rpm, 210 rpm, 215 rpm or the range value between any two of them; the time is 5 - 6 h, preferably, including but not limited to any point value among 5.3 h, 5.6 h, 5.9 h or the range value between any two of them; the ball-to-material ratio is 4:1 - 5:1, preferably, including but not limited to any point value among 4.3:1, 4.6:1, 4.9:1 or the range value between any two of them; argon protection is used. The intermediate material is subjected to vacuum drying and screening treatment to obtain a mixed powder. The process parameters of the vacuum drying treatment are the same as those described above. The particle size of the screening treatment is 150 mesh and 325 mesh. The mixed powder obtained by the above process treatment has uniform particle size and high sphericity, and the ceramic particles can be embedded on the surface of the alloy powder.

[0038] 2. Preparation by additive manufacturing:

[0039] Printing is carried out using a powder feeding type additive manufacturing equipment. First, high-purity argon is used to wash and circulate and purify the forming space of the additive manufacturing equipment. The purity of the high-purity argon is 99.999%. The argon flow rate during the washing process is 0.6 - 1.0 MPa. After the oxygen content in the forming space is lower than 100 ppm, the washing is turned off and the circulation purification is started. In the circulation purification process, copper catalyst is used to absorb oxygen, and molecular sieve for water is used to absorb water. The flow rate of the circulation fan is 90 m3 / h. After washing and circulating purification treatment, the water and oxygen contents in the forming space are both reduced to below 10 ppm, and the gas pressure in the chamber is 0.6 - 0.9 mbar.

[0040] Next, set the additive manufacturing process parameters. The additive manufacturing process parameters include: a spot size of 2 - 3 mm. Preferably, it includes, but is not limited to, a point value of any one of 2.3 mm, 2.6 mm, 2.9 mm or a range value between any two of them; a powder spot size of 0.8 - 2.0 mm. Preferably, it includes, but is not limited to, a point value of any one of 1.0 mm, 1.4 mm, 1.8 mm or a range value between any two of them; a powder spot focal length of 16 - 18 mm. Preferably, it includes, but is not limited to, a point value of any one of 16.5 mm, 17.0 mm, 17.5 mm or a range value between any two of them; a layer thickness of 0.5 - 0.6 mm. Preferably, it includes, but is not limited to, a point value of any one of 0.53 mm, 0.56 mm, 0.59 mm or a range value between any two of them; the first layer thickness is 70% - 90%. Preferably, it includes, but is not limited to, a point value of any one of 75%, 80%, 85% or a range value between any two of them; a track pitch of 1.0 - 1.5 mm. Preferably, it includes, but is not limited to, a point value of any one of 1.16 mm, 1.32 mm, 1.48 mm or a range value between any two of them; zigzag filling; a starting angle of 0°; an alternating angle of 45° - 90°. Preferably, it includes, but is not limited to, a point value of any one of 60°, 70°, 80° or a range value between any two of them; a filling speed of 400 - 800 mm / min. Preferably, it includes, but is not limited to, a point value of any one of 500 mm / min, 600 mm / min, 700 mm / min or a range value between any two of them; an idle running speed of 2400 mm / min; a filling power of 600 - 1500 W. Preferably, it includes, but is not limited to, a point value of any one of 800 W, 1000 W, 1200 W or a range value between any two of them; external continuous light output; a powder feeding rate of 3.0 - 8.0 g / min. Preferably, it includes, but is not limited to, a point value of any one of 4.5 g / min, 6.0 g / min, 7.5 g / min or a range value between any two of them; a powder barrel temperature of 60 - 65 °C. Preferably, it includes, but is not limited to, a point value of any one of 62 °C, 63 °C, 64 °C or a range value between any two of them; a powder feeding carrier gas flow rate of 6.0 - 9.0 L / min. Preferably, it includes, but is not limited to, a point value of any one of 6.5 L / min, 7.5 L / min, 8.5 L / min or a range value between any two of them; a protective mirror argon gas flow rate of 10.0 - 12.0 L / min. Preferably, it includes, but is not limited to, a point value of any one of 10.5 L / min, 11.0 L / min, 11.5 L / min or a range value between any two of them; a high-temperature circulating water temperature of 25 - 26 °C. Preferably, it includes, but is not limited to, a point value of any one of 25.3 °C, 25.6 °C, 25.9 °C or a range value between any two of them; a low-temperature circulating water temperature of 22 - 23 °C. Preferably, it includes, but is not limited to, a point value of any one of 22.3 °C, 22.The point value of any one of 6°C and 22.9°C or the range value between any two of them. In particular, the present invention uses a follow-up ultrasonic vibration device to assist the additive manufacturing process, forming a uniformly distributed network-shaped reinforcement skeleton, achieving the purpose of depolymerizing the network boundary reinforcement clusters, thereby realizing the improvement of the mechanical properties of the network-shaped titanium matrix composite. The follow-up ultrasonic vibration device includes: an ultrasonic generator, an ultrasonic impact needle, and a pneumatic slide table. The process parameters of the follow-up ultrasonic vibration include: the ultrasonic amplitude is 20 - 25 μm, preferably, including but not limited to the point value of any one of 22 μm, 23 μm, and 24 μm or the range value between any two of them; the vibration frequency is 20 kHz, the action spacing is 10 - 15 mm, preferably, including but not limited to the point value of any one of 12 mm, 13 mm, and 14 mm or the range value between any two of them; the pre-pressure is 120 - 200 N, preferably, including but not limited to the point value of any one of 140 N, 160 N, and 180 N or the range value between any two of them.

