High performance in-situ self-generated ti5s13 phase reinforced titanium-aluminum matrix composite near-net forming method

Abstract

The application is a near-net forming method of high-performance in-situ self-grown Ti5Si3 phase reinforced titanium-aluminum matrix composite material, which is a process of in-situ reaction of Ti, Al and Si elements in a molten pool by using an electron beam double-wire additive manufacturing process to form Ti5Si3 reinforced phase, Ti3Al and TiAl matrix; the solidification path is regulated by cooling conditions and molten pool composition during the solidification process to realize the proportion change of primary Ti5Si3 phase and eutectic Ti5Si3 phase, and based on the eutectic reaction, a new site correlation characteristic of Ti5Si3 reinforced phase and matrix is formed; the multi-axis movement of the working platform is used to realize layer-by-layer deposition to realize the near-net forming of the in-situ self-grown Ti5Si3 phase reinforced titanium-aluminum matrix composite material with high performance. The application can realize the near-net forming of large-scale titanium-aluminum matrix composite material components, has high forming efficiency, and is not prone to defects such as cracks and deformation during the additive process; compared with the titanium-aluminum matrix composite materials reported at present stage, the titanium-aluminum matrix composite material prepared by the application has equivalent plasticity and significantly improved yield strength at room temperature and 750 DEG C.

Description

Technical Field

[0001] This invention relates to the field of titanium-aluminum matrix composite material preparation technology, specifically to a near-net-shape forming method for high-performance in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composite materials. Background Technology

[0002] High-temperature alloys are key basic materials for aero-engines, and there is an urgent need to further develop lightweight and high-strength high-temperature alloy materials to meet the requirements of lightweight aerospace equipment. Lightweight and high-strength titanium-aluminum alloys are the best candidate materials to replace nickel-based high-temperature alloys in the 650–850℃ temperature range. By adding alloying elements with high melting points and excellent oxidation resistance, the strength of titanium-aluminum alloys is significantly improved. In the 650–850℃ range, their specific strength is higher than that of nickel-based high-temperature alloys, but the strength of titanium-aluminum alloys drops sharply above 850℃, limiting their service temperature. Composite technology, as an important means of improving the performance of titanium-aluminum alloys, utilizes TiB2, TiC, Al2O3, B4C, and Ti2AlC as reinforcing agents, improving overall performance through translaminar fracture, interface debonding, crack deflection, and fiber pull-out.

[0003] Typically, reinforcing phases are introduced directly into the titanium-aluminum alloy matrix. For example, invention patent CN202010925825.X discloses a novel titanium-aluminum matrix composite material and its preparation method. This material utilizes Ti, Al, Nb, Y, CaF2, TiC, and TiB2 powders for hot-pressing sintering to form a titanium-aluminum matrix composite material with Ti45Al8Nb0.5Y as the matrix and 7.5wt% TiC and 3wt% TiB2 as reinforcing phases, achieving a maximum flexural strength of 502 MPa. However, directly adding the reinforcing phase into the titanium-aluminum alloy matrix and forming it through hot-pressing results in a relatively random orientation relationship between the reinforcing phase and the matrix, insufficient interfacial strength, and difficulty in fully realizing its reinforcing effect.

[0004] The in-situ self-generation of reinforcing phases can enhance the interfacial bonding strength between the reinforcing phase and the matrix, significantly improving the performance of the titanium-aluminum alloy matrix. Patent CN201911298379.8 discloses a method for preparing a high-strength, high-ductility TiAl-based composite material. This method involves introducing high-melting-point Nb into the titanium-aluminum alloy matrix and then obtaining a high-strength, high-ductility TiAl intermetallic compound-based composite material reinforced with a fibrous, tough, Nb-rich phase and granular Ti2AlNb phase through processes such as powder mixing, vacuum hot extrusion, and high-temperature encapsulation extrusion. Patent CN109694971B discloses a powder metallurgy titanium-aluminum-based composite material and its preparation method. This material is prepared by combining high-energy ball milling with spark plasma sintering. It involves mixing 30%–40% Ti powder, 2%–8% TiO2 powder, 1%–5% Nb2O5 powder, and the balance aluminum powder to form a titanium-aluminum-based composite material. This method enables in-situ synthesis of the second-phase Al2O3 particles during the high-energy ball milling stage. Although the reinforcing phase in the above method is formed in situ, the preparation process is relatively complex and it is difficult to achieve near-net-shape of the sample.

