A method for preparing a large-size molybdenum-titanium alloy rotating target

Abstract

The present invention discloses a method for preparing a large-sized molybdenum-titanium alloy rotating target. The method comprises the following steps: pressing high-purity titanium powder into a pure titanium slab, crushing the pure titanium slab to obtain titanium powder particles, mixing the titanium powder particles with high-purity molybdenum powder in a vacuum mixer to obtain molybdenum-titanium alloy powder, densifying the molybdenum-titanium alloy powder to obtain a molybdenum-titanium alloy ingot, placing the molybdenum-titanium alloy ingot into a sheath, vacuum heating and sealing the ingot, and then sequentially undergoing extrusion molding, annealing, and finishing and binding steps to produce a large-sized, high-purity molybdenum-titanium alloy rotating target with uniform microstructure composition, no segregation and cracking. By making a pure titanium slab to improve the strength and density of the microscopic high-purity titanium powder aggregates, and then crushing to obtain titanium powder particles, the density of the high-purity titanium powder and the high-purity molybdenum powder are close, thereby improving the mixing uniformity of the molybdenum-titanium alloy powder, so that the molybdenum-titanium alloy rotating target is free of segregation and cracking, and improving the structural uniformity and purity of the molybdenum-titanium alloy rotating target.

Description

Technical Field

[0001] The present invention relates to the technical field of target material preparation, and in particular to a method for preparing a large-sized molybdenum-titanium alloy rotary target material. Background Art

[0002] With the development of the display industry, flat panel displays (FPDs) such as liquid crystal displays (TFT-LCDs), plasma displays (PDPs), and touch screens (TPs) have become the mainstream of displays. As display panel sizes continue to increase, the wiring films of thin-film transistors (TFTs), which serve as the driving elements of FPDs, require conductive film materials with lower resistivity. When Cu, the main wiring film, comes into direct contact with Si, it undergoes thermal diffusion due to the heating process in TFT manufacturing, increasing the dielectric constant of the entire film and easily causing performance degradation or even failure of semiconductor devices, resulting in poor TFT characteristics. Therefore, a stacked wiring film with a molybdenum-titanium alloy layer with excellent heat resistance is primarily used between Cu and Si as the coating. Consequently, the demand for molybdenum-titanium alloy sputtering targets is also increasing. The utilization rate of tubular rotating targets for coating is approximately 70%, significantly higher than the 30% utilization rate of flat targets for coating. Therefore, tubular rotating targets are primarily used.

[0003] The requirements for molybdenum-titanium alloy targets required for high-generation lines are quite stringent. They must have a relative density of ≥99.5%, a purity of ≥99.95%, an average grain size of ≤100 microns, a uniform structure without segregation, and strict requirements for oxygen content and trace elements. They must also have large dimensions, with single-section lengths ranging from 2600 to 3500 mm. Existing molybdenum-titanium alloy targets are primarily manufactured using powder metallurgy, primarily by mixing molybdenum powder with titanium powder or titanium hydride powder and then pressing it into shape. The targets are then produced through vacuum sintering or hot pressing. This preparation process has the following problems: 1. Due to the large difference in the specific gravity of molybdenum and titanium (molybdenum = 10.2g / cm3, titanium 4.5g / cm3), which is about more than twice, directly mixing the two powders will easily cause molybdenum powder or titanium powder to agglomerate and segregate, resulting in uneven mixing. The sintering alloying process is prone to segregation, resulting in uneven alloying inside the target material, severe segregation of molybdenum or titanium, and coarse target grains, which cannot meet the requirements of the electronics industry for target materials; 2. The target material density is relatively low, and the content of gas impurity elements (carbon, oxygen, nitrogen, etc.) exceeds the standard; 3. Due to the specification limitations of hot isostatic pressing equipment, it is impossible to prepare large-size (length greater than 2500mm) high-generation tube targets. There is also a method of splicing multiple small-size target blanks and then hot isostatic pressing to prepare large-size targets, but the density of the adjacent joints of the produced target material is quite different from that of the target material itself, and there are problems of composition segregation and low strength, which cannot meet the coating needs of high-generation lines. Therefore, it is necessary to improve it. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for preparing a large-sized molybdenum-titanium alloy rotating target material, which simplifies the process, is easy to implement and can prepare large-sized molybdenum-titanium alloy rotating targets with uniform microstructure composition, no segregation and cracking, and high purity.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: a method for preparing a large-sized molybdenum-titanium alloy rotating target, comprising the following steps:

