In-situ reinforced high-sphericity titanium-based composite powder and method for preparing the same

Abstract

The present application relates to a kind of in situ enhanced high sphericity titanium matrix composite powder and its preparation method, belong to titanium matrix composite technical field.To solve the problem that the sphericity of existing titanium matrix composite powder is poor, the interface bonding of reinforcing phase is weak, and it is easy to splash, the present application provides a kind of in situ enhanced high sphericity titanium matrix composite powder, which is composed of titanium alloy matrix and in situ generated TiB+TiC mixed reinforcing phase;TiB+TiC mixed reinforcing phase is obtained by in situ reaction of 2.5% of precursor and titanium matrix by volume fraction;The precursor is B4C and graphite powder with volume ratio of 1:1.The present application generates TiB, TiC reinforcing phase in situ by introducing B4C and graphite powder through vacuum self-consumption arc melting, realizes metallurgical bonding, improves interface stability and high-temperature reliability;After three times of melting, β phase zone hot deformation and high-pressure argon atomization, high-quality powder is obtained, defects are inhibited, flowability and processing adaptability are improved, and forming quality is improved.

Description

Technical Field

[0001] This invention belongs to the field of titanium-based composite material technology, and particularly relates to an in-situ reinforced high sphericity titanium-based composite material powder and its preparation method. Background Technology

[0002] Titanium-based composite materials possess advantages such as low density, high specific strength, high temperature resistance, and corrosion resistance, making them key materials for structural-functional integration in aerospace, biomedical, and marine engineering fields. Laser additive manufacturing technologies, such as selective laser melting (SLM) and laser powder bed melting (L-PBF), can achieve near-net-shape forming of complex components, significantly shortening processes and reducing waste, thus becoming an important direction for the efficient manufacturing of titanium-based composite materials. Laser additive manufacturing requires raw material powders to possess high sphericity, good flowability, concentrated particle size, controllable oxygen content, and uniform distribution of the reinforcing phase to ensure stable powder spreading, dense forming, excellent surface quality, and avoid processing defects.

[0003] TiC and TiB are preferred reinforcing phases for titanium matrices due to their good interfacial compatibility, thermodynamic stability, and high reinforcing efficiency. However, they are difficult to distribute uniformly in titanium alloy matrices. Existing preparation methods all have their own limitations and cannot simultaneously achieve uniformity of reinforcing phase and powder compatibility.

[0004] When preparing composite powders for additive manufacturing by mechanical ball milling, the reinforcing phase and the matrix are only mechanically embedded, resulting in low interfacial bonding strength and easy detachment or interfacial cracking. At the same time, this method is difficult to obtain powders with high sphericity, resulting in poor flowability and affecting powder spreading stability. Moreover, the ceramic particles are exposed on the surface during laser irradiation, which can easily cause defects such as splashing and pores, seriously affecting the forming quality and microstructure uniformity.

[0005] The invention application with application number 202110344701.7 employs an in-situ generation method of TiB / TiC reinforcing phases, while simultaneously introducing externally added nano-Y2O3 to form a composite system. High-temperature strength of the bulk material is enhanced through processes such as melting and forging. However, nanoparticles are prone to agglomeration, and their interfacial bonding with the matrix relies on mechanical mixing. Even when attempting to prepare powders using this technology, defects such as spatter and voids are easily generated during laser forming. The core objective of this method is bulk heat-resistant titanium-based composite materials; it does not offer effective solutions to the inherent problems of reinforcing phase agglomeration and interfacial weakening in powders, thus failing to meet the practical application requirements of laser additive manufacturing. Summary of the Invention

[0006] To address the problems of poor sphericity, weak interfacial bonding, and easy splashing in existing titanium-based composite powders, this invention provides an in-situ reinforced high-sphericity titanium-based composite powder and its preparation method.

[0007] The technical solution of this invention:

[0008] An in-situ reinforced high sphericity titanium-based composite powder is composed of a titanium alloy matrix and an in-situ generated TiB+TiC mixed reinforcing phase. The TiB+TiC mixed reinforcing phase is generated in-situ by reacting 2.5 vol.% of a precursor, wherein the precursor is B4C and graphite powder in a volume ratio of 1:1. The composition of the titanium alloy matrix, by mass fraction, is: Al 6%, Sn 4%, Zr 7%, Nb 1%, Mo 1%, W 1%, and Si 0.2%, with the balance being Ti and unavoidable impurities.

[0009] A method for preparing an in-situ reinforced high sphericity titanium-based composite powder includes the following steps:

[0010] Step 1: Preparation of electrodes for consumable arc melting:

[0011] Using sponge titanium, high-purity aluminum, sponge zirconium, Ti-Sn alloy, Al-Nb alloy, Al-Mo alloy, Al-W alloy and industrial silicon powder as raw materials, and B4C ceramic powder and graphite powder as reinforcing phase precursors, the raw materials and reinforcing phase precursors are accurately weighed according to the target alloy ratio, and fully mixed evenly in an inert atmosphere, and pressed into an electrode for self-consuming arc melting.

[0012] Step 2: Vacuum self-consumable melting:

[0013] The electrode obtained in step one was subjected to three vacuum arc melting processes, each lasting at least 10 minutes, with the vacuum level of the first melting process being ≤1×10⁻⁶. -2 Pa; the vacuum degree for the second and third melting processes was 0.08~0.10 Pa, and the melting current density was 45~70 A / cm². 2 The melting voltage is 20~40V; the ingot is flipped after each melting, and a dense titanium-based composite material ingot is obtained after all melting is completed.

