A high-strength titanium alloy and a laser additive manufacturing method thereof

Abstract

The application discloses a high-strength titanium alloy and a laser additive manufacturing method thereof, and belongs to the technical field of titanium alloys.The mass fraction of alloy components is as follows: Cu 3.5%-6%, Zr 20%-45%, and the balance of Ti and inevitable impurities.The titanium alloy provided by the application does not add expensive alloy elements such as Nb, Mo and V, and does not need any post-heat treatment, and through additive manufacturing, the microstructure of the finally formed titanium alloy is ultra-fine or nano alpha lath and discontinuous nano (Ti, Zr) 2Cu particles on the lath interface, and finally, 1200MPa-1300MPa of yield strength R p0.2 , 1400MPa-1490MPa of tensile strength and 4.5%-6% of elongation can be directly obtained in the laser directional energy deposition forming alloy, and the mechanical properties can meet the engineering structure requirements.The titanium alloy obtained by the application has wide application prospects in the fields of aerospace, aviation, military and civil use, and can significantly improve production efficiency and economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of laser additive manufacturing technology, specifically relating to a high-strength titanium alloy and its laser additive manufacturing method. Background Technology

[0002] Laser additive manufacturing of titanium alloys is of great significance in high-end manufacturing fields such as aerospace. However, the high cost of laser additive manufacturing of titanium alloys limits its broader development. This high cost stems primarily from the expensive price of currently available titanium alloys for laser additive manufacturing, and the need for post-processing such as heat treatment to improve mechanical properties and meet application requirements. These factors result in long manufacturing cycles and high economic costs for laser additive manufacturing titanium alloy products. Developing low-cost titanium alloy grades specifically for laser additive manufacturing, reducing costs, and ensuring that the mechanical properties of the deposited state directly meet application requirements without subsequent heat treatment or hot working, thereby shortening the manufacturing cycle, is of great importance to the development of laser additive manufacturing of titanium alloys.

[0003] Replacing expensive isomorphous β-stabilizing elements such as Mo, Nb, V, and Ta in titanium alloys with inexpensive eutectoid β-stabilizing elements is an important approach to designing high-strength, low-cost titanium alloys. Eutectoid β-stabilizing elements such as Fe, Cu, and Ni have higher β-stabilizing and solid solution strengthening capabilities than Mo, Nb, V, and Ta. Theoretically, adding a small amount can achieve the same effect, thus significantly reducing the cost of titanium alloys. For example, some low-cost Fe-containing titanium alloys have been successfully developed, such as the patent "A Low-Cost Near-β High-Strength Titanium Alloy Containing Fe and Its Preparation Method" (CN106521236 B), which uses Fe instead of V. However, Fe has a high melting point (1538℃) and is prone to segregation, leading to microstructural defects such as β spots and macroscopic regions in Fe-containing titanium alloys, as well as the formation of coarse, unevenly distributed TiFe brittle intermetallic compounds, which degrades the performance of Fe-containing titanium alloys. Therefore, the amount of Fe added is generally less than 2%, resulting in a very narrow alloying window. Unlike Fe, Cu has a low melting point (1083℃) and strong diffusion ability. Melting Cu with Ti lowers the melting point, improves the fluidity of the molten metal, results in more uniform casting composition, reduces the likelihood of macroscopic defects, and enhances the flame retardancy and corrosion resistance of the alloy. Furthermore, Cu is very inexpensive and readily available, with raw materials costing only 60-200 yuan per kilogram. Therefore, using Cu to replace expensive β-stabilizing elements such as Mo and V in the design and preparation of low-cost titanium alloys has significant economic benefits. However, Cu is an active eutectoid element, readily leading to the formation of numerous lamellar α+Ti₂Cu pearlite clusters, resulting in poor plasticity in Ti-Cu alloys. These pearlite eutectoid structures are almost impossible to eliminate through rapid cooling or heat treatment, which has limited the development of low-cost titanium alloys alloyed with eutectoid Cu to date. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-strength titanium alloy and its laser additive manufacturing method, so as to solve the problem that it is difficult to find suitable eutectoid β-stabilizing elements for titanium alloys in the prior art.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A high-strength titanium alloy, by mass fraction, comprises: Cu 3.5%–6%, Zr 20%–45%, with the balance being Ti and unavoidable impurities;

[0007] The high-strength titanium alloy has a deposited alloy microstructure consisting of submicron-sized or nano-sized α-lamellae, with nano-(Ti,Zr)2Cu particles distributed at the interfaces of adjacent laths.

[0008] The high-strength titanium alloy was prepared by additive manufacturing.

[0009] A further improvement of the present invention is that:

[0010] Preferably, the yield strength R of the high-strength titanium alloy is... p0.2 The pressure is 1200MPa to 1300MPa.

[0011] Preferably, the high-strength titanium alloy has a tensile strength of 1400MPa to 1490MPa and an elongation of 4.5% to 6%.

[0012] A method for preparing the above-mentioned high-strength titanium alloy includes the following steps:

[0013] Step 1: After mixing the sponge titanium, sponge zirconium and copper materials according to the designed composition, vacuum arc remelting is carried out to obtain ingots;

[0014] Step 2: Melt the ingot using a rotating electrode to produce alloy powder;

[0015] Step 3: Heat the alloy powder in a vacuum environment and then cool it to obtain the powder after vacuum drying.

[0016] Step 4: The vacuum-treated powder is deposited on the substrate using laser directional energy deposition or laser powder bed melting to obtain a high-strength titanium alloy workpiece.

