TiB / Ti-4. 5Al-7Mo titanium-based composite material and preparation method thereof

Abstract

The invention discloses a TiB / Ti-4. 5Al-7Mo titanium-based composite material and a preparation method thereof.The preparation method comprises the steps that TiB serves as a reinforcing phase, Ti serves as a matrix, the TiB / Ti-4. 5Al-7Mo titanium-based composite material is prepared from, by mass, 4-5% of Al, 6-8% of Mo, 0.2-1% of TiB2 and the balance Ti, Ti powder, Al powder, Mo powder and TiB2 powder are weighed and mixed, and mixed powder is obtained; sLM forming process parameters are set, mixed powder is subjected to SLM forming, the TiB / Ti-4. 5Al-7Mo titanium-based composite material is obtained, the mechanical property is remarkably improved, the tensile strength can reach 1100 MPa, meanwhile, the TiB / Ti-4. 5Al-7Mo titanium-based composite material has the plastic deformation capacity, brittle fracture is avoided when the TiB / Ti-4. 5Al-7Mo titanium-based composite material is stressed, the requirements for high strength and light weight of materials in the aerospace field are met, and the TiB / Ti-4. 5Al- and the requirements on mechanical properties and biocompatibility of materials in the field of biomedicine are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite materials, and particularly relates to a TiB / Ti-4.5Al-7Mo titanium matrix composite material and a preparation method thereof. Background Art

[0002] Traditional preparation processes of titanium matrix composite materials, such as powder metallurgy method, casting method, etc., are widely used. Among them: the powder metallurgy method mixes metal powder and reinforcing phase powder, and then makes a composite material through processes such as pressing and sintering. It can effectively control the composition and structure, but there are problems such as easy occurrence of pores during sintering and difficulty in precisely regulating the interfacial bonding strength; the casting method mixes molten metal and reinforcing phase and then casts and forms. The process is simple and the production efficiency is high. However, the reinforcing phase is prone to agglomeration and uneven distribution in the molten metal, affecting the consistency of the properties of the composite material.

[0003] After the rise of additive manufacturing technology, selective laser melting (SLM) technology has gradually been applied to the preparation of titanium matrix composite materials. The SLM technology uses a high-energy density laser beam to melt metal powder layer by layer and directly manufactures complex-shaped parts, with advantages such as high manufacturing precision, near-net shaping, and significant reduction in subsequent processing volume. During the preparation process of titanium matrix composite materials, this technology can precisely control the addition amount and distribution of the reinforcing phase, and is expected to improve the properties of the composite material. Currently, there are already studies on using SLM technology to prepare titanium matrix composite materials with different compositions.

[0004] However, although the SLM technology shows certain potential in the preparation of titanium matrix composite materials, it still faces many challenges. The main problems are: (a) Difficulty in optimizing process parameters: When using the SLM technology to prepare titanium matrix composite materials, there are many process parameters and they are interrelated, such as laser power, scanning speed, line spacing, layer thickness, interlayer rotation angle, and substrate preheating temperature, etc. Small changes in these parameters will affect the structure and properties of the composite material. Currently, there is a lack of systematic theoretical guidance for the optimization of these parameters, and it mostly relies on a large number of experimental explorations, resulting in a long R & D cycle and high costs. (b) Problem of reinforcing phase dispersion: It is difficult to ensure the uniform dispersion of the added reinforcing phase in the metal matrix. During the SLM process, due to the characteristics of rapid laser melting and solidification, the reinforcing phase is prone to agglomeration, resulting in non-uniform internal structure of the composite material, and then causing anisotropy in the material properties, reducing the comprehensive properties and reliability of the material. (c) Limited improvement in mechanical properties: Currently, the titanium matrix composite materials prepared by the SLM technology still cannot fully meet the harsh requirements of some high-end fields for the comprehensive properties of materials in terms of mechanical properties such as tensile strength and elongation. Although certain performance improvements can be obtained under certain parameter combinations, there is still a gap compared with the theoretical expectation, restricting the wide application of titanium matrix composite materials in fields with extremely high material property requirements such as aerospace and biomedicine. Summary of the Invention