[0041] Then, 3D printing is carried out using the above process parameters, and a network-shaped titanium matrix composite with high mechanical properties and no reinforcement segregation can be obtained.

[0042] Example 1

[0043] This embodiment provides a network-shaped TiB / Ti6Al4V composite with a high reinforcement content (3.5 vol.%) and its additive manufacturing method, including the following implementation steps.

[0044] Step 1: Weigh 2.06 wt.% of TiB2 powder and 97.94 wt.% of Ti6Al4V powder respectively, and the corresponding TiB content is 3.5 vol.%. Among them, the Ti6Al4V powder is purchased from Xi'an Saillon Additive Technology Co., Ltd., and the TiB2 powder is purchased from Shandong Pengcheng New Ceramic Materials Technology Co., Ltd. The Ti6Al4V powder is spherical, with a nominal particle size of 45 - 106 μm, D10 particle size of 46.73 μm, D50 particle size of 83.34 μm, D90 particle size of 128.0 μm, fluidity of 23.4 s / 50 g, and loose bulk density of 2.59 g / cm 3 and tapped bulk density of 2.88 g / cm 3The TiB2 powder is irregular in shape, with a nominal particle size of 1 - 10 μm and a purity of 99.99%. The symmetrically taken powder is subjected to vacuum drying treatment. The process parameters of the vacuum drying treatment are a working temperature of 120 °C, a holding time of 4 h, a heating rate of 4 °C / min, and a cooling rate of 1 °C / min. After it is cooled to room temperature, it is taken out. The powder after vacuum drying treatment is subjected to low-energy ball milling for powder mixing, and an intermediate material is obtained after mixing. The process parameters of the low-energy ball milling are: a rotation speed of 220 rpm, a time of 5 h, a ball-to-material ratio of 5:1, and argon protection is used. The intermediate material is subjected to vacuum drying and screening treatment to obtain a mixed powder. The process parameters of the vacuum drying treatment are the same as those described above. The particle sizes of the screening treatment are 150 mesh and 325 mesh.

[0045] Step 2: Use a powder-fed additive manufacturing equipment for printing. First, use high-purity argon to wash and circulate and purify the forming space of the additive manufacturing equipment. The purity of the high-purity argon is 99.999%, and it is purchased from Air Liquide (Shanghai) Co., Ltd. The argon flow rate during the washing process is 0.6 MPa. After the oxygen content in the forming space is lower than 100 ppm, the washing is turned off and the circulation and purification are started. In the circulation and purification process, copper catalyst is used to absorb oxygen, and molecular sieve for water is used to absorb water. The flow rate of the circulation fan is 90 m 3 / h. After the washing and circulation and purification treatment, the water and oxygen contents in the forming space are both reduced to below 10 ppm, and the gas pressure in the chamber is 0.9 mbar.

[0046] Then, the additive manufacturing is carried out according to the following parameters, and a reticulated configuration titanium matrix composite material with high mechanical properties and no reinforcement segregation can be obtained. The additive manufacturing process parameters include: a spot size of 2 mm, a powder spot size of 1.0 mm, a powder spot focal length of 17 mm, a layer thickness of 0.5 mm, a first layer thickness of 80%, a track spacing of 1.3 mm, zigzag filling, a starting angle of 0°, an alternating angle of 90°, a filling speed of 420 mm / min, an idle running speed of 2400 mm / min, a filling power of 1500 W, external continuous light output, a powder feeding rate of 4.0 g / min, a powder cylinder temperature of 65 °C, a powder feeding carrier gas flow rate of 9.0 L / min, a protective mirror argon gas flow rate of 12.0 L / min, a high-temperature circulating water temperature of 26 °C, and a low-temperature circulating water temperature of 23 °C. A follow-up type ultrasonic vibration device is used to assist the additive manufacturing process. The process parameters of the follow-up type ultrasonic vibration include: an ultrasonic amplitude of 25 μm, a vibration frequency of 20 kHz, an action spacing of 15 mm, and a pre-pressure of 120 N.

