A high-strength, heat-resistant titanium-based composite material and its preparation method

Abstract

This invention discloses an ultra-high strength heat-resistant titanium-based composite material and its preparation method. The preparation method includes: ball milling and mixing titanium alloy powder, reinforcing phase raw material, and β-stabilizing element powder to obtain a mixed powder, wherein the content of the β-stabilizing element in the mixed powder is 0.01 wt.%–9 wt.%; and using a laser melting deposition additive manufacturing method: delivering the mixed powder to a molten pool on the surface of a substrate via a powder feeding gas flow, melting and depositing it on the substrate surface under laser action, and obtaining the ultra-high strength heat-resistant titanium-based composite material through layer-by-layer deposition. The ultra-high strength heat-resistant titanium-based composite material prepared by this method achieves ultra-high strength, breaking through the performance bottleneck of the ultimate load-bearing capacity of titanium-based composite materials.

Description

Technical Field

[0001] This invention belongs to the field of advanced manufacturing of metal matrix composites, specifically relating to an ultra-high strength heat-resistant titanium matrix composite material and its preparation method. Background Technology

[0002] Titanium matrix composites (TMCs) have enormous application potential in high-end equipment fields such as aerospace and defense due to their high specific strength, excellent heat resistance, and impact resistance. Traditionally, titanium matrix composites improve tensile strength by adding ceramic reinforcing phases, but the introduction of these reinforcing phases sacrifices plasticity and fracture toughness, resulting in significant brittleness, which is fatal for engineering applications.

[0003] Previous studies have focused on designing and controlling the spatial distribution of reinforcing phases in titanium-based composites using additive manufacturing technology. This successfully constructed a non-uniformly distributed reinforcing phase structure within a titanium alloy matrix. Among these, titanium-based composites with a spatially networked reinforcing phase distribution controlled by additive manufacturing exhibited good strength and ductility. However, the limited controllable levels of the reinforcing phase structure and the insufficient strengthening effect induced by a single reinforcing phase in improving the strength of titanium-based composites make them unsuitable for extreme service environments.

[0004] Therefore, as high-end equipment places higher performance requirements on structural materials, it is urgent to optimize the microstructure design and control methods of titanium-based composite materials to improve their mechanical properties, especially their ultimate load-bearing capacity.

[0005] Patent application CN113373335A discloses a method for preparing high-strength titanium-based composite materials. The method involves uniformly mixing titanium powder with fine aluminum carbide and zirconium boride powder, followed by forming, sintering, and hot deformation processes to obtain a high-performance titanium-based composite material. In this invention, aluminum carbide and zirconium boride react with titanium powder during sintering, generating fine, uniformly distributed TiC / TiB reinforcing particles in situ, refining the grain size. Furthermore, Al and Zr elements can dissolve into the matrix to form a solid solution, further enhancing the material's mechanical properties. Simultaneously, due to the grain boundary pinning effect of the fine, uniform TiC / TiB reinforcing particles, high-temperature hot deformation of the titanium-based composite material is achieved, significantly reducing the material's deformation resistance and eliminating residual porosity, ultimately resulting in a high-performance titanium-based composite material product. This invention emphasizes that in addition to TiC / TiB particles reinforcing the titanium matrix, the solid solution formation of Al and Zr elements further enhances the mechanical properties of the composite material, achieving a synergistic effect of reinforcing phases and solid solution reinforcement.

[0006] The invention patent application with publication number CN117226086A discloses a high-strength, high-plasticity, multiphase heterogeneous titanium-based composite material and its preparation method. The invention uses Cu-doped CNTs modification, combined with the construction of a coarse-grained and fine-grained bimodal matrix using titanium alloy powders of different particle sizes, and controls the generation of intergranular nano-reinforcing phases TiC and intragranular Ti2Cu based on plasma sintering, which significantly improves the strength of the titanium-based composite material.

[0007] It is evident that, based on the strengthening of the structure by the reinforcing phase, the mechanical properties of titanium-based composite materials can be further improved by controlling the microstructure of the matrix phase through alloying, which is an effective means to break through the performance bottleneck of titanium-based composite materials. However, there is still room for improvement in the strength and high-temperature performance of the composite materials prepared by the above-mentioned patented method. Summary of the Invention

[0008] This invention provides a method for preparing ultra-high strength heat-resistant titanium-based composite materials. The ultra-high strength heat-resistant titanium-based composite materials prepared by this method achieve ultra-high strength, breaking through the performance bottleneck of the ultimate load-bearing capacity of titanium-based composite materials.

