A method for preparing large-size aluminum-chromium-boron alloy target

Abstract

The present invention discloses a method for preparing a large-sized aluminum-chromium-boron alloy target, which comprises the following steps: 1. pre-treating chromium powder, boron powder, and aluminum particle raw materials; 2. mixing the chromium powder and boron powder and cold isostatically pressing to obtain a chromium-boron cold-pressed blank; 3. preparing an aluminum-chromium-boron alloy ingot using a controlled aluminum and gradient magnetic levitation one-step melting method; 4. preparing a semi-solid blank; 5. semi-solid forging; 6. vacuum annealing; 7. subsequent machining, straightening, vacuum annealing, and cleaning to obtain the aluminum-chromium-boron alloy target. The present invention adopts controlled aluminum and gradient magnetic levitation one-step melting to obtain an ingot with uniform, stable, and controllable composition and no internal defects. Combined with the semi-solid forging and annealing process, the aluminum-chromium-boron alloy target with uniform, fine, and low-oxygen structure is obtained, thereby improving the utilization rate and production efficiency of the ingot and being suitable for the mass production of large-sized aluminum-chromium-boron targets.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-performance material forming and processing, and in particular relates to a method for preparing a large-size aluminum-chromium-boron alloy target. Background Art

[0002] With the continuous emergence of major national equipment such as China's aerospace, bridges, high-speed rail, and nuclear power, the rapid development of modern industrial technology has placed higher demands on new materials and machining methods. Correspondingly, more stringent requirements are also being placed on machining tools to achieve the high-precision, high-efficiency, environmentally friendly, and low-cost machining needs of ultra-high-strength and ultra-high-hardness components.

[0003] Currently, applying a hard coating to the surface of high-strength, high-toughness cemented carbide is the most effective method for achieving stable and durable cutting tools. Since the 1960s, hard coatings have evolved from binary TiN to ternary TiAlN and even quaternary coatings. Gradually, simple binary coatings such as TiN and CrN have become inadequate for modern machining requirements. Research has shown that by adding Al to these binary coatings, AlTiN and AlCrN coatings exhibit improved high-temperature oxidation resistance, wear resistance, corrosion resistance, and a low coefficient of friction. Extensive research and industrial applications have demonstrated that AlCrN coatings exhibit superior oxidation resistance to AlTiN, with oxidation resistance temperatures reaching 900°C, making them a widely used hard coating. When boron is added to AlCrN coatings, an Al-Cr-BN nanocomposite structure is formed, consisting of an Al-Cr-(B)-N crystalline phase and an amorphous BNx phase. This significantly improves the coating's hardness, wear resistance, and substrate adhesion, while reducing residual stress, making it particularly suitable for high-speed dry machining. Currently, the most mainstream method for preparing hard coatings is physical vapor deposition (PVD). This means that the quality of the target directly determines the stability and performance of the hard coating film. In recent years, to meet the demands of modern industrial technology and the development of new productivity, targets have continued to develop in the direction of larger size, higher purity, and higher sputtering rates. This has further increased the difficulty of precisely controlling target composition, ensuring uniformity of composition, structural uniformity, and minimizing defectivity. Therefore, developing new technologies to produce large-scale, high-purity, high-density, highly uniform, and fine-grained aluminum-chromium-boron alloy targets is particularly important.

[0004] The main methods for preparing targets are powder metallurgy and smelting. Powder metallurgy is limited by equipment and processes, making it difficult to obtain large-scale targets with high density, high purity, and low oxygen content. Furthermore, the powder preparation process is complex and challenging, increasing the overall target preparation cost. The melting points of chromium and aluminum differ by 1247°C, and the melting points of boron and aluminum differ by 1416°C. During the powder metallurgy preparation process, it is difficult to ensure complete alloying of the three, which in turn affects the performance of the hard coating obtained by sputtering deposition. For example, patent CN110527957A prepares an aluminum-boron alloy block by sintering a mixture of aluminum powder and boron powder, which is then crushed to obtain aluminum-boron alloy powder. Finally, chromium powder is mixed with the prepared aluminum-boron powder and hot isostatically pressed to produce an aluminum-chromium-boron alloy target blank. Patent CN114262872A pre-prepares CrB2 alloy powder to enhance the alloying of Cr and B, and then hot isostatically presses the mixed Cr, Al, and CrB2 alloy powders to produce an AlCrB alloy target blank. Both methods involve the preparation of alloy powder, which inevitably introduces metal and non-metallic impurities due to processing, thus affecting the overall performance and stability of the target material; the hot isostatic pressing temperature in both methods is no higher than 600°C, making it difficult to obtain a dense, fully alloyed aluminum-chromium-boron alloy target material; at the same time, they have the disadvantages of a cumbersome process and a long cycle.

[0005] Melting methods for preparing targets mainly include vacuum induction melting, vacuum consumable melting, and vacuum electron beam melting. The main drawbacks of vacuum induction melting and vacuum consumable melting are large alloy component segregation, which cannot be eliminated through subsequent processing. This is a fatal flaw of these methods, limiting their use in the preparation of high-quality alloy targets. Electron beam melting also suffers from significant aluminum volatilization and burning during the high-power, long-term refining process, making precise control of the composition difficult. This method can also introduce impurities, affecting the stability of the sputtered film. Furthermore, this method struggles to ensure alloy composition uniformity. Therefore, new melting methods are urgently needed to produce high-quality AlCrB ingots with uniform, stable, and controllable chemical compositions. Furthermore, AlCrB alloys contain a large amount of brittle aluminum-chromium intermetallic compounds, which are prone to cracking during deformation. This makes it difficult to heat-process them to refine and homogenize the as-cast structure and eliminate defects such as shrinkage porosity and shrinkage cavities within the AlCrB alloy ingot. This significantly limits the use of melting methods for preparing high-quality AlCrB alloy targets. Currently, there are few literatures on Al-Cr-B targets, and patented technologies are rarely reported, especially the smelting method.

[0006] In summary, the forming and processing of high-quality Al-Cr-B alloy targets are currently difficult forming and processing technology problems that need to be solved urgently, which will affect the development and application of Al-Cr-B alloy targets. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned prior art and provide a method for preparing a large-sized aluminum-chromium-boron alloy target. This method uses chromium powder, boron powder, and aluminum particles as raw materials. The chromium powder and boron powder are first mixed and pressed into a blank. Then, a magnetic levitation melting process with batch feeding and gradient power addition is combined with a semi-solid forging and annealing process. This avoids severe burnout of aluminum, ensures complete alloying of the aluminum-chromium-boron alloy target, and improves its purity and composition uniformity. At the same time, it reduces the difficulty of deformation, allowing the ingot to be smoothly formed, and obtains a large-sized, dense aluminum-chromium-boron alloy target with stable and uniform composition, high purity, fine grains, and uniform crystal orientation. This method solves the problems of poor uniformity and stability of the organizational composition, and easy cracking due to deformation, which exist in the current preparation of large-sized aluminum-chromium-boron alloy targets.