[0014] Step 3: Multi-pass hot forging in the β phase region:

[0015] The ingot obtained in step two is heated to fully enter the β phase region, and then subjected to multi-pass axial hot forging. During the hot forging process, the deformation rate is controlled at 10. -3 ~10 -2 s -1 The overall compression ratio is 40-60%;

[0016] Step 4: Multi-pass hot rolling:

[0017] The ingot obtained from hot forging in step three is heated to 1150~1220℃ and hot rolled in multiple passes. The thinning rate of each pass is controlled at 15~25%. After hot rolling, the ingot is cooled and straightened to obtain titanium-based composite material rods.

[0018] Step 5: High-pressure atomization of inert gas:

[0019] The titanium-based composite material rods obtained in step four are placed in a gas atomization device protected by an inert atmosphere. After evacuation, the titanium-based composite material rods are partially melted by induction heating. The melt and an inert gas with a pressure of 3-5 MPa are sprayed out from the nozzle at the same time. The melt is broken and atomized. The broken droplets are cooled and solidified in the inert atmosphere to form titanium-based composite material powder.

[0020] Step Six: Degassing and Oxygen Control

[0021] The titanium-based composite powder obtained in step five is dried and degassed, with the oxygen content controlled below 0.5 wt%, to obtain titanium-based composite powder with high sphericity.

[0022] Furthermore, in step one, the Sn content in the Ti-Sn alloy is 80wt%, the Nb content in the Al-Nb alloy is 83wt%, the Mo content in the Al-Mo alloy is 52wt%, and the W content in the Al-W alloy is 53wt%.

[0023] Furthermore, the density of the electrode obtained in step one for consumable arc melting is not less than 3.2 g / cm³. 3 .

[0024] Furthermore, the ingot heating temperature in step three is 1200~1280℃, and the holding time is 0.5~1.5h.

[0025] Furthermore, the titanium-based composite rods obtained in step four have a diameter of 50-60 mm and a length of 500-600 mm.

[0026] Furthermore, step five involves evacuating the gas atomizing device to a vacuum level below 1 × 10⁻⁶. -2 Pa, the diameter of the nozzle is 2.5 mm.

[0027] Further, in step five, powder particles with a diameter of 45~105μm are selected as target powders.

[0028] Furthermore, the D50 of the high sphericity titanium-based composite powder described in step six is ​​60~80μm, and the sphericity is not less than 0.95.

[0029] The application of a high sphericity titanium-based composite powder in laser additive manufacturing or powder metallurgy forming, wherein the laser additive manufacturing includes selective laser melting and electron beam melting, and the powder metallurgy forming includes hot isostatic pressing, metal injection molding, and powder metallurgy sintering.

[0030] The beneficial effects of this invention are:

[0031] This invention introduces B4C and graphite powder as reinforcing precursors during vacuum arc melting. Through in-situ reaction, dispersed TiB and TiC reinforcing particles are generated in the titanium matrix, enabling the reinforcing phase and the matrix to form a stable metallurgical bond. This effectively improves the bonding strength and thermal stability of the reinforcing interface, thereby enhancing the high-temperature service reliability of the composite material. At the same time, it avoids the interface weakening problem caused by the addition of ceramic particles, reducing the risk of defects in subsequent processing from the root.

[0032] This invention employs a three-stage vacuum consumable arc melting process combined with ingot turning, which can fully promote the homogenization of alloying elements and reinforcing phase precursors, effectively suppress reinforcing phase agglomeration, and achieve the refinement and dispersion of TiB / TiC particles. At the same time, multi-pass hot deformation in the β phase region, combined with subsequent hot rolling, can refine grains, improve texture, and enhance microstructure isotropy, significantly improving the microstructure uniformity, overall performance stability, and strength-toughness matching of the composite material, thus ensuring the consistency of product performance.

[0033] This invention employs a 4-5 MPa high-pressure argon atomization powder preparation process to successfully obtain composite material powders with high sphericity, concentrated particle size, and controllable oxygen content. This significantly improves the powder's flowability and spreading stability, enhancing its adaptability to high-end powder metallurgy processing fields such as selective laser melting, hot isostatic pressing, and additive manufacturing. Furthermore, the in-situ generation of the reinforcing phase and its embedded dispersion within the powder avoids spatter and defect sources caused by exposed ceramic particles on the powder surface, improving the stability of the laser processing and thus enhancing the density and surface quality of the formed components. The titanium-based composite material powder prepared by this invention, after hot isostatic pressing or powder metallurgy densification, exhibits a tensile strength of not less than 550 MPa at 700°C and an elongation after fracture of not less than 8%. Attached Figure Description

[0034] Figure 1 This is a macroscopic morphology image of the dense titanium-based composite material ingot obtained by three melting processes in step two of Example 1;

[0035] Figure 2 The image shows the macroscopic morphology of the titanium-based composite rod prepared in step four of Example 1.

[0036] Figure 3 This is a microscopic morphology diagram of the titanium-based composite powder obtained in step six of Example 1. Detailed Implementation

[0037] The technical solution of the present invention will be further described below with reference to embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention. In the following embodiments, the process equipment or apparatus not specifically specified are all conventional equipment or apparatus in the art. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commercially available; unless otherwise specified, the technical means used in the embodiments of the present invention are all conventional means well known to those skilled in the art.