[0005] In-situ self-generation of reinforcing phases in titanium-aluminum alloy matrices can also be achieved through reasonable element addition and simple process design. Patent CN202011310311.X discloses a method for preparing a toughened titanium-aluminum matrix composite material. This method involves adding TiC to a titanium-aluminum alloy and preparing the composite material using vacuum melting. The high C content allows for the in-situ self-generation of Ti3AlC reinforcement. Through the second-phase strengthening and dislocation strengthening effects of the reinforcement, crack formation and propagation are hindered, and fragile interfaces in the microstructure under high-temperature conditions are pinned, significantly improving the high-temperature tensile strength of the titanium-aluminum matrix composite material. However, the titanium-aluminum matrix composite material obtained by this method has poor plasticity and is difficult to process further. Therefore, the preparation of titanium-aluminum matrix composite materials faces challenges in the design of in-situ self-generated reinforcing phases and sample processing.

[0006] Additive manufacturing offers a novel method for preparing titanium-aluminum matrix composites, but currently, electron beam selective melting is the primary method, which has low processing efficiency and is difficult to meet the needs of large-scale industrial production. Titanium-aluminum alloys prepared by arc additive manufacturing are highly susceptible to oxidation, and the current research remains in the exploratory stage regarding binary titanium-aluminum alloys. Electron beam wire additive manufacturing, as a high-vacuum, high-efficiency forming method, has significant application potential in the preparation of titanium-aluminum alloys and titanium-aluminum matrix composites. However, the additive manufacturing of titanium-aluminum matrix composites faces the following challenges: the compositional design of in-situ self-generated reinforcing phases, and the control of the microstructure and orientation relationships of the reinforcing phases. Summary of the Invention

[0007] The purpose of this invention is to provide a near-net-shape forming method for high-performance in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites. By designing solidification conditions, a reinforcing phase with a special phase relationship is obtained, which improves the interfacial bonding strength between the reinforcing phase and the matrix, avoids the increase in brittleness caused by the introduction of the reinforcing phase, and further improves the high-temperature strength of the titanium-aluminum alloy matrix, enabling the titanium-aluminum alloy matrix to serve at higher temperatures.

[0008] The technical solution adopted by this invention to solve its technical problem is as follows:

[0009] A near-net-shape forming method for high-performance in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites is proposed. This method utilizes the in-situ reaction of Ti, Al, and Si elements in the molten pool during electron beam dual-wire additive manufacturing to form a Ti5Si3 reinforcing phase, Ti3Al, and TiAl matrix. By controlling the solidification path through cooling conditions and molten pool composition during the solidification process, the ratio of primary Ti5Si3 phase to eutectic Ti5Si3 phase is varied. Based on the eutectic reaction, a novel phase relationship between the Ti5Si3 reinforcing phase and the matrix is ​​formed. Layer-by-layer deposition is achieved through multi-axis movement of the working platform, realizing the near-net-shape forming of high-performance in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites.

[0010] Furthermore, this method includes three processes: preheating, layer-by-layer deposition, and sample cooling. The specific steps are as follows:

[0011] (1) Preheating: The titanium alloy substrate, after being sanded and cleaned with ethanol, is fixed on the working platform of the electron beam fused wire additive manufacturing system, and the working platform is placed in the vacuum chamber of the electron beam fused wire additive manufacturing system; wait until the vacuum degree reaches the working vacuum degree of 7×10 -2 At Pa, the substrate is preheated by rapid electron beam scanning until the titanium alloy substrate becomes red-hot.