[0008] To solve the above technical problems, the present invention adopts a technical solution: a method for preparing a large-sized aluminum-chromium-boron alloy target, characterized in that the method comprises the following steps:

[0009] Step 1: Pretreatment: Pre-treating the raw materials of chromium powder, boron powder and aluminum particles by baking; the atomic percentages of chromium, boron and aluminum in the raw materials are 40% to 80%, 10% to 50% and 5% to 20% respectively;

[0010] Step 2: Powder mixing and cold isostatic pressing: Under argon protection, the chromium powder and boron powder pretreated in step 1 are mixed, and then cold isostatic pressing is performed to obtain a chromium-boron cold-pressed blank;

[0011] Step 3: Controlled aluminum and gradient magnetic levitation melting: The chromium-boron cold-pressed billet obtained in step 2 and some of the aluminum particles pretreated in step 1 are added to a water-cooled copper crucible in the order of the chromium-boron cold-pressed billet at the bottom and the aluminum particles at the top, and then evacuated to a vacuum degree of 6×10 -3 Pa~4×10 -4 Pa, filled with high-purity argon gas for magnetic levitation melting, during the magnetic levitation melting process, when the chromium-boron cold-pressed billet and part of the pretreated aluminum particles are completely melted, the remaining pretreated aluminum particles are added to the water-cooled copper crucible in batches through a feeder, and after each batch of aluminum particles is melted to be completely melted, the remaining batches of aluminum particles are added in sequence until the aluminum particles are completely added, and then the melting power is increased to continue melting. After the melting is completed, it is slowly cooled to room temperature to obtain an aluminum-chromium-boron alloy ingot with uniform chemical composition;

[0012] Step 4: preparing a semi-solid aluminum-chromium-boron alloy billet: removing the bottom end and the riser portion of the aluminum-chromium-boron alloy ingot obtained in step 3, and cleaning the surface defects to obtain a semi-solid aluminum-chromium-boron alloy billet;

[0013] Step 5, semi-solid forging: The semi-solid aluminum-chromium-boron alloy billet obtained in step 4 is subjected to hot forging by first drawing and then upsetting, with the drawing ratio being 200% to 300% and the upsetting ratio being 40% to 50%, and the drawing and upsetting treatments are repeated twice to obtain an aluminum-chromium-boron alloy semi-finished product;

[0014] Step 6: Vacuum annealing: vacuum annealing the aluminum-chromium-boron alloy semi-finished product obtained in step 5;

[0015] Step 7, subsequent processing: machining, straightening, vacuum annealing and cleaning the aluminum-chromium-boron alloy semi-finished product after vacuum annealing in step 6 to obtain an aluminum-chromium-boron alloy target; the diameter of the aluminum-chromium-boron alloy target is more than 6 inches.

[0016] The vacuum degree during magnetic suspension melting is controlled to be 6×10 -3 Pa~4×10 -4 Pa, by adopting high vacuum degree, is conducive to obtaining aluminum-chromium-boron alloy targets with stable impurity content and low oxygen, thus ensuring the quality of the targets.

[0017] The aforementioned method for preparing a large-sized aluminum-chromium-boron alloy target is characterized in that the aluminum particles in step 1 are 1 cm to 3 cm in size and have a mass purity of 99.99% or greater, and the chromium powder and boron powder each have a particle size of less than 100 mesh and a mass purity of greater than 99%. The use of chromium and boron powders of these sizes facilitates improved mixing, thereby improving the melting uniformity of the chromium-boron cold-pressed billet during subsequent magnetic levitation melting, increasing the alloying layer density of the aluminum-chromium-boron alloy ingot, and simultaneously reducing melting power and time, saving energy, and improving efficiency.

[0018] The aforementioned method for preparing a large-sized aluminum-chromium-boron alloy target is characterized in that the mixing in step 2 is performed using a V-type powder mixer for 2 to 5 hours, the cold isostatic pressing pressure is 200 MPa to 300 MPa, and the holding time is 10 to 20 minutes. By controlling the cold isostatic pressing pressure and holding time, the present invention produces a chromium-boron cold-pressed billet with good strength, which facilitates movement and subsequent magnetic levitation melting.

[0019] The above-mentioned method for preparing a large-size aluminum-chromium-boron alloy target material is characterized in that, during the magnetic levitation smelting process described in step three, the smelting power for completely melting the chromium-boron cold-pressed billet and partially pretreated aluminum particles is 240kW to 320kW, and the smelting time is 5min to 15min. The smelting power after each batch of the remaining pretreated aluminum particles is 100kW to 150kW, and the smelting time is 2min to 5min. The smelting power after the pretreated aluminum particles are completely added is 240kW to 300kW, and the smelting time is 5min to 10min. After the smelting is completed, the power is first rapidly reduced to 50kW within 1s to 2s, and then uniformly reduced from 50kW to 0kW within 1min to 2min.

[0020] The present invention adopts high power to melt the chromium-boron cold-pressed billet and partially pretreated aluminum particles, ensuring the complete melting and complete alloying of chromium and boron. When the remaining pretreated aluminum particles are added in batches, the melting point of the entire molten pool is reduced. At this time, low power is used to ensure the alloying of aluminum with chromium and boron, avoiding the burning of aluminum caused by high power, and improving the overall metallurgical quality and composition stability. Finally, after the pretreated aluminum particles are completely added, the melting power is increased again to improve the magnetic levitation stirring effect, thereby improving the high chemical composition uniformity of the aluminum-chromium-boron alloy ingot. Therefore, the present invention improves the alloying degree and composition uniformity of the aluminum-chromium-boron alloy by adopting a magnetic levitation melting method with batch feeding and gradient power addition, while avoiding the problem of aluminum burning caused by excessive power, thereby improving the metallurgical quality. At the same time, the present invention ensures the large-scale precipitation of high-temperature aluminum-boron phase by controlling the cooling process and speed after magnetic levitation melting, thereby effectively refining the aluminum-chromium phase and the overall grain size, reducing the difficulty of subsequent semi-solid deformation, and being beneficial to improving the overall quality of the aluminum-chromium-boron alloy target; and by controlling the cooling rate, the shrinkage cavity of the ingot is retained at the top rather than the core, further improving the utilization rate of the ingot, which is beneficial to the smooth implementation of the subsequent semi-solid forging process.

[0021] The aforementioned method for preparing a large-sized aluminum-chromium-boron alloy target is characterized by first uniformly coating the surface of the semi-solid aluminum-chromium-boron alloy billet with a glass protective lubricant for high-temperature deformation and air-drying it, then vacuum-encapsulating it with 304 stainless steel, and then heating and holding it in a furnace until it reaches temperature for 20 to 50 minutes; the hot forging temperature is 680°C to 800°C. The present invention ensures smooth semi-solid forging deformation by controlling the heating and holding method, time, and forging temperature of the semi-solid aluminum-chromium-boron alloy billet.

