A method for preparing high-strength and high-ductility TC4 titanium alloy composite materials by microwave sintering

Abstract

This invention discloses a method for preparing high-strength and ductile TC4 titanium alloy composite materials by microwave sintering, comprising the following steps: 1. Selecting TC4 titanium alloy powder as the matrix and nano-sized silicon carbide powder as the reinforcement; 2. Ball milling and mixing the TC4 titanium alloy powder and silicon carbide powder; 3. Pressing the mixed powder into a mold; 4. Microwave sintering the blank to obtain the high-strength and ductile TC4 titanium alloy composite material. This invention uses (α+β)-type TC4 titanium alloy, adding nano-sized silicon carbide as a reinforcing precursor material, and preparing a composite material with high density and excellent mechanical properties through low-energy ball milling, cold isostatic pressing, and microwave sintering. The preparation process has low cost, wide application range, is easy to implement, and the entire preparation process is short. This provides a practical method for the large-scale industrial production of complex titanium-based composite materials and also provides new ideas for the design and development of ultra-high-strength metal matrix composite materials.

Description

Technical Field

[0001] This invention belongs to the field of advanced structural materials technology, specifically relating to a method for preparing high-strength and high-ductility TC4 titanium alloy composite materials by microwave sintering. Background Technology

[0002] Ceramic particle-reinforced titanium matrix composites have advantages such as simple preparation, low cost, good isotropy, and ultra-high strength, making them promising for applications in key national industrial sectors such as aerospace, weaponry, and petrochemicals.

[0003] Taking Ti-6Al-4V (TC4) titanium alloy as an example, TC4 is the most commercially mature titanium alloy and has a similar coefficient of thermal expansion to ceramic reinforcements such as TiC and Ti5Si3, making it the ideal matrix for high-strength, high-ductility titanium-based composite materials. Currently, the main methods for preparing TC4 titanium alloy composites are casting and powder metallurgy. In composites prepared by casting, the morphology and distribution of the reinforcement are uncontrollable, and the matrix grains tend to grow excessively.

[0004] Conventional powder metallurgy methods mainly include vacuum sintering, hot pressing sintering, and spark plasma sintering. Among these, vacuum sintering produces composite materials with low density, severely impacting performance. Hot pressing and spark plasma sintering produce composite materials with a density exceeding 95%, but their biggest problem is the size limitation imposed by the equipment cavity space, resulting in only small material blanks per sintering cycle. This severely restricts material design and application, and leads to high production costs and long production cycles, posing significant challenges to industrialization. Compared to vacuum sintering and hot pressing sintering, microwave sintering offers a high heating rate and uniform sample heating, significantly improving the microstructure and mechanical properties of sintered products. Compared to spark plasma sintering, it eliminates the need for molds, making it suitable for preparing complex shapes and larger sizes, thus possessing promising industrial application prospects. Microwave sintering technology is primarily used for sintering ceramic materials. Although the traditional notion that metallic materials cannot be heated by microwaves has been overcome, and various bulk metallic materials have been successfully prepared using microwave sintering to heat metal powders, its application in preparing titanium-based composite materials still needs further development. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a method for preparing high-strength and high-ductility TC4 titanium alloy composite materials by microwave sintering. This method uses an (α+β)-type TC4 titanium alloy matrix material, incorporating nano-silicon carbide as a reinforcing precursor material. The composite material with high density and excellent mechanical properties is prepared through low-energy ball milling, cold isostatic pressing, and microwave sintering. The preparation process is low-cost, widely applicable, easy to implement, and time-efficient. This provides a practical method for the large-scale industrial production of complex titanium-based composite materials and offers new ideas for the design and development of novel ultra-high-strength metal matrix composite materials.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing high-strength and high-ductility TC4 titanium alloy composite materials by microwave sintering, characterized in that the method includes the following steps:

[0007] Step 1, Material Selection: (α+β) type TC4 titanium alloy powder is selected as the matrix material, and nano-scale silicon carbide powder is selected as the precursor material for the reinforcement.

[0008] Step 2, Powder Mixing: Place the TC4 titanium alloy powder and silicon carbide powder selected in Step 1 into a ball mill and mix them evenly to obtain a mixed powder.

