Preparation method of large-size molybdenum-titanium alloy rotating target material

Abstract

The invention discloses a preparation method of a large-size molybdenum-titanium alloy rotating target material, which comprises the following steps: pressing high-purity titanium powder into a pure titanium plate blank, crushing the pure titanium plate blank to obtain titanium powder particles, putting the titanium powder particles and high-purity molybdenum powder into a vacuum mixer, and mixing to obtain molybdenum-titanium alloy powder; molybdenum-titanium alloy powder is sintered and densified to prepare molybdenum-titanium alloy billets, the molybdenum-titanium alloy billets are loaded into a sheath to be subjected to vacuum heating and sealing, and then the molybdenum-titanium alloy rotating target which is large in size specification, uniform in microstructure component, free of segregation and cracking and high in purity is prepared through the extrusion forming step, the annealing step and the finish machining binding step in sequence. The pure titanium plate blank is prepared to improve the strength and density of the microcosmic high-purity titanium powder aggregate, and then crushing is performed to obtain the titanium powder particles, so that the density of the high-purity titanium powder is close to that of the high-purity molybdenum powder, the mixing uniformity of the molybdenum-titanium alloy powder can be improved, the molybdenum-titanium alloy rotating target material is free of segregation and cracking, and the service life of the molybdenum-titanium alloy rotating target material is prolonged. And the structure uniformity and purity of the molybdenum-titanium alloy rotating target material are improved.

Description

Technical Field

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

[0002] With the development of the display industry, flat panel displays (FPD) such as liquid crystal displays TFT-LCD, plasma displays PDP and touch screens TP have become the mainstream of displays, and the size of display panels continues to increase. The wiring film of thin film transistors (TFT) used as driving elements of FPD requires a conductive film material with a lower resistivity. When Cu, which is the main wiring film, is in direct contact with Si, it will undergo thermal diffusion due to the heating process in TFT manufacturing, increasing the dielectric constant of the entire film and easily causing the performance degradation or even failure of semiconductor devices, resulting in poor characteristics of TFT. Therefore, a molybdenum-titanium alloy film layer with excellent heat resistance is mainly used as a laminated wiring film between Cu and Si, and the corresponding demand for molybdenum-titanium alloy sputtering targets is also increasing. The utilization rate of tubular rotating target coating is about 70%, which is much higher than the 30% utilization rate of planar target coating. Therefore, tubular rotating targets are mainly used.

[0003] The requirements for molybdenum-titanium alloy targets required for high-generation line display are relatively strict, requiring the relative density of molybdenum-titanium alloy targets to be ≥99.5%, purity ≥99.95%, average grain size ≤100 microns, uniform structure without segregation, and strict requirements for oxygen content and trace elements. At the same time, it has a certain large size, and the length of a single section is 2600-3500mm. The existing molybdenum-titanium alloy targets are mainly made by powder metallurgy, mainly using molybdenum powder and titanium powder or titanium hydride powder mixed and then pressed into shape, and the targets are prepared by vacuum sintering or hot pressing. This preparation process has the following problems: 1. Due to the large difference in specific gravity between molybdenum and titanium (molybdenum = 10.2g / cm3, titanium 4.5g / cm3), about more than one time, directly mixing the two powders is likely to cause molybdenum powder or titanium powder agglomeration and segregation, 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 low, and the content of gas impurity elements (carbon, oxygen, nitrogen, etc.) exceeds the standard; 3. Due to the specification limitations of the hot isostatic pressing equipment, it is impossible to prepare large-sized (length greater than 2500mm) high-generation tube targets. There are also methods that use multiple sections of small-sized target blanks to splice and then perform hot isostatic pressing to prepare large-sized 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 component segregation and low strength, which cannot meet the needs of high-generation line coating. Therefore, it is necessary to improve it. Summary of the invention

[0004] In view of the shortcomings of the prior art, 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 a large-sized molybdenum-titanium alloy rotating target material 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, comprising the following sub-steps:

[0007] Step S1.1: a pressing and crushing sub-step, in which the high-purity titanium powder is pressed into a pure titanium slab by a cold isostatic press, and the pure titanium slab is crushed by a jet crusher 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 the mold cavity of the hot pressing furnace for hot pressing and sintering, the mold cavity is made of graphite, and the mold cavity is cylindrical. The mold cavity is first evacuated and heated to 600-800°C and then kept at a constant temperature and pressure for 4-10 hours, and then the mold cavity is continued to be heated to 950-1200°C, and then the mold cavity is pressurized and kept at a constant temperature and pressure for 4-8 hours, and finally the mold cavity is depressurized and cooled 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 sleeve, and welding and sealing the inner and outer circles and both end faces, so that the sleeve completely wraps the molybdenum-titanium alloy ingot, and then placing the sleeve containing the molybdenum-titanium alloy ingot into a muffle furnace, heating it to 300-500°C, and evacuating the sleeve to 2*10-3Pa, and welding and sealing the sleeve after detecting that there is no leakage point in the sleeve;

[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 um and high-purity molybdenum powder are selected and put into a vacuum mixer and filled with argon gas, 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 um, the oxygen content is ≤1000 ppm, and the purity is ≥99.95%; the particle size of the high-purity molybdenum powder is 5-15 um, 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 10-60at%: 10-70at%.

[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, a second vacuum is performed 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°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 40-70Mpa, and maintaining constant temperature and pressure for 4-8 hours;

[0021] Step S2.3: a cooling sub-step, releasing the pressure in the mold cavity, reducing the temperature in the mold cavity to 70-90°C at a cooling rate of 5°C / min, and obtaining 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 compared with the prior art are: by pressing high-purity titanium powder into a block-shaped pure titanium slab with a certain density, the strength and density of the microscopic high-purity titanium powder aggregate are improved in advance, and then the pure titanium slab is crushed to obtain titanium powder particles with a certain particle size range, so that the packing density of the high-purity titanium powder is 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 material has no segregation and cracking, and the organizational uniformity and purity of the molybdenum-titanium alloy rotating target material are improved, which fully meets 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, so that the purity of the molybdenum-titanium alloy rotating target material is ≥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. There is no need to inject atmosphere for protective heating, which reduces consumption and cost. The sheath can also prevent the molybdenum-titanium alloy ingot from being directly exposed to the air and causing oxidation, cracking and delamination, reduce temperature loss during extrusion, and improve 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 is further described below in conjunction with the accompanying drawings and embodiments.

[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 The microscopic morphology of the titanium powder particles of the present invention;

[0033] Figure 4 The microscopic morphology 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 rotating target of the present invention;

[0036] Figure 7 This is a purity detection diagram of the molybdenum-titanium alloy rotating 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] Fig. 9 The alloy metallographic diagram of the molybdenum-titanium alloy rotary target of Comparative Example 1;

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

[0040] Fig.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] Fig.12 This is a physical picture of the molybdenum-titanium alloy ingot of Comparative Example 2 being broken in step S4;

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

[0043] Fig.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 only preferred embodiments of the present invention, and are not intended to limit the protection scope 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, comprising the following sub-steps:

[0047] Step S1.1: a pressing and crushing sub-step, selecting 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%, pressing the high-purity titanium powder into a pure titanium slab at a pressure of 400 MPa by a cold isostatic press, and crushing the pure titanium slab into titanium powder particles by a jet crusher;

[0048] Step S1.2: a mixing sub-step, sieving the titanium powder particles, selecting titanium powder particles with a particle size of 6 to 15 μm, selecting 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%, placing the high-purity molybdenum powder and titanium powder particles in a mixing ratio of 55 at%:45 at% into a vacuum mixer and filling with argon, mixing for 6 hours at a pressure of 0.05 to 0.01 Pa, and obtaining 300 kg of molybdenum-titanium alloy powder;

[0049] Since the specific gravity of molybdenum and titanium is quite different, about more than one time (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 the high-purity titanium powder is close to the density of the high-purity molybdenum powder, thereby improving the mixing uniformity of the molybdenum-titanium alloy powder. Figure 1 As shown, the molybdenum-titanium alloy rotating target material can be free of segregation and cracking, and the organizational uniformity and purity of the molybdenum-titanium alloy rotating target material can be improved, fully meeting the requirements of the high-generation high-definition liquid crystal display industry for high-purity sputtering materials.