[0012] (2) Layer-by-layer deposition: Aluminum wire and titanium wire are placed in the independent wire feeding mechanism of the electron beam fused wire additive manufacturing system. The angle and height of the wire feeding gun are adjusted, and the wire feeding speed of aluminum wire and titanium wire is set. The wires are fed into the common molten pool and deposited according to the set path. After single-pass deposition, the wires are cooled for 60-80 seconds and the worktable is lowered a certain distance to continue deposition to ensure that the electron beam focus is on the surface of the additive component until the deposition is completed.

[0013] (3) Sample cooling: The in-situ additive titanium-aluminum intermetallic compound component was placed in a vacuum environment and cooled until it was cooled to room temperature.

[0014] The basic parameters for substrate preheating are as follows: accelerating voltage 60kV, focusing current 1000-1200mA, scanning frequency 300-600Hz, scanning range 300%-600%, circular scanning mode, and scanning speed 20mm / s. A stepped preheating method is used, gradually increasing the preheating beam current from 5mm to 25mm until the substrate is red-hot. The wire feeder angle is adjusted between 45° and 55°. The distance between the wire at the front end of the wire feeder and the substrate is within 1mm, allowing for continuous droplet transition and forming. The additive sample cooling process is carried out in a vacuum environment using segmented cooling: cooling for 2-3 hours under high vacuum and holding at low vacuum for 10-15 hours. The high vacuum range is below 7×10⁻⁶. -2 Pa, with a low vacuum range of 0-10 Pa.

[0015] Furthermore, the raw materials selected for the near-net-shape forming process of the in-situ self-generated Ti5Si3 phase reinforced titanium aluminum matrix composite are ERTi-1 wire and ER4047 wire, with a diameter of 1.0 to 2.0 mm. The composition of ERTi-1 wire is C≤0.03wt%, O 0.03 to 0.10wt%, N≤0.012wt%, H≤0.005wt%, Fe≤0.08wt%, and Ti balance. The composition of ER4047 wire is Si12wt%, Mn<0.15wt%, Cu<0.05wt%, Ti<0.15wt%, Zn<0.20wt%, Fe<0.6wt%, and Al balance.

[0016] Furthermore, the composition of the high-performance titanium-aluminum matrix composite material is Ti-(34~38)at%Al-(5.5~9.5)at%Si; wherein, the relationship between the wire feeding speed and the composition is:

[0017]

[0018]

[0019] Among them, E x and A x These are the design mass fraction and atomic fraction of the main elements, respectively; E xi (i = 1, 2, ..., n) represents the mass fraction of elements in the silk material; S i D is the wire feeding speed, in mm / min; i ρ is the diameter of the wire, in mm; i This refers to the density of the filament, expressed in g / cm³. 3 M x This refers to the relative atomic mass of the element; during the electron beam filament additive manufacturing process, different elements will be burned off, therefore the actual atomic fraction of different elements will vary. for

[0020]

[0021] λ x denoted as the evaporation coefficient of the element, where only the volatilization of Ti, Al, and Si is considered, with volatilization coefficients of 1, 1.15, and 0.71, respectively; the wire feeding speed ranges from 300 mm / min to 800 mm / min.

[0022] Furthermore, the high-performance titanium-aluminum matrix composite material is mainly composed of micron-scale primary polygonal Ti5Si3 phase, nano-scale eutectic needle-like Ti5Si3 phase, and eutectoid lamellar structure of Ti3Al+TiAl. Among them, the eutectic needle-like Ti5Si3 phase and the eutectoid lamellar structure of Ti3Al+TiAl have the following special phase relationship.