[0006] Step S1: preparing molybdenum-titanium alloy powder, including the following sub-steps:

[0007] Step S1.1: a pressing and pulverizing sub-step, wherein the high-purity titanium powder is pressed into a pure titanium slab by a cold isostatic press, and the pure titanium slab is pulverized by a jet mill to obtain titanium powder particles;

[0008] Step S1.2: a mixing sub-step, placing titanium powder particles and high-purity molybdenum powder into a vacuum mixer and mixing to obtain molybdenum-titanium alloy powder;

[0009] Step S2: Sintering and densification step, filling the molybdenum-titanium alloy powder into a mold cavity of a hot pressing furnace for hot pressing and sintering, the mold cavity is made of graphite and has a cylindrical shape, first evacuating the mold cavity and heating it to 600-800°C, then maintaining constant temperature and pressure for 4-10 hours, then continuing to heat the mold cavity to 950-1200°C, then increasing the pressure of the mold cavity and maintaining constant temperature and pressure for 4-8 hours, finally depressurizing the mold cavity and cooling it to 70-90°C, to obtain a tubular molybdenum-titanium alloy ingot with a relative density of 90-99% and an oxygen content of ≤800ppm;

[0010] Step S3: Target blank packaging step, placing the molybdenum-titanium alloy ingot into a cylindrical can, and welding the inner and outer circles and both end faces so that the can completely wraps the molybdenum-titanium alloy ingot, then placing the can containing the molybdenum-titanium alloy ingot into a muffle furnace, heating it to 300-500°C, and evacuating the can to 2*10-3Pa. After checking that there are no leaks in the can, welding and sealing the can;

[0011] Step S4: extrusion molding step, placing the sealed package into a muffle furnace, heating it to 1100-1350° C., keeping it warm for 2-6 hours, and then extruding it through an extruder to obtain a molybdenum-titanium tube target with a shape and size close to the preset specifications;

[0012] Step S5: annealing step, vacuum annealing treatment is performed on the molybdenum-titanium tube target, the annealing temperature is set to 900-1150° C., and the annealing time is set to 2-5 hours;

[0013] Step S6: Finishing and binding step, turning the inner circle, outer circle and end face of the annealed molybdenum-titanium tube target to obtain a molybdenum-titanium tube target of preset specifications, and finally binding and welding the molybdenum-titanium tube and the titanium back tube to obtain a molybdenum-titanium alloy rotating target.

[0014] In a further technical solution, in step S1.2, the titanium powder particles are sieved, and titanium powder particles with a particle size of 6 to 15 μm and high-purity molybdenum powder are selected and put into a vacuum mixer and filled with argon, and mixed for 5 to 10 hours at a pressure of 0.05 to 0.01 Pa to obtain molybdenum-titanium alloy powder.

[0015] In a further technical solution, in step S1.1, the particle size of the high-purity titanium powder is 3-6 μm, the oxygen content is ≤1000 ppm, and the purity is ≥99.95%; the particle size of the high-purity molybdenum powder is 5-15 μm, the oxygen content is ≤600 ppm, and the purity is ≥99.95%.

[0016] In a further technical solution, in step S1.2, the mixing ratio of high-purity molybdenum powder and titanium powder particles in the molybdenum-titanium alloy powder is 10-60 at %: 10-70 at %.

[0017] In a further technical solution, step S2 includes the following sub-steps:

[0018] Step S2.1: a primary sintering sub-step, wherein the molybdenum-titanium alloy powder obtained in step S1 is filled into a mold cavity of a hot pressing furnace for hot pressing and sintering. The mold cavity is made of graphite and has a cylindrical shape.