[0017] Preferably, in step 1, the number of vacuum self-consumable melting cycles is 2 to 5; before step 2, the riser of the ingot obtained in step 1 is removed.

[0018] Preferably, in step 2, during the rotating electrode melting process, the oxygen content of the environment and the oxygen content of the alloy powder obtained by rotating electrode melting are both ≤0.1wt%.

[0019] Preferably, in step 3, before vacuum heating, the alloy powder obtained in step 2 is screened to obtain powder with a particle size range of 50μm to 150μm.

[0020] Preferably, in step 4, the process parameters for deposition using laser-directed energy deposition are as follows:

[0021] With a laser spot diameter of 2.5 mm to 3.5 mm, a laser power of 900 W to 1500 W, a laser beam scanning speed of 480 mm / min to 1200 mm / min, a scanning interval of 1.2 mm to 1.8 mm, and an interlayer deposition time of 10 to 60 s;

[0022] With a laser spot diameter of 3.5 mm to 5.5 mm, a laser power of 1200 W to 2500 W, a laser beam scanning speed of 480 mm / min to 1200 mm / min, a scanning interval of 1.8 mm to 2.8 mm, and an interlayer deposition time of 10 to 60 s.

[0023] Preferably, in step 3, before vacuum heating, the alloy powder obtained in step 2 is screened to obtain powder with a particle size range of 10μm to 53μm.

[0024] Preferably, in step 4, the process parameters for preparing high-strength titanium alloy workpieces by laser powder bed melting are as follows:

[0025] The laser spot diameter is 60μm, the laser power is 120W~250W, the laser scanning speed is 800mm / s~2000mm / s, the layer thickness is 30μm~45μm, and the scanning line spacing is 80μm~120μm.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] This invention discloses a high-strength titanium alloy with the following composition by mass fraction: Cu 3.5%–6%, Zr 20%–45%, and the balance being Ti and unavoidable impurities. The titanium alloy provided by this invention does not contain expensive alloying elements such as Nb, Mo, and V, and requires no post-heat treatment. Through additive manufacturing, the final microstructure of the titanium alloy consists of ultrafine or nano-α-lamellae and discontinuous nano-(Ti,Zr)₂Cu particles at the lamellar interfaces. Ultimately, in laser-directed energy deposition forming, a yield strength Rp₀.₂ of 1200 MPa–1300 MPa, a tensile strength exceeding 1400 MPa (1400 MPa–1490 MPa), and an acceptable elongation of 4.5%–6% can be directly obtained. Its mechanical properties meet the requirements of engineering structures. This invention has broad application prospects in aerospace, aviation, military, and civilian fields, and can significantly improve production efficiency and economic benefits.

[0028] Furthermore, the alloy composition and process design of this invention are based on the design concept of alloying titanium alloys with the low-cost active eutectoid element Cu. Using phase diagram calculations combined with high-throughput experimental methods, it was determined that Zr alloying can suppress the formation of lamellar pearlite structure, while simultaneously improving the strength and plasticity of the alloy, without introducing other phases. When 20%–45% Zr is combined with 3.5%–6% Cu for composite alloying, the deposited alloy microstructure consists of ultrafine or nano-α-lamellae and discontinuous nano-(Ti,Zr)₂Cu particles at the lamellar interfaces.

[0029] This invention also discloses a method for preparing a high-strength titanium alloy. Firstly, the composition is designed, and Zr alloy is added to the eutectoid β-stabilizing element Cu. This eliminates the lamellar pearlite eutectoid product morphology, transforming the intermetallic compound (Ti,Zr)₂Cu into a granular form, reducing the adverse effects of the intermetallic compound on plasticity, and transforming the lamellar α phase of the plastic phase into a lath-like form, thus improving plastic deformation capacity. Furthermore, the titanium alloy composition disclosed in this invention has a low eutectoid transformation temperature (650–550℃), and the eutectoid reaction β… The formation of ultrafine or nano-α-lamellae microstructure during the β→α+(Ti,Zr)₂Cu transformation allows the alloy to directly achieve extremely high yield strength and tensile strength in the deposited state. In contrast, ordinary single-type transformation titanium alloys form the α phase through a relatively high-temperature allotropic transformation β→α, such as TC4 with a β→α transformation temperature of 980–900°C. This makes it difficult to directly obtain a uniform ultrafine or nano-α-lamellae microstructure in the additive manufacturing deposited state of titanium alloys like TC4, thus limiting the mechanical properties of the deposited state and requiring further heat treatment to improve mechanical properties. The ultrafine microstructure of the titanium alloy disclosed in this invention is generated by a low-temperature eutectoid phase transformation β→α+(Ti,Zr)₂Cu determined by the alloy composition. Therefore, the formed nano- or ultrafine α-lamellae microstructure is uniform and unaffected by the deposition size, ensuring the stable mechanical properties of the titanium alloy described in this invention. In the preparation process, firstly, a uniform alloy raw material is obtained through consumable melting. The alloy raw material is then subjected to several vacuum consumable melting processes to reduce the oxygen and other impurity elements in the entire alloy. The alloy workpiece is then prepared by laser directional energy deposition or laser powder bed melting. Through additive manufacturing, the growth direction of columnar crystals can be controlled during the preparation process. This results in a macrostructure of columnar crystals that grow epitaxially along the deposition height direction during deposition, with columnar crystal sizes reaching hundreds of micrometers to millimeters. After cooling, the microstructure consists of uniform submicron or nano-sized α-lamps and nano-(Ti,Zr)₂Cu particles distributed on the lath interfaces. Attached Figure Description

[0030] Figure 1 Microstructure diagrams of Ti-5Cu alloy and Ti-42Zr-5Cu alloy;

[0031] Figure (a) shows the microstructure of a Ti-5Cu alloy prepared by laser-directed energy deposition (LDED) as provided in Comparative Example 1, which has a lamellar pearlite-type eutectoid microstructure.