[0023]

[0024]

[0025] Furthermore, titanium can react with silicon, aluminum, and other elements. By changing the ratio of aluminum and silicon near the titanium-aluminum-silicon eutectic composition point, the proportion of primary polygonal Ti5Si3 phase and eutectic needle-like Ti5Si3 phase can be adjusted, thereby controlling the mechanical properties of titanium-aluminum matrix composites.

[0026] Furthermore, obtaining Ti5Si3 phase-reinforced titanium-aluminum matrix composites with special phase relationships through electron beam dual-wire additive manufacturing requires providing high superheated solidification conditions above 1000K during the additive manufacturing process to obtain supercooling above 200K, thereby generating a eutectic reaction of L→α+Ti5Si3 during solidification.

[0027] Furthermore, the achieved additive manufacturing process parameters are as follows: accelerating voltage 60kV, focusing current 1000-1200mA, scanning frequency 600-900Hz, scanning range 700%-900%, scanning mode circular, deposition rate 1mm / s-5mm / s, single layer height 0.75-2mm, and electron beam current 25mA-45mA; and the cooling rate is controlled at 300-500K / s by using an interlayer waiting time of 50-70s.

[0028] Compared with the prior art, the present invention has significant advantages: it can achieve near-net-shape forming of large-scale titanium-aluminum matrix composite components with high forming efficiency and the additive process is less prone to defects such as cracks and deformation; compared with the titanium-aluminum matrix composites reported at present, the titanium-aluminum matrix composites prepared by the present invention have the same plasticity but significantly improved yield strength at room temperature and 750℃. Attached Figure Description

[0029] Figure 1This is a physical image of a high-performance in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composite material.

[0030] Figure 2 These are micrographs of high-performance in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites: a) micrograph of the microstructure within the additive component layers; b) lamellar structure and acicular eutectic Ti5Si3 phase; c) morphology of the eutectic Ti5Si3 phase and primary Ti5Si3 phase; d) micrograph of the microstructure between the additive component layers.

[0031] Figure 3 The images show the phase relationship between the reinforcing phase and the titanium-aluminum alloy matrix in in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites. a) EBSD grayscale image, b) phase distribution diagram of titanium-aluminum matrix composite component, c) pole diagram of Ti3Al phase in additive component, d) pole diagram of Ti5Si3 phase in additive component, and e) pole diagram of TiAl phase in additive component.

[0032] Figure 4 It refers to the phase boundary distribution of the in-situ self-generated Ti5Si3 phase with a special phase relationship with the matrix, a) special grain boundary distribution between Ti5Si3 phase and Ti3Al phase, b) special grain boundary distribution between TiAl phase and Ti5Si3 and Ti3Al phase, c) frequency statistics of special grain boundary distribution, and d) grain boundary statistics of different phases.

[0033] Figure 5 This document presents the performance test results of in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites and their performance comparison with existing materials. The results include: a) nanoindentation test results of different phases; b) compression test results of in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites at room temperature and 750℃; and c) performance comparison of in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites with existing titanium-aluminum alloys and composites. Detailed Implementation

[0034] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments.

[0035] A near-net-shape forming method for high-performance in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites is proposed. This method utilizes the in-situ reaction of Ti, Al, and Si elements in the molten pool during electron beam dual-wire additive manufacturing to form a Ti5Si3 reinforcing phase, Ti3Al, and TiAl matrix. By controlling the solidification path through cooling conditions and molten pool composition during the solidification process, the ratio of primary Ti5Si3 phase to eutectic Ti5Si3 phase is varied. Based on the eutectic reaction, a novel phase relationship between the Ti5Si3 reinforcing phase and the matrix is ​​formed. Layer-by-layer deposition is achieved through multi-axis movement of the working platform, realizing the near-net-shape forming of high-performance in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites.