[0019] The mold cavity is vacuumed to reduce the pressure inside the mold cavity to 50-100 Pa, and then the mold cavity is heated. When the temperature of the mold cavity reaches 150-250 ° C, vacuum is performed again until the pressure inside the mold cavity reaches 6*10-3 Pa to 2*10-4 Pa. When the temperature of the mold cavity reaches 600-800 ° C, the temperature and pressure are kept constant for 4-10 hours;

[0020] Step S2.2: Secondary sintering sub-step, raising the temperature in the mold cavity to 950-1200°C at a heating rate of 1.5-3°C / min, and then raising the pressure in the mold cavity to 40-70 MPa, maintaining constant temperature and pressure for 4-8 hours;

[0021] Step S2.3: a cooling sub-step, releasing the pressure in the mold cavity and reducing the temperature in the mold cavity to 70-90°C at a cooling rate of 5°C / min, to obtain a tubular molybdenum-titanium alloy ingot with a relative density of 90-99% and an oxygen content of ≤800ppm.

[0022] In a further technical solution, in step S3, the surface of the molybdenum-titanium alloy ingot prepared in step S2 is rough-machined by CNC machining equipment, and the surface roughness of each surface is Ra≤1.6. At the same time, chamfers of C3 to C5 are machined at the two ends in the length direction, and then the rough-machined molybdenum-titanium alloy ingot is placed in the sheath.

[0023] In a further technical solution, in step S3, the material of the sheath is 20# steel or Q235 steel, and the thickness of the sheath is 5 to 10 mm.

[0024] In a further technical solution, in step S4, the extrusion treatment adopts forward extrusion, the extrusion ratio is 4.5-6.5, the extrusion speed is 30-90 mm / s, and the extrusion pressure is 450-600 MN.

[0025] In a further technical solution, in step S6, the prepared molybdenum-titanium alloy rotary target is subjected to C-SCAN inspection, and the binding welding rate ≥98.5% is judged to be qualified, and then the qualified molybdenum-titanium alloy rotary target is ultrasonically cleaned and then dried to finally prepare a large-size molybdenum-titanium alloy rotary target with a purity greater than 99.95% and a length greater than 2700 mm.

[0026] After adopting the above structure, the advantages of the present invention over the prior art are: by pressing high-purity titanium powder into a block-shaped pure titanium slab with a certain density to pre-improve the strength and density of the microscopic high-purity titanium powder aggregates, and then crushing the pure titanium slab to obtain titanium powder particles with a certain particle size range, the bulk density of the high-purity titanium powder is made close to the density of the high-purity molybdenum powder, thereby improving the mixing uniformity of the molybdenum-titanium alloy powder, so that the molybdenum-titanium alloy rotating target is free of segregation and cracking, and improving the structural uniformity and purity of the molybdenum-titanium alloy rotating target, fully meeting the requirements of the high-generation high-definition liquid crystal display industry for high-purity sputtering materials;

[0027] After the molybdenum-titanium alloy powder is prepared, sintering and densification treatment is directly carried out without pre-isostatic pressing and vacuum sintering, which simplifies the process flow and removes the gas impurities in the molybdenum-titanium alloy powder in a preset temperature range and a high vacuum environment, thereby improving the purity of the molybdenum-titanium alloy rotating target material to ≥99.95%;

[0028] By encapsulating the molybdenum-titanium alloy ingot and extruding it together with the sheath during extrusion molding, the sheath can effectively avoid the problem of high-temperature oxidation during the heating process, without the need to inject atmosphere for protective heating, reducing consumption and cost. In addition, the sheath can prevent the molybdenum-titanium alloy ingot from being directly exposed to the air and causing oxidation, cracking and delamination, reducing temperature loss during extrusion, and improving the uniformity of the organization and grain size distribution, so as to facilitate the production of large-sized molybdenum-titanium alloy rotary targets. The length of the molybdenum-titanium alloy rotary target can be greater than 2700mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be further described below with reference to the accompanying drawings and examples.

[0030] Figure 1 The alloy metallographic diagram of the molybdenum-titanium alloy rotary target of the present invention;

[0031] Figure 2 This is a physical picture of the molybdenum-titanium tube target obtained after extrusion molding in step S4 of the present invention;

[0032] Figure 3 This is a microscopic morphology of the titanium powder particles of the present invention;

[0033] Figure 4 This is a microscopic morphology diagram of the molybdenum-titanium alloy powder of the present invention;

[0034] Figure 5 This is a nondestructive testing diagram of the molybdenum-titanium alloy rotating target of the present invention;

[0035] Figure 6 This is a diagram for detecting the oxygen content of the molybdenum-titanium alloy rotary target of the present invention;