[0038] Example 1

[0039] This embodiment provides a method for preparing in-situ reinforced high sphericity titanium-based composite powder, the steps of which are as follows:

[0040] Step 1: Preparation of electrodes for the first vacuum consumable melting process:

[0041] (a) Raw material preparation

[0042] Raw materials meeting purity requirements are selected, specifically including: Grade 0 sponge titanium, high-purity aluminum briquettes, Ti-80wt.%Sn alloy, high-purity sponge zirconium, Al-83wt.%Nb alloy, Al-52wt.%Mo alloy, Al-53wt.%W alloy, and industrial silicon powder. B4C ceramic powder and graphite powder are used as reinforcing phase precursors, with B4C ceramic powder having a purity of no less than 99% and high-purity graphite powder to ensure sufficient in-situ reaction and minimize impurity interference. All raw materials are inspected in advance to remove surface oxide layers, oil, and impurities, laying the foundation for subsequent batching and mixing.

[0043] (ii) Ingredients and Mixing

[0044] The titanium alloy matrix, by mass fraction, consists of: Al 6%, Sn 4%, Zr 7%, Nb 1%, Mo 1%, W 1%, Si 0.2%, with the balance being Ti and unavoidable impurities. According to the target alloy design proportions, the total amount of precursor added is 2.5 vol.%, and the precursor is B4C and graphite powder in a 1:1 volume ratio.

[0045] All raw materials were accurately weighed, with a weighing accuracy controlled within ±0.1%, to ensure accurate component proportions. The weighed raw materials were then placed in a drying chamber for degassing at 150℃ for 6 hours. They were then transferred to a mixing device and mixed under the protection of high-purity argon (purity conforming to GB / T4842). Block metals and metal master alloys were pre-crushed to appropriate sizes and thoroughly mixed with the powdered raw materials for 3 hours to ensure uniform distribution of alloying elements and reinforcing phase precursors, thus preventing component segregation during subsequent smelting.

[0046] (III) Electrode Preparation

[0047] The uniformly mixed raw materials are fed into a pressing and molding equipment to form electrodes that meet the charging and melting requirements of vacuum self-consuming arc melting (VAR) equipment. The pressing pressure is 200 MPa, and the pressing pressure is controlled within a suitable range to ensure that the electrode density is not less than 3.2 g / cm³. 3 For larger electrodes, argon-protected plasma beam welding can be used to assemble the electrode blocks into electrode rods. The welded areas can then be machined to remove surface contaminants and welding defects, preventing welding impurities from affecting the subsequent melting quality.

[0048] Step 2: Vacuum self-consumable melting:

[0049] The electrodes were melted three times using vacuum consumable arc melting technology, with strict control of melting parameters throughout to ensure uniform composition and dense microstructure of the ingot. Each melting cycle lasted 15 minutes, with specific parameters as follows:

[0050] The electrode rod obtained in step one was placed in a vacuum consumable melting furnace for the first melting process. When the vacuum level in the furnace reached 1×10⁻⁶, -2 Arc initiation and melting should be performed below Pa; during the melting process, the vacuum level of the melting chamber should be maintained at no higher than 1×10⁻⁶. -2 Pa, controlling the melting voltage at 32V and the melting current density at 55A / cm². 2 , thus obtaining one ingot.

[0051] The obtained primary ingot is machined to prepare an electrode rod that meets the requirements for charging and melting in a vacuum consumable melting furnace. The surface of the electrode rod, especially the welded parts, is machined to remove surface contaminants. The resulting electrode rod is then placed in a vacuum consumable melting furnace for a second melting process, with a melting voltage of 32V and a melting current density of 55A / cm³. 2 The vacuum degree was controlled at 0.09 Pa to obtain a secondary ingot.

[0052] The obtained secondary ingots were machined to prepare electrode rods that meet the requirements of vacuum consumable melting. The surface of the electrode rods, especially the welded parts, was machined to remove surface contaminants. The resulting electrode rods were then placed in a vacuum consumable melting furnace for a third melting process, with a melting voltage of 32V and a melting current density of 55A / cm³. 2 The vacuum degree was controlled at 0.09 Pa to obtain three-stage ingot casting.

[0053] During the smelting process, the reinforcing precursor B4C and graphite powder react chemically with titanium to generate dispersed TiB and TiC reinforcing particles in situ. The specific reaction pathways are: Ti + C → TiC, 5Ti + B4C → 4TiB + TiC. This in-situ reaction method ensures high interfacial bonding strength between the reinforcing particles and the titanium matrix, resulting in good thermodynamic stability. It effectively avoids problems such as reinforcing phase agglomeration and poor interfacial bonding inherent in the external particle method. Simultaneously, it refines the size of the reinforcing particles, improving the mechanical properties of the composite powder.

[0054] To further promote homogenization of composition and reinforcing phase, the ingot was flipped after each melting process to ensure thorough mixing of the melt and reduce component segregation. After three melting processes, a dense titanium-based composite material ingot with dimensions of Φ296mm × 570mm and a weight of approximately 177kg was finally obtained. Figure 1 As shown, the ingot is free of defects such as porosity and cracks, and the reinforcing phase is initially dispersed.

[0055] Step 3: Multi-pass hot forging in the β phase region:

[0056] The ingots obtained from the three melting processes were fed into a heating furnace and heated to 1240℃ to enter the β-phase region. They were held at this temperature for 1 hour to ensure uniform heating and full entry into the β-phase region. Axial compression force was applied using a hydraulic hammer to perform multiple axial hot forging passes on the ingots. The deformation rate was controlled at 5 × 10⁻⁶ during the hot forging process. -3 s -1 The total compression ratio is 50%. Through five deformation passes, the ingot is extended along the length direction and the cross-sectional diameter is reduced. Finally, the ingot diameter is reduced from Φ296mm to Φ110mm, and the total deformation compression ratio is controlled between 40 and 50%.

