Yttrium-boron double-element doped Ti-Mo-Ni titanium alloy plate and preparation method thereof

Abstract

The invention discloses an yttrium-boron double-element doped Ti-Mo-Ni titanium alloy plate and a preparation method thereof, and relates to the technical field of titanium metal. The preparation method of the titanium alloy plate comprises the steps that Mo, Ni, Y, B and Ti alloy raw materials including sponge titanium, Ti-15Mo intermediate alloy, pure nickel scraps, high-purity Y particles and TiB2 particles are weighed according to the proportion, the sponge titanium, the Ti-15Mo intermediate alloy and the pure nickel scraps are evenly mixed to obtain mixed powder, and then the high-purity Y particles and the TiB2 particles are prepared into an alloy material bag; filling is conducted in a layered filling mode, a mixture is obtained, and the mixture is pressed into material blocks; smelting the material block to obtain an alloy cast ingot; and the alloy cast ingot is subjected to face milling and then subjected to forging-free direct rolling, and the yttrium-boron double-element doped Ti-Mo-Ni titanium alloy plate is obtained. According to the Ti-Mo-Ni titanium alloy, the double elements of yttrium and boron are doped into the Ti-Mo-Ni titanium alloy, a new nucleation position is provided, grains are refined, and meanwhile the strength is improved. According to the method, the component uniformity of the titanium alloy cast ingot can be improved, a uniform and fine structure is obtained, and the comprehensive mechanical property of the plate is remarkably improved by cooperating with a rolling deformation process.

Description

TECHNICAL FIELD

[0001] The present application relates to a yttrium and boron double element doped Ti-Mo-Ni titanium alloy plate and a preparation method thereof, and belongs to the technical field of titanium metal. BACKGROUND

[0002] Ti-0.3Mo-0.8Ni (TA10) titanium alloy is a low-alloyed near-alpha type corrosion-resistant titanium alloy, which has good resistance to pitting corrosion and crevice corrosion. Compared with pure titanium, the corrosion resistance is obviously improved. Compared with high corrosion-resistant Ti-0.2Pd (TA9) titanium alloy, the cost is significantly reduced due to the replacement of expensive Pd element with low-cost Mo and Ni elements, and the corrosion resistance is good. It is widely used in marine engineering environment and chlor-alkali industry, but due to its poor corrosion resistance in non-oxidizing acid and low strength, the industrial TA10 titanium alloy parts need to be replaced regularly, so it is urgent to develop a high-strength and high-corrosion-resistant titanium alloy.

[0003] In the actual titanium alloy smelting process, yttrium (Y) can be used as a surface active substance to improve the nucleation rate and the diffusion activation energy of crystal nucleus, reduce the surface tension and growth rate of crystal nucleus, and hinder the grain growth, so as to refine the grain. At the same time, Y2O3 type stabilizing compound is formed at the grain boundary to improve the strength and hardness of the alloy. Boron doped into titanium alloy can refine the grain as a heterogeneous nucleation point, improve the uniform plastic deformation capacity, and form TiB reinforcing phase with Ti to improve the strength. However, due to the use of powder and metal particles as raw materials, it is difficult to control the uniformity of the finished product during alloy smelting. In addition, due to the different melting points and densities of different elements, composition segregation is easily produced in the conventional smelting process, resulting in uneven distribution of the structure. Due to the introduction of Y and boron (B) elements, TiB is easy to grow into coarse and needle-shaped phase under conventional process, and the distribution is irregular, which becomes a crack source. Y2O3 is easy to excessively gather at the grain boundary, causing the initiation and expansion of micro-cracks, leading to stress concentration and deterioration of plasticity. These factors increase the difficulty of adding Y and B to titanium alloy to optimize the performance. Therefore, it is of great significance and application value to control the element volatilization and the uniformity of the ingot during smelting for the development of high-strength and high-corrosion-resistant titanium alloy. SUMMARY

[0004] One of the purposes of the present application is to provide a preparation method of a yttrium and boron double element doped Ti-Mo-Ni titanium alloy plate, which specifically comprises the following steps: (1) The Ti, Mo, Ni, Y, B alloy raw materials of sponge titanium, Ti-15Mo intermediate alloy, pure nickel scrap, high-purity Y particles and TiB2 particles are weighed according to the proportion.

[0005] (2) First, the sponge titanium, Ti-15Mo intermediate alloy, pure nickel scrap is mixed evenly to obtain a mixed powder, then the high-purity Y particles, TiB2 particles are dried, and then the dried high-purity Y particles, TiB2 particles are coated with pure titanium foil to form a plurality of small spherical alloy material packages.

[0006] (3) The mixed powder obtained in step (2) is divided into 3 equal parts, and the alloy material packages are divided into 2 equal parts, and the divided mixed powder and alloy material packages are filled in a layered manner, specifically: the first part of the mixed powder is placed in the bottom layer, the first part of the alloy material package is arranged on the mixed powder in the bottom layer, the second part of the mixed powder is placed in the middle layer, and the second part of the alloy material package is arranged on the mixed powder in the bottom layer, and the third part of the mixed powder is placed in the top layer to obtain a mixed material, and the mixed material is pressed into a cuboid block.