[0036] Figure 7 This is a purity detection diagram of the molybdenum-titanium alloy rotary target material of the present invention;

[0037] Figure 8 This is a microscopic morphology of the molybdenum-titanium alloy powder obtained by directly mixing the high-purity molybdenum powder and the high-purity titanium powder in Comparative Example 1;

[0038] Figure 9 This is the alloy metallographic diagram of the molybdenum-titanium alloy rotary target of Comparative Example 1;

[0039] Figure 10 This is a nondestructive testing image of the molybdenum-titanium alloy rotary target of Comparative Example 1;

[0040] Figure 11 This is a schematic diagram of the state in which the molybdenum-titanium alloy ingot of Comparative Example 2 undergoes oxidation and volatilization in step S4;

[0041] Figure 12 This is a physical picture of the molybdenum-titanium alloy ingot of Comparative Example 2 that is broken in step S4;

[0042] Figure 13 This is the alloy metallographic diagram of the molybdenum-titanium alloy ingot of Comparative Example 2;

[0043] Figure 14 This is a comparison chart of experimental data of sample 1#, sample 2# and sample 3# of the present invention. DETAILED DESCRIPTION

[0044] The following are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention.

[0045] A method for preparing a large-sized molybdenum-titanium alloy rotating target, such as Figures 1 to 14 As shown, the following steps are included:

[0046] Step S1: preparing molybdenum-titanium alloy powder, including the following sub-steps:

[0047] Step S1.1: In a pressing and pulverizing sub-step, high-purity titanium powder with a particle size of 3 to 6 μm, an oxygen content of ≤1000 ppm, and a purity of ≥99.95% is selected. The high-purity titanium powder is pressed into a pure titanium slab using a cold isostatic press at a pressure of 400 MPa. The pure titanium slab is then pulverized using a jet mill to obtain titanium powder particles.

[0048] Step S1.2: A mixing substep: sieve the titanium powder particles to select titanium powder particles with a particle size of 6 to 15 μm, select high-purity molybdenum powder with a particle size of 5 to 15 μm, an oxygen content of ≤600 ppm, and a purity of ≥99.95%, place the high-purity molybdenum powder and titanium powder particles in a mixing ratio of 55 at%:45 at% in a vacuum mixer, fill it with argon, and mix for 6 hours at a pressure of 0.05 to 0.01 Pa to obtain 300 kg of molybdenum-titanium alloy powder;

[0049] Since the specific gravity of molybdenum and titanium is quite different, about more than double (molybdenum = 10.2g / cm3, titanium 4.5g / cm3), Figure 8 As shown, directly mixing the two powders according to the traditional process is likely to cause molybdenum powder segregation, resulting in serious segregation of molybdenum or titanium inside the final target material and poor uniformity. In addition, titanium powder has a low density and is less bound by gravity. When mixed with molybdenum powder, it will float above the barrel, while the molybdenum powder particles with high density tend to sink, making it difficult to mix evenly, resulting in a large deviation in the final material ratio. The present invention presses high-purity titanium powder into block-shaped pure titanium slabs with a certain density to pre-improve the strength and density of microscopic high-purity titanium powder aggregates, and then crushes the pure titanium slabs to obtain titanium powder particles with a certain particle size range, so that the bulk density of high-purity titanium powder is close to the density of high-purity molybdenum powder, thereby improving the mixing uniformity of molybdenum-titanium alloy powder. Figure 1 As shown, the molybdenum-titanium alloy rotating target material is free of segregation and cracking, and the organizational uniformity and purity of the molybdenum-titanium alloy rotating target material are improved, fully meeting the requirements of the high-generation high-definition liquid crystal display industry for high-purity sputtering materials.

[0050] Step S2: Sintering and densification step, including the following sub-steps:

[0051] Step S2.1: a primary sintering sub-step, wherein the molybdenum-titanium alloy powder obtained in step S1 is filled into a mold cavity of a hot pressing furnace for hot pressing and sintering. The mold cavity is made of graphite and has a cylindrical shape.