[0022] The aforementioned method for preparing a large-sized aluminum-chromium-boron alloy target is characterized in that the vacuum annealing in step 6 is performed at a temperature of 240°C to 450°C for a time of 1 to 3 hours. The present invention controls the temperature and time of the vacuum annealing to achieve recrystallization and obtain uniform and fine grains.

[0023] The above-mentioned method for preparing a large-sized aluminum-chromium-boron alloy target is characterized in that the metallographic structure of the aluminum-chromium-boron alloy target described in step seven is composed of an aluminum matrix and a uniformly distributed aluminum-chromium phase, the average grain size does not exceed 50 μm, the mass purity of the aluminum-chromium-boron alloy target is above 99.9%, and the oxygen content is less than 180 ppm. Usually, an optical microscope is used to observe the microstructure of the aluminum-chromium-boron alloy target to analyze its phase composition and grain size range, and an inductively coupled plasma emission spectrometer ICP and a carbon-sulfur analyzer are used to analyze the purity and oxygen content of the aluminum-chromium-boron alloy target. The aluminum-chromium-boron alloy target prepared by the present invention has high purity, low oxygen content, and uniform composition and structure, which improves the thickness distribution uniformity of the target used for coating and improves the coating rate and quality.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. The present invention selects chromium powder, boron powder and aluminum particles as raw materials, mixes the chromium powder and boron powder and presses them into a blank, which is conducive to promoting their rapid melting and subsequent alloying with aluminum particles, and realizing stable control of the metallurgical quality of the aluminum-chromium-boron alloy ingot. Then, gradient magnetic levitation melting with gradient power addition is performed by first adding the blank and part of the aluminum particles, and then adding the remaining aluminum particles in batches, thereby avoiding severe burning of aluminum, promoting the alloying process, and improving the overall metallurgical quality and composition uniformity, stability and purity of the aluminum-chromium-boron alloy ingot. Therefore, an aluminum-chromium-boron alloy ingot with high uniformity of composition and low oxygen content can be obtained through one smelting, thereby improving processing efficiency and saving energy.

[0026] 2. The present invention adopts semi-solid forging combined with vacuum annealing process to smoothly form the aluminum-chromium-boron alloy ingot, solving the problems of difficult deformation and easy cracking of the aluminum-chromium-boron alloy ingot, thereby preparing a large-size aluminum-chromium-boron alloy target with uniform and dense structure, fine grains and low oxygen, significantly improving the quality of the aluminum-chromium-boron alloy target; at the same time, semi-solid forming improves the utilization rate and production efficiency of the aluminum-chromium-boron alloy ingot, which is conducive to the efficient and stable preparation of the aluminum-chromium-boron alloy target, and is suitable for the mass production of large-size targets.

[0027] 3. The magnetic levitation melting process of the present invention adopts high vacuum and argon protection, which not only improves the purity of the aluminum-chromium-boron alloy ingot, especially realizes the stable control of the gas element content, but also the argon protection ensures a higher pressure in the melting chamber, effectively reduces the splashing and volatilization of the molten pool, thereby improving the metallurgical quality and facilitating the acquisition of high-quality aluminum-chromium-boron alloy targets with stable performance.

[0028] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the metallographic structure diagram of the aluminum-chromium-boron alloy target prepared in Example 1 of the present invention.

[0030] Figure 2 This is the metallographic structure diagram of the aluminum-chromium-boron alloy target prepared in Comparative Example 1 of the present invention.

[0031] Figure 3 This is a physical picture of the aluminum-chromium-boron alloy target prepared in Example 2 of the present invention.

[0032] Figure 4 This is a physical picture of the aluminum-chromium-boron alloy target prepared in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0033] Example 1

[0034] This embodiment includes the following steps:

[0035] Step 1: Pretreatment: Chromium powder, boron powder, and aluminum particle raw materials are placed in an oven for baking pretreatment; the atomic percentages of chromium, boron, and aluminum in the raw materials are 80%, 10%, and 10%, respectively, and the corresponding mass percentages are 77%, 19%, and 4%, respectively; the aluminum particles are 1 cm to 3 cm in size and have a mass purity of 99.99%. The chromium powder and boron powder both have a particle size of 120 mesh and a mass purity of 99.6%.

[0036] Step 2: Powder mixing and cold isostatic pressing: Under argon protection, the chromium powder and boron powder pretreated in step 1 are mixed in a V-type powder mixer for 3 hours to obtain a chromium-boron mixed powder. The chromium-boron mixed powder is placed in a sheath mold and vibrated, and then pressed in a cold isostatic press at a pressure of 200 MPa and a holding time of 20 minutes to obtain a chromium-boron cold-pressed blank.

[0037] Step 3: Controlled aluminum and gradient magnetic levitation melting: The chromium-boron cold-pressed billet obtained in step 2 and the aluminum particles accounting for 15% of the total mass of the pre-treated aluminum particles in step 1 are added into a water-cooled copper crucible in the order of the chromium-boron cold-pressed billet at the bottom and the aluminum particles at the top, and then evacuated to a vacuum degree of 6×10 -3Pa, filled with high-purity argon protection for smelting, and stabilized the smelting power at 240kW, the smelting time was 10min, after the chromium-boron cold-pressed billet and the aluminum particles were completely melted, the remaining pretreated aluminum particles were added to the water-cooled copper crucible in 5 batches through a feeder for smelting, each time adding aluminum particles accounting for 15% to 25% of the total mass of the pretreated aluminum particle raw materials, and the smelting power after each batch of aluminum particles was added was 150kW, and the smelting time was 2min. After each batch of aluminum particles was melted to be completely melted, the remaining batches of aluminum particles were added in sequence until the pretreated aluminum particles were completely added, the smelting power was increased to 300kW, and the power was maintained for 10min. After the smelting was completed, the power was first reduced to 50kW at a rate of not less than 120kW / s, and then uniformly reduced from 50kW to 0kW within 2min, and cooled to room temperature to obtain an aluminum-chromium-boron alloy ingot with uniform chemical composition;

[0038] Step 4: Preparation of a semi-solid aluminum-chromium-boron alloy billet: The bottom end and riser portion of the aluminum-chromium-boron alloy ingot obtained in Step 3 are removed, and the unevenness and defects on the surface of the ingot are cleaned using a lathe to obtain a semi-solid aluminum-chromium-boron alloy billet with a diameter of 7 inches.