[0036] Furthermore, this method includes three processes: preheating, layer-by-layer deposition, and sample cooling. The specific steps are as follows:

[0037] (1) Preheating: The titanium alloy substrate, after being sanded and cleaned with ethanol, is fixed on the working platform of the electron beam fused wire additive manufacturing system, and the working platform is placed in the vacuum chamber of the electron beam fused wire additive manufacturing system; wait until the vacuum degree reaches the working vacuum degree of 7×10 -2 At Pa, the substrate is preheated by rapid electron beam scanning until the titanium alloy substrate becomes red-hot.

[0038] (2) Layer-by-layer deposition: Aluminum wire and titanium wire are placed in the independent wire feeding mechanism of the electron beam fused wire additive manufacturing system. The angle and height of the wire feeding gun are adjusted, and the wire feeding speed of aluminum wire and titanium wire is set. The wires are fed into the common molten pool and deposited according to the set path. After single-pass deposition, the wires are cooled for 60-80 seconds and the worktable is lowered a certain distance to continue deposition to ensure that the electron beam focus is on the surface of the additive component until the deposition is completed.

[0039] (3) Sample cooling: The in-situ additive titanium-aluminum intermetallic compound component was placed in a vacuum environment and cooled until it was cooled to room temperature.

[0040] The basic parameters for substrate preheating are as follows: accelerating voltage 60kV, focusing current 1000-1200mA, scanning frequency 300-600Hz, scanning range 300%-600%, circular scanning mode, and scanning speed 20mm / s. A stepped preheating method is used, gradually increasing the preheating beam current from 5mm to 25mm until the substrate is red-hot. The wire feeder angle is adjusted between 45° and 55°. The distance between the wire at the front end of the wire feeder and the substrate is within 1mm, allowing for continuous droplet transition and forming. The additive sample cooling process is carried out in a vacuum environment using segmented cooling: cooling for 2-3 hours under high vacuum and holding at low vacuum for 10-15 hours. The high vacuum range is below 7×10⁻⁶. -2 Pa, with a low vacuum range of 0-10 Pa.

[0041] Furthermore, the raw materials selected for the near-net-shape forming process of the in-situ self-generated Ti5Si3 phase reinforced titanium aluminum matrix composite are ERTi-1 wire and ER4047 wire, with a diameter of 1.0 to 2.0 mm. The composition of ERTi-1 wire is C≤0.03wt%, O 0.03 to 0.10wt%, N≤0.012wt%, H≤0.005wt%, Fe≤0.08wt%, and Ti balance. The composition of ER4047 wire is Si12wt%, Mn<0.15wt%, Cu<0.05wt%, Ti<0.15wt%, Zn<0.20wt%, Fe<0.6wt%, and Al balance.

[0042] Furthermore, the composition of the high-performance titanium-aluminum matrix composite material is Ti-(34~38)at%Al-(5.5~9.5)at%Si; wherein, the relationship between the wire feeding speed and the composition is:

[0043]

[0044]

[0045] Among them, E x and A x These are the design mass fraction and atomic fraction of the main elements, respectively; E xi (i = 1, 2, ..., n) represents the mass fraction of elements in the silk material; S i D is the wire feeding speed, in mm / min; i ρ is the diameter of the wire, in mm; i This refers to the density of the filament, expressed in g / cm³. 3 M x This refers to the relative atomic mass of the element; during the electron beam filament additive manufacturing process, different elements will be burned off, therefore the actual atomic fraction of different elements will vary. for

[0046]

[0047] λ x The evaporation coefficient is denoted by , and in this method only the volatilization of Ti, Al, and Si is considered, with volatilization coefficients of 1, 1.15, and 0.71, respectively; the wire feeding speed ranges from 300 mm / min to 800 mm / min.

[0048] Furthermore, the high-performance titanium-aluminum matrix composite material is mainly composed of micron-scale primary polygonal Ti5Si3 phase, nano-scale eutectic needle-like Ti5Si3 phase, and eutectoid lamellar structure of Ti3Al+TiAl. Among them, the eutectic needle-like Ti5Si3 phase and the eutectoid lamellar structure of Ti3Al+TiAl have the following special phase relationship.