[0007] (4) The block is arranged in the feed chamber of the melting device (preferably an electron beam cold bed furnace), and is continuously fed, and then is heated and vacuum melted, and after melting, is poured and cooled to obtain an alloy ingot.

[0008] (5) After the alloy ingot is milled, a yttrium-boron double-element doped Ti-Mo-Ni titanium alloy plate is obtained by straight rolling without forging.

[0009] Preferably, in step (1), the alloy raw materials are weighed according to the proportions of 0.8% Mo, 0.3% Ni, 0.01-0.06% Y, 0.1% B, and the balance of Ti.

[0010] Preferably, in step (2), the drying conditions are: drying at 100-150℃ for 3-4h.

[0011] Preferably, in step (3), when the mixed material is pressed into a block, the pressure is 200-300MPa.

[0012] Preferably, in step (4), the vacuum melting conditions are: under the condition of a vacuum degree of 1×10 -3 Pa~1×10 -5 Pa, melting at a temperature of 1800-2000℃, a melting speed of 600-700kg / h, and the melting process is carried out in a protective atmosphere (such as argon).

[0013] Preferably, in step (5), the conditions for straight rolling without forging are: two-fire rolling process is adopted, the first fire rolling temperature is 890-910℃, rolling 4 passes with a reduction rate of 60-65%; the second fire rolling direction is reversed by 90°, the rolling temperature is 850-870℃, rolling 6 passes with a reduction rate of 70-75%; the total rolling passes of straight rolling without forging are 10, and the total deformation amount is 90%.

[0014] The second objective of this invention is to provide a yttrium boron dual-element doped Ti-Mo-Ni titanium alloy plate prepared by the preparation method of this invention.

[0015] Mechanism of the invention: This invention relates to a novel Ti-Mo-Ni-YB titanium alloy produced by doping with both Y and B elements. A layered filling method is used for the raw material, and the alloy is finally pressed into blocks. The melting temperature and speed are controlled during the melting process in an electron beam cold hearth furnace, resulting in a uniformly composed Y and B-doped Ti-Mo-Ni titanium alloy. During the melting process, the Y element reacts with the O element in the titanium matrix to form Y₂O₃ particles, with the reaction equation: 2Y + 3O → Y₂O₃. TiB₂ reacts to form TiB, with the reaction equation: TiB₂ + Ti → 2TiB.

[0016] This invention controls the formation of Y₂O₃ particles by controlling the doping content of different amounts of Y element, effectively controlling the degree of grain refinement and preventing grain growth. Simultaneously, with a fixed amount of B element doping, the number of TiB reinforcing phase particles generated is also fixed, and the TiB particles are distributed at the grain boundaries, further inhibiting grain growth. This invention obtains a uniformly composed titanium alloy ingot by doping with trace amounts of Y element while controlling the doping amount of B element, and by controlling the melting temperature and speed during the melting process to reduce element volatilization. Then, through two-stage reversing rolling, the overall mechanical properties of the alloy are improved, achieving the effect of Y and B dual-element doping strengthening the alloy.

[0017] The beneficial effects of this invention are: (1) This invention prepares a Ti-Mo-Ni-YB titanium alloy doped with both Y and B elements by using a layered filler method. A schematic diagram of the layered filler is shown below. Figure 1 As shown, a material bag containing Y particles and TiB2 particles is filled between three layers (bottom, middle and top layers) of uniformly mixed sponge titanium, Ti-15Mo master alloy and pure nickel scrap. This method can reduce the influence of differences in density, melting point and particle size between raw materials, avoid component segregation during the melting process, achieve regular and directional distribution control of TiB reinforcing phase and Y2O3 particles, effectively promote the dissolution of Y and B elements during the melting process, and improve the uniformity of alloy composition.

[0018] (2) The novel Ti-Mo-Ni titanium alloy prepared by the present invention, through the doping of trace rare earth elements Y and B, combined with layered filler and smelting and two-fire rolling process, synergistically generates Y2O3 and TiB particles in the titanium alloy matrix, which significantly refines the grain size of the titanium alloy and increases the hardness of the alloy by 6.2~18.3%.

[0019] (3) The present invention uses an electron beam cold hearth furnace (EB furnace) to melt the alloy ingot in one go, while the general melting process using a vacuum consumable arc furnace (VAR furnace) requires 3 to 4 meltings, which makes it difficult to completely remove impurities. Multiple meltings will increase the O content in the alloy. Using an EB furnace to melt can control high and low density inclusions, reduce costs, and one melting can also reduce the volatilization of elements, resulting in a more uniform alloy ingot. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the layered packing material of the present invention.

[0021] Figure 2 This is a schematic diagram showing the hardness of the yttrium boron dual-element doped Ti-Mo-Ni titanium alloy plates prepared in Examples 1-3 and Comparative Example 1 of the present invention.