[0032] (b) The figure shows the microstructure of the laser-directed energy deposition Ti-42Zr-5Cu alloy provided in Example 1. The alloy has an ultrafine α-lamellae structure with discontinuous nano (Ti,Zr)2Cu particles distributed on the lamellar interfaces.

[0033] Figure 2 Verification of the tensile mechanical properties of the Ti-5Cu alloy prepared by the laser-directed energy deposition (LDED) process provided in Comparative Example 1.

[0034] Figure 3 The microstructure and phase size statistics of the laser-directed energy deposition Ti-42Zr-5Cu alloy provided in Example 1 are as follows;

[0035] Among them, (a) is the TEM bright-field image; (b) is the morphology under HAADF image; and (c) is the size statistics of α laths and (Ti,Zr)₂Cu particles.

[0036] Figure 4 This is to verify the tensile mechanical properties of the laser-directed energy deposition Ti-42Zr-5Cu alloy provided in Example 1. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the accompanying drawings:

[0038] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0039] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0040] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0041] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0042] The first aspect of the present invention discloses a low-cost, high-strength titanium alloy for laser additive manufacturing, wherein the mass fraction of the constituent elements of the titanium alloy is: Cu 3.5% to 6%, Zr 20% to 45%, and the balance is Ti and unavoidable impurities.

[0043] The final microstructure of the laser additive manufacturing-specific low-cost, high-strength titanium alloy consists of uniform submicron or nanoscale α-lamellae and nano-(Ti,Zr)₂Cu particles distributed on the lamellar interfaces.

[0044] The yield strength R of the low-cost, high-strength titanium alloy specifically designed for laser additive manufacturing p0.2 Its strength ranges from 1200MPa to 1300MPa, its tensile strength from 1400MPa to 1490MPa, and its elongation from 4.5% to 6%.

[0045] A second aspect of the present invention discloses a method for laser additive manufacturing of low-cost, high-strength titanium alloys, comprising the following steps:

[0046] Step 1: Distribute the titanium sponge, zirconium sponge, and copper materials according to the design;

[0047] Step 2: Perform several vacuum self-consumption melting processes on the ingredients from Step 1 to obtain ingots;

[0048] The melting process is a vacuum self-consuming melting process, and the melting is carried out 2 to 5 times to ensure uniform composition. The melting temperature is 2000℃ to 2500℃.

[0049] Step 3: Remove the riser from the ingot from Step 2 and cut it into several round bars with a diameter of 50mm and a length of 70mm.

[0050] Step 4: The round bar obtained in Step 3 is subjected to rotating electrode melting to produce alloy powder with a particle size ≤250μm, ensuring that the oxygen increase of the alloy does not exceed 300ppm during the rotating electrode process.

[0051] The powder preparation method is rotary electrode preparation, aiming to ensure the sphericity of the powder and the content of low interstitial element impurities. The prepared alloy powder composition meets the following requirements: Cu 3.5%–6% by mass, Zr 20%–45%, with the balance being Ti and unavoidable impurities. The low-interstitial alloy powder composition meets the following requirements: oxygen content less than 0.1% by mass, hydrogen content less than 0.003%, carbon content less than 0.009%, and nitrogen content less than 0.03%.

[0052] Perform step five or step seven.

[0053] Step 5: Screen out the alloy powder from Step 4 to obtain powder with a particle size range of 50μm to 150μm. Heat the powder to 120℃ under a vacuum of ≤133Pa and hold it for 120 to 180 minutes. Then cool it to room temperature under the same vacuum environment to remove moisture from the powder.

[0054] Step 6: The powder from Step 5 is prepared by laser directional energy deposition. During the deposition process, the oxygen content in the atmosphere is maintained at 1000-3000ppm. Under the conditions of laser spot diameter of 2.5mm-3.5mm, laser power of 900W-1500W, laser beam scanning speed of 480mm / min-1200mm / min, scanning interval of 1.2mm-1.8mm, and interlayer interval of 10-60s, TC4 castings or forgings are used as substrate materials, and are used after grinding and cleaning.

[0055] With a laser spot diameter of 3.5mm to 5.5mm, a laser power of 1200W to 2500W, a laser beam scanning speed of 480mm / min to 1200mm / min, a scanning interval of 1.8mm to 2.8mm, and an interlayer deposition time of 10 to 60s, TC4 castings or forgings are used as the substrate material, and are polished and cleaned before use.

[0056] The laser-directed energy deposition method described in step six is ​​performed on an optical fiber or semiconductor laser.

[0057] Step 7: Screen out the alloy powder from Step 4 to obtain powder with a particle size range of 10μm to 53μm. Heat the powder to 120℃ under a vacuum of ≤133Pa and hold it for 120 to 180 minutes. Then cool it to room temperature under the same vacuum environment to remove moisture from the powder.