[0049]

[0050]

[0051] Furthermore, titanium can react with silicon, aluminum, and other elements. By changing the ratio of aluminum and silicon near the titanium-aluminum-silicon eutectic composition point, the proportion of primary polygonal Ti5Si3 phase and eutectic needle-like Ti5Si3 phase can be adjusted, thereby controlling the mechanical properties of titanium-aluminum matrix composites.

[0052] Furthermore, obtaining Ti5Si3 phase-reinforced titanium-aluminum matrix composites with special phase relationships through electron beam dual-wire additive manufacturing requires providing high superheated solidification conditions above 1000K during the additive manufacturing process to obtain supercooling above 200K, thereby generating a eutectic reaction of L→α+Ti5Si3 during solidification.

[0053] Furthermore, the achieved additive manufacturing process parameters are as follows: accelerating voltage 60kV, focusing current 1000-1200mA, scanning frequency 600-900Hz, scanning range 700%-900%, scanning mode circular, deposition rate 1mm / s-5mm / s, single layer height 0.75-2mm, and electron beam current 25mA-45mA; and the cooling rate is controlled at 300-500K / s by using an interlayer waiting time of 50-70s.

[0054] Example 1

[0055] This embodiment describes a near-net-shape forming method for high-performance in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites. The materials used are ERTi-1 and ER4047 wires with a diameter of 1.6 mm, and the substrate has dimensions of 120 × 60 × 10 mm. 3 The pure titanium sheet, substrate, and wire composition are shown below.

[0056]

[0057]

[0058] The near-net-shape forming process of titanium-aluminum matrix composites is as follows:

[0059] (1) Preheating: The titanium alloy substrate, after being sanded and cleaned with ethanol, is fixed on the working platform of the electron beam fused wire additive manufacturing system, and the working platform is placed in the vacuum chamber of the electron beam fused wire additive manufacturing system. When the vacuum level reaches the working vacuum level, the substrate is preheated by rapid electron beam scanning until the titanium alloy substrate becomes red-hot;

[0060] (2) Layer-by-layer deposition: Place aluminum wire and titanium wire in the independent wire feeding mechanism of the electron beam fused wire additive manufacturing system, adjust the angle and height of the wire feeding gun, set the wire feeding speed of aluminum wire and titanium wire and feed them at the same time, feed them into the common molten pool, and perform deposition according to the set path. After single-pass deposition, cool for 60s, lower the worktable by 1mm, and continue deposition to ensure that the electron beam focus is on the surface of the additive component until deposition is completed.

[0061] (3) Cooling of additive components: The in-situ additive titanium-aluminum intermetallic compound components are placed in a vacuum environment and cooled until they are cooled to room temperature.

[0062] The basic parameters for substrate preheating are as follows: accelerating voltage 60kV, focusing current 1032mA, scanning frequency 500Hz, scanning range 600%, circular scanning mode, and scanning speed 20mm / s. A stepped preheating method is used, gradually increasing the preheating beam current from 5mm to 25mm until the substrate is red-hot, indicating preheating is complete. The wire feed gun angle is set to 45°, and the distance between the wire at the front of the wire feed gun and the substrate is 1mm.

[0063] The titanium wire feeding speed for the additive manufacturing process was set to 380 mm / min, and the aluminum wire feeding speed was set to 420 mm / min. The additive manufacturing process parameters were set as follows: accelerating voltage 60 kV, focusing current 1141 mA, scanning frequency 600 Hz, scanning range 800%, scanning mode circular, single layer height 1 mm, electron beam current 25 mA, and interlayer waiting time 60 s.

[0064] The cooling process for the additive manufacturing sample needs to be carried out in a vacuum environment using segmented cooling: cooling for 3 hours under high vacuum and holding at low vacuum for 15 hours. The vacuum level under the high vacuum condition is 3 × 10⁻⁶. -2 Pa, the vacuum level under high vacuum conditions is 7 Pa.