[0047] The macroscopic photograph of the 3.5 vol.% TiB / Ti6Al4V composite material sample with ultrasonic is as Figure 1 shown. By Figure 1It can be seen that the specimens prepared by this method have good formability, smooth surfaces, and no defects such as macroscopic cracks and surface pores. The obtained 3.5 vol.% TiB / Ti6Al4V composite material with ultrasonic treatment has a macroscopic network structure as shown in Figure 2 . The shaded part in the figure is the network structure unit. As can be seen from Figure 2 , a titanium matrix composite material with a network configuration can be prepared by this method. The SEM micrograph of the obtained 3.5 vol.% TiB / Ti6Al4V composite material with ultrasonic treatment is shown in Figure 3 . The boundary of the network structure is outlined by the dashed line in the figure. As can be seen from Figure 3 , when the TiB content is relatively high (3.5 vol.%), the TiB reinforcements distributed at the grain boundaries do not show local segregation, but maintain a certain distance between the TiB whiskers. At the same time, the network structure formed by TiB is relatively uniform. The room temperature mechanical properties of the obtained 3.5 vol.% TiB / Ti6Al4V composite material with ultrasonic treatment are shown in Figure 4 . As can be seen from Figure 4 , the 3.5 vol.% TiB / Ti6Al4V composite material has good room temperature mechanical properties. Its yield strength reaches 1223 MPa, the tensile strength reaches 1316 MPa, and the elongation reaches 6.4%. The synergy of strength and plasticity is achieved. On the one hand, the ultrasonic nonlinear effect creates a sound pressure gradient, provides the driving force for acoustic streaming, stirs the molten pool, and jointly reduces the porosity with the ultrasonic-induced cavitation effect. On the other hand, the follow-up ultrasonic significantly increases the dislocation density by impacting the solid deposition layer at high frequencies, converts the residual tensile stress into compressive stress, and heals the internal defects to improve the density. Therefore, the titanium matrix composite material with a network configuration and a high reinforcement content can simultaneously possess high strength and high plasticity.

[0048] Example 2

[0049] This embodiment provides a TiB / Ti6Al4V composite material with a network configuration and a higher reinforcement content (5.0 vol.%) and its additive manufacturing method, including the following implementation steps.

[0050] Step 1: Weigh 2.94 wt.% TiB2 powder and 97.06 wt.% Ti6Al4V powder respectively, corresponding to a TiB content of 5.0 vol.%. The Ti6Al4V powder is purchased from Xi'an Sialon Additive Technology Co., Ltd., and the TiB2 powder is purchased from Shandong Pengcheng New Ceramic Materials Technology Co., Ltd. The Ti6Al4V powder is spherical, with a nominal particle size of 45 - 106 μm, D10 particle size of 48.22 μm, D50 particle size of 80.74 μm, D90 particle size of 115.17 μm, fluidity of 22.6 s / 50 g, loose bulk density of 2.58 g / cm 3 , and tapped bulk density of 2.87 g / cm 3。The TiB2 powder is irregular in shape, with a nominal particle size of 1 - 10 μm and a purity of 99.99%. The symmetrically taken powder is subjected to vacuum drying treatment. The process parameters of the vacuum drying treatment are a working temperature of 110 °C, a heat preservation time of 3 h, a heating rate of 4 °C / min, and a cooling rate of 1 °C / min. After it is cooled to room temperature, it is taken out. The powder after vacuum drying treatment is subjected to low-energy ball milling for powder mixing, and an intermediate material is obtained after mixing. The process parameters of the low-energy ball milling are: a rotation speed of 200 rpm, a time of 6 h, a ball-to-material ratio of 4:1, and argon protection is used. The intermediate material is subjected to vacuum drying and screening treatment to obtain a mixed powder. The process parameters of the vacuum drying treatment are the same as those described above. The particle sizes of the screening treatment are 150 mesh and 325 mesh.