[0009] Step 3, Molding: The mixed powder obtained in Step 2 is pressed into a blank using a cold isostatic pressing device;

[0010] Step 4, Sintering: The blank obtained in Step 3 is sintered in a microwave sintering furnace to obtain a high-strength and high-plasticity TC4 titanium alloy composite material; the density of the high-strength and high-plasticity TC4 titanium alloy composite material reaches more than 95%, the tensile strength is 1150MPa to 1350MPa, and the elongation after fracture is 6% to 14%.

[0011] This invention uses (α+β)-type TC4 titanium alloy as the matrix material and nano-silicon carbide as the precursor material for reinforcement. A low-energy ball milling method is employed to first mix TC4 powder and silicon carbide powder, followed by microwave sintering to obtain a high-strength, high-ductility TC4 titanium alloy composite material. The purpose of low-energy ball milling in this invention is to ensure uniform mixing of TC4 powder and silicon carbide powder, which is crucial for the uniform heating of the composite powder during subsequent microwave sintering. Furthermore, low-energy ball milling ensures that different powders are mixed uniformly without damaging the shape of the TC4 and silicon carbide powders, maintaining good sphericity and fluidity. This guarantees the high density and excellent mechanical properties of the composite material after microwave sintering.

[0012] In this invention, during the microwave heating process, both electric and magnetic fields act on the material simultaneously. Heating and sintering of metal powder in a microwave field are achieved through both thermal and non-thermal effects. The thermal effect is related to the powder particle size; the smaller the particle size, the better the heating effect in microwaves. However, while maintaining high purity, smaller particle sizes result in higher costs, hindering mass production. Larger particle sizes, although cheaper, significantly reduce microwave sintering efficiency and material density, leading to decreased mechanical properties. Therefore, this invention uses fine alloy powder with a particle size between 15μm and 53μm, improving sintering efficiency and quality while controlling raw material costs.

[0013] This invention incorporates 0.6% to 1.2% nano-silicon carbide powder into the matrix powder. In terms of composition, a certain amount of nano-silicon carbide powder can react in situ with titanium elements in the matrix to generate ceramic reinforcing phases titanium carbide and titanium silicide. Since the silicon carbide adheres to the surface of the TC4 powder after ball milling, the titanium carbide on the powder surface forms a three-dimensional network structure in the internal space of the composite material after sintering. Meanwhile, silicon elements can dissolve in the β phase of the TC4 alloy and precipitate in the form of nano-sized titanium silicide during the sintering process. Therefore, the titanium silicide is dispersed in the composite material. It can not only significantly reduce the grain size of the matrix and improve the strength and plasticity of the material, but also the three-dimensional network structure of titanium carbide and the dispersed distribution of titanium silicide can further increase the mechanical properties of the material. Too low a reinforcing phase content is insufficient to strengthen the TC4 alloy, while too high a reinforcing phase content will seriously reduce the plasticity of the composite material, leading to brittle fracture.

[0014] In terms of the microwave heating mechanism, the silicon carbide introduced in this invention enables the mixed powder to rapidly absorb microwaves at low temperatures, thereby heating itself to a higher temperature. At high temperatures, the mixed powder is continuously heated through a heat transfer mechanism, which ensures that microwave sintering proceeds continuously, efficiently, and stably, thus guaranteeing the uniform microstructure and excellent mechanical properties of the composite material.

[0015] The above-described method for preparing high-strength and high-ductility TC4 titanium alloy composite materials by microwave sintering is characterized in that the particle size of the TC4 titanium alloy powder in step one is 15 μm to 53 μm, and the particle size of the silicon carbide powder is 40 nm. By controlling the particle sizes of the TC4 titanium alloy powder and the silicon carbide powder, this invention ensures that nano-sized silicon carbide adheres to the surface of the TC4 powder during ball milling and easily forms nano- and micro-sized reinforcing phase particles during microwave sintering.