[0009] This invention provides a method for preparing an ultra-high strength, heat-resistant titanium-based composite material, comprising:

[0010] Titanium alloy powder, reinforcing phase raw material, and β-stabilizing element powder are ball-milled to obtain a mixed powder, wherein the content of the β-stabilizing element in the mixed powder is 0.01 wt.% - 9 wt.%.

[0011] The process of manufacturing titanium-based composite materials by laser melting deposition includes: delivering mixed powder to a molten pool on the surface of a substrate via a powder feeding gas flow, melting and depositing the powder onto the substrate surface under the action of a laser, and obtaining an ultra-high strength heat-resistant titanium-based composite material through layer-by-layer deposition.

[0012] By co-designing the spatial distribution of the reinforcing phase and β-stabilizing elements, and based on the network distribution structure of the reinforcing phase, the microstructure of the matrix phase was controlled to construct a two-level structure with a non-uniform network distribution of the reinforcing phase and a non-uniform size distribution of the matrix phase. Compared with a single reinforcing phase structure, by designing a non-uniform structure and increasing the β volume fraction, the upper limit of the tensile strength of the matrix alloy was broken, thus broadening the application fields of titanium-based composite materials.

[0013] More preferably, the content of the β-stabilizing element in the mixed powder is 2 wt.% - 6 wt.%. At this content, the β-phase stabilization, solid solution strengthening, and α-phase refinement effects are best, and the tensile strength of the composite material reaches up to 1500 MPa.

[0014] Meanwhile, further increasing the β phase volume fraction contributes well to solid solution strengthening and grain refinement, allows for a greater number of activated dislocations and slips, resulting in a significant increase in tensile strength. It also avoids excessive β phase content, which would reduce the elastic modulus of the composite material.

[0015] Preferably, the content of the reinforcing phase material in the mixed powder is 0.1 wt.% - 3 wt.%, and the size of the reinforcing phase material is 1 μm - 10 μm.

[0016] By controlling the content and size of the reinforcing phase raw materials, the resulting reinforcing phase exhibits a network structure in the tissue.

[0017] During the solidification of the molten pool and the growth of the microstructure, the initially generated reinforcing phase refines the initial β-Ti size and is enriched at the grain boundaries of β-Ti, constructing a spatial network structure of the reinforcing phase. This further constrains the solidification of the matrix within the network, promotes α-nucleation at the network edge, and hinders its growth, resulting in the formation of nanoscale α-phase at the network edge. The addition of β-stabilizing elements significantly increases the activation energy for grain boundary migration, slows down the growth rate of the α-phase, and expands the β-phase region, which restricts the growth of α-phase grains and promotes the formation of nanoscale α-phase within the network structure. Therefore, under the synergistic effect of the reinforcing phase network structure and β-stabilizing elements, the lath size of the α-phase is significantly reduced, and a non-uniform matrix structure is constructed.

[0018] In terms of reinforcement, the reinforcing phase network structure divides and modularizes the matrix, constrains matrix deformation, and synergistically strengthens through grain refinement and solid solution, thereby improving the yield strength of the composite material. With the addition of β-stabilizing elements, the volume fraction of the β phase increases, which is conducive to activating more dislocations. The network structure encloses dislocations and slip, increasing the barrier to dislocation movement, thus improving the tensile strength of the composite material.

[0019] Preferably, the content of the reinforcing phase material in the mixed powder is 0.01 wt.% - 2 wt.%, and the size of the reinforcing phase material is 1 nm - 100 nm.

[0020] By controlling the content and size of the reinforcing phase raw materials, the resulting reinforcing phase exhibits a network structure in the tissue.