[0022] Figure 3 Metallographic microstructure of the Ti-0.3Mo-0.8Ni-0.01Y-0.1B titanium alloy plate prepared in Example 1 of this invention.

[0023] Figure 4 Metallographic microstructure of the Ti-0.3Mo-0.8Ni-0.03Y-0.1B titanium alloy plate prepared in Example 2 of this invention.

[0024] Figure 5 Metallographic microstructure of the Ti-0.3Mo-0.8Ni-0.06Y-0.1B titanium alloy plate prepared in Example 3 of this invention.

[0025] Figure 6 The image shows the metallographic microstructure of the Ti-0.3Mo-0.8Ni titanium alloy plate prepared in Comparative Example 1 of this invention. Detailed Implementation

[0026] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0027] Unless otherwise specified, all chemical reagents used in the embodiments and comparative examples of this invention were commercially available analytical grade. The sponge titanium used in the embodiments and comparative examples of this invention was grade 0A sponge titanium with a purity ≥99.7%; the high-purity Y particles and TiB2 particles used had a purity ≥99.9%, and both had a particle size of 300 mesh.

[0028] Example 1 A method for preparing a yttrium boron dual-element doped Ti-Mo-Ni titanium alloy plate specifically includes the following steps: (1) Weigh out the following materials according to the proportions: sponge titanium (0.5~1cm in diameter), Ti-15Mo master alloy, pure nickel scrap, high-purity Y particles and TiB2 particles. The composition of the alloy materials includes 0.8% Mo, 0.3% Ni, 0.01% Y, 0.1% B, and the balance is Ti.

[0029] (2) First, mix sponge titanium, Ti-15Mo master alloy and pure nickel scrap with a diameter of 0.5~1cm evenly to obtain mixed powder. Then, vacuum dry high-purity Y particles and TiB2 particles at 125℃ for 3.5h. Then, use pure titanium foil to wrap the dried high-purity Y particles and TiB2 particles to form several small spherical alloy packages with a diameter of 1~2cm.

[0030] (3) Divide the mixed powder obtained in step (2) into 3 equal parts, and then divide the alloy material package into 2 equal parts. Use a layered filling method to fill the equal parts of the mixed powder and alloy material package. Specifically, place the first equal part of mixed powder at the bottom layer, and arrange the first equal part of alloy material package on the bottom mixed powder with intervals between them. Place the second equal part of mixed powder in the middle layer, and arrange the second equal part of alloy material package on the bottom mixed powder with intervals between them. Place the third equal part of mixed powder at the top layer to obtain the mixture. Press the mixture into a cuboid block under a pressure of 250MPa.

[0031] (4) The material blocks are evenly distributed in the feeding chamber of the electron beam cold hearth furnace and fed continuously, followed by a vacuum of 1×10⁻⁶. -3 Under Pa conditions, the material blocks are melted uniformly at a temperature of 1900℃ at a melting rate of 650 kg / h. The melting process is carried out in an argon atmosphere. After melting, the alloy ingot is cast and cooled in the furnace to obtain the alloy ingot.

[0032] (5) The oxide scale of the alloy ingot is milled off by a milling machine. The milled flat ingot with a length of 1400mm × width of 400mm × thickness of 200mm is subjected to forging-free direct rolling. A two-fire rolling process is adopted. The first fire rolling temperature is 900℃, and the rolling is carried out in 4 passes with a reduction rate of 65% to ensure that the large dendrites of the broken ingot are broken. The second fire rolling direction is reversed by 90°, the rolling temperature is 860℃, and the rolling is carried out in 6 passes with a reduction rate of 70%. The total rolling is carried out in 10 passes with a total deformation of 90%. Finally, a yttrium boron dual-element doped Ti-Mo-Ni titanium alloy plate with a thickness of 2mm is obtained.

[0033] The yttrium boron dual-element doped Ti-Mo-Ni titanium alloy sheet prepared in this embodiment was air-cooled to room temperature, and metallographic analysis was performed from the core of the sheet (see...). Figure 3 ) and mechanical property sample sampling and testing. From Figure 3As can be seen, after adding Y and B elements, the microstructure of the plate is a typical Widmanstätten structure, with more interwoven α / β clusters and refined grains. Mechanical property testing showed that the titanium alloy plate prepared in this embodiment has a hardness of 214.2 HV, indicating that this embodiment, by introducing Y and B elements and combining the synergistic effects of layered filling, smelting, and rolling processes, achieved control over element volatilization and ingot uniformity, thus preparing a titanium alloy with high strength and high corrosion resistance.

[0034] Example 2 A method for preparing a yttrium boron dual-element doped Ti-Mo-Ni titanium alloy plate specifically includes the following steps: (1) Weigh out the following materials according to the proportions: sponge titanium (0.5~1cm in diameter), Ti-15Mo master alloy, pure nickel scrap, high-purity Y particles and TiB2 particles. The composition of the alloy materials includes 0.8% Mo, 0.3% Ni, 0.03% Y, 0.1% B, and the balance is Ti.