[0016] The above-mentioned method for preparing high-strength and high-ductility TC4 titanium alloy composite materials by microwave sintering is characterized in that the mass content of silicon carbide powder in the mixed powder in step two is 0.6% to 1.2%. In this invention, by controlling the ratio of TC4 titanium alloy powder to silicon carbide powder, nano-silicon carbide powder can react in situ with titanium elements in the matrix to generate ceramic reinforcing phases titanium carbide and titanium silicide. These not only significantly reduce the grain size of the matrix and improve the strength and ductility of the material, but the three-dimensional network structure of titanium carbide and the dispersed distribution of titanium silicide can further increase the mechanical properties of the material. Too low a reinforcing phase content is insufficient to strengthen the TC4 alloy, while too high a reinforcing phase content will severely reduce the ductility of the composite material, leading to brittle fracture.

[0017] The method for preparing high-strength and ductile TC4 titanium alloy composite materials by microwave sintering, as described above, is characterized in that the ball milling speed in step two is 180 rpm to 250 rpm. This invention controls the ball milling speed; at this parameter, the ball milling capacity is relatively low, ensuring uniform powder mixing while maintaining good sphericity, which is beneficial for improving the density of the sintered material. Too low a speed, ball-to-powder ratio, or ball milling time will result in uneven powder mixing and agglomeration of the precursor powder, severely affecting the mechanical properties of the sintered material. Too high a speed, ball-to-powder ratio, or ball milling time will severely damage the sphericity of the powder, reducing the density and mechanical properties of the material.

[0018] The method for preparing high-strength and high-ductility TC4 titanium alloy composite materials by microwave sintering, as described above, is characterized in that the pressing in step three is cold isostatic pressing. This invention increases the density of the material by compacting the mixed powder through cold isostatic pressing.

[0019] The above-described method for preparing high-strength and ductile TC4 titanium alloy composite materials by microwave sintering is characterized in that the microwave sintering temperature in step four is 850℃~1050℃, and the microwave sintering is carried out under an argon atmosphere. This invention avoids severe oxidation of the material by purging with argon gas after vacuuming during microwave sintering. By controlling the parameters of microwave sintering, it avoids incomplete powder sintering caused by excessively low sintering temperatures, which leads to increased porosity and decreased density within the material, and severe grain growth within the composite material caused by excessively high sintering temperatures, which significantly reduces the material's strength.

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

[0021] 1. This invention uses (α+β) type TC4 titanium alloy matrix material, in which nano-silicon carbide is added as a reinforcing phase precursor material. High density and excellent mechanical properties composite material are prepared by low-energy ball milling, cold isostatic pressing and microwave sintering. The preparation process has low cost, wide application range, is easy to implement, and the whole preparation process is short. This provides a practical method for the industrial large-scale production of complex titanium-based composite materials, and also provides new ideas for the design and development of novel ultra-high strength metal matrix composite materials.

[0022] 2. The TC4 titanium alloy composite material prepared by microwave sintering in this invention has a microstructure composed of lath-like (α+β) phases, micron-sized titanium carbide particles with a three-dimensional network structure, and nano-sized dispersed titanium silicide particles. Through fine-grain strengthening, heterogeneous strengthening of the α and β phases, and multi-level, multi-scale strengthening of titanium carbide and titanium silicide particles, the sintered TC4 composite material exhibits excellent mechanical properties.

[0023] 3. The TC4 titanium alloy composite material prepared by this invention has excellent mechanical properties. The density of the composite material reaches more than 95%, the tensile strength is between 1150MPa and 1350MPa, and the elongation after fracture is between 6% and 13%. It is a high-strength and high-elongation composite material.

[0024] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0025] Example 1

[0026] This embodiment includes the following steps:

[0027] Step 1, Material Selection: (α+β) type TC4 titanium alloy with a particle size of 15μm to 53μm is selected as the matrix material, and silicon carbide powder with a particle size of 40nm is selected as the precursor material for the reinforcement.

[0028] Step 2, Powder Mixing: The TC4 titanium alloy powder and silicon carbide powder selected in Step 1 are placed in a ball mill and ball-milled to obtain a mixed powder; the mass content of silicon carbide powder in the mixed powder is 0.6%, the ball milling speed is 180 rpm, the ball-to-powder ratio is 5:1, and the ball milling time is 7 hours.

