B microalloying high-performance Ti2AlNb-based alloy and preparation method and application thereof

Abstract

The invention discloses a B micro-alloyed high-performance Ti2AlNb-based alloy as well as a preparation method and application of the B micro-alloyed high-performance Ti2AlNb-based alloy. The B microalloyed high-performance Ti2AlNb-based alloy is prepared from the following components in percentage by mass: 8.1 percent to 17.5 percent of Al, 18.9 percent to 50.6 percent of Nb, 0.0005 percent to 0.05 percent of B and the balance of Ti and inevitable impurities. The invention also provides two methods for preparing the Ti2AlNb-based alloy disclosed by the invention. According to the invention, through reasonable design of the components and proportion of the Ti2AlNb-based alloy, the plasticity of the alloy is remarkably improved while the strength of the traditional Ti2AlNb-based alloy is improved, the requirement of the Ti2AlNb-based alloy on plasticity in the processing process is further met, and the problem of cracking of the traditional Ti2AlNb-based alloy in the processing process due to insufficient plasticity is completely or partially solved.

Description

Technical Field

[0001] The present invention relates to the technical field of new metal materials, and particularly to a B-microalloyed high-performance Ti 2 AlNb-based alloy and its preparation method and application. Background Art

[0002] Ti 2 AlNb-based alloys have excellent high-temperature properties, oxidation resistance, creep resistance, etc., and are a kind of superalloys that can be used for a long time in the temperature range of 650°C to 750°C or for a short time at higher temperatures. In advanced aeroengines, the proportion of superalloys used exceeds 50%. Using Ti 2 AlNb-based alloys to replace the currently commonly used nickel-based superalloys can reduce the weight by about 40% and significantly improve the thrust ratio and fuel efficiency of the engine. The excellent comprehensive properties make Ti 2 AlNb-based alloys become a kind of lightweight high-temperature structural materials with great application prospects in the aerospace field.

[0003] Compared with γ-TiAl and Ti 3 Al-based alloys, Ti 2 AlNb-based alloys have been greatly improved in plasticity and workability. However, as an intermetallic compound alloy, Ti 2 AlNb-based alloys still have intrinsic brittleness. Due to relatively poor plasticity, a large number of fine iterative processing steps are required to prevent Ti 2 AlNb-based alloys from cracking during casting, hot working, and machining processes, resulting in a significant increase in their production cost and time, which limits the application of this alloy. Developing Ti 2 AlNb-based alloys with higher plasticity to avoid cracking during processing has become one of the urgent problems to be solved for the large-scale application of this alloy. Summary of the Invention

[0004] Aiming at the problem that Ti 2 AlNb-based alloys are extremely prone to cracking during casting, hot working, and machining processes due to insufficient plasticity, the present invention provides a new type of Ti 2 AlNb-based alloy with excellent plasticity and its preparation method and application. Through the microalloying of B element, a Ti 2 AlNb-based alloy with a high β-phase content is obtained, thereby achieving a significant improvement in the plasticity of the alloy.

[0005] To achieve the above object and other related objects, the present invention is obtained through the following technical solutions.

[0006] The first aspect of the present invention lies in providing a B-microalloyed high-performance Ti 2AlNb-based alloy, the B microalloyed high-performance Ti 2 The AlNb-based alloy, calculated by mass percentage, includes the following components: 8.1% - 17.5% of Al, 18.9% - 50.6% of Nb, 0.0005% - 0.05% of B, and the balance is Ti and inevitable impurities.

[0007] In some embodiments of the present invention, the B microalloyed high-performance Ti 2 The AlNb-based alloy, calculated by mass percentage, includes the following components: 8.1% - 17.5% of Al, 18.9% - 50.6% of Nb, 0.0025% - 0.02% of B, and the balance is Ti and inevitable impurities.

[0008] In some embodiments of the present invention, the B microalloyed high-performance Ti 2 The AlNb-based alloy, calculated by mass percentage, further includes 0% - 7.5% of X, where X is one or a combination of several of Mo, Zr, V, Cr, Ta, W, Y, Sn, Hf.

[0009] The second aspect of the present invention provides a B microalloyed high-performance Ti 2 preparation method of the above AlNb-based alloy, including the following steps:

[0010] (1) Weigh the raw materials according to the ratio, press them with a hydraulic press, and assemble and weld them to make a consumable electrode;

[0011] (2) Use the vacuum consumable method for melting, and after three times of melting, pour it into a mold to obtain a Ti 2 AlNb-based alloy ingot.

[0012] The third aspect of the present invention provides another B microalloyed high-performance Ti 2 preparation method of the above AlNb-based alloy, in addition to including the above steps (1) and (2), further includes the following steps:

[0013] (3) Subject the Ti 2 AlNb-based alloy ingot obtained in step (2) to vacuum gas atomization to make a Ti 2 AlNb-based alloy powder;

[0014] (4) Use the additive manufacturing method to prepare the Ti 2 AlNb-based alloy powder into a Ti 2 AlNb-based alloy.

[0015] The fourth aspect of the present invention provides the use of the above B microalloyed high-performance Ti 2 AlNb-based alloy in aerospace equipment.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The present invention provides a B-microalloyed high-performance Ti 2 AlNb-based alloy. Through the reasonable design of the composition and proportion of the Ti 2 AlNb-based alloy, by adding a small amount of B element, the content of the disordered β phase in the alloy is regulated. At the same time, the B element segregates at the grain boundaries, improving the grain boundary bonding force. While increasing the strength of the traditional Ti 2 AlNb-based alloy, the plasticity of the alloy is significantly improved, further meeting the requirement for plasticity of the Ti 2 AlNb-based alloy during the processing process, and heat treatment will not reduce the mechanical properties of the alloy, completely or partially solving the problem of cracking of the traditional Ti 2 AlNb-based alloy due to insufficient plasticity during the processing process.