[0052] The mold cavity is vacuumed to reduce the pressure inside the mold cavity to 50-100 Pa, and then the mold cavity is heated. When the temperature of the mold cavity reaches 250°C, vacuum is performed again until the pressure inside the mold cavity reaches 6*10-3 Pa~2*10-4 Pa. When the temperature of the mold cavity reaches 700°C, the temperature and pressure are kept constant for 7 hours.

[0053] Step S2.2: Secondary sintering sub-step, raising the temperature in the mold cavity to 1050°C at a heating rate of 3°C / min, and then raising the pressure in the mold cavity to 60 MPa, and maintaining constant temperature and pressure for 8 hours;

[0054] Step S2.3: a cooling sub-step of releasing the pressure in the mold cavity and reducing the temperature in the mold cavity to 80°C at a cooling rate of 5°C / min, thereby obtaining a tubular molybdenum-titanium alloy ingot having a relative density of 99% and an oxygen content of ≤800 ppm;

[0055] The traditional molybdenum-titanium alloy rotary target material is prepared by pre-isostatic pressing of molybdenum-titanium alloy powder and then vacuum sintering. The process is complicated and the production efficiency is low. However, the present invention directly performs sintering and densification treatment after preparing the molybdenum-titanium alloy powder, without the need for pre-isostatic pressing and then vacuum sintering, simplifying the process flow. Through the first sintering and the second sintering, the temperature and pressure are gradually increased and changed, so that the gas (C, N, H, O) impurity content in the molybdenum-titanium alloy powder is removed, thereby improving the purity of the molybdenum-titanium alloy rotary target material and making the purity of the molybdenum-titanium alloy rotary target material ≥99.95%.

[0056] Step S3: Target blank packaging step, rough machining the surface of the molybdenum-titanium alloy ingot by CNC machining equipment, and process the molybdenum-titanium alloy ingot into a hollow cylindrical ingot with an inner diameter of 80 mm and an outer diameter of 420 mm, so that the surface roughness of each surface is Ra≤1.6, and C5 chamfers are machined at both ends in the longitudinal direction.

[0057] Use 20# steel or Q235 steel to make a can that matches the shape and size of the molybdenum-titanium alloy ingot. The thickness of the can is 5mm.

[0058] The rough-machined molybdenum-titanium alloy ingot is placed in a cylindrical can, and the inner and outer circles and both end faces are welded and sealed so that the can completely covers the molybdenum-titanium alloy ingot. The can containing the molybdenum-titanium alloy ingot is then placed in a muffle furnace and heated to 350°C. The can is then vacuumed to 2*10-3Pa. After the can is tested for leaks, it is welded and sealed.

[0059] By encapsulating the molybdenum-titanium alloy ingot and extruding it together with the sheath during extrusion molding, the sheath can effectively avoid the problem of high-temperature oxidation during the heating process, without the need to inject atmosphere for protective heating, reducing consumption and cost. In addition, the sheath can prevent the molybdenum-titanium alloy ingot from being directly exposed to the air and causing oxidation, cracking and delamination, reducing temperature loss during extrusion, and improving the uniformity of the organization and grain size distribution, so as to facilitate the production of large-sized molybdenum-titanium alloy rotary targets. The length of the molybdenum-titanium alloy rotary target can be greater than 2700mm.

[0060] Step S4: Extrusion molding step, the sealed package is placed in a muffle furnace, heated to 1200 ° C, kept warm for 4 hours, and then subjected to forward extrusion processing by a horizontal extruder, with an extrusion ratio of 4.5, an extrusion speed of 50 mm / s, and an extrusion pressure of 450-600 MN. Figure 2 As shown, a molybdenum-titanium tube target with an outer diameter of 175 mm, an inner diameter of 125 mm, a length of 3000 mm, and a weight of 260 kg was obtained;

[0061] The extrusion speed directly affects the microstructure and performance of the finished product. If the extrusion speed is too low, more heat will be dissipated from the metal, resulting in the appearance of processed microstructure at the tail end of the molybdenum-titanium tube target. If the extrusion speed is too fast, the molybdenum-titanium tube target will crack. The present invention controls the extrusion speed within a preferred range. The density of the molybdenum-titanium tube target can be increased through extrusion treatment. At the same time, the metal microstructure can be made more fibrous and fine-grained, and the molybdenum-titanium tube target can be made closer to the net finished product size, thereby achieving a higher material input-output ratio.