[0057] Hot forging in the β phase region further refines the ingot microstructure, ensuring uniform distribution of the TiB and TiC reinforcing phases, eliminating internal defects in the ingot, and improving the ingot's plasticity and density.

[0058] Step 4: Multi-pass hot rolling:

[0059] The hot-forged ingot billet was fed back into the heating furnace and heated to 1180℃, held for 1 hour to ensure uniform billet temperature, and then subjected to four passes of hot rolling. Rolling deformation was controlled by gradually reducing the roll gap, with the thinning rate controlled at 20% per pass to avoid excessive deformation in a single pass that could lead to billet cracking. Through multiple passes of hot rolling, the grain size and reinforcing phase particles were further refined, improving the uniformity of the material structure and laying a good microstructure foundation for subsequent powder production.

[0060] After hot rolling, the material is cooled and straightened to obtain titanium-based composite rods with a diameter of approximately Φ55mm and a length of 550mm. Figure 2As shown, the rod surface is smooth, the dimensions are uniform, and there are no obvious scratches, cracks, or other defects. The TiB and TiC reinforcing phases inside the rod are finely dispersed and evenly distributed, with a dense structure and stable properties, meeting the raw material requirements for subsequent gas atomization powder production.

[0061] Step 5: High-pressure atomization of inert gas:

[0062] The obtained titanium-based composite rods were placed in a gas atomization device protected by high-purity argon gas. The vacuum level inside the device was first evacuated to below 1 × 10⁻⁶. -2 Pa, removes air and impurity gases from the device.

[0063] The titanium-based composite rods are partially melted by induction heating. The melt, along with 4MPa high-pressure argon gas, is ejected at high speed from a nozzle with a diameter of 2.5mm. Under the action of the high-pressure argon gas flow, the melt is broken and atomized. The atomization process is carried out under the protection of high-purity argon gas to prevent the melt from oxidizing. The broken droplets are rapidly cooled and solidified in the high-purity argon gas environment to form titanium-based composite powder with good sphericity and uniform distribution of reinforcing phase particles.

[0064] During the atomization process, the nozzle size and argon pressure are strictly controlled to avoid defects such as satellite spheres and irregular shapes in the powder, and to ensure that the sphericity of the powder meets the standards.

[0065] The atomized powder is collected from the atomizing device and allowed to cool naturally to room temperature. Then, it is sieved using a multi-stage sieving method to select powder particles with a diameter of 45–105 μm as the target powder. The powder's particle size characteristic is a D50 of 60–80 μm. Powder within this size range exhibits good flowability and formability, making it suitable for subsequent 3D printing, powder metallurgy, and other molding processes. The sieving process removes excessively large or small particles and impurities, ensuring uniform powder particle size.

[0066] Step Six: Degassing, Oxygen Control, and Encapsulation:

[0067] The sieved target powder is placed under an inert atmosphere or vacuum for low-temperature drying and degassing. The degassing temperature is 100℃, and the degassing time is 4 hours. The degassing temperature is controlled within a suitable range to remove adsorbed moisture and gas from the powder surface, effectively reducing the powder oxygen content to below 0.15 wt.%. Strict control of oxygen content can prevent powder oxidation, ensuring the mechanical properties and corrosion resistance of subsequently molded parts, meeting the requirements of high-end applications.

[0068] After degassing, the powder is packaged and stored under the protection of high-purity argon gas. The packaging container is selected with good sealing performance to prevent air and moisture from entering and to ensure stability during storage.

[0069] like Figure 3As shown, the sphericity of the packaged powder is not less than 0.95, there is no obvious agglomeration inside the powder, the particle size distribution is uniform, the oxygen content is ≤0.15wt.%, the total amount of precursor added is 2.5vol.%, and all performance indicators are stable, and it can be directly used for subsequent molding and processing.

[0070] The titanium-based composite powder obtained in this embodiment was densified by hot isostatic pressing at 1200℃ and 100MPa for 2 hours. The tensile strength at 700℃ was 586MPa and the elongation after fracture was 9.1%.

[0071] Example 2

[0072] This embodiment provides a method for preparing in-situ reinforced high sphericity titanium-based composite powder, the steps of which are as follows:

[0073] Step 1: Preparation of electrodes for the first vacuum consumable melting process:

[0074] (a) Raw material preparation

[0075] Raw materials meeting purity requirements are selected, specifically including: Grade 0 sponge titanium, high-purity aluminum briquettes, Ti-80wt.%Sn alloy, high-purity sponge zirconium, Al-83wt.%Nb alloy, Al-52wt.%Mo alloy, Al-53wt.%W alloy, and industrial silicon powder; B4C ceramic powder and graphite powder are selected as reinforcing phase precursors.

[0076] (ii) Ingredients and Mixing

[0077] The titanium alloy matrix, by mass fraction, consists of: Al 6%, Sn 4%, Zr 7%, Nb 1%, Mo 1%, W 1%, Si 0.2%, with the balance being Ti and unavoidable impurities. According to the target alloy design proportions, the total amount of precursor added is 2.5 vol.%, and the precursor is a 1:1 volume ratio of B4C and graphite powder.

[0078] All raw materials were accurately weighed, with a weighing accuracy controlled within ±0.1%, to ensure accurate component proportions. The weighed raw materials were then placed in a drying chamber for degassing at 150℃ for 6 hours. They were then transferred to a mixing device and mixed under the protection of high-purity argon (purity conforming to GB / T4842). Block metals and metal master alloys were pre-crushed to appropriate sizes and thoroughly mixed with the powdered raw materials for 3 hours to ensure uniform distribution of alloying elements and reinforcing phase precursors, thus preventing component segregation during subsequent smelting.