[0039] Step 5, semi-solid forging: The surface of the semi-solid aluminum-chromium-boron alloy blank obtained in step 4 is evenly coated with a glass protective lubricant for high-temperature deformation and air-dried, then vacuum-encased with 304 stainless steel, heated to 680° C. and held for 50 minutes by placing it in a furnace upon reaching the desired temperature, first stretched to 200% of the original length, then upset to 40% of the stretched length, and the stretching and upset processes are repeated twice to obtain an aluminum-chromium-boron alloy semi-finished product;

[0040] Step 6: Vacuum annealing: The aluminum-chromium-boron alloy semi-finished product obtained in step 5 is subjected to vacuum annealing at a temperature of 240° C. for 3 hours;

[0041] Step 7: Subsequent processing: The aluminum-chromium-boron alloy semi-finished product after vacuum annealing in step 6 is machined, straightened, vacuum annealed, and cleaned to obtain a circular aluminum-chromium-boron alloy target with a diameter of 6 inches.

[0042] Figure 1 The metallographic structure of the aluminum-chromium-boron alloy target prepared in this embodiment is shown in FIG. Figure 1 It can be seen that the metallographic structure of the aluminum-chromium-boron alloy target material consists of an aluminum matrix and a uniformly distributed aluminum-chromium intermetallic compound phase. The structure is fine, uniform and dense, and is suitable as a high-quality hard coating target material.

[0043] Comparative Example 1

[0044] This comparative example comprises the following steps:

[0045] Step 1: Pretreatment: Chromium powder, boron powder, and aluminum particle raw materials are placed in an oven for baking pretreatment; the atomic percentages of chromium, boron, and aluminum in the raw materials are 80%, 10%, and 10%, respectively, and the corresponding mass percentages are 77%, 19%, and 4%, respectively; the aluminum particles are 1 cm to 3 cm in size and have a mass purity of 99.99%. The chromium powder and boron powder both have a particle size of 120 mesh and a mass purity of 99.6%.

[0046] Step 2: Powder mixing and cold isostatic pressing: Under argon protection, the chromium powder and boron powder pretreated in step 1 are mixed in a V-type powder mixer for 3 hours to obtain a chromium-boron mixed powder. The chromium-boron mixed powder is placed in a sheath mold and vibrated, and then pressed in a cold isostatic press at a pressure of 200 MPa and a holding time of 20 minutes to obtain a chromium-boron cold-pressed blank.

[0047] Step 3: Magnetic levitation melting: Add the chromium-boron cold-pressed billet obtained in step 2 and all the pre-treated aluminum particles in step 1 into a water-cooled copper crucible in the order of chromium-boron cold-pressed billet at the bottom and aluminum particles at the top, and then evacuate to a vacuum degree of 6×10 -3 Pa, filled with high-purity argon protection for smelting, and stabilized the smelting power at 240 kW for 22 min. After the smelting was completed, the power was first reduced to 50 kW at a rate of not less than 120 kW / s, and then uniformly reduced from 50 kW to 0 kW within 2 min. The alloy was cooled to room temperature to obtain an aluminum-chromium-boron alloy ingot with uniform chemical composition.

[0048] Step 4: Preparation of a semi-solid aluminum-chromium-boron alloy billet: The bottom end and riser portion of the aluminum-chromium-boron alloy ingot obtained in Step 3 are removed, and the unevenness and defects on the surface of the ingot are cleaned using a lathe to obtain a semi-solid aluminum-chromium-boron alloy billet with a diameter of 7.2 inches.

[0049] Step 5, semi-solid forging: The surface of the semi-solid aluminum-chromium-boron alloy blank obtained in step 4 is evenly coated with a glass protective lubricant for high-temperature deformation and air-dried, then vacuum-encased with 304 stainless steel, heated to 680° C. and held for 50 minutes by placing it in a furnace upon reaching the desired temperature, first stretched to 200% of the original length, then upset to 40% of the stretched length, and the stretching and upset processes are repeated twice to obtain an aluminum-chromium-boron alloy semi-finished product;

[0050] Step 6: Vacuum annealing: The aluminum-chromium-boron alloy semi-finished product obtained in step 5 is subjected to vacuum annealing at a temperature of 240° C. for 3 hours;

[0051] Step 7: Subsequent processing: The aluminum-chromium-boron alloy semi-finished product after vacuum annealing in step 6 is machined, straightened, vacuum annealed, and cleaned to obtain a circular aluminum-chromium-boron alloy target with a diameter of 6 inches.

[0052] Figure 2 The metallographic structure of the aluminum-chromium-boron alloy target prepared in this comparative example is as follows: Figure 2 It can be seen that the metallographic structure of the aluminum-chromium-boron alloy target is composed of an aluminum matrix, an aluminum-chromium intermetallic compound phase and elemental chromium, and the structure is coarse and has poor uniformity.

[0053] contrast Figure 1 and Figure 2 It was found that the aluminum chromium boron target material prepared by the present invention using a one-time magnetic levitation melting method with batch addition of aluminum particles and gradient power addition has complete alloying, high degree of organizational uniformity, and small grain size, which is conducive to the preparation of a hard coating with excellent performance.

[0054] Example 2

[0055] This embodiment includes the following steps:

[0056] Step 1: Pretreatment: Chromium powder, boron powder, and aluminum particle raw materials are placed in an oven for baking pretreatment. The atomic percentages of chromium, boron, and aluminum in the raw materials are 60%, 20%, and 20%, respectively, and the corresponding mass percentages are 56.3%, 36.1%, and 7.6%, respectively. The aluminum particles have a size of 1 cm to 3 cm and a mass purity of 99.994%. The chromium powder and boron powder both have a particle size of 120 mesh and a mass purity of 99.7%.

[0057] Step 2: Powder mixing and cold isostatic pressing: Under argon protection, the chromium powder and boron powder pretreated in step 1 are mixed in a V-type powder mixer for 5 hours to obtain a chromium-boron mixed powder. The chromium-boron mixed powder is placed in a sheath mold and vibrated to compact it. Then, a cold isostatic press is used to press the powder at a pressure of 300 MPa and a holding time of 10 minutes to obtain a chromium-boron cold-pressed blank.