[0058] Step 8: Prepare the powder from Step 7 using laser powder bed melting. First, reduce the forming chamber of the powder bed melting equipment to 10... -5A vacuum of 99.999% (Pa) is established, followed by the introduction of a protective atmosphere of high-purity argon gas. Throughout the powder bed fusion deposition process, the oxygen content within the forming chamber is controlled below 100 ppm. TC4 castings or forgings are used as the substrate material, after grinding and cleaning. The laser spot diameter is approximately 60 μm, the laser power is 120 W–250 W, the laser scanning speed is 800 mm / s–2000 mm / s, the layer thickness is 30 μm–45 μm, and the scanning line spacing is 80 μm–120 μm. The substrate material is TC4 castings or forgings, after grinding and cleaning. The substrate is not preheated or is preheated to below 100°C. After deposition, the protective atmosphere continues to be introduced until cooling to room temperature before the chamber is opened and the substrate is removed.

[0059] Comparative Example 1

[0060] This comparative example uses sponge titanium and copper sheet raw materials, with a weight percentage of 94% sponge titanium and 6% copper.

[0061] Place the raw materials into a vacuum arc remelting furnace and evacuate the furnace to a vacuum level of 10. -4 After the pressure drops below 100 Pa, high-purity argon gas (99.999% purity) is introduced, and the first melting is carried out at 2000℃ for 30 minutes, with the oxygen content controlled at ≤1000ppm, to obtain a primary ingot. After the alloy cools, the furnace door is opened, the ingot is inverted, and the same melting process is used to remelt the ingot to obtain a cylindrical ingot with a diameter of 150mm.

[0062] The cylindrical ingot is cut off at the head and tail shrinkage cavities and then cut into several round bars with a diameter of 50 mm and a length of 70 mm using electrical discharge machining. The round bars are then subjected to rotary electrode melting to prepare alloy powder with a particle size range of ≤250 μm.

[0063] Powder with a particle size range of 50 μm to 150 μm was sieved from the alloy powder. It was placed in a vacuum drying oven and heated to 120 °C under a vacuum of ≤133 Pa, then held at that temperature for 120 min, and cooled to room temperature under the same vacuum conditions. Immediately after cooling to room temperature, the powder was transferred from the vacuum drying oven to the powder feeder of a laser-directed energy deposition (LDED) system. The powder feeder used high-purity argon gas (99.999% purity) to transport the powder at a flow rate of 5 L / min.

[0064] The surface of the TC4 casting substrate was polished with 120-grit sandpaper until it was non-reflective, and then cleaned with acetone. Laser-directed energy deposition was performed under a protective atmosphere of high-purity argon (99.999% purity). The laser was a 1060nm fiber laser with a spot diameter of 3mm, a laser power of 1300W, a scanning speed of 480mm / min, a scanning spacing of 1.5mm, a lift of 0.35mm, and an interlayer interval of 45s.

[0065] The deposited sample was a bulk sample measuring 96mm x 40mm x 40mm. Electron probe microanalysis determined the alloy composition to be Ti-5Cu, wt.%.

[0066] Figure 1 (a) shows the microstructure of the Ti-5Cu alloy prepared in Comparative Example 1, which exhibits a pearlitic structure composed of alternating layers of α- and Ti2Cu. This pearlitic structure tends to make the alloy brittle.

[0067] The mechanical properties of the Ti-5Cu alloy prepared in Comparative Example 1 were tested in accordance with the national standard GB / T 228.1-2010 "Metallic materials, tensile testing - Part 1: Room temperature test method".

[0068] Figure 2 To verify the tensile mechanical properties of the Ti-5Cu alloy prepared in Comparative Example 1. The Ti-5Cu alloy has very low tensile plasticity; the tensile plasticity of all three comparative example samples is less than 1%, and they have not reached the yield point. The tensile mechanical properties of the three comparative example samples are shown in Table 1.

[0069] Table 1. Room temperature tensile mechanical properties of the alloys in Comparative Example 1

[0070]

[0071] Example 1

[0072] In this embodiment, sponge titanium, sponge zirconium and copper sheet raw materials are mixed in the following weight percentages: 50% sponge titanium, 45% sponge zirconium and 5% copper.

[0073] Place the raw materials into a vacuum arc remelting furnace and evacuate the furnace to a vacuum level of 10. -4 After the pressure drops below Pa, high-purity argon gas (99.999% purity) is introduced, and the first melting is carried out at 2000℃ for 30 minutes. The oxygen content during the process is controlled at ≤1000ppm to obtain a first-cast ingot.

[0074] After the alloy cools, the furnace door is opened and the ingot is inverted. The same melting process is used to remelt the ingot to obtain a cylindrical ingot with a diameter of 150mm.

[0075] The cylindrical ingot was cut away at the head and tail shrinkage cavities and then cut into several round bars with a diameter of 50 mm and a length of 70 mm using electrical discharge machining. These bars were then subjected to rotary electrode melting to prepare alloy powder with a particle size range of ≤250 μm. The powder was chemically analyzed according to the methods specified in GB / T4698.14-2011, YS / T 1262-2018, and JY / T 0567-2020. The results are shown in Table 2.

[0076] Table 2 Chemical composition of alloy powder in Example 1

[0077]

[0078]

[0079] The same powder pretreatment and laser-directed energy deposition process as in Comparative Example 1 were used.

[0080] Powder with a particle size range of 50 μm to 150 μm was sieved from the alloy powder. It was placed in a vacuum drying oven and heated to 120 °C under a vacuum of ≤133 Pa, then held at that temperature for 120 min, and cooled to room temperature under the same vacuum conditions. Immediately after cooling to room temperature, the powder was transferred from the vacuum drying oven to the powder feeder of a laser-directed energy deposition (LDED) system. The powder feeder used high-purity argon gas (99.999% purity) to transport the powder at a flow rate of 5 L / min.