[0062] Step S5: Annealing step, vacuum annealing treatment is performed on the molybdenum-titanium tube target, the annealing temperature is set to 980° C., and the annealing time is set to 5 hours; so as to carry out subsequent fine processing and obtain a microstructure with uniform organization and fine grains.

[0063] Step S6: Finishing and binding step, the inner circle, outer circle and end face of the annealed molybdenum-titanium tube target are turned to obtain a molybdenum-titanium tube target with a preset length of 2700 mm, and finally the molybdenum-titanium tube and the titanium back tube are bound and welded to obtain a molybdenum-titanium alloy rotating target material, and the prepared molybdenum-titanium alloy rotating target material is subjected to C-SCAN inspection, and the binding welding rate is ≥98.5% and it is judged to be qualified, and then the qualified molybdenum-titanium alloy rotating target material is ultrasonically cleaned and then dried to finally prepare a large-size molybdenum-titanium alloy rotating target material with a purity greater than 99.95% and a length greater than 2700 mm.

[0064] Comparative Example 1

[0065] The main production process of Comparative Example 1 is basically the same as that of the embodiments of the present invention. The difference between Comparative Example 1 and the embodiments of the present invention is that Comparative Example 1 does not have step S1.1. In step S1 of Comparative Example 1, high-purity molybdenum powder with a particle size of 5 to 15 μm, an oxygen content of ≤600 ppm, and a purity of ≥99.95% and high-purity titanium powder with a particle size of 3 to 6 μm, an oxygen content of ≤1000 ppm, and a purity of ≥99.95% are directly placed into a vacuum mixer in a mixing ratio of 55 at%:45 at% and filled with argon. The mixture is mixed for 6 hours at a pressure of 0.05 to 0.01 Pa to obtain 300 kg of molybdenum-titanium alloy powder, and the subsequent steps are exactly the same as those in the embodiments.

[0066] Comparative Example 2

[0067] The main production process of Comparative Example 2 is basically the same as that of the embodiment of the present invention. Steps S1 and S2 of Comparative Example 2 are exactly the same as those of the embodiment. The difference between Comparative Example 2 and the embodiment of the present invention lies in steps S3 and S4.

[0068] In step S3 of Comparative Example 2, the surface of the molybdenum-titanium alloy ingot was rough-machined using CNC machining equipment to form a hollow cylindrical ingot with an inner diameter of 80 mm and an outer diameter of 420 mm. The surface roughness Ra on each surface was set to ≤ 1.6, and C5 chamfers were formed at both ends in the longitudinal direction. Comparative Example 2 did not perform the canning treatment on the molybdenum-titanium alloy ingot as in the example.

[0069] Comparative Example 2 In step S4, the molybdenum-titanium alloy ingot that has not been jacketed is placed in a muffle furnace and filled with nitrogen to be heated to 1200°C. After being kept warm for 4 hours, it is subjected to forward extrusion treatment by a horizontal extruder with an extrusion ratio of 4.5, an extrusion speed of 50 mm / s, and an extrusion pressure of 500 MN. Figure 11 As shown in the figure, a large amount of oxides are volatilized during extrusion, and the temperature of the front and rear ends of the molybdenum-titanium alloy ingot drops very quickly. The temperature difference between the front and rear ends of the molybdenum-titanium alloy ingot reaches 150°C. Figure 12 As shown, cracks occurred at the final extrusion tail end, the molybdenum-titanium alloy ingot was greatly bent and deformed, and could not be formed and used, and no qualified molybdenum-titanium tube target was obtained.

[0070] The molybdenum-titanium alloy rotary targets prepared in Example 1, Comparative Example 1, and Comparative Example 2 were sampled to obtain Sample 1#, Sample 2#, and Sample 3#, respectively (since no qualified molybdenum-titanium tube target was obtained in step S4 of Comparative Example 2, the unqualified molybdenum-titanium tube target was sampled in Comparative Example 2). The relative density, purity, oxygen content, average grain size, and organizational uniformity of Sample 1#, Sample 2#, and Sample 3# were tested and compared, and non-destructive testing was performed on the cracking (since Sample 3# had obvious cracking, non-destructive testing was not performed on Sample 3#). Figure 14As shown, the molybdenum-titanium alloy rotary target material prepared in the embodiment has a relative density of 99.80%, a purity of 99.97%, an oxygen content of 840ppm, an average grain size of 50um, good organizational uniformity, and qualified non-destructive testing; the molybdenum-titanium alloy rotary target material prepared in comparative example 1 has a relative density of 99.50%, a purity of 99.96%, an oxygen content of 900ppm, an average grain size of 60um, poor organizational uniformity, severe segregation, and dispersed internal cracks in non-destructive testing; the molybdenum-titanium tube target prepared in comparative example 2 has a relative density of 98%, a purity of 99.2%, an oxygen content of 2600ppm, an average grain size of 50um, poor organizational uniformity, and the existence of extrusion cracking and difficulty in forming.