[0005] To solve the following technical problems existing in the preparation of TiB / Ti-4.5Al-7Mo titanium matrix composites in the prior art: First, solve the problem of difficult optimization of SLM process parameters, avoid blind experiments, accurately determine the best process parameter combination that can improve the performance of the composite material, shorten the R & D cycle and reduce costs; Second, overcome the problems of uneven dispersion and easy agglomeration of the reinforcing phase TiB in the Ti-4.5Al-7Mo matrix, make the reinforcing phase evenly distributed, reduce the anisotropy of the material properties, and improve the comprehensive performance and reliability of the material; Third, break through the bottleneck of mechanical property improvement in the prior art, and significantly improve the mechanical properties such as tensile strength and elongation of the TiB / Ti-4.5Al-7Mo titanium matrix composite material. The main purpose of the present invention is to provide a preparation method of a TiB / Ti-4.5Al-7Mo titanium matrix composite material, which uses TiB as the reinforcing phase and is prepared by the SLM forming process with optimized process parameters to meet the stringent performance requirements of materials in high-end fields such as aerospace and biomedicine.

[0006] Another object of the present invention is to provide a TiB / Ti-4.5Al-7Mo titanium matrix composite material, which is prepared by the preparation method of the TiB / Ti-4.5Al-7Mo titanium matrix composite material.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] The present invention provides a preparation method of a TiB / Ti-4.5Al-7Mo titanium matrix composite material, comprising the following steps:

[0009] (1) Using TiB as the reinforcing phase and Ti as the matrix, the composition of the components by mass percentage is: Al 4-5wt%, Mo 6-8wt%, TiB 2 0.2-1wt%, and the balance is Ti. Weigh Ti powder, Al powder, Mo powder and TiB 2 powder as raw materials according to the above component ratio;

[0010] (2) Using a three-dimensional powder feeder to mix the Ti powder, Al powder, Mo powder and TiB 2 powder in step (1) until they are evenly dispersed to obtain a mixed powder;

[0011] (3) Set process parameters including laser power, scanning speed, line spacing, layer thickness, interlayer rotation angle and substrate preheating temperature, and perform SLM forming on the mixed powder in step (2) to obtain a TiB / Ti-4.5Al-7Mo titanium matrix composite material.

[0012] Preferably, in step (1), the particle sizes of Ti powder and Al powder are both 15 - 53 μm, the particle size of Mo powder is 3 μm, and the particle size of TiB 2 powder is 1 - 5 μm.

[0013] Preferably, in step (1), the content of Al powder is 4.5 wt%, the content of Mo powder is 7 wt%, and the content of TiB 2 powder is 0.6 wt%, and the balance is Ti powder.

[0014] Preferably, in step (2), mechanical stirring for powder mixing is carried out using a high-speed mechanical stirrer, with a rotation speed of 40 - 120 r / min and a powder mixing time of 8 - 14 h. Compared with a three-dimensional stacking machine, the high-speed mechanical stirrer applies shear force and impact force to the powder through the stirring paddle rotating at a high speed, accelerating powder mixing. The shape, rotation speed, and powder mixing time of its stirring paddle can be flexibly adjusted. For example, using a stirring paddle with a special blade shape (such as serrated or spiral blades), and controlling the powder mixing time within 8 - 10 h under the condition of a rotation speed of 80 - 120 r / min, uniform mixing of the powder can be achieved in a relatively short time, improving production efficiency. However, it is necessary to pay attention to controlling the stirring speed to avoid problems such as powder particle breakage or heat-induced agglomeration caused by too high a speed.

[0015] More preferably, in step (2), the powder mixing time for the mechanical stirring is 12 h, and the rotation speed of the three-dimensional stacking machine is 50 r / min.