[0021] During the solidification of the molten pool and the growth of the microstructure, the initially formed reinforcing phase refines the initial β-Ti size and simultaneously pins itself to the grain boundaries of β-Ti or precipitates in small amounts within the grains. This subsequently promotes α nucleation and hinders its growth, and nanoscale α phases easily form near the reinforcing phase. Similarly, the addition of β-stabilizing elements significantly increases the activation energy for grain boundary migration, slows down the growth rate of the α phase, and the expanded β-phase region further hinders the growth of α-phase grains, resulting in the formation of nanoscale α phases within the network structure. Therefore, under the synergistic effect of the reinforcing phase and β-stabilizing elements, the lath size of the α phase is significantly reduced, which is beneficial for constructing a non-uniform structure.

[0022] When contributing to strengthening, the dispersed reinforcing phase leads to a more short-axis and homogeneous matrix phase, effectively coordinating deformation and improving the composite material's plastic deformation capacity. When the reinforcing phase exhibits a network distribution, it also serves to constrain matrix deformation. The reinforcing phase synergistically strengthens through grain refinement and solid solution treatment, increasing the composite material's yield strength. With the addition of β-stabilizing elements, the volume fraction of the β phase increases, facilitating the activation of more dislocations. The reinforcing phase increases the barrier to dislocation movement, thereby improving the composite material's tensile strength.

[0023] Preferably, the reinforcing phase raw material is one or more of TiB, TiC, TiN, La2O3, TiB2, and Ti5Si3. This reinforcing phase raw material is a compound or elemental particle capable of chemically reacting with Ti to generate a ceramic reinforcing phase, serving as the initial additive for the reinforcing phase.

[0024] Preferably, the β-stabilizing element includes one or more of molybdenum, vanadium, niobium, tantalum, iron, copper, and silicon.

[0025] Preferably, the laser melting deposition additive manufacturing process has a power of 600 W - 1000 W, a printing rate of 500 mm / min - 1000 mm / min, an overlap rate of 35% - 45%, a layer thickness of 0.3 mm - 0.6 mm, an oxygen content of less than 200 ppm, and is protected by an argon atmosphere.

[0026] Preferably, the ball milling mixing speed is 100-300 r / min. This ensures the sphericity of the matrix alloy powder and the β-stabilizing element powder; higher sphericity is beneficial for powder feeding stability during printing.

[0027] Preferably, the mixed powder is placed in a powder carrier tank and laser melt deposition is performed layer by layer according to the set parameters to complete the printing of the composite material block.

[0028] Preferably, in the laser fused deposition modeling, the laser power should be selected to ensure sufficient remelting depth, so as to achieve secondary remelting and homogenization of the reinforcing phase and β-stabilizing element.

[0029] Preferably, the non-uniform distribution of the reinforcing phase is achieved by adjusting the reinforcing phase parameters to cause the reinforcing phase to pin onto the grain surface, forming a spatial network non-uniform distribution structure of the reinforcing phase.

[0030] Preferably, the non-uniform distribution of the matrix phase size is achieved by controlling the type and parameters of β-stabilizing elements and laser melt deposition forming strategies to promote the formation of nano-sized matrix phases, thus forming a non-uniform matrix phase size structure.

[0031] On the other hand, the present invention also provides an ultra-high strength heat-resistant titanium-based composite material, which is prepared by the ultra-high strength heat-resistant titanium-based composite material.

[0032] The ultra-high strength heat-resistant titanium-based composite material has a tensile strength greater than 1400 MPa, a high-temperature tensile strength greater than 900 MPa at 400 ℃, and a high-temperature tensile strength greater than 750 MPa at 500 ℃.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] This invention utilizes β-stabilizing elements to expand the β-phase region, promoting solid solution strengthening and matrix phase refinement. Furthermore, by controlling the volume fraction of the β-phase, the number of operable dislocations is increased. Therefore, this invention refines the initial β- and α-phases by pinning the reinforcing phase to the grain surface, forming a network or diffuse distribution, and increases the motion barriers for dislocation movement and slip. Subsequently, under the synergistic effect of the β-stabilizing elements and the reinforcing phase, during laser melting and forming, the precipitation and short-axis formation of the nanoscale α-phase in certain regions are promoted, constructing a non-uniform matrix phase structure, which is beneficial for improving the tensile strength and high-temperature performance of titanium-based composite materials.