[0079] (III) Electrode Preparation

[0080] The uniformly mixed raw materials are fed into a pressing and molding equipment to form electrodes that meet the charging and melting requirements of vacuum self-consuming arc melting (VAR) equipment. The pressing pressure is 200 MPa, and the pressing pressure is controlled within a suitable range to ensure that the electrode density is not less than 3.2 g / cm³. 3 For larger electrodes, argon-protected plasma beam welding can be used to assemble the electrode blocks into electrode rods. The welded areas can then be machined to remove surface contaminants and welding defects, preventing welding impurities from affecting the subsequent melting quality.

[0081] Step 2: Vacuum self-consumable melting:

[0082] The electrodes were melted three times using vacuum consumable arc melting technology, with strict control of melting parameters throughout to ensure uniform composition and dense microstructure of the ingot. Each melting cycle lasted 15 minutes, with specific parameters as follows:

[0083] The electrode rod obtained in step one was placed in a vacuum consumable melting furnace for the first melting process. When the vacuum level in the furnace reached 1×10⁻⁶, -2 Arc initiation and melting should be performed below Pa; during the melting process, the vacuum level of the melting chamber should be maintained at no higher than 1×10⁻⁶. -2 Pa, controlling the melting voltage at 27V and the melting current density at 45A / cm². 2 , thus obtaining one ingot.

[0084] The obtained primary ingot is machined to prepare an electrode rod that meets the requirements for charging and melting in a vacuum consumable melting furnace. The surface of the electrode rod, especially the welded parts, is machined to remove surface contaminants. The resulting electrode rod is then placed in a vacuum consumable melting furnace for a second melting process, with a melting voltage of 27V and a melting current density of 45A / cm³. 2 The vacuum degree was controlled at 0.08 Pa to obtain a secondary ingot.

[0085] The obtained secondary ingots were machined to prepare electrode rods that meet the requirements of vacuum consumable melting. The surface of the electrode rods, especially the welded parts, was machined to remove surface contaminants. The resulting electrode rods were then placed in a vacuum consumable melting furnace for a third melting process, with a melting voltage of 27V and a melting current density of 45A / cm³. 2 The vacuum degree was controlled at 0.08 Pa to obtain three-stage ingot casting.

[0086] During the smelting process, the reinforcing precursor B4C and graphite powder react chemically with titanium to generate dispersed TiB and TiC reinforcing particles in situ. The specific reaction pathways are: Ti + C → TiC, 5Ti + B4C → 4TiB + TiC. This in-situ reaction method ensures high interfacial bonding strength between the reinforcing particles and the titanium matrix, resulting in good thermodynamic stability. It effectively avoids problems such as reinforcing phase agglomeration and poor interfacial bonding inherent in the external particle method. Simultaneously, it refines the size of the reinforcing particles, improving the mechanical properties of the composite powder.

[0087] To further promote the homogenization of composition and reinforcing phase, the ingot was flipped after each melting process to ensure thorough mixing of the melt and reduce component segregation. After three melting processes, a dense titanium-based composite material ingot with dimensions of Φ296mm×570mm and a weight of approximately 177kg was finally obtained. The ingot was free of defects such as porosity and cracks, and the reinforcing phase was initially dispersed.

[0088] Step 3: Multi-pass hot forging in the β phase region:

[0089] The ingots obtained from the three melting processes were fed into a heating furnace and heated to 1200℃ to enter the β-phase region. They were held at this temperature for 0.5 hours to ensure uniform heating and full entry into the β-phase region. Axial compressive force was applied using a hydraulic hammer to perform multi-pass axial hot forging of the ingots. The deformation rate was controlled at 1×10⁻⁶ during the hot forging process. -3 s -1 The total compression ratio is 40%. Through four passes of deformation, the ingot is extended along the length direction and the cross-sectional diameter is reduced. Finally, the ingot diameter is reduced from Φ296mm to Φ100mm, and the total deformation compression ratio is controlled between 40% and 50%.

[0090] Hot forging in the β phase region further refines the ingot microstructure, ensuring uniform distribution of the TiB and TiC reinforcing phases, eliminating internal defects in the ingot, and improving the ingot's plasticity and density.

[0091] Step 4: Multi-pass hot rolling:

[0092] The hot-forged ingot billet is then fed back into the heating furnace and heated to 1150℃, held for 0.5 hours to ensure uniform billet temperature, and then subjected to five passes of hot rolling. Rolling deformation is controlled by gradually reducing the roll gap, with the thinning rate controlled at 15% per pass to avoid excessive deformation in a single pass that could lead to billet cracking. Through multiple passes of hot rolling, the grain size and reinforcing phase particles are further refined, improving the uniformity of the material structure and laying a good microstructure foundation for subsequent powder production.

[0093] After hot rolling, the titanium-based composite rods with a diameter of approximately Φ50mm and a length of 500mm are obtained through cooling and straightening. The rods have a smooth surface, uniform dimensions, and no obvious scratches, cracks, or other defects. The TiB and TiC reinforcing phases inside the rods are finely dispersed and uniformly distributed, with a dense structure and stable properties, meeting the raw material requirements for subsequent gas atomization powder production.

[0094] Step 5: High-pressure atomization of inert gas:

[0095] The obtained titanium-based composite rods were placed in a gas atomization device protected by high-purity argon gas. The vacuum level inside the device was first evacuated to below 1 × 10⁻⁶. -2 Pa, removes air and impurity gases from the device.