[0016] Preferably, in step (2), pneumatic powder mixing is adopted, with an air flow pressure of 0.3 - 0.5 MPa and a powder mixing time of 15 - 20 min. The high-pressure air flow drives the powder to flow in a closed powder mixing chamber, causing the powder to collide and mix with each other. Baffles or flow guiding plates can be added in the design of the powder mixing chamber to change the air flow direction, promoting uniform dispersion of the powder and achieving rapid and efficient powder mixing, and it is not easy to introduce impurities. It is particularly suitable for the preparation of titanium matrix composites with high requirements for impurity content. This method has high requirements for the sealing performance of the equipment and the purity of the gas, and the equipment cost is relatively high.

[0017] Preferably, in step (3), the laser power is 180 - 220 W, the scanning speed is 600 - 1000 mm / s, the line spacing is 120 μm, the layer thickness is 30 μm, the fixed interlayer rotation angle is 67°, and the substrate preheating temperature is 60°C.

[0018] More preferably, in step (3), the laser power is 200 W, the scanning speed is 800 mm / s, the line spacing is fixed at 120 μm, the layer thickness is 30 μm, the fixed interlayer rotation angle is 67°, and the substrate preheating temperature is 60°C.

[0019] The invention also provides a TiB / Ti-4.5Al-7Mo titanium-based composite material, which is prepared by the preparation method of the TiB / Ti-4.5Al-7Mo titanium-based composite material.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. On the one hand, the present invention uses the design and precise proportion of matrix components to uniformly mix and effectively melt the powders during the SLM process. 2 The specific particle size and content of the powder can not only ensure the reinforcement effect, but also avoid problems such as agglomeration caused by excessive content or inappropriate particle size. On the other hand, the TiB / Ti-4.5Al-7Mo titanium-based composite material was obtained by optimizing the SLM molding process parameters, in which Al is an α-stabilizing element and Mo is a β-stabilizing element. The reinforcement phase TiB is composed of Ti+TiB 2 =TiB is generated by reaction, 4.5wt% Al addition can effectively enhance the strength and heat resistance of titanium alloy, 7wt% Mo not only improves the strength of the alloy, but also optimizes its processing performance. When the laser power is 200W and the scanning speed is 800mm / s, the tensile strength reaches 1100MPa and the elongation is 2%, which is significantly different from the composition system of traditional titanium alloy.

[0022] 2. Use a three-dimensional stacker to mix powder for a long time (12h) and at an appropriate speed (50r / min), which can make TiB 2 The powder is more evenly dispersed in the Ti-4.5Al-7Mo matrix. During the SLM molding process, the agglomeration of the reinforcement phase is reduced by precise control of various process parameters. The uniform distribution of the reinforcement phase makes the internal structure of the composite material more uniform, thereby reducing the anisotropy of the material performance, improving the comprehensive performance and reliability of the material, ensuring the consistency of the material performance in different directions, and meeting the use requirements under complex working conditions.

[0023] 3. The TiB / Ti-4.5Al-7Mo titanium-based composite material prepared by the present invention has achieved significant improvement in mechanical properties, and its tensile strength can reach 1100MPa, which provides the possibility for the application of the material in structural parts bearing high loads; a certain elongation (2%) ensures that the material has a certain plastic deformation ability to avoid brittle fracture when subjected to stress, so that the composite material can meet the requirements of high strength and lightweight materials in the aerospace field, as well as the special requirements of mechanical properties and biocompatibility of materials in the biomedical field. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a photo of the TiB / Ti-4.5Al-7Mo titanium-based composite material test sample in the example.

[0025] Figure 2This is a microstructure picture of the TiB / Ti-4.5Al-7Mo titanium-based composite material test sample in the embodiment (size: 100 μm).

[0026] Figure 3 This is a microstructure picture of the TiB / Ti-4.5Al-7Mo titanium-based composite material test sample in the embodiment (size: 10 μm). DETAILED DESCRIPTION

[0027] In order to more fully understand and demonstrate the technical solutions, purposes and advantages of the present invention, the technical effects produced by the present invention are further described in detail and completely in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all. It should be pointed out that for ordinary technicians in this field, other embodiments obtained without departing from the concept of the present invention all belong to the protection scope of the present invention.