[0065] Using the method of this embodiment, a well-formed in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composite material was obtained. Figure 1 To obtain the macroscopic morphology of the titanium-aluminum matrix composite component, its composition is uniform, the interlayer bonding is good, and there are no defects such as cracks and pores. Its calculated composition is Ti-42.88at%Al-5.7at%Si, and the actual composition is Ti-34.74at%Al-7.25at%Si. Figure 2 These are micrographs of high-performance in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites. The in-situ self-generated Ti5Si3 phase and titanium-aluminum alloy matrix can be clearly seen in the images. The Ti5Si3 phase is divided into primary polygonal Ti5Si3 phase and eutectic needle-like Ti5Si3 phase. Figure 3 This describes the phase relationship between the reinforcing phase and the titanium-aluminum alloy matrix in in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites. A clear phase relationship between the reinforcing phase and the matrix can be observed. Based on... Figure 4 The phase boundary distribution of the in-situ self-generated Ti5Si3 phase with a special phase relationship with the matrix reveals that phase relationships are ubiquitous. Figure 5 The results of performance testing of in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites show that their room temperature yield strength is significantly higher than that of existing commercial Ti-48Al-2Nb-2Cr alloys, and their high temperature yield strength is comparable to that of most materials.

[0066] This invention introduces the Ti5Si3 phase in situ through an innovative design of the titanium-aluminum alloy composition, thereby obtaining a high-performance titanium-aluminum matrix composite material. This material significantly improves the yield strength of the titanium-aluminum alloy matrix at both room temperature and high temperature without reducing its plasticity.

Claims

1. A near-net-shape forming method for high-performance in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites, characterized in that, By utilizing the in-situ reaction of Ti, Al, and Si elements in the molten pool during electron beam dual-wire additive manufacturing, Ti5Si3 reinforcing phase, Ti3Al, and TiAl matrix are formed. The solidification path is controlled by adjusting the cooling conditions and molten pool composition during the solidification process to achieve changes in the ratio of primary Ti5Si3 phase to eutectic Ti5Si3 phase. Based on the eutectic reaction, a novel phase relationship between the Ti5Si3 reinforcing phase and the matrix is ​​formed. Layer-by-layer deposition is achieved through multi-axis movement of the working platform to realize near-net-shape forming of high-performance in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composite material. This method includes three processes: preheating, layer-by-layer deposition, and sample cooling. The specific steps are as follows: (1) Preheating: The titanium alloy substrate, after being sanded and cleaned with ethanol, is fixed on the working platform of the electron beam fused wire additive manufacturing system, and the working platform is placed in the vacuum chamber of the electron beam fused wire additive manufacturing system; wait until the vacuum degree reaches the working vacuum degree of 7×10 -2 At Pa, the substrate is preheated by rapid electron beam scanning until the titanium alloy substrate becomes red-hot. (2) Layer-by-layer deposition: aluminum wire and titanium wire are placed in the independent wire feeding mechanism of the electron beam fused wire additive manufacturing system. The angle and height of the wire feeding gun are adjusted, and the wire feeding speed of aluminum wire and titanium wire is set. The wires are fed into the common molten pool and deposited according to the set path. After single-pass deposition, the wires are cooled for 60~80 s and the worktable is lowered a certain distance to continue deposition to ensure that the electron beam focus is on the surface of the additive component until the deposition is completed. (3) Sample cooling: The in-situ additive titanium-aluminum intermetallic compound component was placed in a vacuum environment and cooled until it reached room temperature; The substrate preheating parameters are as follows: accelerating voltage 60 kV, focusing current 1000-1200 mA, scanning frequency 300-600 Hz, scanning range 300%-600%, circular scanning mode, and scanning speed 20 mm / s. A stepped preheating method is used, gradually increasing the preheating beam current from 5 mA to 25 mA until the substrate is red-hot. The wire feeder angle is adjusted between 45° and 55°. The distance between the wire at the front end of the wire feeder and the substrate is within 1 mm, allowing for continuous droplet transition and forming. The additive sample cooling process is carried out in a vacuum environment using segmented cooling: cooling for 2-3 hours under high vacuum and holding at low vacuum for 10-15 hours. The high vacuum range is below 7 × 10⁻⁶. -2 Pa, with a low vacuum range of 0-10 Pa; High-performance titanium-aluminum matrix composites include micron-scale primary polygonal Ti5Si3 phase, nanoscale eutectic acicular Ti5Si3 phase, and eutectoid lamellar structure of Ti3Al+TiAl. Among them, the eutectic acicular Ti5Si3 phase and the eutectoid lamellar structure of Ti3Al+TiAl exhibit the following special phase relationship. ； 。 2. The near-net-shape forming method for high-performance in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites according to claim 1, characterized in that, The raw materials used in the near-net-shape forming process of in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites are ERTi-1 wire and ER4047 wire, with diameters ranging from 1.0 to 2.0 mm. The composition of ERTi-1 wire is C≤0.03 wt%, O 0.03~0.10 wt%, N≤0.012 wt%, H≤0.005 wt%, Fe≤0.08 wt%, with Ti as the balance. The composition of ER4047 wire is Si 12 wt%, Mn<0.15 wt%, Cu<0.05 wt%, Ti<0.15 wt%, Zn<0.20 wt%, Fe<0.6 wt%, with Al as the balance.