[0018] 2. The preparation method of the B-microalloyed high-performance Ti 2 AlNb-based alloy provided by the present invention is to proportion the Ti 2 AlNb-based alloy, press the prepared raw materials by a hydraulic press, then assemble and weld them into a consumable electrode, and then use the vacuum consumable method for melting, pour it into a mold to obtain a Ti 2 AlNb-based alloy ingot (part), or further obtain Ti 2 AlNb-based alloy powder by vacuum atomization of the Ti 2 AlNb-based alloy ingot, and then perform additive manufacturing to obtain a Ti 2 AlNb-based alloy.

[0019] 3. In the B-microalloyed high-performance Ti 2 AlNb-based alloy provided by the present invention, the B element is in a solid solution state, no boride precipitates, or the amount of boride precipitation in the alloy is small. The volume fraction of the disordered β phase is increased by 5% - 100% compared with the Ti 2 AlNb-based alloy without adding B element. The average grain diameter is 100 - 300 μm, the room temperature tensile strength is 953 MPa - 1180 MPa, and the room temperature elongation is 7.0% - 19.7%. It has excellent strength and plasticity and can meet the mechanical property requirements of aerospace equipment, especially can be applied to advanced aeroengines. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Shown is the microstructure diagram of a part of the Ti 2 AlNb-based alloy in Example 1 of the present invention, where (a): 1#; (b): 4#; (c): 6#; (d): 7#; (e): 9#.

[0021] Figure 2 Shown as part of Ti in Embodiment 1 of the present invention 2 Electron backscatter diffraction (EBSD) inverse pole figure images of AlNb-based alloys, where (a): 1#; (b): 4#; (c): 6#.

[0022] Figure 3 Shown as 21# Ti in Embodiment 4 of the present invention 2 Backscattered microstructure images (BSE) of AlNb-based alloys, where (a): low magnification microstructure; (b): interdendritic microstructure; (c): dendrite trunk microstructure; (d): microstructure at grain boundaries.

[0023] Figure 4 Shown as 23# Ti in Embodiment 4 of the present invention 2 Backscattered microstructure images (BSE) of AlNb-based alloys, where (a): low magnification microstructure; (b): interdendritic microstructure: (c): dendrite trunk microstructure; (d): microstructure at grain boundaries. Detailed implementation manners

[0024] In order to make the invention objectives, technical solutions and beneficial technical effects of the present invention clearer, the present invention will be further described in detail below in combination with embodiments. Those familiar with this technology can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0025] The first aspect of the present invention lies in providing a B-microalloyed high-performance Ti 2 AlNb-based alloy, and the B-microalloyed high-performance Ti 2 AlNb-based alloy, calculated by mass percentage, includes the following components: 8.1% - 17.5% of Al, 18.9% - 50.6% of Nb, 0.0005% - 0.05% of B, and the balance is Ti and unavoidable impurities.

[0026] The present invention significantly improves the plasticity of Ti 2 AlNb-based alloy by adding a trace amount of B element and adjusting and optimizing the composition and ratio of the alloy. The addition of a trace amount of B element will segregate along the grain boundaries, thereby enhancing the grain boundary bonding force. In addition, the addition of a trace amount of B element can also regulate the proportion of the disordered β phase in the alloy to achieve the purpose of improving the plasticity of the alloy and meeting the plasticity requirements of Ti 2 AlNb-based alloy during the processing process. In addition, while significantly improving the plasticity of the alloy, the present invention can also improve the strength of the alloy, making the alloy have excellent comprehensive properties.

[0027] In some embodiments of the present invention, the B-microalloyed high-performance Ti 2The AlNb-based alloy, calculated by mass percentage, comprises the following components: 8.1% to 17.5% of Al, 18.9% to 50.6% of Nb, 0.0025% to 0.02% of B, and the balance is Ti and inevitable impurities.

[0028] In some specific embodiments of the present invention, the mass percentage of Al can be 8.1% to 8.5%, 8.5% to 9.0%, 9.0% to 9.5%, 9.5% to 10.0%, 10.0% to 10.5%, 10.5% to 11.0%, 11.0% to 11.5%, 11.5% to 12.0%, 20.0% to 12.5%, 12.5% to 13.0%, 13.0% to 13.5%, 13.5% to 14.0%, 14.0% to 14.5%, 14.5 to 15.0%, 15.0% to 15.5%, 15.5% to 16.0%, 16.0% to 16.5%, 16.5% to 17.0%, and can also be 17.0% to 17.5%; typically but not restrictively, for example, it can be 8.1%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17% and 17.5%, etc.

[0029] In some specific embodiments of the present invention, the mass percentage of Nb can be 18.9% to 20.4%, 20.4% to 21.9%, 21.9% to 23.4%, 23.4% to 24.9%, 24.9% to 26.4%, 26.4% to 27.9%, 27.9% to 29.4%, 29.4% to 30.9%, 30.9% to 32.4%, 32.4% to 33.9%, 33.9% to 35.4%, 35.4% to 36.9%, 36.9% to 38.4%, 38.4% to 39.9%, 39.9% to 41.4%, 41.4% to 42.9%, 42.9% to 44.4%, 44.4% to 45.9%, 45.9% to 47.4%, 47.4% to 48.9%, and can also be 48.9% to 50.6%; typically but not restrictively, for example, it can be 18.9%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50% and 50.6%, etc.

[0030] In some specific embodiments of the present invention, the mass percentage of B can be 0.0005% - 0.0008%, 0.0008% - 0.001%, 0.001% - 0.0012%, 0.0012% - 0.0014%, 0.0014% - 0.0016%, 0.0016% - 0.0018%, 0.0018% - 0.002%, 0.002% - 0.004%, 0.004% - 0.005%, 0.005% - 0.006%, 0.006% - 0.008%, 0.008% - 0.01%, 0.01% - 0.012%, 0.012% - 0.014%, 0.014% - 0.015%, 0.015% - 0.016%, 0.016% - 0.017%, 0.017% - 0.018%, 0.018% - 0.019%, 0.019% - 0.02%, 0.02% - 0.025%, 0.025% - 0.03%, 0.03% - 0.035%, 0.035% - 0.04%, 0.04% - 0.045%, and can also be 0.045% - 0.05%; typically but not restrictively, for example, it can be 0.0005%, 0.0025%, 0.005%, 0.0075%, 0.01%, 0.0125%, 0.015%, 0.0175%, 0.02%, 0.03%, etc.