[0035] (2) First, mix sponge titanium, Ti-15Mo intermediate alloy and pure nickel scrap with a diameter of 0.5~1cm evenly to obtain mixed powder. Then, vacuum dry high-purity Y particles and TiB2 particles at 150℃ for 3h. Then, use pure titanium foil to wrap the dried high-purity Y particles and TiB2 particles to form several small spherical alloy packages with a diameter of 1~2cm.

[0036] (3) Divide the mixed powder obtained in step (2) into 3 equal parts, and then divide the alloy material package into 2 equal parts. Use a layered filling method to fill the equal mixed powder and alloy material package. Specifically, place the first equal part of mixed powder at the bottom layer, and arrange the first equal part of alloy material package on the bottom mixed powder with intervals between them. Place the second equal part of mixed powder in the middle layer, and arrange the second equal part of alloy material package on the bottom mixed powder with intervals between them. Place the third equal part of mixed powder at the top layer to obtain the mixture. Press the mixture into a cuboid block under a pressure of 200MPa.

[0037] (4) The material blocks are evenly distributed in the feeding chamber of the electron beam cold hearth furnace and fed continuously, followed by a vacuum of 1×10⁻⁶. -5 Under Pa conditions, the material blocks are melted uniformly at a temperature of 2000℃ at a melting rate of 600 kg / h. The melting process is carried out in an argon atmosphere. After melting, the alloy ingot is cast and cooled in the furnace to obtain the alloy ingot.

[0038] (5) The oxide scale of the alloy ingot is milled off by a milling machine. The milled flat ingot with a length of 1400mm × width of 400mm × thickness of 200mm is subjected to forging-free direct rolling. A two-fire rolling process is adopted. The first fire rolling temperature is 890℃, and the rolling is carried out in 4 passes with a reduction rate of 62% to ensure that the large dendrites of the broken ingot are removed. The second fire rolling direction is reversed by 90°, the rolling temperature is 870℃, and the rolling is carried out in 6 passes with a reduction rate of 73.7%. A total of 10 rolling passes are carried out, and the total deformation is 90%. Finally, a yttrium boron dual-element doped Ti-Mo-Ni titanium alloy plate with a thickness of 2mm is obtained.

[0039] The yttrium boron dual-element doped Ti-Mo-Ni titanium alloy sheet prepared in this embodiment was air-cooled to room temperature, and metallographic analysis was performed from the core of the sheet (see...). Figure 4 Sampling was taken from samples of mechanical properties and test specimens. Figure 4 As can be seen, adding more Y element generates Y2O3, providing nucleation sites while inhibiting grain growth, further refining the microstructure of the plate, and resulting in more short α / β clusters appearing within the grain boundaries. Mechanical property testing showed that the titanium alloy plate prepared in this embodiment has a hardness of 226.17 HV, indicating that this embodiment, by introducing Y and B elements and combining the synergistic effects of layered filling, smelting, and rolling processes, achieved control over element volatilization and ingot uniformity, thus preparing a titanium alloy with high strength and high corrosion resistance.

[0040] Example 3 A method for preparing a yttrium boron dual-element doped Ti-Mo-Ni titanium alloy plate specifically includes the following steps: (1) Weigh out the following materials according to the proportions: sponge titanium (0.5~1cm in diameter), Ti-15Mo master alloy, pure nickel scrap, high-purity Y particles and TiB2 particles. The composition of the alloy materials includes 0.8% Mo, 0.3% Ni, 0.06% Y, 0.1% B, and the balance is Ti.

[0041] (2) First, mix sponge titanium, Ti-15Mo master alloy and pure nickel scrap with a diameter of 0.5~1cm evenly to obtain mixed powder. Then, vacuum dry high-purity Y particles and TiB2 particles at 100℃ for 4h. Then, use pure titanium foil to wrap the dried high-purity Y particles and TiB2 particles to form several small spherical alloy packages with a diameter of 1~2cm.

[0042] (3) Divide the mixed powder obtained in step (2) into 3 equal parts, and then divide the alloy material package into 2 equal parts. Use a layered filling method to fill the equal mixed powder and alloy material package. Specifically, place the first equal part of mixed powder at the bottom layer, and arrange the first equal part of alloy material package on the bottom mixed powder with intervals and uniformity. Place the second equal part of mixed powder in the middle layer, and arrange the second equal part of alloy material package on the bottom mixed powder with intervals and uniformity. Place the third equal part of mixed powder at the top layer to obtain the mixture. Press the mixture into a cuboid block under a pressure of 300MPa.

[0043] (4) The material blocks are evenly distributed in the feeding chamber of the electron beam cold hearth furnace and fed continuously, followed by a vacuum of 1×10⁻⁶. -4 Under Pa conditions, the material blocks are melted uniformly at a temperature of 1800℃ at a melting rate of 700 kg / h. The melting process is carried out in an argon atmosphere. After melting, the alloy ingot is cast and cooled in the furnace to obtain the alloy ingot.