[0081] The surface of the TC4 casting substrate was polished with 120-grit sandpaper until it was non-reflective, and then cleaned with acetone. Laser-directed energy deposition was performed under a protective atmosphere of high-purity argon (99.999% purity). The laser was a 1060nm fiber laser with a spot diameter of 3mm, a laser power of 1300W, a scanning speed of 480mm / min, a scanning spacing of 1.5mm, a lift of 0.35mm, and an interlayer interval of 45s to reduce heat accumulation in the deposited area and avoid coarsening of α-lamellae and (Ti,Zr)₂Cu particles.

[0082] The deposited sample was a bulk sample measuring 96mm x 40mm x 40mm. Electron probe microanalysis determined the alloy composition to be Ti-42Zr-5Cu, wt.%.

[0083] Figure 1 Figure (b) shows the microstructure of the Ti-42Zr-5Cu alloy prepared in Example 1, which consists of ultrafine or nanoscale α-lamellae and (Ti,Zr)2Cu nanoparticles at the lamellar interfaces. (Comparison) Figure 1 Figures (a) and (b) in the figure verify that 42% Zr alloying transforms the eutectoid microstructure of Ti-5Cu eutectoid titanium alloy from lamellar pearlite to ultrafine or nanoscale lath microstructure.

[0084] Figure 3 Figures (a) and (b) show the morphology of the microstructure of the Ti-42Zr-5Cu alloy prepared in Example 1 under TEM imaging mode, demonstrating the microstructure of discontinuous (Ti,Zr)2Cu nanoparticles on the α nanoplate interface. Figure 3Figure (c) shows the statistics of the widths of α nanoplatelets and (Ti,Zr)2Cu nanoparticles in the Ti-42Zr-5Cu alloy prepared in Example 1. The average width of the α nanoplatelets is about 102 nm, and the average width of the (Ti,Zr)2Cu nanoparticles is about 23 nm.

[0085] The mechanical properties of the Ti-42Zr-5Cu alloy prepared in Example 1 were tested according to the national standard GB / T 228.1-2010 "Metallic materials, tensile testing - Part 1: Room temperature test method".

[0086] Figure 4 The Ti-42Zr-5Cu alloy prepared for Example 1 was divided into three pieces for tensile mechanical property verification. The tensile yield strength, tensile strength, and tensile plasticity of the Ti-42Zr-5Cu alloy were significantly improved compared with the Ti-5Cu alloy prepared in Comparative Example 1. The tensile mechanical properties of the three sets of sample samples are shown in Table 3.

[0087] Table 3 Room temperature tensile mechanical properties of the alloy in Example 1

[0088]

[0089] Example 2

[0090] The same alloy smelting and powdering process as in Example 1 was used.

[0091] The powder obtained from the rotating electrode was sieved to obtain powder with a particle size of 50μm to 150μm, and dried using the same drying method as in Example 1. The powder cooled to room temperature was immediately transferred to the powder feeder of the laser directional energy deposition equipment. The powder feeder used high-purity argon gas (99.999% purity) to transport the powder, and the powder flow rate was 6L / min.

[0092] The surface of the TC4 forged substrate was polished with 120-grit sandpaper until it was non-reflective, and then cleaned with acetone. Laser-directed energy deposition was performed under a protective atmosphere of high-purity argon (99.999% purity). The laser was a 1040nm fiber laser with a spot diameter of 5.5mm, a laser power of 2500W, a scanning speed of 1200mm / min, a scanning spacing of 2.8mm, a lift of 0.4mm, and an interlayer interval of 60s to reduce heat accumulation in the deposited area and avoid coarsening of α-lamellae and (Ti,Zr)₂Cu particles.

[0093] The deposited sample was a block sample measuring 80mm*35mm*40mm. The alloy composition, determined by electron probe microanalysis, was Ti-44Zr-4Cu, wt.%. Mechanical properties of the deposited alloy were tested according to the national standard GB / T228.1-2010 "Metallic materials, tensile testing—Part 1: Tests at room temperature," and the results are shown in Table 4.

[0094] Table 4. Room temperature tensile mechanical properties of the alloy in Example 2

[0095]

[0096] Example 3

[0097] The same alloy smelting and powdering process as in Example 1 was used.

[0098] The powder obtained from the rotating electrode was sieved to obtain powder with a particle size of 15μm to 53μm, and dried using the same drying method as in Example 1. The powder cooled to room temperature was immediately transferred to the powder chamber of a laser powder bed fusion deposition apparatus. A high-purity argon atmosphere (99.999% purity) was used as the protective atmosphere, and the oxygen content in the sample chamber was less than 100ppm throughout the deposition process.

[0099] The surface of the TC4 forged substrate was polished with 120-grit sandpaper until it was non-reflective, and then the substrate surface was cleaned with acetone. The laser was a fiber laser with a maximum power of 400W, a spot diameter of 60μm, a laser power of 120W, a scanning speed of 800mm / s, a scanning spacing of 100μm, and a lift of 30μm.

[0100] The deposited sample was a block sample measuring 15mm*12mm*70mm. The alloy composition, determined by electron probe microanalysis, was Ti-44Zr-5Cu, wt.%. Mechanical properties of the deposited alloy were tested according to the national standard GB / T228.1-2010 "Metallic Materials - Tensile Testing - Part 1: Room Temperature Test Method", and the results are shown in Table 5.

[0101] Table 5. Room temperature tensile mechanical properties of the alloy in Example 3

[0102]

[0103] Example 4

[0104] In this embodiment, sponge titanium, sponge zirconium and copper sheet raw materials are mixed in the following weight percentages: 76.5% sponge titanium, 20% sponge zirconium and 3.5% copper.