[0031] In some embodiments of the present invention, the B microalloyed high-performance Ti 2 AlNb-based alloy, calculated by mass percentage, further includes 0% - 7.5% of X, where X is one or a combination of several of Mo, Zr, V, Cr, Ta, W, Y, Sn, Hf; in certain specific embodiments, the X is Mo, Zr, V, Ta, W. In some specific embodiments of the present invention, the mass percentage of X can be 0% - 0.1%, 0.1% - 0.2%, 0.2% - 0.3%, 0.3% - 0.4%, 0.4% - 0.5%, 0.5% - 1%, 1.0% - 1.5%, 1.5% - 2%, 2% - 2.5%, 2.5% - 3%, 3% - 3.5%, 3.5% - 4%, 4% - 4.5%, 4.5% - 5%, 5% - 5.5%, 5.5% - 6%, 6% - 6.5%, 6.5 - 7%, 7% - 7.1%, 7.1% - 7.2%, 7.2% - 7.3%, 7.3% - 7.4%, and can also be 7.4% - 7.5%; typically but not restrictively, for example, it can be 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, and 7.5%, etc.

[0032] In some embodiments of the present invention, the B microalloyed high-performance Ti 2In the AlNb-based alloy, element B is in a solid solution state, with no boride precipitation or only a small amount of boride precipitation. From Figure 1 it can be seen that, calculated by mass percentage, when the addition amount of element B in the Ti 2 AlNb-based alloy prepared in Example 1 of the present invention is 0.0005% - 0.02%, the alloy has a solid solution structure, in which element B is in a solid solution state and no boride precipitates. The addition of trace element B will segregate along the grain boundaries, thereby enhancing the grain boundary bonding force. In addition, the addition of trace element B can also regulate the proportion of the disordered β-phase in the alloy to achieve the purpose of improving the plasticity of the alloy and meeting the plasticity requirements of the Ti 2 AlNb-based alloy during the processing. When the addition amount of element B in the Ti 2 AlNb-based alloy prepared in Example 1 of the present invention is 0.02% - 0.05%, a small amount of boride will precipitate. The precipitation of boride will reduce the plasticity of the alloy while increasing the strength of the alloy. However, when the addition amount of element B does not exceed 0.05%, the effect of plasticity reduction caused by boride precipitation is less than the effect of plasticity increase caused by the above-mentioned element B increasing the proportion of the disordered β-phase and strengthening the grain boundaries. Compared with the alloy without adding element B, the plasticity is still improved. In the reported examples of strengthening titanium alloys with element B, the addition amount of element B is relatively large, and the alloy properties are mainly improved by the precipitation of a large amount of borides. Although the precipitation of borides can effectively limit the growth of alloy grains and thus improve the strength of the alloy, the appearance of a large amount of borides will completely offset the effect of plasticity increase caused by the above-mentioned element B increasing the proportion of the disordered β-phase and strengthening the grain boundaries, significantly reducing the room temperature plasticity of the alloy. In the present invention, by controlling the addition amount of element B, it is ensured that no boride precipitates in the alloy or the amount of boride precipitation will not significantly reduce the plasticity of the alloy.

[0033] In some embodiments of the present invention, the volume fraction of the disordered β-phase in the B-microalloyed high-performance Ti 2 AlNb-based alloy is 50% - 100%, which is 5% - 100% higher than that of the Ti 2 AlNb-based alloy without adding element B. The volume fraction of the disordered β-phase in the alloy is measured by X-ray diffraction and transmission electron microscopy. The addition of trace element B in the present invention increases the volume fraction of the β-phase with better plasticity in the alloy, thereby improving the plasticity of the alloy.

[0034] In some embodiments of the present invention, the average grain diameter of the B-microalloyed high-performance Ti 2 AlNb-based alloy is 100 - 300 μm.

[0035] In some embodiments of the present invention, the B-microalloyed high-performance Ti 2The room temperature tensile strength of the AlNb-based alloy is 953 MPa to 1180 MPa, and the room temperature elongation is 7.0% to 19.7%. In some preferred embodiments of the present invention, the B-microalloyed high-performance Ti 2 The room temperature tensile strength of the AlNb-based alloy is 970 MPa to 1172 MPa, and the room temperature elongation is 12.6% to 19.7%. From the test results in the examples, it can be seen that Ti 2 The strength of the AlNb-based alloy increases significantly with the increase in the content of boron element; Ti 2 The plasticity of the AlNb-based alloy increases significantly with the increase in boron content when the boron content is low; when the boron content increases to 0.01%, the plasticity of the alloy increases the most; when the boron content is greater than 0.01%, with the increase in boron content, the increase in the plasticity of the alloy gradually decreases. When the boron content increases to 0.05%, the plasticity of the alloy is still slightly better than that of the alloy without boron addition, while when the boron content increases to 0.055%, the plasticity of the alloy is worse than that of the alloy without boron addition.

[0036] In some embodiments of the present invention, the B-microalloyed high-performance Ti 2 After heat treatment of the AlNb-based alloy, the B element in the alloy remains in a solid solution state, and no boride precipitates, having high thermal stability. The heat treatment can be one or more heat treatments, and the heat treatment temperature includes but is not limited to 700 - 900 °C and / or 900 - 980 °C.