3. The near-net-shape forming method for high-performance in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites according to claim 1, characterized in that, The composition of the high-performance titanium-aluminum matrix composite material is Ti-(34~38) at% Al-(5.5~9.5) at% Si; the relationship between the wire feeding speed and the composition is as follows: ； ； in, and These are the design mass fraction and atomic fraction of the main elements, respectively; (i=1,2,……,n) represents the mass fraction of elements in the silk material; The wire feeding speed is expressed in mm / min. The diameter of the wire is in mm. This refers to the density of the filament, expressed in g / cm³. 3 ; This refers to the relative atomic mass of the element; during the electron beam filament additive manufacturing process, different elements will be burned off, therefore the actual atomic fraction of different elements will vary. for ； denoted as the evaporation coefficient of the element, where only the volatilization of Ti, Al, and Si is considered, with volatilization coefficients of 1, 1.15, and 0.71, respectively; the wire feeding speed ranges from 300 mm / min to 800 mm / min.

4. The near-net-shape forming method for high-performance in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites according to claim 1, characterized in that, Since titanium can react with both silicon and aluminum, the mechanical properties of titanium-aluminum composite materials can be controlled by changing the ratio of aluminum and silicon near the titanium-aluminum-silicon eutectic composition point, thereby altering the proportion of primary polygonal Ti5Si3 phase and eutectic acicular Ti5Si3 phase.

5. The near-net-shape forming method for high-performance in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites according to claim 1, characterized in that, Obtaining Ti5Si3 phase-reinforced titanium-aluminum matrix composites with special phase relationships through electron beam dual-wire additive manufacturing requires providing high superheated solidification conditions above 1000 K during the additive manufacturing process, thereby achieving a supercooling degree above 200 K, and generating a eutectic reaction of L→α+Ti5Si3 during solidification.

6. The near-net-shape forming method for high-performance in-situ self-generated Ti5Si3 phase reinforced titanium-aluminum matrix composites according to claim 5, characterized in that, The achieved additive manufacturing process parameters are: accelerating voltage 60 kV, focusing current 1000-1200 mA, scanning frequency 600-900 Hz, scanning range 700%-900%, scanning mode circular, deposition rate 1 mm / s-5 mm / s, single layer height 0.75-2 mm, and electron beam current 25 mA-45 mA; and the cooling rate is controlled at 300-500 K / s by interlayer waiting time of 50-70 s.

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