[0105] Place the raw materials into a vacuum arc remelting furnace and evacuate the furnace to a vacuum level of 10. -4 After the pressure drops below Pa, high-purity argon gas (99.999% purity) is introduced, and the first melting is carried out at 2000℃ to obtain a primary ingot.

[0106] After the alloy cools, the furnace door is opened and the ingot is inverted. The same melting process is used to remelt the ingot to obtain a cylindrical ingot with a diameter of 150mm.

[0107] The cylindrical ingot is cut off at the head and tail shrinkage cavities and then cut into several round bars with a diameter of 50 mm and a length of 70 mm using electrical discharge machining. The round bars are then subjected to rotary electrode melting to prepare alloy powder with a particle size range of ≤250 μm.

[0108] Powder with a particle size range of 50 μm to 150 μm was sieved from the alloy powder. It was placed in a vacuum drying oven and heated to 120 °C under a vacuum of less than 133 Pa, then held at that temperature for 120 min, and cooled to room temperature under the same vacuum conditions. Immediately after cooling to room temperature, the powder was transferred from the vacuum drying oven to the powder feeder of a laser-directed energy deposition (LDED) system. The powder feeder used high-purity argon gas (99.999% purity) to transport the powder at a flow rate of 6 L / min.

[0109] The surface of the TC4 casting substrate was polished with 120-grit sandpaper until it was non-reflective, and then cleaned with acetone. Laser-directed energy deposition was performed under a protective atmosphere of high-purity argon (99.999% purity). The laser was a 1060nm fiber laser with a spot diameter of 3.5mm, a laser power of 1200W, a scanning speed of 480mm / min, a scanning spacing of 1.8mm, a lift of 0.45mm, and an interlayer interval of 10s.

[0110] Example 5

[0111] In this embodiment, sponge titanium, sponge zirconium and copper sheet raw materials are mixed in the following weight percentages: 66% sponge titanium, 30% sponge zirconium and 4% copper.

[0112] Place the raw materials into a vacuum arc remelting furnace and evacuate the furnace to a vacuum level of 10. -4 After the pressure drops below Pa, high-purity argon gas (99.999% purity) is introduced, and the first melting is carried out at 2000℃ to obtain a primary ingot.

[0113] After the alloy cools, the furnace door is opened and the ingot is inverted. The same melting process is used to remelt the ingot to obtain a cylindrical ingot with a diameter of 150mm.

[0114] The cylindrical ingot is cut off at the head and tail shrinkage cavities and then cut into several round bars with a diameter of 50 mm and a length of 70 mm using electrical discharge machining. The round bars are then subjected to rotary electrode melting to prepare alloy powder with a particle size range of ≤250 μm.

[0115] Powder with a particle size range of 50 μm to 150 μm was sieved from the alloy powder. It was placed in a vacuum drying oven and heated to 120 °C under a vacuum of less than 133 Pa, then held at that temperature for 180 min, and cooled to room temperature under the same vacuum conditions. Immediately after cooling to room temperature, the powder was transferred from the vacuum drying oven to the powder feeder of a laser-directed energy deposition (LDED) system. The powder feeder used high-purity argon gas (99.999% purity) to transport the powder at a flow rate of 6 L / min.

[0116] The surface of the TC4 casting substrate was polished with 120-grit sandpaper until it was non-reflective, and then cleaned with acetone. Laser-directed energy deposition was performed under a protective atmosphere of high-purity argon (99.999% purity). The laser was a 1040nm fiber laser with a spot diameter of 4mm, a laser power of 1500W, a scanning speed of 1000mm / min, a scanning spacing of 2mm, a lift of 0.35mm, and an interlayer interval of 30s.

[0117] Example 6

[0118] In this embodiment, sponge titanium, sponge zirconium and copper sheet raw materials are mixed in the following weight percentages: 50% sponge titanium, 45% sponge zirconium and 5% copper.

[0119] Place the raw materials into a vacuum arc remelting furnace and evacuate the furnace to a vacuum level of 10. -4 After the pressure drops below Pa, high-purity argon gas (99.999% purity) is introduced, and the first melting is carried out at 2500℃ to obtain a primary ingot.

[0120] After the alloy cools, the furnace door is opened and the ingot is inverted. The same melting process is used to remelt the ingot to obtain a cylindrical ingot with a diameter of 150mm.

[0121] The cylindrical ingot is cut off at the head and tail shrinkage cavities and then cut into several round bars with a diameter of 50 mm and a length of 70 mm using electrical discharge machining. The round bars are then subjected to rotary electrode melting to prepare alloy powder with a particle size range of ≤250 μm.

[0122] Powder with a particle size range of 50 μm to 150 μm was sieved from the alloy powder. It was placed in a vacuum drying oven and heated to 120 °C under a vacuum of less than 133 Pa, then held at that temperature for 140 min, and cooled to room temperature under the same vacuum conditions. Immediately after cooling to room temperature, the powder was transferred from the vacuum drying oven to the powder feeder of a laser-directed energy deposition (LDED) system. The powder feeder used high-purity argon gas (99.999% purity) to transport the powder at a flow rate of 5 L / min.

[0123] The surface of the TC4 casting substrate was polished with 120-grit sandpaper until it was non-reflective, and then cleaned with acetone. Laser-directed energy deposition was performed under a protective atmosphere of high-purity argon (99.999% purity). The laser was a 1060nm fiber laser with a spot diameter of 2.5mm, a laser power of 900W, a scanning speed of 800mm / min, a scanning spacing of 1.2mm, a lift of 0.3mm, and an interlayer interval of 10s.