[0037] The second aspect of the present invention provides a method for preparing the above-mentioned B-microalloyed high-performance Ti 2 AlNb-based alloy, and the preparation method includes the following steps:

[0038] (1) Weigh the raw materials in proportion, press them with a hydraulic press, assemble and weld them to make a consumable electrode;

[0039] (2) Use the vacuum consumable method for melting, and after three times of melting, pour it into a mold to obtain a Ti 2 AlNb-based alloy ingot.

[0040] In some embodiments of the present invention, the weighing the raw materials in proportion in step (1) specifically means weighing the powders of pure Ti (99.99% wt.%), Al (99.99% wt.%), Nb (99.99% wt.%), B (99.999% wt.%) and X (99.95% wt.%) (using master alloys when necessary) in proportion.

[0041] In some embodiments of the present invention, in step (1), after batching, the obtained material is mechanically stirred in a mixer for 1 to 3 h, which can be 1 to 1.5 h, 1.5 to 2 h, 2 to 2.5 h, or can also be 2.5 to 3 h; in certain specific embodiments of the present invention, it can be 1 h, 1.2 h, 1.5 h, 1.8 h, 2 h, 2.3 h, 2.5 h, 2.7 h, 3 h.

[0042] In some embodiments of the present invention, in step (2), the arc voltage for melting is 30 to 40 V, which can be 30 to 32 V, 32 to 34 V, 34 to 36 V, 36 to 38 V, or can also be 38 to 40 V; in certain specific embodiments of the present invention, it can be 30 V, 32 V, 34 V, 35 V, 36 V, 37 V, 39 V, 40 V; the arc current is 1 to 24 kA, which can be 1 to 4 kA, 4 to 8 kA, 8 to 12 kA, 12 to 16 kA, 16 to 20 kA, or can also be 20 to 24 kA; in certain specific embodiments of the present invention, it can be 1 kA, 5 kA, 10 kA, 15 kA, 20 kA, 24 kA.

[0043] In some embodiments of the present invention, in step (2), after each melting, the ingot is subjected to flat head treatment, then turned around, and then the next melting is carried out, so that the obtained alloy composition is relatively uniform.

[0044] The third aspect of the present invention provides another preparation method of the above-mentioned B microalloyed high-performance Ti 2 AlNb-based alloy, which, in addition to including the above steps (1) and (2), further includes the following steps:

[0045] (3) The Ti 2 AlNb-based alloy ingot obtained in step (2) is made into Ti 2 AlNb-based alloy powder by vacuum gas atomization method;

[0046] (4) The Ti 2 AlNb-based alloy powder is prepared into Ti 2 AlNb-based alloy by additive manufacturing method.

[0047] In some embodiments of the present invention, in step (3), the prepared Ti 2 AlNb-based alloy powder is dried at a temperature of 110 to 130 °C for 4 to 8 h, which can be dried at 110 to 115 °C for 7 to 8 h, 115 to 120 °C for 6 to 7 h, 120 to 125 °C for 5 to 6 h, or can also be dried at 125 to 130 °C for 4 to 5 h. The drying equipment has no special limitation, as long as it can achieve the corresponding function, for example, an electric heating forced air drying oven can be used.

[0048] In some embodiments of the present invention, in step (3), the prepared Ti 2 AlNb-based alloy powder is sieved, and powders with appropriate particle sizes are sieved according to the subsequent additive manufacturing method. For example, when selective laser melting is used, the sieved powder particle size is 10 - 60 μm.

[0049] In some embodiments of the present invention, in step (4), the additive manufacturing method is selected from selective laser melting (SLM), electron beam melting (EBM), laser metal deposition (LMD), wire arc additive manufacturing (WAAM), direct energy deposition (DED), powder metallurgy, etc.

[0050] Additive Manufacturing (AM) technology is a technology for manufacturing solid parts by gradually adding materials. Compared with the traditional material removal - machining technology, it is a "bottom-up" manufacturing method. In some embodiments of the present invention, in step (4), the additive manufacturing method is preferably a 3D printing method. In some specific embodiments of the present invention, the additive manufacturing method is selected from selective laser melting; preferably, the inside of the printing device is an argon atmosphere, and the oxygen content is 200 - 1000 ppm, which can be 200 - 400 ppm, 400 - 600 ppm, 600 - 800 ppm, and can also be 800 - 1000 ppm; preferably, the printing strategy is as follows: the printing layer thickness is 0.02 - 0.04 mm, which can be 0.02 - 0.025 mm, 0.025 - 0.03 mm, 0.03 - 0.035 mm, and can also be 0.035 - 0.04 mm; the laser power is 200 - 360 W, which can be 200 - 240 W, 240 - 280 W, 280 - 320 W, and can also be 320 - 360 W; the laser scanning speed is 800 - 1200 mm / s, which can be 800 - 900 mm / s, 900 - 1000 mm / s, 1000 - 1100 mm / s, and can also be 1100 - 1200 mm / s; raster scanning is adopted; the filling spacing is 0.10 - 0.15 mm, which can be 0.10 - 0.11 mm, 0.11 - 0.12 mm, 0.12 - 0.13 mm, 0.13 - 0.14 mm, and can also be 0.14 - 0.15 mm.

[0051] The fourth aspect of the present invention provides the use of the above-mentioned B-microalloyed high-performance Ti 2 AlNb-based alloy in aerospace equipment. The present invention uses alloy raw materials with specific components and ratios, and obtains Ti 2AlNb-based alloy, in which element B is in a solid solution state, with no precipitation of boride or a small amount of boride precipitation. Trace element B will also segregate along the grain boundaries of the BCC phase, thereby enhancing the grain boundary bonding force. In addition, the addition of trace element B can also regulate the proportion of the disordered β phase in the alloy, increasing the proportion of the β phase with better plasticity. For the above reasons, the addition of trace element B makes Ti 2 AlNb-based alloy have high strength and excellent plasticity, can avoid cracking during processing, and can be applied to aerospace equipment, especially advanced aeroengines.