[0050] Step S2: Sintering 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, a second vacuum is performed 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 60Mpa, and maintaining constant temperature and pressure for 8 hours;

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

[0055] The traditional molybdenum-titanium alloy rotating target material is prepared by pre-isostatic pressing of molybdenum-titanium alloy powder and then vacuum sintering, which has a complex process and low production efficiency. 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, thereby simplifying the process flow, and forming a step-by-step temperature increase and pressure change through primary sintering and secondary sintering to remove the gas (C, N, H, O) impurity content in the molybdenum-titanium alloy powder, thereby improving the purity of the molybdenum-titanium alloy rotating target material, so that the purity of the molybdenum-titanium alloy rotating target material is ≥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 processed at the two ends in the length direction.

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

[0058] The rough-machined 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. The sleeve containing the molybdenum-titanium alloy ingot is then placed in a muffle furnace and heated to 350°C. The sleeve is evacuated to 2*10-3Pa. After the sleeve 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. There is no need to inject atmosphere for protective heating, which reduces consumption and cost. The sheath can also prevent the molybdenum-titanium alloy ingot from being directly exposed to the air and causing oxidation, cracking and delamination, reduce temperature loss during extrusion, and improve 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 treatment 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 is obtained;

[0061] The extrusion speed directly affects the structure and performance of the finished product. If the extrusion speed is too low, more metal heat will be dissipated, resulting in the appearance of processed structure 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 good range. The density of the molybdenum-titanium tube target can be increased by extrusion treatment. At the same time, the metal structure can be made more fibrous and fine-grained, and the molybdenum-titanium tube target can be made closer to the net finished product size, so that the material input-output ratio of the production is higher.

[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, turning the inner circle, outer circle and end face of the annealed molybdenum-titanium tube target to obtain a molybdenum-titanium tube target with a preset length of 2700 mm, and finally binding and welding the molybdenum-titanium tube and the titanium back tube to obtain a molybdenum-titanium alloy rotating target material, and performing C-SCAN detection on the prepared molybdenum-titanium alloy rotating target material, and judging it as qualified if the binding welding rate is ≥98.5%, and then performing ultrasonic cleaning treatment on the qualified molybdenum-titanium alloy rotating target material, and then performing drying treatment, finally preparing 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 5-15um, an oxygen content of ≤600ppm, and a purity of ≥99.95% and high-purity titanium powder with a particle size of 3-6um, an oxygen content of ≤1000ppm, and a purity of ≥99.95% are directly put into a vacuum mixer in a mixing ratio of 55at%:45at% and filled with argon, and mixed for 6 hours at a pressure of 0.05-0.01pa to obtain 300kg 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 substantially the same as that of the embodiment of the present invention. Steps S1 and S2 of Comparative Example 2 are completely 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 is roughly processed by CNC machining equipment to form 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 processed at both ends in the length direction. Comparative Example 2 does not perform sheathing treatment on the molybdenum-titanium alloy ingot as in the embodiment.

[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 for protection and heated to 1200°C. After being kept warm for 4 hours, it is forward extruded 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. Fig.11 As shown in the figure, a large amount of oxides volatilize during extrusion, and the temperature of the molybdenum-titanium alloy billet drops very quickly before and after extrusion. The temperature difference between the front and rear sections of the molybdenum-titanium alloy billet reaches 150°C. Fig.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 target materials prepared in Example 1, Comparative Example 1 and Comparative Example 2 were sampled to obtain Sample 1#, Sample 2# and Sample 3#, respectively (since Comparative Example 2 did not produce a qualified molybdenum-titanium tube target in step S4, Comparative Example 2 sampled the unqualified molybdenum-titanium tube target). 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 the cracking was tested by non-destructive testing (since Sample 3# had obvious cracking, non-destructive testing was not performed on Sample 3#). Fig.14As shown, the relative density of the molybdenum-titanium alloy rotary target prepared in the embodiment is 99.80%, the purity is 99.97%, the oxygen content is 840ppm, the average grain size is 50um, the organizational uniformity is good, and the non-destructive testing is qualified; the relative density of the molybdenum-titanium alloy rotary target prepared in comparative example 1 is 99.50%, the purity is 99.96%, the oxygen content is 900ppm, the average grain size is 60um, the organizational uniformity is poor, there is serious segregation, and there are dispersed internal cracks in non-destructive testing; the relative density of the molybdenum-titanium tube target prepared in comparative example 2 is 98%, the purity is 99.2%, the oxygen content is 2600ppm, the average grain size is 50um, the organizational uniformity is poor, and there is a phenomenon of extrusion cracking and difficulty in forming.