[0044] (5) The oxide scale of the alloy ingot is milled off by a milling machine. The milled flat ingot with a length of 1400mm × width of 400mm × thickness of 200mm is subjected to forging-free direct rolling. A two-fire rolling process is adopted. The first fire rolling temperature is 910℃, and the rolling is carried out in 4 passes with a reduction rate of 60% to ensure that the large dendrites of the broken ingot are broken. The second fire rolling direction is reversed by 90°, the rolling temperature is 850℃, and the rolling is carried out in 6 passes with a reduction rate of 75%. The total rolling is carried out in 10 passes with a total deformation of 90%. Finally, a yttrium boron dual-element doped Ti-Mo-Ni titanium alloy plate with a thickness of 2mm is obtained.

[0045] The yttrium boron dual-element doped Ti-Mo-Ni titanium alloy sheet prepared in this embodiment was air-cooled to room temperature, and metallographic analysis was performed from the core of the sheet (see...). Figure 5 Sampling was taken from samples of mechanical properties and test specimens. Figure 5 As can be seen, the microstructure of the plate shows the most significant refinement, with a markedly refined α / β cluster and an increased aspect ratio. With the increase in added Y element, the generated Y₂O₃ particles restrict grain growth at the grain boundaries, while the added B element generates TiB, providing more nucleation sites, further enhancing the microstructure refinement. Mechanical property testing revealed that the titanium alloy plate prepared in this embodiment has a hardness of 251.4 HV, indicating that this embodiment, through the synergistic effect of introducing Y and B elements and combining them with the layered filling process, smelting, and rolling processes, achieved control over element volatilization and ingot uniformity, resulting in a titanium alloy with high strength and high corrosion resistance.

[0046] Comparative Example 1 A method for preparing Ti-Mo-Ni titanium alloy sheet, the raw materials and steps used in this comparative example are the same as those in Example 1, the difference being that Y and TiB2 particles are not added, specifically including the following steps: (1) Weigh out the Mo, Ni, B and Ti alloy raw materials sponge titanium (0.5~1cm in diameter), Ti-15Mo master alloy and pure nickel scrap according to the proportion. The composition of the alloy raw materials includes 0.8% Mo, 0.3% Ni and the balance Ti by mass percentage.

[0047] (2) First, mix sponge titanium with a diameter of 0.5~1cm, Ti-15Mo master alloy and pure nickel scrap evenly to obtain mixed powder.

[0048] (3) Divide the mixed powder obtained in step (2) into 3 equal parts and fill the mixed powder after division by layering. Specifically, the first equal part of mixed powder is placed at the bottom layer, the second equal part of mixed powder is placed in the middle layer, and the third equal part of mixed powder is placed at the top layer to obtain the mixture. The mixture is pressed into a cuboid block under a pressure of 250 MPa.

[0049] (4) The material blocks are evenly distributed in the feeding chamber of the electron beam cold hearth furnace and fed continuously, followed by a vacuum of 1×10⁻⁶. -3 Under Pa conditions, the material blocks are melted uniformly at a temperature of 1900℃ at a melting rate of 650 kg / h. The melting process is carried out in a nitrogen atmosphere. After melting, the alloy ingot is cast and cooled in the furnace to obtain an alloy ingot.

[0050] (5) The oxide scale of the alloy ingot is milled off by a milling machine. The milled flat ingot with a length of 1400mm × width of 400mm × thickness of 200mm is subjected to forging-free direct rolling. A two-fire rolling process is adopted. The first fire rolling temperature is 900℃, and the rolling is carried out in 4 passes with a reduction rate of 65% to ensure that the large dendrites of the broken ingot are broken. The second fire rolling direction is reversed by 90°, the rolling temperature is 860℃, and the rolling is carried out in 6 passes with a reduction rate of 70%. The total rolling is carried out in 10 passes with a total deformation of 90%, and finally a Ti-Mo-Ni titanium alloy plate with a thickness of 2mm is obtained.

[0051] The titanium alloy prepared in Comparative Example 1 did not contain Y or B elements. The mechanical properties of the titanium alloy sheet prepared in Comparative Example 1 were tested, and the results are as follows: Figure 2 As shown, the hardness is 172HV, derived from... Figure 2 It can be seen that the hardness of the titanium alloy plates in Examples 1-3 increased by 6.2%, 13.7%, and 18.3% respectively compared to Comparative Example 1. This indicates that after doping with both Y and B elements, the hardness of the titanium alloy was significantly improved due to the synergistic effect of the layered filling process, smelting, and rolling process. Figure 6 The metallographic images show that, due to the lack of Y and B doping, the microstructure of the titanium alloy sheet prepared in Comparative Example 1 was not refined and the grains were coarse.