[0052] The present invention will be further described below by way of examples, but the scope of the present invention is not limited thereby.

[0053] When numerical ranges are given in the examples, it should be understood that unless otherwise specified in the present invention, any value between the two endpoints of each numerical range and either endpoint can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art of this technology. For those conditions not specified in the examples, they are carried out under conventional conditions or the conditions recommended by the manufacturer. For all reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through commercial purchase. In addition to the specific methods, equipment, and materials used in the examples, according to the knowledge of the prior art by those skilled in the art of this technology and the description of the present invention, any methods, equipment, and materials of the prior art similar to or equivalent to those described in the examples of the present invention can also be used to implement the present invention.

[0054] Example 1

[0055] This example provides a preparation method of Ti 2 AlNb-based alloy. The composition of the prepared Ti 2 AlNb-based alloy is shown in Table 1 below.

[0056] Table 1 Composition of Ti 2 AlNb-based alloy prepared in Example 1

[0057] Alloy number Alloy composition (wt.%) 1# (control) 10.9% Al, 42.6% Nb, balance Ti 2# 10.9% Al, 42.6% Nb, 0.0005% B, balance Ti 3# 10.9% Al, 42.6% Nb, 0.0025% B, balance Ti 4# 10.9% Al, 42.6% Nb, 0.005% B, balance Ti 5# 10.9% Al, 42.6% Nb, 0.01% B, balance Ti 6# 10.9% Al, 42.6% Nb, 0.02% B, balance Ti 7# 10.9% Al, 42.6% Nb, 0.03% B, balance Ti 8# 10.9% Al, 42.6% Nb, 0.05% B, balance Ti 9# (control) 10.9% Al, 42.6% Nb, 0.055% B, balance Ti

[0058] Preparation method 1

[0059] The above-mentioned vacuum consumable preparation method of Ti 2 AlNb-based alloy includes the following steps:

[0060] (A1) Preparation of ingredients and consumable electrode: Titanium with a purity of 99.99 wt%, aluminum with a purity of 99.99 wt%, niobium with a purity of 99.99 wt%, and boron with a purity of 99.99 wt% are selected. Ingredients are prepared according to the composition ratio in Table 1. After mechanical stirring in a mixer for 1 - 3 h, it is pressed into a dense electrode block by a hydraulic press and assembled and welded to make a consumable electrode.

[0061] (A2) Melting is carried out by the vacuum consumable method. During stable melting, the arc voltage is 30 V and the arc current is 15 kA. After each melting, the ingot is flattened, then turned around for the next melting. After three times of vacuum consumable arc melting, it is poured into a mold to obtain the above-mentioned Ti 2 AlNb-based alloy ingot.

[0062] Preparation method two

[0063] The above-mentioned Ti 2 The preparation method of additive manufacturing of AlNb-based alloy includes the following steps:

[0064] (B1) Powder preparation: The Ti 2 AlNb-based alloy ingot obtained in Preparation method one is processed by the vacuum gas atomization method to obtain Ti 2 AlNb-based alloy powder. The obtained Ti 2 AlNb-based alloy powder is processed, and powders with a particle size of 30 - 60 μm are sieved. Before printing, the powder is dried at 120 °C for 6 hours.

[0065] (B2) A selective laser melting 3D printing device is used. Argon atmosphere protection is required to be introduced into the printing device, and the oxygen content is required to be 200 - 1000 ppm. The printing strategy is as follows: The printing layer thickness is 0.03 mm, the laser power is 250 W, the laser scanning speed is 1000 mm / s, raster scanning is used, and the filling spacing is 0.10 mm.

[0066] The following Table 2 shows the mechanical property test results of alloys prepared by two different preparation methods for the corresponding components in Table 1. It can be seen from Table 2 that the room temperature tensile strength of the Ti 2 AlNb-based alloy (2# - 8#) prepared by the vacuum consumable method in Example 1 of the present invention is 984 MPa - 1180 MPa, and the room temperature elongation is 8.5 - 19.7%. With the increase of the B content, the tensile strength of the Ti 2 AlNb-based alloy (2# - 8#) prepared in Example 1 of the present invention shows an increasing trend, while the plasticity has a law of increasing first and then decreasing. Compared with alloy 1# (control), the strength is improved, and the maximum improvement is up to 25% (7#), and the plasticity is greatly improved, and the maximum improvement is up to 153% (4#).

[0067] As can be seen from Table 2, the room-temperature tensile strength of the Ti 2 AlNb-based alloys (No. 2# to No. 8#) prepared by selective laser melting in Example 1 of the present invention is 953 MPa to 1163 MPa, and the room-temperature elongation is 7.0 to 18.6%. With the increase of the B content, the tensile strength of the Ti 2 AlNb-based alloys (No. 2# to No. 8#) prepared in Example 1 of the present invention shows an increasing trend, while the plasticity has a law of increasing first and then decreasing. Compared with the No. 1 alloy (control), the strength is improved, and the maximum improvement reaches 25% (No. 7#), and the plasticity is greatly improved, and the maximum improvement reaches 138% (No. 4#).