[0058] Step 3: Controlled aluminum and gradient magnetic levitation melting: The chromium-boron cold-pressed billet obtained in step 2 and the aluminum particles accounting for 25% of the total mass of the pre-treated aluminum particles in step 1 are added into a water-cooled copper crucible in the order of the chromium-boron cold-pressed billet at the bottom and the aluminum particles at the top, and then evacuated to a vacuum degree of 9×10 -3Pa, filled with high-purity argon protection for smelting, and stabilized the smelting power at 320kW, the smelting time was 5min, after the chromium-boron cold-pressed billet and the aluminum particles were completely melted, the remaining pretreated aluminum particles were added to the water-cooled copper crucible in 4 batches through a feeder for smelting, each time adding aluminum particles accounting for 20% to 30% of the total mass of the pretreated aluminum particle raw materials, and the smelting power after each batch of aluminum particles was added was 100kW, and the smelting time was 5min, after each batch of aluminum particles was melted to be completely melted, the remaining batches of aluminum particles were added in sequence, until the pretreated aluminum particles were completely added, the smelting power was increased to 240kW, and the power was maintained for 5min. After the smelting was completed, the power was first reduced to 50kW at a rate of not less than 80kW / s, and then uniformly reduced from 50kW to 0kW within 1min, and cooled to room temperature to obtain an aluminum-chromium-boron alloy ingot with uniform chemical composition;

[0059] Step 4: Preparation of a semi-solid aluminum-chromium-boron alloy billet: The bottom end and riser portion of the aluminum-chromium-boron alloy ingot obtained in Step 3 are removed, and the unevenness and defects on the surface of the ingot are cleaned using a lathe to obtain a semi-solid aluminum-chromium-boron alloy billet with a diameter of 8.5 inches.

[0060] Step 5, semi-solid forging: The surface of the semi-solid aluminum-chromium-boron alloy blank obtained in step 4 is evenly coated with a glass protective lubricant for high-temperature deformation and air-dried, then vacuum-encased with 304 stainless steel, heated to 800°C and held for 20 minutes in a furnace, first drawn to 300% of the original length, then upset to 50% of the drawn length, and the drawing and upset processes are repeated twice to obtain an aluminum-chromium-boron alloy semi-finished product;

[0061] Step 6: Vacuum annealing: vacuum anneal the aluminum-chromium-boron alloy semi-finished product obtained in step 5 at a temperature of 450° C. for 1 hour.

[0062] Step 7: Subsequent processing: The aluminum-chromium-boron alloy semi-finished product after vacuum annealing in step 6 is machined, straightened, vacuum annealed, and cleaned to obtain a circular aluminum-chromium-boron alloy target with a diameter of 7 inches.

[0063] Figure 3 This is a physical picture of the aluminum-chromium-boron alloy target prepared in this embodiment. Figure 3 It can be seen that the macroscopic structure uniformity of the aluminum-chromium-boron alloy target is good.

[0064] After testing, it was found that the metallographic structure of the aluminum-chromium-boron alloy target prepared in this embodiment consists of an aluminum matrix and a uniformly distributed aluminum-chromium intermetallic compound phase. The structure is fine, uniform and dense, and is suitable as a high-quality hard coating target.

[0065] Comparative Example 2

[0066] This comparative example comprises the following steps:

[0067] Step 1: Pretreatment: Chromium powder, boron powder, and aluminum particle raw materials are placed in an oven for baking pretreatment. The atomic percentages of chromium, boron, and aluminum in the raw materials are 60%, 20%, and 20%, respectively, and the corresponding mass percentages are 56.3%, 36.1%, and 7.6%, respectively. The aluminum particles have a size of 1 cm to 3 cm and a mass purity of 99.994%. The chromium powder and boron powder both have a particle size of 120 mesh and a mass purity of 99.7%.

[0068] Step 2: Powder mixing and cold isostatic pressing: Under argon protection, the chromium powder and boron powder pretreated in step 1 are mixed in a V-type powder mixer for 5 hours to obtain a chromium-boron mixed powder. The chromium-boron mixed powder is placed in a sheath mold and vibrated to compact it. Then, a cold isostatic press is used to press the powder at a pressure of 300 MPa and a holding time of 10 minutes to obtain a chromium-boron cold-pressed blank.

[0069] Step 3: Primary magnetic levitation melting: the chromium-boron cold-pressed blank obtained in step 2 and the aluminum particles accounting for 25% of the total mass of the pre-treated aluminum particles in step 1 are added into a water-cooled copper crucible in the order of the chromium-boron cold-pressed blank at the bottom and the aluminum particles at the top, and then evacuated to a vacuum degree of 9×10 -3 Pa, filled with high-purity argon protection for smelting, and stabilized the smelting power at 320 kW, the smelting time being 5 minutes, after the chromium-boron cold-pressed billet and the aluminum particles are completely melted, the remaining pretreated aluminum particles are added to the water-cooled copper crucible in 4 batches through a feeder for smelting, each time adding aluminum particles accounting for 20% to 30% of the total mass of the pretreated aluminum particle raw materials, and the smelting power after each batch of aluminum particles is added is 100 kW, the smelting time is 5 minutes, after each batch of aluminum particles is melted to be completely melted, the remaining batches of aluminum particles are added in sequence until the pretreated aluminum particles are completely added, and cooled to room temperature to obtain a primary ingot;

[0070] Step 4: Secondary magnetic levitation melting: Turn the primary ingot obtained in step 3 over to the bottom upward and place it in a water-cooled copper crucible, then evacuate to a vacuum degree of 9×10 -3 Pa, filled with high-purity argon protection for melting, and stabilized the melting power at 320 kW for 5 minutes. After the melting is completed, the power is reduced to 50 kW at a rate of not less than 90 kW / s, and then the average speed is reduced from 50 kW to 0 kW within 1 minute. The alloy is cooled to room temperature to obtain an aluminum-chromium-boron alloy ingot with uniform chemical composition.

[0071] Step 5: Preparation of a semi-solid aluminum-chromium-boron alloy billet: The bottom end and riser portion of the aluminum-chromium-boron alloy ingot obtained in Step 4 are removed, and the unevenness and defects on the surface of the ingot are cleaned using a lathe to obtain a semi-solid aluminum-chromium-boron alloy billet with a diameter of 8.5 inches.

[0072] Step 6, semi-solid forging: The surface of the semi-solid aluminum-chromium-boron alloy blank obtained in step 5 is evenly coated with a glass protective lubricant for high-temperature deformation and air-dried. The blank is then vacuum-encased with 304 stainless steel and heated to 800°C for 20 minutes. The blank is first drawn to 300% of its original length and then upset to 50% of its final length. The drawing and upset processes are repeated twice to obtain an aluminum-chromium-boron alloy semi-finished product.

[0073] Step 7: Vacuum annealing: vacuum anneal the aluminum-chromium-boron alloy semi-finished product obtained in step 6 at a temperature of 450° C. for 1 hour.

[0074] Step 8. Subsequent processing: The aluminum-chromium-boron alloy semi-finished product after vacuum annealing in step 7 is machined, straightened, vacuum annealed and cleaned to obtain a circular aluminum-chromium-boron alloy target with a diameter of 7 inches.

[0075] Figure 4 This is a physical picture of the aluminum-chromium-boron alloy target prepared in this embodiment. Figure 4 It can be seen that the Al-Cr-B alloy target material has serious macroscopic structural segregation.