[0071] Through sampling and detection comparison, the molybdenum-titanium alloy rotary target prepared in the embodiment of the present invention has the best comprehensive performance. The length of the molybdenum-titanium alloy rotary target not only exceeds 2700 mm, but also has the characteristics of high density, high purity, low oxygen content, low average grain size, high organizational uniformity, and no cracking and segregation. However, the molybdenum-titanium alloy rotary target prepared in Comparative Example 1 is initially directly mixed with molybdenum powder and titanium powder, and the molybdenum-titanium powders agglomerate and segregate, resulting in uneven mixing, resulting in uneven segregation of the final alloy organization, relatively low density, coarse internal grains, and distributed cracks inside after extrusion. The molybdenum-titanium tube target prepared in Comparative Example 2 is the same as the embodiment of the present invention in steps S1 and S2, but is heated and extruded without sheath protection, resulting in severe oxidation of the molybdenum-titanium tube target, low density, and microstructure showing a large amount of oxides and pores around the grain boundaries. The content of gas impurity elements (C, N, H, O) exceeds the standard, and cracking occurs during the extrusion process.

[0072] The above contents are only preferred embodiments of the present invention. For ordinary technicians in this field, according to the concept of the present invention, there may be changes in the specific implementation methods and application scopes. The contents of this specification should not be understood as limiting the present invention.

Claims

1. A method for preparing a large-sized molybdenum-titanium alloy rotary target, characterized in that: The following steps are included: Step S1: preparing molybdenum-titanium alloy powder, including the following sub-steps: Step S1.1: a pressing and pulverizing sub-step, wherein high-purity titanium powder is pressed into pure titanium slabs using a cold isostatic press, wherein the particle size of the high-purity titanium powder is 3-6 μm, and the pure titanium slabs are pulverized using a jet mill to obtain titanium powder particles; Step S1.2: a mixing sub-step, wherein titanium powder particles are sieved, titanium powder particles with a particle size of 6 to 15 μm and high-purity molybdenum powder are selected and placed in a vacuum mixer to mix to obtain molybdenum-titanium alloy powder, wherein the particle size of the high-purity molybdenum powder is 5 to 15 μm; Step S2: Sintering and densification step, filling the molybdenum-titanium alloy powder into a mold cavity of a hot pressing furnace for hot pressing and sintering, the mold cavity is made of graphite and has a cylindrical shape, first evacuating the mold cavity and heating it to 600-800°C, then maintaining constant temperature and pressure for 4-10 hours, then continuing to heat the mold cavity to 950-1200°C, then increasing the pressure of the mold cavity and maintaining constant temperature and pressure for 4-8 hours, finally depressurizing the mold cavity and cooling it to 70-90°C, to obtain a tubular molybdenum-titanium alloy ingot with a relative density of 90-99% and an oxygen content of ≤800ppm; Step S3: Target blank packaging step, the molybdenum-titanium alloy ingot is placed in a cylindrical sleeve, and the inner and outer circles and both end faces are welded and sealed, so that the sleeve completely wraps the molybdenum-titanium alloy ingot, and then the sleeve containing the molybdenum-titanium alloy ingot is placed in a muffle furnace and heated to 300-500℃ and the sleeve is vacuumed to 2*10 -3 pa, after checking that there is no leakage point in the package, weld and seal the package; Step S4: extrusion molding step, placing the sealed package into a muffle furnace, heating it to 1100-1350°C, keeping it warm for 2-6 hours, and then extruding it through an extruder to obtain a molybdenum-titanium tube target with a shape and size close to the preset specifications; Step S5: annealing step, vacuum annealing treatment is performed on the molybdenum-titanium tube target, the annealing temperature is set to 900-1150° C., and the annealing time is set to 2-5 hours; Step S6: Finishing and binding step, turning the inner circle, outer circle and end face of the annealed molybdenum-titanium tube target to obtain a molybdenum-titanium tube target of preset specifications, and finally binding and welding the molybdenum-titanium tube and the titanium back tube to obtain a large-sized molybdenum-titanium alloy rotating target with a length greater than 2700 mm.