[0068] Scanning electron microscopy tests were carried out on the Ti 2 AlNb-based alloys (No. 1#, No. 4#, No. 6#, No. 7# and No. 9#) prepared in Example 1, and the results are as Figure 1 shown. After microstructure observation, no large amount of boride precipitation occurred in the matrix and grain boundaries of the Ti 2 AlNb-based alloys prepared in Example 1 of the present invention (No. 1# to No. 6#), and the B element is in a solid solution state. The B element is dissolved in the alloy, and due to the solid solution strengthening effect, the strength of the alloy is effectively improved. In addition, the B element will also segregate at the grain boundaries, thereby enhancing the binding force of the grain boundaries. In addition, the addition of trace B elements can also regulate the proportion of the disordered β phase in the alloy to achieve the purpose of improving the plasticity of the alloy. The above reasons make the addition of trace B elements greatly improve the plasticity of the Ti 2 AlNb-based alloy. When the added B content is greater than 0.02% and reaches 0.03% (No. 7#), a small amount of boride begins to precipitate. The precipitation of boride reduces the plasticity of the alloy and partly offsets the above-mentioned effect of improving plasticity. When the B content is further increased to 0.05% (No. 8#), the volume fraction of boride increases, and the effect of plasticity reduction caused by the precipitation of boride is almost equivalent to the effect of plasticity improvement caused by the B element dissolved in the matrix and segregated at the grain boundaries. The plasticity of the alloy is slightly better than that of the No. 1 control alloy. When the B content is greater than 0.05% (No. 9#), the volume fraction of the precipitate further increases, and the effect of plasticity reduction caused by the precipitation of boride is greater than the effect of plasticity improvement caused by the B element dissolved in the matrix and segregated at the grain boundaries. The plasticity of the alloy is lower than that of the No. 1 control alloy.

[0069] Electron backscatter diffraction (EBSD) tests were carried out on the Ti 2 AlNb-based alloys (No. 1#, No. 4#, No. 6#) prepared in Example 1, and the results are as Figure 2 shown. The average grain diameter of the No. 1 alloy is 150 μm, the average grain diameter of the No. 4 alloy is 228 μm, and the average grain diameter of the No. 5 alloy is 189 μm. It can be seen that after adding the B element, compared with the No. 1 alloy, the grain sizes of the No. 4 alloy and the No. 5 alloy do not change. The Ti prepared by the present invention2 The significant improvement in the plasticity of the AlNb-based alloy has little relation with the grain size.

[0070] Table 2 Mechanical properties of the alloy prepared in Example 1

[0071]

[0072] Example 2

[0073] This example provides a preparation method of the Ti 2 AlNb-based alloy. The composition of the prepared Ti 2 AlNb-based alloy is shown in Table 3 below.

[0074] Table 3 Composition of the Ti 2 AlNb-based alloy prepared in Example 2

[0075]

[0076] Preparation method 1

[0077] The above-mentioned Ti 2 The preparation method of the AlNb-based alloy by vacuum consumable includes the following steps:

[0078] (A1) Batching and preparation of the consumable electrode: Select titanium with a purity of 99.99 wt%, aluminum with a purity of 99.99 wt%, niobium with a purity of 99.99 wt%, boron with a purity of 99.99 wt%, and molybdenum, zirconium, tantalum, vanadium, and tungsten with a purity of 99.95 wt%. Batch according to the composition ratio in Table 3, mechanically stir in a mixer for 1 - 3 h, then press into a dense electrode block by a hydraulic press, and assemble and weld to make a consumable electrode.

[0079] (A2) Melting is carried out by the vacuum consumable method. When the melting is stable, the arc voltage is 32 V and the arc current is 12 kA. After each melting, the ingot is flattened, then turned around, and the next melting is carried out. After three times of vacuum consumable arc melting, it is poured into a mold to obtain the above-mentioned Ti 2 AlNb-based alloy ingot.

[0080] Preparation method 2

[0081] The above-mentioned Ti 2 The preparation method of the AlNb-based alloy by additive manufacturing includes the following steps:

[0082] (B1) Powder preparation: The Ti 2 AlNb-based alloy ingot prepared in Preparation method 1 is processed by the vacuum gas atomization method to obtain Ti 2 AlNb-based alloy powder. For the obtained Ti 2The AlNb-based alloy powder is processed, and the powder with a particle size of 30 - 60 μm is sieved. Before printing, the powder is dried at 120 °C for 6 hours.

[0083] (B2) A selective laser melting 3D printing device is used. Argon atmosphere protection is required inside the printing device, and the oxygen content is required to be 200 - 1000 ppm. The printing strategy is as follows: the printing layer thickness is 0.03 mm, the laser power is 270 W, the laser scanning speed is 1100 mm / s, raster scanning is used, and the filling spacing is 0.12 mm.

[0084] The following Table 4 shows the mechanical property test results of the alloys prepared by two different preparation methods for the corresponding components in Table 3. It can be seen from Table 4 that compared with the Ti 2 AlNb-based alloy without adding B, the Ti 2 AlNb-based alloy prepared by vacuum consumable melting in Example 2 of the present invention has effectively improved room temperature tensile strength, with a maximum increase of 17.3% (11#). The plasticity has been greatly improved, with a maximum increase of 132.8% (13#). It can be seen from Table 4 that compared with the Ti 2 AlNb-based alloy without adding B, the Ti 2 AlNb-based alloy prepared by selective laser melting in Example 2 of the present invention has effectively improved room temperature tensile strength, with a maximum increase of 16.6% (12#). The plasticity has been greatly improved, with a maximum increase of 172.1% (10#).

[0085] Table 4 Mechanical properties of the alloys prepared in Example 2

[0086]

[0087] Example 3

[0088] This example provides a preparation method of Ti 2 AlNb-based alloy. The composition of the prepared Ti 2 AlNb-based alloy is shown in the following Table 5.

[0089] Table 5 Composition of the Ti 2 AlNb-based alloy prepared in Example 3

[0090]

[0091]

[0092] Preparation method 1

[0093] The above-mentioned preparation method of the vacuum consumable Ti 2 AlNb-based alloy includes the following steps:

[0094] (A1) Preparation of ingredients and consumable electrode: Select titanium with a purity of 99.99 wt%, aluminum with a purity of 99.99 wt%, niobium with a purity of 99.99 wt%, boron with a purity of 99.99 wt%, and molybdenum, zirconium, tantalum, vanadium, and tungsten with a purity of 99.95 wt%. Mix the ingredients according to the composition ratio in Table 5, mechanically stir in a mixer for 1 - 3 h, then press into a dense electrode block by a hydraulic press, and assemble and weld to make a consumable electrode.