[0076] contrast Figure 3 and Figure 4 It was found that the present invention adopts a single magnetic levitation melting method with batch addition of aluminum particles and gradient power addition, which realizes the preparation of aluminum-chromium-boron alloy target materials with complete alloying, high degree of structural uniformity and small grain size, which is conducive to the preparation of hard coatings with excellent performance. However, the use of secondary melting is prone to severe macro-segregation, which is mainly related to the structural characteristics of the aluminum-chromium-boron alloy. The solid solubility of chromium in its matrix aluminum is very low, its melting point is low, its magnetic permeability is poor, and it has a large difference from the melting point of the aluminum-chromium phase, which makes the entire ingot prone to severe structural segregation during the secondary melting.

[0077] Example 3

[0078] This embodiment includes the following steps:

[0079] Step 1: Pretreatment: Chromium powder, boron powder, and aluminum particle raw materials are placed in an oven for baking pretreatment; the atomic percentages of chromium, boron, and aluminum in the raw materials are 40%, 50%, and 10%, respectively, and the corresponding mass percentages are 28.5%, 68.6%, and 2.9%, respectively; the aluminum particles are 1 cm to 3 cm in size and have a mass purity of 99.999%. The chromium powder and boron powder both have a particle size of 120 mesh and a mass purity of 99.8%.

[0080] Step 2: Powder mixing and cold isostatic pressing: Under argon protection, the chromium powder and boron powder pretreated in step 1 are mixed in a V-type powder mixer for 2 hours to obtain a chromium-boron mixed powder. The chromium-boron mixed powder is placed in a sheath mold and vibrated to compact it. Then, a cold isostatic press is used to press the powder at a pressure of 260 MPa and a holding time of 15 minutes to obtain a chromium-boron cold-pressed blank.

[0081] Step 3: Controlled aluminum and gradient magnetic levitation melting: The chromium-boron cold-pressed billet obtained in step 2 and the aluminum particles accounting for 40% of the total mass of the pre-treated aluminum particles in step 1 are added into a water-cooled copper crucible in the order of the chromium-boron cold-pressed billet at the bottom and the aluminum particles at the top, and then evacuated to a vacuum degree of 4×10 -4 Pa, filled with high-purity argon protection for smelting, and stabilized the smelting power at 240kW, the smelting time was 15min, after the chromium-boron cold-pressed billet and the aluminum particles were completely melted, the remaining pretreated aluminum particles were added to the water-cooled copper crucible in 3 batches through a feeder for smelting, each time adding aluminum particles accounting for 25% to 35% of the total mass of the pretreated aluminum particle raw materials, and the smelting power after each batch of aluminum particles was added was 150kW, and the smelting time was 2min, after each batch of aluminum particles was melted to be completely melted, the remaining batches of aluminum particles were added in sequence, until the pretreated aluminum particles were completely added, the smelting power was increased to 300kW, and the power was maintained for 10min, and after the smelting was completed, the power was first reduced to 50kW at a rate of not less than 130kW / s, and then uniformly reduced from 50kW to 0kW within 2min, and cooled to room temperature to obtain an aluminum-chromium-boron alloy ingot with uniform chemical composition;

[0082] Step 4: Preparation of a semi-solid aluminum-chromium-boron alloy billet: The bottom end and riser portion of the aluminum-chromium-boron alloy ingot obtained in Step 3 are removed, and the unevenness and defects on the surface of the ingot are cleaned using a lathe to obtain a semi-solid aluminum-chromium-boron alloy billet with a diameter of 6.8 inches.

[0083] Step 5, semi-solid forging: The surface of the semi-solid aluminum-chromium-boron alloy blank obtained in step 4 is evenly coated with a glass protective lubricant for high-temperature deformation and air-dried. The blank is then vacuum-encased with 304 stainless steel and heated to 780° C. for 30 minutes. The blank is first drawn to 240% of its original length and then upset to 48% of its final length. The drawing and upset processes are repeated twice to obtain an aluminum-chromium-boron alloy semi-finished product.

[0084] Step 6: Vacuum annealing: The aluminum-chromium-boron alloy semi-finished product obtained in step 5 is subjected to vacuum annealing at a temperature of 320° C. for 2.2 h.

[0085] Step 7: Subsequent processing: The aluminum-chromium-boron alloy semi-finished product after vacuum annealing in step 6 is machined, straightened, vacuum annealed, and cleaned to obtain a circular aluminum-chromium-boron alloy target with a diameter of 6 inches.

[0086] After testing, it was found that the metallographic structure of the aluminum-chromium-boron alloy target prepared in this embodiment consists of an aluminum matrix and a uniformly distributed aluminum-chromium intermetallic compound phase. The structure is fine, uniform and dense, and is suitable as a high-quality hard coating target.

[0087] Comparative Example 3

[0088] This comparative example comprises the following steps:

[0089] Step 1: Pretreatment: Chromium powder, boron powder, and aluminum particle raw materials are placed in an oven for baking pretreatment; the atomic percentages of chromium, boron, and aluminum in the raw materials are 40%, 50%, and 10%, respectively, and the corresponding mass percentages are 28.5%, 68.6%, and 2.9%, respectively; the aluminum particles are 1 cm to 3 cm in size and have a mass purity of 99.999%. The chromium powder and boron powder both have a particle size of 120 mesh and a mass purity of 99.8%.

[0090] Step 2: Powder mixing and cold isostatic pressing: Under argon protection, the chromium powder and boron powder pretreated in step 1 are mixed in a V-type powder mixer for 2 hours to obtain a chromium-boron mixed powder. The chromium-boron mixed powder is placed in a sheath mold and vibrated to compact it. Then, a cold isostatic press is used to press the powder at a pressure of 260 MPa and a holding time of 15 minutes to obtain a chromium-boron cold-pressed blank.

[0091] Step 3: Controlled aluminum and gradient magnetic levitation melting: The chromium-boron cold-pressed billet obtained in step 2 and the aluminum particles accounting for 40% of the total mass of the pre-treated aluminum particles in step 1 are added into a water-cooled copper crucible in the order of the chromium-boron cold-pressed billet at the bottom and the aluminum particles at the top, and then evacuated to a vacuum degree of 4×10 -4Pa, filled with high-purity argon protection for smelting, and stabilized the smelting power at 240kW, the smelting time was 15min, after the chromium-boron cold-pressed billet and the aluminum particles were completely melted, the remaining pretreated aluminum particles were added to the water-cooled copper crucible in 3 batches through a feeder for smelting, each time adding aluminum particles accounting for 25% to 35% of the total mass of the pretreated aluminum particle raw materials, and the smelting power after each batch of aluminum particles was added was 150kW, and the smelting time was 2min, after each batch of aluminum particles was melted to be completely melted, the remaining batches of aluminum particles were added in sequence, until the pretreated aluminum particles were completely added, the smelting power was increased to 300kW, and the power was maintained for 10min, and after the smelting was completed, the power was first reduced to 50kW at a rate of not less than 130kW / s, and then uniformly reduced from 50kW to 0kW within 2min, and cooled to room temperature to obtain an aluminum-chromium-boron alloy ingot with uniform chemical composition;

[0092] Step 4: Preparing an Al-Cr-B alloy billet for hot deformation: The bottom end and riser portion of the Al-Cr-B alloy ingot obtained in Step 3 are removed, and the unevenness and defects on the surface of the ingot are cleaned using a lathe to obtain an Al-Cr-B alloy billet for hot deformation with a diameter of 6.8 inches.