[0124] Example 7

[0125] In this embodiment, sponge titanium, sponge zirconium and copper sheet raw materials are mixed in the following weight percentages: 50% sponge titanium, 45% sponge zirconium and 5% copper.

[0126] Place the raw materials into a vacuum arc remelting furnace and evacuate the furnace to a vacuum level of 10. -4 After the pressure drops below Pa, high-purity argon gas (99.999% purity) is introduced, and the first melting is carried out at 2500℃ to obtain a primary ingot.

[0127] After the alloy cools, the furnace door is opened and the ingot is inverted. The same melting process is used to remelt the ingot to obtain a cylindrical ingot with a diameter of 150mm.

[0128] The cylindrical ingot is cut off at the head and tail shrinkage cavities and then cut into several round bars with a diameter of 50 mm and a length of 70 mm using electrical discharge machining. The round bars are then subjected to rotary electrode melting to prepare alloy powder with a particle size range of ≤250 μm.

[0129] Powder with a particle size range of 50 μm to 150 μm was sieved from the alloy powder. It was placed in a vacuum drying oven and heated to 120 °C under a vacuum of less than 133 Pa, then held at that temperature for 160 min, and cooled to room temperature under the same vacuum conditions. Immediately after cooling to room temperature, the powder was transferred from the vacuum drying oven to the powder feeder of a laser-directed energy deposition (LDED) system. The powder feeder used high-purity argon gas (99.999% purity) to transport the powder at a flow rate of 4 L / min.

[0130] The surface of the TC4 forged substrate was polished with 120-grit sandpaper until it was non-reflective, and then cleaned with acetone. Laser-directed energy deposition was performed under a protective atmosphere of high-purity argon (99.999% purity). The laser was a 1060nm fiber laser with a spot diameter of 3mm, a laser power of 1500W, a scanning speed of 1200mm / min, a scanning spacing of 1.5mm, a lift of 0.3mm, and an interlayer interval of 60s.

[0131] Example 8

[0132] In this embodiment, sponge titanium, sponge zirconium and copper sheet raw materials are mixed in the following weight percentages: 50% sponge titanium, 45% sponge zirconium and 5% copper.

[0133] Place the raw materials into a vacuum arc remelting furnace and evacuate the furnace to a vacuum level of 10. -4 After the pressure drops below Pa, high-purity argon gas (99.999% purity) is introduced, and the first melting is carried out at 2300℃ to obtain a primary ingot.

[0134] After the alloy cools, the furnace door is opened and the ingot is inverted. The same melting process is used to remelt the ingot to obtain a cylindrical ingot with a diameter of 150mm.

[0135] The cylindrical ingot is cut off at the head and tail shrinkage cavities and then cut into several round bars with a diameter of 50 mm and a length of 70 mm using electrical discharge machining. The round bars are then subjected to rotary electrode melting to prepare alloy powder with a particle size range of ≤250 μm.

[0136] Powder with a particle size range of 10 μm to 53 μm was sieved from the alloy powder. The powder was placed in a vacuum drying oven and heated to 120 °C under a vacuum of less than 133 Pa, then held at that temperature for 120 min, and cooled to room temperature under the same vacuum environment. Immediately after cooling to room temperature, the powder was transferred from the vacuum drying oven to the powder chamber of a laser powder bed melting device. A high-purity argon atmosphere (99.999% purity) was used as the protective atmosphere, and the oxygen content in the sample chamber remained below 100 ppm throughout the entire deposition process.

[0137] The surface of the TC4 forging substrate was polished with 120-grit sandpaper until it was non-reflective, and then the substrate surface was cleaned with acetone. The laser was a fiber laser with a maximum power of 300W, a laser spot diameter of 60μm, a laser power of 250W, a scanning speed of 2000mm / s, a scanning spacing of 120μm, and a lift of 45μm.

[0138] Example 9

[0139] In this embodiment, sponge titanium, sponge zirconium and copper sheet raw materials are mixed in the following weight percentages: 50% sponge titanium, 45% sponge zirconium and 5% copper.

[0140] Place the raw materials into a vacuum arc remelting furnace and evacuate it to 10°C. -4 After the pressure drops below Pa, high-purity argon gas (99.999% purity) is introduced, and the first melting is carried out at 2500℃ to obtain a primary ingot.

[0141] After the alloy cools, the furnace door is opened and the ingot is inverted. The same melting process is used to remelt the ingot to obtain a cylindrical ingot with a diameter of 150mm.

[0142] The cylindrical ingot is cut off at the head and tail shrinkage cavities and then cut into several round bars with a diameter of 50 mm and a length of 70 mm using electrical discharge machining. The round bars are then subjected to rotary electrode melting to prepare alloy powder with a particle size range of ≤250 μm.

[0143] The powder obtained from the rotating electrode was sieved to obtain powder with a particle size of 15μm to 53μm, and dried using the same drying method as in Example 1. The powder cooled to room temperature was immediately transferred to the powder chamber of a laser powder bed fusion deposition apparatus. A high-purity argon atmosphere (99.999% purity) was used as the protective atmosphere, and the oxygen content in the sample chamber was less than 100ppm throughout the deposition process.

[0144] The surface of the TC4 forged substrate was polished with 120-grit sandpaper until it was non-reflective, and then cleaned with acetone. The substrate was preheated to 80°C before sample deposition began. A 400W fiber laser was used, with a laser spot diameter of 60μm, a laser power of 150W, a scanning speed of 1000mm / s, a scanning line spacing of 80μm, a layer thickness of 30μm, and a sample size of 15mm*12mm*70mm.