[0035] Based on additive manufacturing technology, a high-strength, heat-resistant titanium-based composite material was designed and fabricated by integrating β-stabilizing elements, reinforcing phase raw materials, and matrix alloy powder through integrated printing. This method offers controllable forming process, uniform element distribution, and a wider range of parameter adjustments, meeting the requirements for customized and rapid development of key complex structural components in high-end equipment. Attached Figure Description

[0036] Figure 1 The image shows the BSE microstructure of the titanium-based composite material prepared in Example 1. In the image, the black areas at the grain boundaries represent the reinforcing phase, the matrix α phase is lath-like, and the white areas represent the β phase. The nanoscale matrix α phase (white arrows) is surrounded by larger-scale α phase laths or is located at the edge of the network structure.

[0037] Figure 2 This is a BSE image of the microstructure of the titanium-based composite material prepared in Example 2. In the image, the black part at the grain boundaries represents the reinforcing phase, the matrix α phase is lath-like, the white contrast represents the β phase, and the nanoscale matrix α phase (white arrow) is mainly located at the edge of the network structure.

[0038] Figure 3 This is a SEM image of the microstructure of the titanium-based composite material prepared in Example 4. The white particles in the image are the reinforcing phase (white arrows). Detailed Implementation

[0039] The present invention will be further described in detail below with specific embodiments, so as to facilitate understanding and practice by those skilled in the art.

[0040] The β-stabilizing elements provided in specific embodiments of this invention can expand the β-phase region and increase the volume fraction of the β-phase. The β-phase has a body-centered cubic (BCC) structure, which, compared to the hexagonal close-packed (HCP) structure of the α-phase, has more slip systems, improving dislocation movement and slip capability during material deformation. For example, molybdenum (Mo), as an important alloying element in titanium alloys, contributes to performance mainly through β-phase stabilization, solid solution strengthening, grain refinement, and enhanced thermal stability. In particular, it can enhance the high-temperature performance of materials by stabilizing the β-phase and suppressing high-temperature phase transformation. Therefore, based on laser fused deposition modeling (FDM) additive manufacturing technology, combined with β-stabilizing elements, and on the basis of a ceramic-reinforced structure, multiple strengthening mechanisms can be induced through the synergistic design of the spatial structure of the reinforcing phase and the microscopic features of the matrix phase, thus overcoming the bottlenecks in the ultimate load-bearing capacity and high-temperature performance of titanium-based composite materials.

[0041] Example 1: (1) Material selection: TC4 (Ti6Al4V) titanium alloy was used as the matrix alloy with a particle size of 50 μm-150 μm. B4C powder was used as the original additive for the reinforcing phase in situ reaction with a particle size of 2 μm-4 μm and an addition amount of 0.7 wt.%. Mo powder was used as the β-stabilizing element additive with a particle size of 50 μm-150 μm and an addition amount of 1.0 wt.%.

[0042] (2) Preparation of mixed powder: the rotation speed is 200 r / min, the ball milling time is 5 h, and the ball-to-powder ratio is 3:1.

[0043] (3) Additive manufacturing parameters: printing power 800 W, powder feeding rate 5%, scanning speed 700 mm / min, layer thickness 0.37 mm, overlap rate 40%.

[0044] (4) Laser fused deposition modeling: The mixed powder is delivered to the molten pool on the surface of the substrate by the powder feeding gas flow. Under the action of the laser, it melts and deposits on the surface of the substrate. The layers are staggered and overlapped to form a layer. After printing one layer, the laser head moves up 0.37 mm to print the next layer. The number of printing layers is >100. Ultra-high strength heat-resistant titanium-based composite material is obtained by layer-by-layer deposition.

[0045] Figure 1The image shows the BSE microstructure of the ultra-high strength titanium-based composite material prepared in Example 1. It can be seen that the reinforcing phase (TiB + TiC) obtained from the in-situ reaction is pinned to the grain surface, forming a network structure. The morphology of the matrix phase is significantly altered, with a large number of nano-sized α-matrix phases near the reinforcing phase and inside the grains. That is, both micron-sized and nano-sized α-matrix phases are formed within the microstructure, resulting in a non-uniform matrix phase size structure, thereby improving the tensile strength.

[0046] The ultra-high strength titanium-based composite material prepared in Example 1 has a tensile strength of up to 1420 MPa, which is significantly higher than the tensile strength of the matrix alloy (963 MPa) and the tensile strength of the titanium-based composite material reinforced with a single reinforcing phase (1285 MPa). Its high-temperature tensile strength at 400 °C is greater than 900 MPa.