[0052] Comparative Example 2 A method for preparing boron-doped Ti-Mo-Ni titanium alloy plates. The raw materials and steps used in this comparative example are the same as those in Example 1, except that Y is not added. The specific steps include: (1) Weigh out the following materials according to the proportion: Mo, Ni, B and Ti alloy raw materials sponge titanium (diameter 0.5~1cm), Ti-15Mo master alloy, pure nickel scrap and TiB2 particles. The composition of the alloy raw materials includes 0.8% Mo, 0.3% Ni, 0.1% B by mass percentage, with the balance being Ti.

[0053] (2) First, mix sponge titanium with a diameter of 0.5~1cm, Ti-15Mo master alloy and pure nickel scrap evenly to obtain mixed powder. Then, vacuum dry TiB2 particles at 125℃ for 3.5h. Subsequently, wrap the dried TiB2 particles with pure titanium foil to form several small spherical alloy packages with a diameter of 1~2cm.

[0054] (3) Divide the mixed powder obtained in step (2) into 3 equal parts, and then divide the alloy material package into 2 equal parts. Use a layered filling method to fill the equal parts of the mixed powder and alloy material package. Specifically, place the first equal part of mixed powder at the bottom layer, and arrange the first equal part of alloy material package on the bottom mixed powder with intervals between them. Place the second equal part of mixed powder in the middle layer, and arrange the second equal part of alloy material package on the bottom mixed powder with intervals between them. Place the third equal part of mixed powder at the top layer to obtain the mixture. Press the mixture into a cuboid block under a pressure of 250MPa.

[0055] (4) The material blocks are evenly distributed in the feeding chamber of the electron beam cold hearth furnace and fed continuously, followed by a vacuum of 1×10⁻⁶. -3 Under Pa conditions, the material blocks are melted uniformly at a temperature of 1900℃ at a melting rate of 650 kg / h. The melting process is carried out in a nitrogen atmosphere. After melting, the alloy ingot is cast and cooled in the furnace to obtain an alloy ingot.

[0056] (5) The oxide scale of the alloy ingot is milled off by a milling machine. The milled flat ingot with a length of 1400mm × width of 400mm × thickness of 200mm is rolled without forging. The first hot rolling temperature is 900℃, and the rolling is done in 4 passes with a reduction rate of 65%. To ensure that the broken ingot has large dendrites, a two-fire rolling process is adopted. The rolling direction of the second fire is reversed by 90°, the rolling temperature is 860℃, and the rolling is done in 6 passes with a reduction rate of 70%. The total rolling is done in 10 passes with a total deformation of 90%. Finally, a boron-doped Ti-Mo-Ni titanium alloy plate with a thickness of 2mm is obtained.

[0057] The titanium alloy prepared in Comparative Example 2 did not contain Y. The mechanical properties of the titanium alloy sheet prepared in Comparative Example 2 were tested, and the hardness was 195.48 HV. The performance of this comparative example was not good. This is because no Y2O3 particles were formed in the alloy, resulting in insufficient nucleation sites and poor grain refinement.

[0058] Comparative Example 3 A method for preparing yttrium-doped Ti-Mo-Ni titanium alloy plates is disclosed. The raw materials and steps used in this comparative example are the same as those in Example 1, except that TiB2 is not added. The specific steps include: (1) Weigh out the following materials according to the proportion: Mo, Ni, Y and Ti alloy raw materials sponge titanium (diameter 0.5~1cm), Ti-15Mo master alloy, pure nickel scrap and high-purity Y particles. The composition of the alloy raw materials includes 0.8% Mo, 0.3% Ni, 0.01% Y by mass percentage, with the balance being Ti.

[0059] (2) First, mix sponge titanium with a diameter of 0.5~1cm, Ti-15Mo master alloy and pure nickel scrap evenly to obtain mixed powder. Then, vacuum dry the high-purity Y particles at 125℃ for 3.5h. Then, wrap the dried high-purity Y particles with pure titanium foil to form several small spherical alloy packages with a diameter of 1~2cm.

[0060] (3) Divide the mixed powder obtained in step (2) into 3 equal parts, and then divide the alloy material package into 2 equal parts. Use a layered filling method to fill the equal parts of the mixed powder and alloy material package. Specifically, place the first equal part of mixed powder at the bottom layer, and arrange the first equal part of alloy material package on the bottom mixed powder with intervals between them. Place the second equal part of mixed powder in the middle layer, and arrange the second equal part of alloy material package on the bottom mixed powder with intervals between them. Place the third equal part of mixed powder at the top layer to obtain the mixture. Press the mixture into a cuboid block under a pressure of 250MPa.

[0061] (4) The material blocks are evenly distributed in the feeding chamber of the electron beam cold hearth furnace and fed continuously, followed by a vacuum of 1×10⁻⁶. -3 Under Pa conditions, the material blocks are melted uniformly at a temperature of 1900℃ at a melting rate of 650 kg / h. The melting process is carried out in a nitrogen atmosphere. After melting, the alloy ingot is cast and cooled in the furnace to obtain an alloy ingot.