[0096] The titanium-based composite rods are partially melted by induction heating. The melt, along with 3MPa high-pressure argon gas, is ejected at high speed from a nozzle with a diameter of 2.5mm. Under the action of the high-pressure argon gas flow, the melt is broken and atomized. The atomization process is carried out under the protection of high-purity argon gas to prevent the melt from oxidizing. The broken droplets are rapidly cooled and solidified in the high-purity argon gas environment to form titanium-based composite powder with good sphericity and uniform distribution of reinforcing phase particles.

[0097] During the atomization process, the nozzle size and argon pressure are strictly controlled to avoid defects such as satellite spheres and irregular shapes in the powder, and to ensure that the sphericity of the powder meets the standards.

[0098] The atomized powder is collected from the atomizing device and allowed to cool naturally to room temperature. Then, it is sieved using a multi-stage sieving method to select powder particles with a diameter of 45–105 μm as the target powder. The powder's particle size characteristic is a D50 of 60–80 μm. Powder within this size range exhibits good flowability and formability, making it suitable for subsequent 3D printing, powder metallurgy, and other molding processes. The sieving process removes excessively large or small particles and impurities, ensuring uniform powder particle size.

[0099] Step Six: Degassing, Oxygen Control, and Encapsulation:

[0100] The sieved target powder is placed under an inert atmosphere or vacuum for low-temperature drying and degassing. The degassing temperature is 100℃, and the degassing time is 4 hours. The degassing temperature is controlled within a suitable range to remove adsorbed moisture and gas from the powder surface, effectively reducing the powder oxygen content to below 0.15 wt.%. Strict control of oxygen content can prevent powder oxidation, ensuring the mechanical properties and corrosion resistance of subsequently molded parts, meeting the requirements of high-end applications.

[0101] After degassing, the powder is packaged and stored under the protection of high-purity argon gas. The packaging container is selected with good sealing performance to prevent air and moisture from entering and to ensure stability during storage.

[0102] The sphericity of the encapsulated powder is not less than 0.95, there is no obvious agglomeration inside the powder, the particle size distribution is uniform, the oxygen content is ≤0.15wt.%, the total amount of precursor added is 2.5vol.%, and all performance indicators are stable, and it can be directly used for subsequent molding and processing.

[0103] The titanium-based composite powder obtained in this embodiment was densified by hot isostatic pressing at 1200℃ and 100MPa for 2 hours. The tensile strength at 700℃ was 580MPa and the elongation after fracture was 8%.

[0104] Example 3

[0105] This embodiment provides a method for preparing in-situ reinforced high sphericity titanium-based composite powder, the steps of which are as follows:

[0106] Step 1: Preparation of electrodes for the first vacuum consumable melting process:

[0107] (a) Raw material preparation

[0108] Raw materials meeting purity requirements are selected, specifically including: Grade 0 sponge titanium, high-purity aluminum briquettes, Ti-80wt.%Sn alloy, high-purity sponge zirconium, Al-83wt.%Nb alloy, Al-52wt.%Mo alloy, Al-53wt.%W alloy, and industrial silicon powder; B4C ceramic powder and graphite powder are selected as reinforcing phase precursors.

[0109] (ii) Ingredients and Mixing

[0110] The titanium alloy matrix, by mass fraction, consists of: Al 6%, Sn 4%, Zr 7%, Nb 1%, Mo 1%, W 1%, Si 0.2%, with the balance being Ti and unavoidable impurities. According to the target alloy design proportions, a 2.5 vol.% reinforcing phase precursor is added, consisting of B4C and graphite powder in a 1:1 volume ratio.

[0111] All raw materials were accurately weighed, with a weighing accuracy controlled within ±0.1%, to ensure accurate component proportions. The weighed raw materials were then placed in a drying chamber for degassing at 150℃ for 6 hours. They were then transferred to a mixing device and mixed under the protection of high-purity argon (purity conforming to GB / T4842). Block metals and metal master alloys were pre-crushed to appropriate sizes and thoroughly mixed with the powdered raw materials for 3 hours to ensure uniform distribution of alloying elements and reinforcing phase precursors, thus preventing component segregation during subsequent smelting.

[0112] (III) Electrode Preparation

[0113] The uniformly mixed raw materials are fed into a pressing and molding equipment to form electrodes that meet the charging and melting requirements of vacuum self-consuming arc melting (VAR) equipment. The pressing pressure is 200 MPa, and the pressing pressure is controlled within a suitable range to ensure that the electrode density is not less than 3.2 g / cm³. 3 For larger electrodes, argon-protected plasma beam welding can be used to assemble the electrode blocks into electrode rods. The welded areas can then be machined to remove surface contaminants and welding defects, preventing welding impurities from affecting the subsequent melting quality.

[0114] Step 2: Vacuum self-consumable melting:

[0115] The electrodes were melted three times using vacuum consumable arc melting technology, with strict control of melting parameters throughout to ensure uniform composition and dense microstructure of the ingot. Each melting cycle lasted 15 minutes, with specific parameters as follows:

[0116] The electrode rod obtained in step one was placed in a vacuum consumable melting furnace for the first melting process. When the vacuum level in the furnace reached 1×10⁻⁶, -2 Arc initiation and melting should be performed below Pa; during the melting process, the vacuum level of the melting chamber should be maintained at no higher than 1×10⁻⁶. -2 Pa, controlling the melting voltage at 40V and the melting current density at 70A / cm². 2 , thus obtaining one ingot.

[0117] The obtained primary ingot is machined to prepare an electrode rod that meets the requirements for charging and melting in a vacuum consumable melting furnace. The surface of the electrode rod, especially the welded parts, is machined to remove surface contaminants. The resulting electrode rod is then placed in a vacuum consumable melting furnace for a second melting process, with a melting voltage of 40V and a melting current density of 70A / cm³. 2 The vacuum degree was controlled at 0.1 Pa to obtain a secondary ingot.