2. The method for preparing a large-sized molybdenum-titanium alloy rotary target according to claim 1, characterized in that: In the step S1.2, the molybdenum-titanium alloy powder is obtained by mixing at a pressure of 0.05-0.01 Pa for 5-10 hours.

3. The method for preparing a large-sized molybdenum-titanium alloy rotary target according to claim 2, characterized in that: In the step S1.1, the oxygen content of the high-purity titanium powder is ≤1000ppm and the purity is ≥99.95%. In the step S1.2, the oxygen content of the high-purity molybdenum powder is ≤600ppm and the purity is ≥99.95%.

4. The method for preparing a large-sized molybdenum-titanium alloy rotary target according to claim 3, characterized in that: In the step S1.2, the mixing ratio of the high-purity molybdenum powder and the titanium powder particles in the molybdenum-titanium alloy powder is 10-60 at %: 10-70 at %.

5. The method for preparing a large-sized molybdenum-titanium alloy rotary target according to claim 1, characterized in that: The step S2 includes the following sub-steps: Step S2.1: a primary sintering sub-step, wherein the molybdenum-titanium alloy powder obtained in step S1 is filled into the mold cavity of the hot pressing furnace for hot pressing and sintering. The mold cavity is made of graphite and has a cylindrical shape. The mold cavity is vacuumed to reduce the pressure inside the mold cavity to 50~100pa, and then the mold cavity is heated. When the temperature of the mold cavity reaches 150~250℃, vacuum is performed again until the pressure inside the mold cavity reaches 6*10 -3 pa~2*10 -4 Pa, when the temperature of the mold cavity reaches 600~800℃, keep constant temperature and pressure for 4~10 hours; Step S2.2: Secondary sintering sub-step, raising the temperature in the mold cavity to 950-1200°C at a heating rate of 1.5-3°C / min, and then raising the pressure in the mold cavity to 40-70 MPa, maintaining constant temperature and pressure for 4-8 hours; Step S2.3: a cooling sub-step, releasing the pressure in the mold cavity and reducing the temperature in the mold cavity to 70-90°C at a cooling rate of 5°C / min, to obtain the tubular molybdenum-titanium alloy ingot with a relative density of 90-99% and an oxygen content of ≤800ppm.

6. The method for preparing a large-sized molybdenum-titanium alloy rotary target according to claim 1, characterized in that: In the step S3, the surface of the molybdenum-titanium alloy ingot prepared in the step S2 is rough-machined by CNC machining equipment, and the surface roughness of each surface is Ra≤1.

6. At the same time, chamfers of C3~C5 are machined at the two ends in the length direction, and then the rough-machined molybdenum-titanium alloy ingot is placed in the sheath.

7. The method for preparing a large-sized molybdenum-titanium alloy rotary target according to claim 1, characterized in that: In step S3, the material of the sheath is 20# steel or Q235 steel, and the thickness of the sheath is 5-10 mm.

8. The method for preparing a large-sized molybdenum-titanium alloy rotary target according to claim 1, characterized in that: In step S4, the extrusion process adopts forward extrusion, the extrusion ratio is 4.5-6.5, the extrusion speed is 30-90 mm / s, and the extrusion pressure is 450-600 MN.

9. The method for preparing a large-sized molybdenum-titanium alloy rotary target according to claim 1, characterized in that: In step S6, the prepared molybdenum-titanium alloy rotary target is subjected to C-SCAN inspection, and is judged to be qualified if the binding welding rate is ≥98.5%. Then, the qualified molybdenum-titanium alloy rotary target is subjected to ultrasonic cleaning treatment and then to drying treatment, and finally a large-sized molybdenum-titanium alloy rotary target with a purity greater than 99.95% and a length greater than 2700 mm is prepared.

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