[0062] (5) The oxide scale of the alloy ingot is milled off by a milling machine. The milled flat ingot with a length of 1400mm × width of 400mm × thickness of 200mm is subjected to forging-free direct rolling. A two-fire rolling process is adopted. The first fire rolling temperature is 900℃, and the rolling is carried out in 4 passes with a reduction rate of 65% to ensure that the large dendrites of the broken ingot are broken. The second fire rolling direction is reversed by 90°, the rolling temperature is 860℃, and the rolling is carried out in 6 passes with a reduction rate of 70%. The total rolling is carried out in 10 passes with a total deformation of 90%. Finally, a yttrium-doped Ti-Mo-Ni titanium alloy plate with a thickness of 2mm is obtained.

[0063] The titanium alloy prepared in Comparative Example 3 did not contain added boron (B). Mechanical property tests were performed on the titanium alloy sheet prepared in Comparative Example 3, and the hardness was 191.81 HV. The performance of this comparative example is poor because the alloy did not form TiB particles, resulting in insufficient nucleation sites and poor grain refinement.

[0064] Comparative Example 4 A method for preparing a yttrium boron dual-element doped Ti-Mo-Ni titanium alloy plate. The raw materials and steps used in this comparative example are the same as those in Example 1, except that a layered filler method is not used. The specific steps include: (1) Weigh out the following materials according to the proportions: Mo, Ni, Y, B, Ti alloy raw materials sponge titanium (diameter 0.5~1cm), Ti-15Mo master alloy, pure nickel scrap, high-purity Y particles and TiB2 particles. The composition of the alloy raw materials includes 0.8% Mo, 0.3% Ni, 0.01% Y, 0.1% B, and the balance is Ti.

[0065] (2) High-purity Y particles and TiB2 particles are vacuum dried at 125℃ for 3.5h. Then, sponge titanium with a diameter of 0.5~1cm, Ti-15Mo master alloy, pure nickel scrap, high-purity Y particles and TiB2 particles are mixed evenly to obtain a mixed powder.

[0066] (3) The mixed powder obtained in step (2) is pressed into a cuboid block under a pressure of 250 MPa.

[0067] (4) The material blocks are evenly distributed in the feeding chamber of the electron beam cold hearth furnace and fed continuously, followed by a vacuum of 1×10⁻⁶. -3 Under Pa conditions, the material blocks are melted uniformly at a temperature of 1900℃ at a melting rate of 650 kg / h. The melting process is carried out in a nitrogen atmosphere. After melting, the alloy ingot is cast and cooled in the furnace to obtain an alloy ingot.

[0068] (5) The oxide scale of the alloy ingot is milled off by a milling machine. The milled flat ingot with a length of 1400mm × width of 400mm × thickness of 200mm is subjected to forging-free direct rolling. A two-fire rolling process is adopted. The first fire rolling temperature is 900℃, and the rolling is carried out in 4 passes with a reduction rate of 65% to ensure that the large dendrites of the broken ingot are broken. The second fire rolling direction is reversed by 90°, the rolling temperature is 860℃, and the rolling is carried out in 6 passes with a reduction rate of 70%. The total rolling is carried out in 10 passes with a total deformation of 90%. Finally, a yttrium boron dual-element doped Ti-Mo-Ni titanium alloy plate with a thickness of 2mm is obtained.

[0069] The titanium alloy prepared in Comparative Example 4 was not subjected to layered filler. Mechanical property tests were performed on the titanium alloy sheet prepared in Comparative Example 4, and the hardness result was 182.7 HV. The performance of this comparative example was poor because the lack of layered filler meant that the added Y and B elements could not be uniformly distributed in the alloy, leading to the segregation of the generated Y₂O₃ with TiB particles, resulting in stress concentration and uneven microstructure.

[0070] Comparative Example 5 A method for preparing a yttrium boron dual-element doped Ti-Mo-Ni titanium alloy sheet is disclosed. The raw materials and steps used in this comparative example are the same as those in Example 1, except that a two-fire rolling process is not used for forging-free direct rolling. The specific steps include: (1) Weigh out the following materials according to the proportions: sponge titanium (0.5~1cm in diameter), Ti-15Mo master alloy, pure nickel scrap, high-purity Y particles and TiB2 particles. The composition of the alloy materials includes 0.8% Mo, 0.3% Ni, 0.01% Y, 0.1% B, and the balance is Ti.

[0071] (2) First, mix sponge titanium, Ti-15Mo master alloy and pure nickel scrap with a diameter of 0.5~1cm evenly to obtain mixed powder. Then, vacuum dry high-purity Y particles and TiB2 particles at 125℃ for 3.5h. Then, use pure titanium foil to wrap the dried high-purity Y particles and TiB2 particles to form several small spherical alloy packages with a diameter of 1~2cm.

[0072] (3) Divide the mixed powder obtained in step (2) into 3 equal parts, and then divide the alloy material package into 2 equal parts. Use a layered filling method to fill the equal parts of the mixed powder and alloy material package. Specifically, place the first equal part of mixed powder at the bottom layer, and arrange the first equal part of alloy material package on the bottom mixed powder with intervals between them. Place the second equal part of mixed powder in the middle layer, and arrange the second equal part of alloy material package on the bottom mixed powder with intervals between them. Place the third equal part of mixed powder at the top layer to obtain the mixture. Press the mixture into a cuboid block under a pressure of 250MPa.