[0095] (A2) Use the vacuum consumable method for melting. During stable melting, the arc voltage is 40 V and the arc current is 10 kA. After each melting, the ingot is flattened, then turned around for the next melting. After three times of vacuum consumable arc melting, it is poured into a mold to obtain the above-mentioned Ti 2 AlNb-based alloy ingot.

[0096] Preparation method two

[0097] The above-mentioned Ti 2 The preparation method for additive manufacturing of the above-mentioned Ti

[0098] (B1) Powder preparation: The Ti 2 AlNb-based alloy ingot obtained in Preparation method one is processed by vacuum gas atomization to obtain Ti 2 AlNb-based alloy powder. The obtained Ti 2 AlNb-based alloy powder is processed, and the powder with a particle size of 30 - 60 μm is sieved. Before printing, the powder is dried at 120 °C for 6 hours.

[0099] (B2) Use a selective laser melting 3D printing device. Argon atmosphere protection is required inside the printing device, and the oxygen content is required to be 200 - 1000 ppm. The printing strategy is as follows: the printing layer thickness is 0.03 mm, the laser power is 300 W, the laser scanning speed is 1200 mm / s, raster scanning is used, and the filling spacing is 0.15 mm.

[0100] The following Table 6 shows the mechanical property test results of the alloys prepared by two different preparation methods for the corresponding components in Table 5. It can be seen from Table 6 that by using the vacuum consumable melting method, compared with the Ti 2 AlNb-based alloy without B, the strength of the Ti 2 AlNb-based alloy prepared in Example 3 of the present invention has been effectively improved, and the maximum improvement amplitude reaches 12.1% (19#). The plasticity has been greatly improved, and the maximum improvement amplitude reaches 126.7% (19#). For the alloys of 17# - 18#, due to the too high Al content, the plasticity of the alloy without B is too poor. Even so, adding a trace amount of B element also slightly improves the strength and plasticity. It can be seen from Table 6 that by using the selective laser melting method, compared with the Ti2 Compared with the AlNb-based alloy, the Ti 2 The strength of the AlNb-based alloy has been effectively improved, with the maximum improvement reaching 12.1% (19#). The plasticity has been greatly improved, with the maximum improvement reaching 186.7% (19#). For the alloys of 17# - 18#, due to the too high Al content, the plasticity of the alloy without adding B is too poor. Even so, adding a trace amount of B element also slightly improves the strength and plasticity.

[0101] Table 6 Mechanical properties of the alloys prepared in Example 3

[0102]

[0103]

[0104] Example 4

[0105] This example provides a heat treatment method for the above-prepared Ti 2 AlNb-based alloy. Specifically, the above-prepared Ti 2 AlNb-based alloy can be heat-treated one or more times. The specific method is as follows:

[0106] Scheme 1: One-time heat treatment.

[0107] Place the above-prepared Ti 2 AlNb-based alloy in a vacuum tube annealing furnace, evacuate and then fill with argon for protection. The heat treatment temperature includes but is not limited to 700 - 900 °C, and the heat treatment time includes but is not limited to 0.25 - 24 h. After reaching the specified heat treatment time, quench or cool the above-prepared Ti 2 AlNb-based alloy.

[0108] Scheme 2: Two-time heat treatment.

[0109] The first heat treatment: Place the above-prepared Ti 2 AlNb-based alloy in a vacuum tube annealing furnace, evacuate and then fill with argon for protection. The heat treatment temperature includes but is not limited to 900 - 980 °C, and the heat treatment time includes but is not limited to 0.25 - 12 h. After reaching the specified heat treatment time, quench or cool the above-prepared Ti 2 AlNb-based alloy.

[0110] The second heat treatment: Place the above-prepared Ti 2After the AlNb-based alloy undergoes the first heat treatment, it is placed in a vacuum tube annealing furnace again. After evacuating the air, argon is filled for protection. The heat treatment temperature includes but is not limited to 700 - 900 °C, and the heat treatment time includes but is not limited to 0.25 - 24 h. After reaching the specified heat treatment time, the prepared Ti 2 AlNb-based alloy is quenched or cooled in the furnace.

[0111] The specific implementation method is as follows:

[0112] The prepared Ti 2 AlNb-based alloys (1# and 4#) are processed using one-time and two-time heat treatment processes. The specific operations are as follows:

[0113] Scheme 1: One-time heat treatment

[0114] The prepared Ti 2 AlNb-based alloys (1# and 4#) are placed in a vacuum tube annealing furnace. After evacuating the air, argon is filled for protection. The heat treatment temperature is 750 °C, and the heat treatment time is 12 h. After reaching the specified heat treatment time, the prepared Ti 2 AlNb-based alloy is quenched or cooled in the furnace. The alloys (20# and 21#) after one-time heat treatment are obtained.

[0115] Scheme 2: Two-time heat treatment.

[0116] The first heat treatment: The prepared Ti 2 AlNb-based alloys (1# and 4#) are placed in a vacuum tube annealing furnace. After evacuating the air, argon is filled for protection. The heat treatment temperature is 900 °C, and the heat treatment time is 6 h. After reaching the specified heat treatment time, the prepared Ti 2 AlNb-based alloys (1# and 4#) are quenched.

[0117] The second heat treatment: The prepared Ti 2 AlNb-based alloys (1# and 4#) after the first heat treatment are placed in a vacuum tube annealing furnace again. After evacuating the air, argon is filled for protection. The heat treatment temperature is 830 °C, and the heat treatment time is 6 h. After reaching the specified heat treatment time, the prepared Ti 2 AlNb-based alloys (1# and 4#) are quenched. The alloys 22# and 23# after two-time heat treatment are obtained.