[0071] Through sampling and detection comparison, the molybdenum-titanium alloy rotary target material prepared in the embodiment of the present invention has the best comprehensive performance. The length of the molybdenum-titanium alloy rotary target material not only exceeds 2700mm, 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 material prepared in Comparative Example 1 is initially directly mixed with molybdenum powder and titanium powder, and the molybdenum-titanium powders agglomerate and segregate, and the mixing is uneven, resulting in uneven segregation of the final alloy organization, relatively low density, and coarse internal grains, resulting in 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 that there are a large number of oxides and pores around the grain boundaries, and 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 will be changes in the specific implementation methods and application scopes. The content of this specification should not be understood as limiting the present invention.

Claims

1. A method for preparing a large-sized molybdenum-titanium alloy rotating target, characterized in that: The following steps are included: Step S1: preparing molybdenum-titanium alloy powder, comprising the following sub-steps: Step S1.1: a pressing and crushing 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 crushed by a jet crusher to obtain titanium powder particles; 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; Step S2: Sintering and densification step, filling the molybdenum-titanium alloy powder into the mold cavity of the hot pressing furnace for hot pressing and sintering, the mold cavity is made of graphite, and the mold cavity is cylindrical. The mold cavity is first evacuated and heated to 600-800°C and then kept at a constant temperature and pressure for 4-10 hours, and then the mold cavity is continued to be heated to 950-1200°C, and then the mold cavity is pressurized and kept at a constant temperature and pressure for 4-8 hours, and finally the mold cavity is depressurized and cooled 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, placing the molybdenum-titanium alloy ingot into a cylindrical sleeve, and welding and sealing the inner and outer circles and both end faces, so that the sleeve completely wraps the molybdenum-titanium alloy ingot, and then placing the sleeve containing the molybdenum-titanium alloy ingot into a muffle furnace, heating it to 300-500°C, and evacuating the sleeve to 2*10-3Pa, and welding and sealing the sleeve after detecting that there is no leakage point in the sleeve; 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 molybdenum-titanium alloy rotating target.

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 titanium powder particles are sieved, titanium powder particles with a particle size of 6 to 15 um and the high-purity molybdenum powder are selected and put into the vacuum mixer and filled with argon gas, and mixed for 5 to 10 hours at a pressure of 0.05 to 0.01 pa to obtain the molybdenum-titanium alloy powder.

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 particle size of the high-purity titanium powder is 3-6 um, the oxygen content is ≤1000 ppm, and the purity is ≥99.95%; the particle size of the high-purity molybdenum powder is 5-15 um, the oxygen content is ≤600 ppm, 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 comprises the following sub-steps: Step S2.1: a primary sintering sub-step, filling the molybdenum-titanium alloy powder obtained in step S1 into the mold cavity of the hot pressing furnace for hot pressing 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 50-100 Pa, and then the mold cavity is heated. When the temperature of the mold cavity reaches 150-250°C, a second vacuum is performed 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°C, the temperature and pressure are kept constant 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 40-70Mpa, and maintaining constant temperature and pressure for 4-8 hours; Step S2.3: a cooling sub-step, releasing the pressure in the mold cavity, reducing the temperature in the mold cavity to 70-90°C at a cooling rate of 5°C / min, and obtaining a 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 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.

7. The method for preparing a large-sized molybdenum-titanium alloy rotary target according to claim 1, characterized in that: In the 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 the 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.

9. The method for preparing a large-sized molybdenum-titanium alloy rotary target according to claim 1, characterized in that: In the 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-size 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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