[0047] The reinforcing phase pins to the grain surface, refining the initial β-crystals and α-phase, and increasing the barriers to dislocation and slip motion. Mo, as a β-stabilizing element, belongs to the β isomorphous stabilizing element and is infinitely miscible in β-type titanium alloys, forming a continuous solid solution. By adjusting the addition amount, the volume fraction of the β-phase is increased, thereby improving dislocation movement and slip capabilities. During laser melting and forming, the reinforcing phase and Mo alter the solidification behavior of the matrix phase, promoting the short-axis formation of the α-phase and facilitating the precipitation of nano-α-phase, thus constructing a non-uniform matrix phase structure.

[0048] Based on Example 1, by simultaneously introducing a non-uniformly distributed reinforcing phase structure and a non-uniformly sized matrix phase structure into the matrix, and with the solid solution strengthening of Mo, the problem of limited tensile strength improvement in traditional titanium-based composite materials is overcome, and the present invention has significant effects.

[0049] Example 2: The difference between this example and Example 1 is that the amount of Mo added is 3.0 wt.%.

[0050] With the increase of Mo content, the titanium-based composite material with finer and more equiaxed microstructure has a further improved tensile strength, reaching 1500 MPa.

[0051] Example 3: The difference between this example and Example 1 is that the amount of Mo added is 6.0 wt.%.

[0052] The obtained titanium-based composite material has a tensile strength of 1567 MPa.

[0053] Based on Examples 1-3, introducing β-isomorphic stabilizing elements to regulate the matrix phase properties on the basis of the non-uniform structure of the reinforcing phase is an effective means to improve the mechanical properties of titanium-based composites. Furthermore, according to our previous research results, the network-distributed non-uniform structure of the reinforcing phase plays a key role in synergistically regulating the microstructure and improving properties with the β-stabilizing elements. This is because the network-distributed reinforcing phase constrains the solidification behavior of the matrix phase. It is noteworthy that the network-distributed non-uniform structure of the reinforcing phase, the non-uniform structure of the matrix phase, and Mo solid solution exhibit a synergistic strengthening effect.

[0054] Example 4: (1) Material selection: TC4 (Ti6Al4V) titanium alloy was used as the matrix alloy with a particle size of 50-150 μm. B powder was used as the original additive for the reinforcing phase in the in-situ reaction with a particle size of 50 nm and an addition amount of 0.05 wt.%. Fe powder was used as the β-stabilizing element additive with a particle size of 50-150 μm and an addition amount of 3 wt.%.

[0055] (2) Preparation of mixed powder: the rotation speed is 200 r / min, the ball milling time is 5 h, and the ball-to-powder ratio is 3:1;

[0056] (3) Additive manufacturing parameters: printing power 1000 W, powder feeding rate 4%, scanning speed 500 mm / min, layer thickness 0.52 mm.

[0057] (4) Laser fused deposition modeling: The mixed powder is delivered to the molten pool on the surface of the substrate by the powder feeding gas flow. Under the action of the laser, it melts and deposits on the surface of the substrate. The layers are staggered and overlapped to form a layer. After printing one layer, the laser head moves up 0.37 mm to print the next layer. The number of printing layers is >100. Ultra-high strength heat-resistant titanium-based composite material is obtained by layer-by-layer deposition.

[0058] Figure 3 The image shows the SEM image of the ultra-high strength titanium-based composite material prepared in Example 4. It can be seen that the TiB obtained from the in-situ reaction is diffusely distributed, the α-phase size is reduced, and it exhibits a short rod-like morphology.

[0059] The ultra-high strength titanium-based composite material prepared in Example 4 has a tensile strength of up to 1450 MPa. The fracture Fe, as a β-eutectoid stabilizing element, changed the matrix phase morphology and elongation by 8%. The tensile strength at 400 ℃ is 1120 MPa, and the tensile strength at 500 ℃ is 940 MPa.

[0060] In Example 4, Fe can significantly reduce the β→α phase transition temperature, expand the β phase region, and increase the volume fraction of the β phase; it can inhibit the growth of α phase grains and promote the equiaxed and refined α phase; at the same time, it can cause lattice distortion in the β phase, hinder dislocation movement, and contribute to the strength.