[0118] The obtained secondary ingots were machined to prepare electrode rods that meet the requirements of vacuum consumable melting. The surface of the electrode rods, especially the welded parts, was machined to remove surface contaminants. The resulting electrode rods were then placed in a vacuum consumable melting furnace for a third melting process, with a melting voltage of 40V and a melting current density of 70A / cm³. 2 The vacuum degree was controlled at 0.1 Pa to obtain three-stage ingot casting.

[0119] During the smelting process, the reinforcing precursor B4C and graphite powder react chemically with titanium to generate dispersed TiB and TiC reinforcing particles in situ. The specific reaction pathways are: Ti + C → TiC, 5Ti + B4C → 4TiB + TiC. This in-situ reaction method ensures high interfacial bonding strength between the reinforcing particles and the titanium matrix, resulting in good thermodynamic stability. It effectively avoids problems such as reinforcing phase agglomeration and poor interfacial bonding inherent in the external particle method. Simultaneously, it refines the size of the reinforcing particles, improving the mechanical properties of the composite powder.

[0120] To further promote the homogenization of composition and reinforcing phase, the ingot was flipped after each melting process to ensure thorough mixing of the melt and reduce component segregation. After three melting processes, a dense titanium-based composite material ingot with dimensions of Φ296mm×570mm and a weight of approximately 177kg was finally obtained. The ingot was free of defects such as porosity and cracks, and the reinforcing phase was initially dispersed.

[0121] Step 3: Multi-pass hot forging in the β phase region:

[0122] The ingots obtained from the three melting processes were fed into a heating furnace and heated to 1280℃ to enter the β-phase region. They were held at this temperature for 1.5 hours to ensure uniform heating and full entry into the β-phase region. Axial compressive force was applied using a hydraulic hammer to perform multi-pass axial hot forging of the ingots. The deformation rate was controlled at 1×10⁻⁶ during the hot forging process. -2 s -1 The total compression ratio is 60%. Through four passes of deformation, the ingot is extended along the length direction and the cross-sectional diameter is reduced. Finally, the ingot diameter is reduced from Φ296mm to Φ120mm, and the total deformation compression ratio is controlled at 40-50%.

[0123] Hot forging in the β phase region further refines the ingot microstructure, ensuring uniform distribution of the TiB and TiC reinforcing phases, eliminating internal defects in the ingot, and improving the ingot's plasticity and density.

[0124] Step 4: Multi-pass hot rolling:

[0125] The hot-forged ingot billet is then fed back into the heating furnace and heated to 1220℃, held for 0.5 hours to ensure uniform billet temperature, and then subjected to five passes of hot rolling. Rolling deformation is controlled by gradually reducing the roll gap, with the thinning rate controlled at 25% per pass to avoid excessive deformation in a single pass that could lead to billet cracking. Through multiple passes of hot rolling, the grain size and reinforcing phase particles are further refined, improving the uniformity of the material structure and laying a good microstructure foundation for subsequent powder production.

[0126] After hot rolling, the titanium-based composite rods with a diameter of approximately Φ60mm and a length of 600mm are obtained through cooling and straightening. The rods have a smooth surface, uniform dimensions, and no obvious scratches, cracks, or other defects. The TiB and TiC reinforcing phases inside the rods are finely dispersed and uniformly distributed, with a dense structure and stable properties, meeting the raw material requirements for subsequent gas atomization powder production.

[0127] Step 5: High-pressure atomization of inert gas:

[0128] The obtained titanium-based composite rods were placed in a gas atomization device protected by high-purity argon gas. The vacuum level inside the device was first evacuated to below 1 × 10⁻⁶. -2 Pa, removes air and impurity gases from the device.

[0129] The titanium-based composite rods are partially melted by induction heating. The melt, along with 5MPa high-pressure argon gas, is ejected at high speed from a nozzle with a diameter of 2.5mm. Under the action of the high-pressure argon gas flow, the melt is broken and atomized. The atomization process is carried out under the protection of high-purity argon gas to prevent the melt from oxidizing. The broken droplets are rapidly cooled and solidified in the high-purity argon gas environment to form titanium-based composite powder with good sphericity and uniform distribution of reinforcing phase particles.

[0130] During the atomization process, the nozzle size and argon pressure are strictly controlled to avoid defects such as satellite spheres and irregular shapes in the powder, and to ensure that the sphericity of the powder meets the standards.

[0131] The atomized powder is collected from the atomizing device and allowed to cool naturally to room temperature. Then, it is sieved using a multi-stage sieving method to select powder particles with a diameter of 45–105 μm as the target powder. The powder's particle size characteristic is a D50 of 60–80 μm. Powder within this size range exhibits good flowability and formability, making it suitable for subsequent 3D printing, powder metallurgy, and other molding processes. The sieving process removes excessively large or small particles and impurities, ensuring uniform powder particle size.

[0132] Step Six: Degassing, Oxygen Control, and Encapsulation:

[0133] The sieved target powder is placed under an inert atmosphere or vacuum for low-temperature drying and degassing. The degassing temperature is 100℃, and the degassing time is 4 hours. The degassing temperature is controlled within a suitable range to remove adsorbed moisture and gas from the powder surface, effectively reducing the powder oxygen content to below 0.15 wt.%. Strict control of oxygen content can prevent powder oxidation, ensuring the mechanical properties and corrosion resistance of subsequently molded parts, meeting the requirements of high-end applications.