[0029] Step 3, Molding: The mixed powder obtained in Step 2 is loaded into a mold and pressed into shape using a cold isostatic pressing device at a pressure of 400 MPa to obtain a green body;

[0030] Step 4, Sintering: The blank obtained in Step 3 is sintered in a microwave sintering furnace. Before sintering, a vacuum is drawn and then argon gas is introduced to avoid severe oxidation of the material. The microwave sintering temperature is 1050℃ and the time is 10min. After sintering, a high-strength and high-plasticity TC4 titanium alloy composite material is obtained.

[0031] According to the test results, the high-strength TC4 titanium alloy composite material prepared in this embodiment has a density of 97%, a tensile strength of 1244 MPa, and an elongation after fracture of 9%.

[0032] Comparative Example 1

[0033] This comparative example includes the following steps:

[0034] Step 1, Material Selection: (α+β) type TC4 titanium alloy is selected as the matrix material, and the particle size of TC4 powder is between 15μm and 53μm;

[0035] Step 2, Powder Mixing: Place the TC4 titanium alloy powder selected in Step 1 into a ball mill and mix it evenly. The ball milling speed is 180 rpm, the ball-to-powder ratio is 5:1, and the ball milling time is 7 hours.

[0036] Step 3, Molding: The powder obtained in Step 2 is loaded into a mold and pressed into shape using a cold isostatic pressing device at a pressure of 400 MPa to obtain a blank.

[0037] Step 4, Sintering: The blank obtained in Step 3 is sintered in a microwave sintering furnace. Before sintering, a vacuum is drawn and then argon gas is introduced to avoid severe oxidation of the material. The microwave sintering temperature is 1050℃ and the time is 10min. After sintering, TC4 titanium alloy is obtained.

[0038] The TC4 titanium alloy prepared in this comparative example has a density of 95%, a tensile strength of 908 MPa, and an elongation after fracture of 7%.

[0039] A comparison between Example 1 and Comparative Example 1 shows that the strength of Comparative Example 1 is reduced because no silicon carbide powder was added.

[0040] Example 2

[0041] This embodiment includes the following steps:

[0042] Step 1, Material Selection: (α+β) type TC4 titanium alloy with a particle size of 15μm to 53μm is selected as the matrix material, and silicon carbide powder with a particle size of 40nm is selected as the precursor material for the reinforcement.

[0043] Step 2, Powder Mixing: The TC4 titanium alloy powder and silicon carbide powder selected in Step 1 are placed in a ball mill and ball-milled to obtain a mixed powder; the mass content of silicon carbide powder in the mixed powder is 1.2%, the ball milling speed is 180 rpm, the ball-to-powder ratio is 5:1, and the ball milling time is 7 hours.

[0044] Step 3, Molding: The mixed powder obtained in Step 2 is loaded into a mold and pressed into shape using a cold isostatic pressing device at a pressure of 400 MPa to obtain a green body;

[0045] Step 4, Sintering: The blank obtained in Step 3 is sintered in a microwave sintering furnace. Before sintering, a vacuum is drawn and then argon gas is introduced to avoid severe oxidation of the material. The microwave sintering temperature is 1050℃ and the time is 10min. After sintering, a high-strength and high-plasticity TC4 titanium alloy composite material is obtained.

[0046] According to the test results, the high-strength TC4 titanium alloy composite material prepared in this embodiment has a density of 97%, a tensile strength of 1350 MPa, and an elongation after fracture of 6%.

[0047] Example 3

[0048] This embodiment includes the following steps:

[0049] Step 1, Material Selection: (α+β) type TC4 titanium alloy with a particle size of 15μm to 53μm is selected as the matrix material, and silicon carbide powder with a particle size of 40nm is selected as the precursor material for the reinforcement.

[0050] Step 2, Powder Mixing: The TC4 titanium alloy powder and silicon carbide powder selected in Step 1 are placed in a ball mill and ball-milled to obtain a mixed powder; the mass content of silicon carbide powder in the mixed powder is 0.6%, the ball milling speed is 250 rpm, the ball-to-powder ratio is 5:1, and the ball milling time is 7 hours.