[0051] Step 2: Use a powder feeding additive manufacturing equipment for printing. First, use high-purity argon to wash and circulate and purify the forming space of the additive manufacturing equipment. The purity of the high-purity argon is 99.999%, and it is purchased from Air Liquide (Shanghai) Co., Ltd. The argon flow rate during the washing process is 0.8 MPa. After the oxygen content in the forming space is lower than 100 ppm, the washing is turned off and the circulation and purification are started. In the circulation and purification process, copper catalyst is used to absorb oxygen, and molecular sieve for water is used to absorb water. The flow rate of the circulation fan is 90 m 3 / h. After the washing and circulation and purification treatment, the water and oxygen contents in the forming space are both reduced to below 10 ppm, and the gas pressure in the chamber is 0.8 mbar.

[0052] Then, the following parameters are used for additive manufacturing, and a reticulated configuration titanium matrix composite material without reinforcement segregation can be obtained. The additive manufacturing process parameters include: a spot size of 3 mm, a powder spot size of 1.7 mm, a powder spot focal length of 16 mm, a layer thickness of 0.6 mm, a first layer thickness of 80%, a track pitch of 1.5 mm, zigzag filling, a starting angle of 0°, an alternating angle of 90°, a filling speed of 420 mm / min, an idle running speed of 2400 mm / min, a filling power of 1500 W, external continuous light output, a powder feeding rate of 4.0 g / min, a powder cylinder temperature of 60 °C, a powder feeding carrier gas flow rate of 7.0 L / min, a protective mirror argon flow rate of 10.0 L / min, a high-temperature circulating water temperature of 25 °C, and a low-temperature circulating water temperature of 23 °C. A follow-up ultrasonic vibration device is used to assist the additive manufacturing process. The process parameters of the follow-up ultrasonic vibration include: an ultrasonic amplitude of 20 μm, a vibration frequency of 20 kHz, an action spacing of 10 mm, and a pre-pressure of 120 N.

[0053] The SEM micrograph of the obtained 5.0 vol.% TiB / Ti6Al4V composite material with ultrasonic is as Figure 5 shown, and the dotted line in the figure outlines the boundary of the reticulated structure. From Figure 5It can be seen that when the TiB content is higher, although the size of TiB coarsens with the increase of TiB content, the reticulated configuration titanium matrix composite without reinforcement segregation can still be prepared by the present method, which proves that the present method still has the potential to further improve the strength and plasticity of the reticulated configuration titanium matrix composite with a higher reinforcement content.

[0054] Comparative Example 1

[0055] The composition of the reticulated configuration titanium matrix composite provided in this comparative example is the same as that in Example 1, but the difference in its preparation method from that in Example 1 is that no ultrasonic assistance is applied during the additive manufacturing process.

[0056] The SEM micrograph of the microstructure of the ultrasonic-free 3.5 vol.% TiB / Ti6Al4V composite obtained is as Figure 6 shown. The dotted line in the figure outlines the boundary of the reticulated structure. By comparison Figure 2 It can be seen that when the TiB content is relatively high, for the reticulated configuration titanium matrix composite directly obtained by 3D printing, significant local segregation of TiB reinforcements occurs at the reticulated boundary, and the spacing between different TiB whiskers is relatively small, which hinders the plastic flow during the deformation of the reticulated configuration titanium matrix composite. The room-temperature mechanical properties of the ultrasonic-free 3.5 vol.% TiB / Ti6Al4V composite obtained are as Figure 7 shown. From Figure 7 it can be seen that when no ultrasonic assistance is applied, the room-temperature mechanical properties of the 3.5 vol.% TiB / Ti6Al4V composite are relatively poor, with a yield strength of only 1001 MPa, a tensile strength of only 1084 MPa, and an elongation of only 3.1%. Compared with Example 1, when no ultrasonic assistance is applied, due to the local segregation of TiB reinforcements, the mechanical properties of the reticulated configuration titanium matrix composite decrease significantly.

[0057] Comparative Example 2

[0058] The composition of the reticulated configuration titanium matrix composite provided in this comparative example is the same as that in Example 2, but the difference in its preparation method from that in Example 2 is that no ultrasonic assistance is applied during the additive manufacturing process.

[0059] The SEM micrograph of the microstructure of the ultrasonic-free 5.0 vol.% TiB / Ti6Al4V composite obtained is as Figure 8 shown. The dotted line in the figure outlines the boundary of the reticulated structure. From Figure 8It can be seen that when the TiB content is higher, not only does the size of TiB further coarsen with the increase in TiB content, but also more obvious local segregation of TiB reinforcements occurs at the network boundaries. When the content of reinforcements is relatively high, a significant increase in the scale of reinforcement clusters will lead to serious damage to the plasticity of the material. Therefore, for the network-structured titanium matrix composites with a higher content of reinforcements prepared by additive manufacturing, if ultrasonic assistance is not applied to solve the problem of reinforcement segregation, the mechanical properties of the network-structured titanium matrix composites cannot be further improved.