[0093] Step 5, semi-solid forging: The aluminum-chromium-boron alloy blank for hot deformation obtained in step 4 is heated to 580° C. and held at this temperature for 30 minutes. The blank is first drawn to 240% of its original length and then upset to 48% of its drawn length. The drawing and upset processes are repeated twice to obtain an aluminum-chromium-boron alloy semi-finished product.

[0094] Step 6: Vacuum annealing: The aluminum-chromium-boron alloy semi-finished product obtained in step 5 is subjected to vacuum annealing at a temperature of 320° C. for 2.2 h.

[0095] Step 7: Subsequent processing: The aluminum-chromium-boron alloy semi-finished product after vacuum annealing in step 6 is machined, straightened, vacuum annealed, and cleaned to obtain a circular aluminum-chromium-boron alloy target with a diameter of 6 inches.

[0096] Example 4

[0097] This embodiment includes the following steps:

[0098] Step 1: Pretreatment: Chromium powder, boron powder, and aluminum particle raw materials are placed in an oven for baking pretreatment; the atomic percentages of chromium, boron, and aluminum in the raw materials are 70%, 25%, and 5%, respectively, and the corresponding mass percentages are 58.2%, 40%, and 1.8%, respectively; the aluminum particles have a size of 1 cm to 3 cm and a mass purity of 99.998%. The particle size of the chromium powder and the boron powder are both 200 mesh and the mass purity is 99.3%;

[0099] Step 2: Powder Mixing and Cold Isostatic Pressing: Under argon protection, the chromium powder and boron powder pretreated in step 1 were mixed in a V-type powder mixer for 3.5 hours to obtain a chromium-boron mixed powder. The chromium-boron mixed powder was placed in a sheath mold and vibrated to compact it. Then, a cold isostatic press was used to press the powder at a pressure of 270 MPa and a holding time of 13 minutes to obtain a chromium-boron cold-pressed blank.

[0100] Step 3: Controlled aluminum and gradient magnetic levitation melting: The chromium-boron cold-pressed billet obtained in step 2 and the aluminum particles accounting for 23% of the total mass of the pre-treated aluminum particles in step 1 are added into a water-cooled copper crucible in the order of the chromium-boron cold-pressed billet at the bottom and the aluminum particles at the top, and then evacuated to a vacuum degree of 8×10 -3 Pa, filled with high-purity argon protection for smelting, and stabilized the smelting power at 280kW, the smelting time is 12min, after the chromium-boron cold-pressed billet and the aluminum particles are completely melted, the remaining pretreated aluminum particles are added to the water-cooled copper crucible in 4 batches through a feeder for smelting, each time adding aluminum particles accounting for 20% to 30% of the total mass of the pretreated aluminum particle raw materials, and the smelting power after each batch of aluminum particles is added is 120kW, the smelting time is 3min, after each batch of aluminum particles is melted to be completely melted, the remaining batches of aluminum particles are added in sequence, until the pretreated aluminum particles are completely added, the smelting power is increased to 280kW, the power is maintained for 8min, after the smelting is completed, the power is first reduced to 50kW at a rate of not less than 120kW / s, and then uniformly reduced from 50kW to 0kW within 1min, and cooled to room temperature to obtain an aluminum-chromium-boron alloy ingot with uniform chemical composition;

[0101] Step 4: Preparation of a semi-solid aluminum-chromium-boron alloy billet: The bottom end and riser portion of the aluminum-chromium-boron alloy ingot obtained in Step 3 are removed, and the unevenness and defects on the surface of the ingot are cleaned using a lathe to obtain a semi-solid aluminum-chromium-boron alloy billet with a diameter of 9.1 inches.

[0102] Step 5, semi-solid forging: The surface of the semi-solid aluminum-chromium-boron alloy blank obtained in step 4 is evenly coated with a glass protective lubricant for high-temperature deformation and air-dried. The blank is then vacuum-encased in 304 stainless steel and heated to 720° C. for 35 minutes. The blank is first drawn to 220% of its original length and then upset to 45% of its final drawn length. The drawing and upset processes are repeated twice to obtain an aluminum-chromium-boron alloy semi-finished product.

[0103] Step 6: Vacuum annealing: The aluminum-chromium-boron alloy semi-finished product obtained in step 5 is subjected to vacuum annealing at a temperature of 270° C. for 2 hours;

[0104] Step 7: Subsequent processing: The aluminum-chromium-boron alloy semi-finished product after vacuum annealing in step 6 is machined, straightened, vacuum annealed, and cleaned to obtain a circular aluminum-chromium-boron alloy target with a diameter of 8 inches.

[0105] After testing, it was found that the metallographic structure of the aluminum-chromium-boron alloy target prepared in this embodiment consists of an aluminum matrix and a uniformly distributed aluminum-chromium intermetallic compound phase. The structure is fine, uniform and dense, and is suitable as a high-quality hard coating target.

[0106] Example 5

[0107] This embodiment includes the following steps:

[0108] Step 1: Pretreatment: Chromium powder, boron powder, and aluminum particle raw materials are placed in an oven for baking pretreatment; the atomic percentages of chromium, boron, and aluminum in the raw materials are 55%, 35%, and 10%, respectively, and the corresponding mass percentages are 43.5%, 53.3%, and 3.2%, respectively; the aluminum particles have a size of 1 cm to 3 cm and a mass purity of 99.999%. The particle size of the chromium powder and the boron powder are both 200 mesh and the mass purity is 99.8%;

[0109] Step 2: Powder mixing and cold isostatic pressing: Under argon protection, the chromium powder and boron powder pretreated in step 1 are mixed in a V-type powder mixer for 4.5 hours to obtain a chromium-boron mixed powder. The chromium-boron mixed powder is placed in a sheath mold and vibrated to compact it. Then, a cold isostatic press is used to press the powder at a pressure of 220 MPa and a holding time of 20 minutes to obtain a chromium-boron cold-pressed blank.