[0028] The raw materials used in the following examples are: Ti powder (15-53 μm), Al powder (15-53 μm), Mo powder (3 μm), TiB 2 Powder (1-5 μm, 0.6 wt%).

[0029] Powder mixing equipment: three-dimensional stacker (time: 12h, speed: 50r / min).

[0030] SLM molding process equipment: Yijia 3D MP-250.

[0031] Examples 1-9

[0032] Raw material preparation: Prepare Ti powder with a particle size of 15-53μm, Al powder with a particle size of 15-53μm, Mo powder with a particle size of 3μm, and TiB powder with a particle size of 1-5μm and a content of 0.6wt%. 2 Powder, ensure that the purity and particle size of each powder meet the requirements, and dry the powder before use to remove moisture and impurities.

[0033] Mixing process: Mix the prepared Ti powder, Al powder, Mo powder and TiB 2 The powder is added into the three-dimensional stacker according to the designed proportion, and the mixing time of the three-dimensional stacker is set to 12 hours and the speed is 50r / min. During the powder mixing process, the powder is fully rolled and mixed in the three-dimensional space to make the components evenly distributed, ensuring that the reinforcement phase TiB is evenly dispersed in the matrix powder.

[0034] SLM molding: Yijia 3D MP-250 equipment is used for molding. First, the mixed powder is evenly spread on the molding substrate, and the substrate preheating temperature is set to 60°C. Preheating can reduce thermal stress during the molding process and reduce the risk of part deformation and cracking.

[0035] Examples 1-9 are different in laser power and scanning speed, as shown in Table 1.

[0036] Laser power selection: The laser power is selected as 200 W, which can not only ensure sufficient melting of the powder but also avoid excessive energy input caused by too high power, resulting in defects such as coarse grains.

[0037] Scanning speed setting: The scanning speed is 800 mm / s. The laser energy can be reasonably distributed on the powder layer, making the powder melting and solidification processes relatively stable, which helps to obtain good forming quality and microstructure.

[0038] Other parameters: The line spacing is fixed at 120 μm, the layer thickness is set at 30 μm, and the interlayer rotation angle is 67°. These parameters cooperate with each other to control the melting area and overlapping degree of each layer of powder, ensuring the accuracy and density of the formed part.

[0039] Table 1

[0040]

[0041] In Example 5, the parameters of each step were strictly controlled from raw material preparation to SLM forming to prepare the TiB / Ti-4.5Al-7Mo titanium matrix composite. After testing, its tensile strength reached 1100 MPa and the elongation was 2%. The microstructure of the sample was observed, as Figure 2 and 3 shown. It was found that the TiB phase was uniformly distributed in the Ti-4.5Al-7Mo matrix, and the interfacial bonding between TiB and the matrix was good, without obvious defects and impurities, indicating that the composite material could form a relatively dense organizational structure and obtain good mechanical properties.

[0042] Comparative Example 1

[0043] The difference from Example 1 is that the powder mixing time was shortened to 8 h, and other conditions remained the same. When the prepared sample was tested, it was found that the dispersion degree of TiB 2 was not as uniform as that in Example 1, and TiB 2 agglomeration occurred in some areas. When testing its mechanical properties, the tensile strength was 950 MPa and the elongation was 1.5%. Compared with Example 1, due to insufficient powder mixing resulting in uneven distribution of the reinforcing phase, the mechanical properties decreased significantly.

[0044] Comparative Example 2

[0045] During the SLM molding process, the laser power was adjusted to 160W, and the other parameters were the same as those in Example 1. The prepared sample was tested and found to have a large number of unmelted powder particles inside, with a low density, a tensile strength of only 800MPa, and an elongation of 1%. Compared with Example 1, the lower laser power cannot fully melt the powder, affecting the molding quality and mechanical properties of the material.