Claims

1. An additive manufacturing method for a titanium matrix composite material with an improved reinforcement network configuration, characterized in that It is carried out according to the following method: Step 1: After vacuum drying Ti6Al4V and TiB2, low-energy ball milling is carried out. After ball milling, vacuum drying and screening are carried out to obtain a mixed powder; Step 2: The ball-milled material is subjected to additive manufacturing and assisted by a follow-up ultrasonic wave, that is, the additive manufacturing of the titanium matrix composite material with improved reinforcement network configuration is completed; the content of the reinforcing phase TiB in the network configuration titanium matrix composite material is 3.5 vol.% to 5.0 vol.%.

2. The additive manufacturing method of a titanium matrix composite material for improving the reticular configuration of the reinforcement according to claim 1, characterized in that The content of the reinforcing phase TiB in the network configuration titanium matrix composite material is 4.0 vol.%.

3. The additive manufacturing method of a titanium matrix composite material for improving the reticular configuration of the reinforcement according to claim 1, wherein The nominal particle size of the Ti6Al4V powder is 45 - 106 μm, and the purity is 99.99%. The nominal particle size of the TiB2 powder is 1 - 10 μm, and the purity is 99.99%.

4. The additive manufacturing method of a titanium matrix composite material for improving the reticular configuration of the reinforcement according to claim 1, characterized in that, The process conditions of the low-energy ball milling in Step 1: the rotation speed is 200 - 220 rpm, the time is 5 - 6 h, the ball-to-material ratio is 4:1 - 5:1, and argon protection is used.

5. The additive manufacturing method of a titanium matrix composite material for improving the reticular configuration of the reinforcement according to claim 1, wherein, The vacuum drying treatment conditions in Step 1: the working temperature is 110 - 120 °C, the heat preservation time is 3 - 4 h, the heating rate is 2 - 4 °C / min, the cooling rate is 1 - 3 °C / min, and it is taken out after cooling to room temperature.

6. The additive manufacturing method of a titanium matrix composite for improving the reticular configuration of the reinforcement according to claim 1, characterized in that, The particle size of the mixed powder obtained by screening in Step 1 is 150 - 325 mesh.

7. An additive manufacturing method for a titanium matrix composite material for improving the reticular configuration of a reinforcement, characterized in that, The additive manufacturing process in Step 2: the spot size is 2 - 3 mm, the powder spot size is 0.8 - 2.0 mm, the powder spot focal length is 16 - 18 mm, the layer thickness is 0.5 - 0.6 mm, the first layer thickness is 70% - 90%, the track spacing is 1.0 - 1.5 mm, zigzag filling, the starting angle is 0°, the alternating angle is 45° - 90°, the filling speed is 400 - 800 mm / min, the idle running speed is 2400 mm / min, the filling power is 600 - 1500 W, external continuous light output, the powder feeding rate is 3.0 - 8.0 g / min, the powder cylinder temperature is 60 - 65 °C, the powder feeding carrier gas flow rate is 6.0 - 9.0 L / min, the protective mirror argon gas flow rate is 10.0 - 12.0 L / min, the high-temperature circulating water temperature is 25 - 26 °C, and the low-temperature circulating water temperature is 22 - 23 °C.

8. An additive manufacturing method for a titanium matrix composite material for improving the reticular configuration of a reinforcement, according to claim 1 or 7, characterized in that, Before carrying out additive manufacturing on the ball-milled material in Step 2, the forming space of the additive manufacturing equipment is washed and circulated and purified with high-purity argon: The purity of the high-purity argon is 99.999%, and the argon flow rate during the gas washing process is 0.6 - 1.0 MPa. After the oxygen content in the forming space is lower than 100 ppm, the gas washing is turned off and the cyclic purification is started. In the cyclic purification process, copper catalyst is used to absorb oxygen, and molecular sieve for water is used to absorb water. The flow rate of the circulation fan is 90 m 3 / h. After gas washing and cyclic purification treatment, the water and oxygen contents in the forming space are both reduced to below 10 ppm, and the gas pressure in the chamber is 0.6 - 0.9 mbar.

9. The additive manufacturing method of a titanium matrix composite material for improving the reticular configuration of the reinforcement according to claim 1, characterized in that, The follow-up ultrasonic assistance process in Step 2 is that the ultrasonic amplitude is 20 - 25 μm, the vibration frequency is 20 kHz, the action spacing is 10 - 15 mm, and the pre-pressure is 120 - 200 N.

10. A titanium matrix composite material with improved reinforcement network configuration obtained by using the preparation method according to any one of claims 1 - 9.

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