[0051] Step 3, Molding: The mixed powder obtained in Step 2 is loaded into a mold and pressed into shape using a cold isostatic pressing device at a pressure of 400 MPa to obtain a green body;

[0052] Step 4, Sintering: The blank obtained in Step 3 is sintered in a microwave sintering furnace. Before sintering, a vacuum is drawn and then argon gas is introduced to avoid severe oxidation of the material. The microwave sintering temperature is 1050℃ and the time is 10min. After sintering, a high-strength and high-plasticity TC4 titanium alloy composite material is obtained.

[0053] Testing revealed that the high-strength TC4 titanium alloy composite material prepared in this embodiment has a density of 97%, a tensile strength of 1201 MPa, and an elongation after fracture of 10%.

[0054] Example 4

[0055] This embodiment includes the following steps:

[0056] Step 1, Material Selection: (α+β) type TC4 titanium alloy with a particle size of 15μm to 53μm is selected as the matrix material, and silicon carbide powder with a particle size of 40nm is selected as the precursor material for the reinforcement.

[0057] Step 2, Powder Mixing: The TC4 titanium alloy powder and silicon carbide powder selected in Step 1 are placed in a ball mill and ball-milled to obtain a mixed powder; the mass content of silicon carbide powder in the mixed powder is 1.0%, the ball milling speed is 200 rpm, the ball-to-powder ratio is 5:1, and the ball milling time is 7 hours.

[0058] Step 3, Molding: The mixed powder obtained in Step 2 is loaded into a mold and pressed into shape using a cold isostatic pressing device at a pressure of 400 MPa to obtain a green body;

[0059] Step 4, Sintering: The blank obtained in Step 3 is sintered using a microwave sintering furnace. Before sintering, a vacuum is drawn and then argon gas is introduced to prevent severe oxidation of the material. The microwave sintering temperature is 950℃ and the time is 10 minutes. After sintering, a high-strength and high-ductility TC4 titanium alloy composite material is obtained.

[0060] Testing revealed that the high-strength TC4 titanium alloy composite material prepared in this embodiment has a density of 95%, a tensile strength of 1150 MPa, and an elongation after fracture of 13%.

[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing high-strength and high-ductility TC4 titanium alloy composite materials by microwave sintering, characterized in that, The method includes the following steps: Step 1, Material Selection: (α+β) type TC4 titanium alloy powder is selected as the matrix material, and nano-scale silicon carbide powder is selected as the precursor material for the reinforcement. Step 2: Powder Mixing: The TC4 titanium alloy powder and silicon carbide powder selected in Step 1 are placed in a ball mill and ball-milled to obtain a mixed powder; the mass content of silicon carbide powder in the mixed powder is 0.6%~1.2%; Step 3, Molding: The mixed powder obtained in Step 2 is pressed into a blank using a cold isostatic pressing device; Step 4, Sintering: The blank obtained in Step 3 is sintered in a microwave sintering furnace at a temperature of 850℃~1050℃ to obtain a high-strength and high-plasticity TC4 titanium alloy composite material. The density of the high-strength and high-plasticity TC4 titanium alloy composite material reaches more than 95%, the tensile strength is 1150MPa~1350MPa, and the elongation after fracture is 6%~14%.

2. The method for preparing high-strength and high-ductility TC4 titanium alloy composite materials by microwave sintering according to claim 1, characterized in that, The particle size of the TC4 titanium alloy powder in step one is 15μm~53μm, and the particle size of the silicon carbide powder is 40nm.

3. The method for preparing high-strength and high-ductility TC4 titanium alloy composite materials by microwave sintering according to claim 1, characterized in that, The ball milling speed in step two is 180 rpm to 250 rpm.

4. The method for preparing high-strength and high-ductility TC4 titanium alloy composite materials by microwave sintering according to claim 1, characterized in that, The pressing process described in step three is cold isostatic pressing.

5. The method for preparing high-strength and high-ductility TC4 titanium alloy composite materials by microwave sintering according to claim 1, characterized in that, The microwave sintering described in step four is performed under an argon atmosphere.