[0134] After degassing, the powder is packaged and stored under the protection of high-purity argon gas. The packaging container is selected with good sealing performance to prevent air and moisture from entering and to ensure stability during storage.

[0135] The sphericity of the encapsulated powder is not less than 0.95, there is no obvious agglomeration inside the powder, the particle size distribution is uniform, the oxygen content is ≤0.15wt.%, the total amount of precursor added is 2.5vol.%, and all performance indicators are stable, and it can be directly used for subsequent molding and processing.

[0136] The titanium-based composite powder obtained in this embodiment was densified by hot isostatic pressing at 1200℃ and 100MPa for 2 hours. The tensile strength at 700℃ was 576MPa and the elongation after fracture was 8.4%.

Claims

1. An in-situ reinforced high-sphericity titanium-based composite powder, characterized in that, It consists of a titanium alloy matrix and an in-situ generated TiB+TiC mixed reinforcing phase; the TiB+TiC mixed reinforcing phase is generated in-situ by the reaction of 2.5 vol.% of precursor, the precursor being B4C and graphite powder in a volume ratio of 1:1; the composition of the titanium alloy matrix, by mass fraction, is: Al 6%, Sn 4%, Zr 7%, Nb 1%, Mo 1%, W 1% and Si 0.2%, with the balance being Ti and unavoidable impurities.

2. A method for preparing in-situ reinforced high sphericity titanium-based composite material powder as described in claim 1, characterized in that, Includes the following steps: Step 1: Preparation of electrodes for consumable arc melting: Using sponge titanium, high-purity aluminum, sponge zirconium, Ti-Sn alloy, Al-Nb alloy, Al-Mo alloy, Al-W alloy and industrial silicon powder as raw materials, and B4C ceramic powder and graphite powder as reinforcing phase precursors, the raw materials and reinforcing phase precursors are accurately weighed according to the target alloy ratio, and fully mixed evenly in an inert atmosphere, and pressed into an electrode for self-consuming arc melting. Step 2: Vacuum self-consumable melting: The electrode obtained in step one was subjected to three vacuum arc melting processes, each lasting at least 10 minutes, with the vacuum level of the first melting process being ≤1×10⁻⁶. -2 Pa; the vacuum degree for the second and third melting processes was 0.08~0.10 Pa, and the melting current density was 45~70 A / cm². 2 The melting voltage is 20~40V; the ingot is flipped after each melting, and a dense titanium-based composite material ingot is obtained after all melting is completed. Step 3: Multi-pass hot forging in the β phase region: The ingot obtained in step two is heated to fully enter the β phase region, and then subjected to multi-pass axial hot forging. During the hot forging process, the deformation rate is controlled at 10. -3 ~10 -2 s -1 The overall compression ratio is 40-60%; Step 4: Multi-pass hot rolling: The ingot obtained from hot forging in step three is heated to 1150~1220℃ and hot rolled in multiple passes. The thinning rate of each pass is controlled at 15~25%. After hot rolling, the ingot is cooled and straightened to obtain titanium-based composite material rods. Step 5: High-pressure atomization of inert gas: The titanium-based composite material rods obtained in step four are placed in a gas atomization device protected by an inert atmosphere. After evacuation, the titanium-based composite material rods are partially melted by induction heating. The melt and an inert gas with a pressure of 3-5 MPa are sprayed out from the nozzle at the same time. The melt is broken and atomized. The broken droplets are cooled and solidified in the inert atmosphere to form titanium-based composite material powder. Step Six: Degassing and Oxygen Control The titanium-based composite powder obtained in step five is dried and degassed, with the oxygen content controlled below 0.5 wt%, to obtain titanium-based composite powder with high sphericity.

3. The method for preparing in-situ reinforced high sphericity titanium-based composite material powder according to claim 2, characterized in that, The Sn content in the Ti-Sn alloy mentioned in step one is 80wt%, the Nb content in the Al-Nb alloy is 83wt%, the Mo content in the Al-Mo alloy is 52wt%, and the W content in the Al-W alloy is 53wt%.

4. The method for preparing in-situ reinforced high sphericity titanium-based composite material powder according to claim 2 or 3, characterized in that, The density of the self-consumable arc melting electrode obtained in step one shall not be less than 3.2 g / cm³. 3 .

5. The method for preparing in-situ reinforced high sphericity titanium-based composite material powder according to claim 4, characterized in that, The ingot heating temperature in step three is 1200~1280℃, and the holding time is 0.5~1.5h.

6. The method for preparing in-situ reinforced high sphericity titanium-based composite material powder according to claim 5, characterized in that, The titanium-based composite rods obtained in step four have a diameter of 50-60 mm and a length of 500-600 mm.

7. The method for preparing in-situ reinforced high sphericity titanium-based composite material powder according to claim 6, characterized in that, Step five involves evacuating the gas atomizing device to a vacuum level below 1 × 10⁻⁶. -2 Pa, the diameter of the nozzle is 2.5 mm.

8. The method for preparing in-situ reinforced high sphericity titanium-based composite powder according to claim 7, characterized in that, Step 5: Select powder with a particle size of 45~105μm as the target powder.

9. The method for preparing in-situ reinforced high sphericity titanium-based composite material powder according to claim 8, characterized in that, The high sphericity titanium-based composite powder described in step six has a D50 of 60~80μm and a sphericity of not less than 0.

95.

10. The application of a high sphericity titanium-based composite material powder as described in claim 1 in laser additive manufacturing or powder metallurgy forming, characterized in that, The laser additive manufacturing includes selective laser melting and electron beam melting, and the powder metallurgy forming includes hot isostatic pressing, metal injection molding, and powder metallurgy sintering.

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