[0073] (4) The material blocks are evenly distributed in the feeding chamber of the electron beam cold hearth furnace and fed continuously, followed by a vacuum of 1×10⁻⁶. -3 Under Pa conditions, the material blocks are melted uniformly at a temperature of 1900℃ and a melting rate of 650 kg / h. The melting process is carried out in an argon atmosphere. After melting, the alloy ingot is cast and cooled in the furnace to obtain the alloy ingot.

[0074] (5) The oxide scale of the alloy ingot is milled off by a milling machine. The milled flat ingot with a length of 1400mm × width of 400mm × thickness of 200mm is then subjected to forging-free direct rolling. The hot rolling start temperature is 900℃, and the rolling is performed in 10 passes with a total deformation of 90%. Finally, a yttrium boron dual-element doped Ti-Mo-Ni titanium alloy plate with a thickness of 2mm is obtained.

[0075] The titanium alloy prepared in Comparative Example 5 was not subjected to a two-stage rolling process. Mechanical property tests were performed on the titanium alloy sheet prepared in Comparative Example 5, and the hardness was 203.6 HV. The performance of this comparative example is poor because the titanium alloy sheet obtained by direct single-stage rolling without a two-stage rolling process has a coarse microstructure, low uniformity, and high anisotropy, resulting in poor performance.

[0076] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing a yttrium boron dual-element doped Ti-Mo-Ni titanium alloy plate, characterized in that, Specifically, the following steps are included: (1) Weigh out the Ti, Mo, Ni, Y, B alloy raw materials sponge titanium, Ti-15Mo master alloy, pure nickel scrap, high-purity Y particles and TiB2 particles according to the proportion; (2) First, mix the sponge titanium, Ti-15Mo master alloy and pure nickel scrap evenly to obtain a mixed powder. Then, dry the high-purity Y particles and TiB2 particles. Then, wrap the dried high-purity Y particles and TiB2 particles with pure titanium foil to form several small spherical alloy packages. (3) Divide the mixed powder obtained in step (2) into 3 equal parts, and then divide the alloy material package into 2 equal parts. Use a layered filling method to fill the equal parts of the mixed powder and alloy material package. Specifically, place the first equal part of the mixed powder at the bottom layer, arrange the first equal part of the alloy material package on the bottom mixed powder, place the second equal part of the mixed powder in the middle layer, arrange the second equal part of the alloy material package on the bottom mixed powder, and place the third equal part of the mixed powder at the top layer to obtain the mixed material. Press the mixed material into a cuboid block. (4) Arrange the material blocks in the feeding chamber of the melting device, feed continuously, then heat up and vacuum melt, pour and cool after melting to obtain alloy ingots; (5) After milling the alloy ingot, straight rolling without forging is used to obtain yttrium boron doped Ti-Mo-Ni titanium alloy plate.

2. The method for preparing the yttrium boron dual-element doped Ti-Mo-Ni titanium alloy plate according to claim 1, characterized in that, In step (1), the alloy raw materials are weighed in the following proportions: 0.8% Mo, 0.3% Ni, 0.01~0.06% Y, 0.1% B, and the balance Ti.

3. The method for preparing the yttrium boron dual-element doped Ti-Mo-Ni titanium alloy plate according to claim 1, characterized in that, The drying conditions in step (2) are: drying at 100~150℃ for 3~4 hours.

4. The method for preparing the yttrium boron dual-element doped Ti-Mo-Ni titanium alloy plate according to claim 1, characterized in that, The pressure when the mixture is pressed into blocks in step (3) is 200~300MPa.

5. The method for preparing the yttrium boron dual-element doped Ti-Mo-Ni titanium alloy plate according to claim 1, characterized in that, The vacuum melting conditions in step (4) are: a vacuum degree of 1×10 -3 Pa ~ 1×10 -5 Under Pa conditions, the metal is smelted at a temperature of 1800~2000℃ at a smelting rate of 600~700 kg / h, and the smelting process is carried out under a protective atmosphere.

6. The method for preparing the yttrium boron dual-element doped Ti-Mo-Ni titanium alloy plate according to claim 1, characterized in that, The conditions for forged straight rolling in step (5) are as follows: a two-fire rolling process is adopted, with the first fire starting at a rolling temperature of 890~910℃, rolling 4 passes, and a reduction rate of 60~65%; the second fire rolling direction is reversed by 90°, the rolling temperature is 850~870℃, rolling 6 passes, and a reduction rate of 70~75%; the forged straight rolling process consists of a total of 10 passes, with a total deformation of 90%.

7. The yttrium boron dual-element doped Ti-Mo-Ni titanium alloy plate prepared by the method according to any one of claims 1 to 6.

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