[0145] Example 10

[0146] In this embodiment, sponge titanium, sponge zirconium and copper sheet raw materials are mixed in the following weight percentages: 50% sponge titanium, 45% sponge zirconium and 5% copper.

[0147] Place the raw materials into a vacuum arc remelting furnace and evacuate the furnace to a vacuum level of 10. -4 After the pressure drops below Pa, high-purity argon gas (99.999% purity) is introduced, and the first melting is carried out at 2200℃ to obtain a primary ingot.

[0148] After the alloy cools, the furnace door is opened and the ingot is inverted. The same melting process is used to remelt the ingot to obtain a cylindrical ingot with a diameter of 150mm.

[0149] The cylindrical ingot is cut off at the head and tail shrinkage cavities and then cut into several round bars with a diameter of 50 mm and a length of 70 mm using electrical discharge machining. The round bars are then subjected to rotary electrode melting to prepare alloy powder with a particle size range of ≤250 μm.

[0150] The powder obtained from the rotating electrode was sieved to obtain powder with a particle size of 15μm to 53μm, and dried using the same drying method as in Example 1. The powder cooled to room temperature was immediately transferred to the powder chamber of a laser powder bed fusion deposition apparatus. A high-purity argon atmosphere (99.999% purity) was used as the protective atmosphere, and the oxygen content in the sample chamber was less than 100ppm throughout the deposition process.

[0151] The surface of the TC4 forged substrate was polished with 120-grit sandpaper until it was non-reflective, and then cleaned with acetone. The laser used was a 500W fiber laser with a 60μm laser spot diameter, 250W laser power, a scanning speed of 2000mm / s, a scanning line spacing of 110μm, a layer thickness of 40μm, and a deposited sample size of 15mm*12mm*70mm.

[0152] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength titanium alloy, characterized in that, Includes the following steps: Step 1: After mixing the sponge titanium, sponge zirconium and copper materials according to the designed composition, vacuum arc remelting is carried out to obtain ingots; Step 2: Melt the ingot using a rotating electrode to produce alloy powder; Step 3: Heat the alloy powder in a vacuum environment and then cool it to obtain the powder after vacuum drying. Step 4: The vacuum-treated powder is deposited on the substrate using laser directional energy deposition or laser powder bed melting to obtain a high-strength titanium alloy workpiece. In step 4, the process parameters for deposition using laser-directed energy deposition are as follows: With a laser spot diameter of 2.5 mm to 3.5 mm, a laser power of 900 W to 1500 W, a laser beam scanning speed of 480 mm / min to 1200 mm / min, a scanning interval of 1.2 mm to 1.8 mm, and an interlayer deposition time of 10 to 60 s; With a laser spot diameter of 3.5 mm to 5.5 mm, a laser power of 1200 W to 2500 W, a laser beam scanning speed of 480 mm / min to 1200 mm / min, a scanning interval of 1.8 mm to 2.8 mm, and an interlayer deposition time of 10 to 60 s; In step 4, the process parameters for preparing high-strength titanium alloy workpieces by laser powder bed melting are as follows: The laser spot diameter is 60 μm, the laser power is 120W~250W, the laser scanning speed is 800 mm / s~2000 mm / s, the layer thickness is 30 μm~45 μm, and the scanning line spacing is 80 μm~120 μm. The high-strength titanium alloy workpiece comprises: Cu 3.5%~6%, Zr 20%~45%, with the balance being Ti and unavoidable impurities; The high-strength titanium alloy has a deposited alloy microstructure consisting of submicron-sized or nano-sized α-lamellae, with nano-(Ti,Zr)2Cu particles distributed at the interfaces of adjacent laths. The yield strength R of the high-strength titanium alloy p0.2 The pressure is 1200 MPa to 1300 MPa.

2. The method for preparing high-strength titanium alloy according to claim 1, characterized in that, In step 1, the vacuum self-consumable melting is performed 2 to 5 times; before step 2, the riser of the ingot obtained in step 1 is removed.

3. The method for preparing high-strength titanium alloy according to claim 1, characterized in that, Step 2: During the rotating electrode melting process, the oxygen content of the environment and the oxygen content of the alloy powder obtained by rotating electrode melting are both ≤0.1 wt%.

4. The method for preparing high-strength titanium alloy according to claim 1, characterized in that, Step 3: Before vacuum heating, the alloy powder obtained in step 2 is screened to obtain powder with a particle size range of 50 μm to 150 μm.

5. The method for preparing high-strength titanium alloy according to claim 1, characterized in that, Step 3: Before vacuum heating, the alloy powder obtained in step 2 is screened to obtain powder with a particle size range of 10 μm to 53 μm.

6. A high-strength titanium alloy obtained by any one of claims 1-5, characterized in that, By mass fraction, it includes: Cu 3.5%~6%, Zr 20%~45%, with the balance being Ti and unavoidable impurities; The high-strength titanium alloy has a deposited alloy microstructure consisting of submicron-sized or nano-sized α-lamellae, with nano-(Ti,Zr)₂Cu particles distributed at the interfaces of adjacent laths.

7. A high-strength titanium alloy according to claim 6, characterized in that, The yield strength R of the high-strength titanium alloy p0.2 The pressure is 1200 MPa to 1300 MPa.

8. A high-strength titanium alloy according to claim 6, characterized in that, The high-strength titanium alloy has a tensile strength of 1400 MPa to 1490 MPa and an elongation of 4.5% to 6%.

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