[0061] Compared with Example 4, Examples 1-3 show that, based on the non-uniform structure of the reinforcing phase, both types of β-stabilizing elements can significantly change the matrix phase characteristics, greatly improving the room temperature tensile strength and high temperature strength of the matrix alloy TC4. The present invention has significant effects.

[0062] Comparative Example 1: The difference between this example and Example 1 is that the amount of Mo added is 0. When no β-stabilizing element is added, the strength of the composite material is 1280 MPa, which is significantly lower than the strength of the composite materials obtained in Examples 1-3.

[0063] Comparative Example 2: The difference between this example and Example 1 is that the amount of B4C added is 0. When there is no in-situ self-generated reinforcing phase and no constructed reinforcing phase network structure, the strength of the alloy is 1105 MPa, which is significantly lower than the strength of Example 1.

[0064] As described above, by designing the proportions of the matrix alloy, ceramic phase, and β-stabilizing element, the microstructure of the reinforcing phase and matrix phase can be adjusted and controlled. This synergistic effect of non-uniform reinforcement structure strengthening, β-phase stabilization, and solid solution strengthening breaks through the upper limit of tensile strength in titanium-based composite materials. The embodiments described are not intended to limit the invention in any way. For example, titanium-based composite materials with non-uniform reinforcing phase structure and non-uniform matrix phase size structure obtained by synergistically controlling β-stabilizing elements and ceramic reinforcing phase using additive manufacturing technology are all within the scope of this invention. Therefore, any simple modifications, equivalent substitutions, and improvements made by those skilled in the art to the above embodiments without departing from the scope of the invention's technical solution and based on its technical essence are all within the scope of protection of this invention.

Claims

1. A method for preparing an ultra-high strength heat-resistant titanium-based composite material, characterized in that, include: Titanium alloy powder, reinforcing phase raw material and β-stabilizing element powder are ball-milled and mixed to obtain a mixed powder, wherein the content of the β-stabilizing element in the mixed powder is 0.01 wt.%-9 wt.%. Titanium-based composite materials are obtained by laser melting deposition additive manufacturing, including: sending mixed powder to the molten pool on the surface of the substrate by a powder feeding gas flow, melting and depositing it on the surface of the substrate under the action of a laser, and obtaining ultra-high strength heat-resistant titanium-based composite materials by layer-by-layer deposition. The reinforcing phase material is one or more of TiB, TiC, TiN, La2O3, TiB2, and Ti5Si3; The reinforcing phase material has a content of 0.1 wt.% to 3 wt.% in the mixed powder, and the size of the reinforcing phase material is 1 μm to 10 μm; Alternatively, the content of the reinforcing phase material in the mixed powder is 0.01 wt.%-2 wt.%, and the size of the reinforcing phase material is 1 nm-100 nm; The β-stabilizing element is present in the mixed powder at a content of 2 wt.% to 6 wt.%. The β-stabilizing element includes one or more of molybdenum, vanadium, niobium, tantalum, iron, copper, and silicon; The microstructure of the ultra-high strength heat-resistant titanium-based composite material includes a two-level structure consisting of a non-uniform network distribution of the reinforcing phase and a non-uniform size distribution of the matrix phase.

2. The preparation method of the ultra-high strength heat-resistant titanium-based composite material according to claim 1, characterized in that, The laser melting deposition additive manufacturing process has a power of 600W-1000W, a printing speed of 500mm / min-1000mm / min, an overlap rate of 35%-45%, a layer thickness of 0.3mm-0.6mm, an oxygen content of less than 200ppm, and is protected by an argon atmosphere.

3. The preparation method of the ultra-high strength heat-resistant titanium-based composite material according to claim 1, characterized in that, The ball milling speed is 100 r / min-300 r / min.

4. A high-strength, heat-resistant titanium-based composite material, characterized in that, It is prepared by the ultra-high strength heat-resistant titanium-based composite material.

5. The ultra-high strength heat-resistant titanium-based composite material according to claim 4, characterized in that, The ultra-high strength heat-resistant titanium-based composite material has a room temperature tensile strength greater than 1400 MPa, a high temperature tensile strength greater than 900 MPa at 400℃, and a high temperature tensile strength greater than 750 MPa at 500℃.

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