[0046] In summary, in the TiB / Ti-4.5Al-7Mo titanium-based composite material of the present invention, Al, as an α-stabilizing element, can effectively stabilize the α-phase of the titanium alloy and improve the strength and heat resistance of the alloy; Mo, as a β-stabilizing element, can expand the β-phase region and enhance the processing performance and toughness of the alloy. The two are reasonably matched and synergistically act in the Ti-5Al-7Mo matrix, so that the composite material has good strength, toughness and processing performance. For example, the α-phase stabilized by Al can maintain structural stability under high temperature conditions, and the β-phase stabilized by Mo can enhance the plastic deformation ability of the material, so that the material can still operate reliably under complex working conditions. In the present invention, the combination of parameters such as power and scanning speed in the SLM forming process is changed to give full play to the advantages of the SLM process, accurately control the heat input and cooling rate in the forming process, optimize the internal organizational structure of the material, and significantly improve the comprehensive performance of the composite material.

[0047] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing a TiB / Ti-4.5Al-7Mo titanium-based composite material, characterized in that: The following steps are involved: (1) TiB is used as a reinforcing phase and Ti is used as a matrix. The components are as follows according to the mass percentage content: Al 4-5wt%, Mo 6-8wt%, TiB2 0.2-1wt%, and the balance is Ti. Ti powder, Al powder, Mo powder and TiB2 powder are weighed as raw materials according to the above component proportions; (2) using a three-dimensional stacking machine to mix the Ti powder, Al powder, Mo powder and TiB2 powder in step (1) until they are uniformly dispersed to obtain a mixed powder; (3) Setting process parameters including laser power, scanning speed, line spacing, layer thickness, interlayer rotation angle and substrate preheating temperature, and performing SLM molding on the mixed powder described in step (2) to obtain a TiB / Ti-4.5Al-7Mo titanium-based composite material.

2. The method for preparing the TiB / Ti-4.5Al-7Mo titanium-based composite material according to claim 1, characterized in that: In step (1), the particle sizes of Ti powder and Al powder are both 15-53 μm, the particle size of Mo powder is 3 μm, and the particle size of TiB2 powder is 1-5 μm.

3. The method for preparing the TiB / Ti-4.5Al-7Mo titanium-based composite material according to claim 1, characterized in that: In step (1), the content of Al powder is 4.5wt%; the content of Mo powder is 7wt%; the content of TiB2 powder is 0.6wt%, and the remainder is Ti powder.

4. The method for preparing the TiB / Ti-4.5Al-7Mo titanium-based composite material according to claim 1, characterized in that: In step (2), the powder mixing is carried out by mechanical stirring with a high-speed mechanical stirrer, the rotation speed is 40-120 r / min, and the mixing time is 8-14 h.

5. The method for preparing the TiB / Ti-4.5Al-7Mo titanium-based composite material according to claim 4, characterized in that: In step (2), the mixing time of the mechanical stirring powder mixing is 12 hours, and the rotation speed of the three-dimensional stacking machine is 50r / min.

6. The method for preparing the TiB / Ti-4.5Al-7Mo titanium-based composite material according to claim 1, characterized in that: In step (2), the powder is mixed by air flow, the air flow pressure is 0.3-0.5 MPa, and the mixing time is 15-20 min.

7. The method for preparing the TiB / Ti-4.5Al-7Mo titanium-based composite material according to claim 1, characterized in that: In step (3), the laser power is 180-220 W, the scanning speed is 600-1000 mm / s, the line spacing is 120 μm, the layer thickness is 30 μm, the fixed interlayer rotation angle is 67°, and the substrate preheating temperature is 60°C.

8. The method for preparing the TiB / Ti-4.5Al-7Mo titanium-based composite material according to claim 7, characterized in that: In step (3), the laser power is 200 W, the scanning speed is 800 mm / s, the line spacing is fixed at 120 μm, the layer thickness is 30 μm, the fixed interlayer rotation angle is 67°, and the substrate preheating temperature is 60°C.

9. A TiB / Ti-4.5Al-7Mo titanium-based composite material, characterized in that: The composite material is prepared by the preparation method of the TiB / Ti-4.5Al-7Mo titanium-based composite material according to any one of claims 1 to 8.

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