[0118] Table 7 below shows the mechanical properties of the prepared Ti 2 AlNb-based alloys (20# - 23#). It can be seen that the Ti 2 AlNb-based alloy without B (1#) and the Ti 2The alloys (20# and 21#) obtained by subjecting the AlNb-based alloy (4#) to a single heat treatment in the first scheme have significantly increased strength, but their plasticity has all decreased. The decrease in the plasticity of the alloy after heat treatment is due to the relatively low heat treatment temperature of only 750 °C. At this temperature, a large number of fine needle-shaped O phases precipitate in the matrix, resulting in a decrease in the plasticity of the alloy. However, there is no difference in either strength or plasticity between the 20# alloy (without B) and the 21# alloy (with B). It can be seen that the addition of trace B element in the present invention does not affect the Ti 2 mechanical properties of the AlNb-based alloy. The backscattered microstructure image (BSE) of the 21# alloy is as Figure 3 shown. It can be seen that no boride precipitates after heat treatment, and the B element remains in a solid solution state in the 21# alloy.

[0119] Similarly, for the Ti 2 AlNb-based alloy (1#) without B and the Ti 2 AlNb-based alloy (4#) with B element, after being subjected to two heat treatments in the second scheme, the obtained alloys (22# and 23#) have significantly increased strength, and their plasticity has all decreased. However, there is no difference in either strength or plasticity between the 22# alloy (without B) and the 23# alloy (with B), which once again proves that the addition of trace B element in the present invention does not affect the Ti 2 mechanical properties of the AlNb-based alloy. The backscattered microstructure image (BSE) of the 23# alloy is as Figure 4 shown. It can be seen that no boride precipitates after heat treatment, and the B element remains in a solid solution state in the 23# alloy.

[0120] Table 7 Mechanical properties of the alloys prepared in Example 4

[0121]

[0122]

[0123] The above embodiments merely illustrate the principles and effects of the present invention by way of example, and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A B microalloyed high-performance Ti 2 AlNb-based alloy It is characterized in that Calculated by mass percentage, it includes the following components: 8.1% - 17.5% of Al, 18.9% - 50.6% of Nb, 0.0005% - 0.05% of B, and the balance is Ti and unavoidable impurities.

2. The B microalloyed high-performance Ti 2 AlNb-based alloy It is characterized in that Calculated by mass percentage, it includes the following components: 8.1% - 17.5% of Al, 18.9% - 50.6% of Nb, 0.0025% - 0.02% of B, and the balance is Ti and unavoidable impurities.

3. The B microalloyed high-performance Ti 2 AlNb-based alloy, It is characterized in that Calculated by mass percentage, it further includes 0% - 7.5% of X, where X is one or a combination of several of Mo, Zr, V, Cr, Ta, W, Y, Sn, Hf.

4. The B microalloyed high-performance Ti 2 AlNb-based alloy, It is characterized in that The B microalloyed high-performance Ti 2 In the AlNb-based alloy, the B element is in a solid solution state and no boride precipitates; and / or, the volume fraction of the disordered β phase in the B microalloyed high-performance Ti 2 AlNb-based alloy is 50% to 100%; and / or, the B microalloyed high-performance Ti 2 The average grain size of the AlNb-based alloy is 100 - 300 μm; and / or, the B microalloyed high-performance Ti 2 The room temperature tensile strength of the AlNb-based alloy is 953 MPa to 1180 MPa, and the room temperature elongation is 7.0% to 19.7%; and / or, said B microalloyed high-performance Ti 2 After heat treatment of the AlNb-based alloy, element B in the alloy remains in a solid solution state and no boride precipitates.

5. A preparation method of a B microalloyed high-performance Ti 2 AlNb-based alloy as described in any one of claims 1 to 4 It is characterized in that It includes the following steps: (1) Weigh the ingredients in proportion, press them with a hydraulic press, and assemble and weld them to make a consumable electrode; (2) The melting is carried out by the vacuum consumable method. After three times of melting, it is poured into the mold to obtain a Ti 2 AlNb-based alloy ingot.

6. The preparation method according to claim 5, It is characterized in that It further includes the following steps: (3) The Ti obtained in step (2) 2 The TiAlNb-based alloy ingot is made into TiAlNb-based alloy powder by the vacuum gas atomization method. 2 powder; (4) Prepare a Ti 2 AlNb-based alloy powder into a Ti 2 AlNb-based alloy by an additive manufacturing method.

7. The preparation method according to claim 5, It is characterized in that In step (1), after weighing the ingredients, mechanically stir the obtained materials in a mixer for 1 - 3 h; And / or, in step (2), the arc voltage for melting is 30 - 40 V, and the arc current is 1 - 24 kA; And / or, in step (2), after each melting, the ingot is flattened, then turned around, and then the next melting is carried out; and / or, in step (2), it further includes performing one or more heat treatments on the obtained Ti 2 AlNb-based alloy ingot; preferably, the heat treatment temperature is 700-900 °C and / or 900-980 °C.

8. The preparation method according to claim 6, It is characterized in that In step (3), the prepared Ti 2 AlNb-based alloy powder is dried at a temperature of 110 to 130 °C for 4 to 8 h; And / or, in step (3), the prepared Ti 2 AlNb-based alloy powder is sieved, and the powder with a particle size of 10 - 60 μm is taken; And / or, in step (4), the additive manufacturing method is selected from selective laser melting, electron beam melting, laser metal deposition, wire deposition, direct energy deposition or powder metallurgy.

9. The preparation method according to claim 6, It is characterized in that In step (4), the additive manufacturing method is selected from selective laser melting; the inside of the printing device is an argon atmosphere, and the oxygen content is 200 - 1000 ppm; And / or, the printing layer thickness is 0.02 - 0.04 mm; And / or, the laser power is 200 - 360 W, and the laser scanning speed is 800 - 1200 mm / s; And / or, the scanning method is raster scanning; And / or, the filling spacing is 0.10 - 0.15 mm.

10. Use of the B microalloyed high-performance Ti 2 AlNb-based alloy in aerospace equipment as described in any one of claims 1 to 9.

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