[0110] Step 3: Controlled aluminum and gradient magnetic levitation melting: The chromium-boron cold-pressed billet obtained in step 2 and the aluminum particles accounting for 45% of the total mass of the pre-treated aluminum particles in step 1 are added into a water-cooled copper crucible in the order of the chromium-boron cold-pressed billet at the bottom and the aluminum particles at the top, and then evacuated to a vacuum degree of 7×10 -3 Pa, filled with high-purity argon protection for smelting, and stabilized the smelting power at 300kW, the smelting time is 10min, after the chromium-boron cold-pressed billet and the aluminum particles are completely melted, the remaining pretreated aluminum particles are added to the water-cooled copper crucible in 2 batches through a feeder for smelting, each time adding aluminum particles accounting for 40% to 60% of the total mass of the pretreated aluminum particle raw materials, and the smelting power after each batch of aluminum particles is added is 140kW, the smelting time is 2min, after each batch of aluminum particles is melted to be completely melted, the remaining batches of aluminum particles are added in sequence, until the pretreated aluminum particles are completely added, the smelting power is increased to 300kW, the power is maintained for 6min, and after the smelting is completed, the power is reduced to 50kW at a rate of not less than 130kW / s, and then uniformly reduced from 50kW to 0kW within 2min, and cooled to room temperature to obtain an aluminum-chromium-boron alloy ingot with uniform chemical composition;

[0111] Step 4: Preparation of a semi-solid aluminum-chromium-boron alloy billet: The bottom end and riser portion of the aluminum-chromium-boron alloy ingot obtained in Step 3 are removed, and the unevenness and defects on the surface of the ingot are cleaned using a lathe to obtain a semi-solid aluminum-chromium-boron alloy billet with a diameter of 12.8 inches.

[0112] Step 5, semi-solid forging: The surface of the semi-solid aluminum-chromium-boron alloy blank obtained in step 4 is evenly coated with a glass protective lubricant for high-temperature deformation and air-dried. The blank is then vacuum-encased in 304 stainless steel and heated to 700°C for 45 minutes. The blank is first drawn to 260% of its original length and then upset to 43% of its final length. The drawing and upset processes are repeated twice to obtain an aluminum-chromium-boron alloy semi-finished product.

[0113] Step 6: Vacuum annealing: The aluminum-chromium-boron alloy semi-finished product obtained in step 5 is subjected to vacuum annealing at a temperature of 330° C. for 1.5 h.

[0114] Step 7: Subsequent processing: The aluminum-chromium-boron alloy semi-finished product after vacuum annealing in step 6 is machined, straightened, vacuum annealed, and cleaned to obtain a circular aluminum-chromium-boron alloy target with a diameter of 12 inches.

[0115] After testing, it was found that the metallographic structure of the aluminum-chromium-boron alloy target prepared in this embodiment consists of an aluminum matrix and a uniformly distributed aluminum-chromium intermetallic compound phase. The structure is fine, uniform and dense, and is suitable as a high-quality hard coating target.

[0116] The aluminum-chromium-boron alloy round targets prepared in Examples 1 to 5 of the present invention and Comparative Examples 1 to 3 were tested and analyzed for mass purity, oxygen content, and average grain size. The specific results are shown in Table 1 below.

[0117] Table 1

[0118]

[0119]

[0120] In Table 1, “--” means that the test content was not available.

[0121] As can be seen from Table 1, compared with Comparative Example 1 in which the remaining aluminum particles are directly added to the crucible at one time for magnetic levitation melting without adding aluminum particles in batches, the aluminum chromium boron alloy round target materials prepared in Examples 1 to 5 of the present invention have a mass purity of more than 99.9%, an oxygen content of less than 180 ppm, a grain size of no more than 50 μm, and a small deviation in the main component, indicating that the present invention adopts magnetic levitation melting with batch addition of aluminum particles and gradient power addition to obtain an aluminum chromium boron alloy ingot with uniform composition and structure, stable and controllable composition, no internal defects, and low oxygen.

[0122] Compared to the two-step magnetic levitation melting process in Comparative Example 2, the aluminum-chromium-boron alloy round targets prepared in Examples 1-5 of the present invention exhibited uniform microstructure and no macrosegregation. This demonstrates that the present invention utilizes a single magnetic levitation melting process with gradient power addition, ensuring compositional uniformity of the aluminum-chromium-boron alloy ingot while avoiding the severe macrosegregation associated with multiple melting processes. This macrosegregation is primarily related to the microstructural characteristics of the aluminum-chromium-boron alloy and the unique characteristics of magnetic levitation melting, and cannot be addressed by multiple melting processes.

[0123] At the same time, compared with Comparative Example 3 in which the aluminum-chromium-boron alloy billet is directly heated and forged at a high temperature of 580°C, Examples 1 to 5 of the present invention all adopt a highly efficient semi-solid thixotropic forging technology, and during semi-solid forging, a high-temperature deformation lubricant is applied and a sheathing treatment is adopted to keep warm, reduce friction and avoid oxidation, effectively promote the smooth progress of semi-solid deformation, solve the problem of difficulty in deforming the aluminum-chromium-boron alloy, ensure the smooth progress of the hot forging process, thereby obtaining a large-sized, uniformly dense aluminum-chromium-boron alloy target, and avoid multiple furnace heating during deformation, thereby achieving a large single-time downward pressure, reducing forging time, and improving forging efficiency. It is suitable for preparing large-sized, fine-grained, uniformly dense aluminum-chromium-boron alloy targets.

[0124] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the essence of the invention technology shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a large-size aluminum-chromium-boron alloy target, characterized in that: The method comprises the following steps: Step 1: Pretreatment: Pre-treating the raw materials of chromium powder, boron powder and aluminum particles by baking; the atomic percentages of chromium, boron and aluminum in the raw materials are 40% to 80%, 10% to 50% and 5% to 20% respectively; Step 2: Powder mixing and cold isostatic pressing: Under argon protection, the chromium powder and boron powder pretreated in step 1 are mixed, and then cold isostatic pressing is performed to obtain a chromium-boron cold-pressed blank; Step 3: Controlled aluminum and gradient magnetic levitation melting: The chromium-boron cold-pressed billet obtained in step 2 and some of the aluminum particles pretreated in step 1 are added to a water-cooled copper crucible in the order of the chromium-boron cold-pressed billet at the bottom and the aluminum particles at the top, and then evacuated to a vacuum degree of 6×10 -3 Pa~4×10 -4 Pa, filled with high-purity argon gas for magnetic levitation melting, during the magnetic levitation melting process, when the chromium-boron cold-pressed billet and part of the pretreated aluminum particles are completely melted, the remaining pretreated aluminum particles are added to the water-cooled copper crucible in batches through a feeder, and after each batch of aluminum particles is melted to be completely melted, the remaining batches of aluminum particles are added in sequence until the aluminum particles are completely added, and then the melting power is increased to continue melting, and after the melting is completed, it is slowly cooled to room temperature to obtain an aluminum-chromium-boron alloy ingot with uniform chemical composition; during the magnetic levitation melting process, the chromium-boron cold-pressed billet and part of the pretreated aluminum particles are completely melted. The smelting power for complete melting of the particles is 240kW~320kW, and the smelting time is 5min~15min. The smelting power for each batch of remaining pretreated aluminum particles added is 100kW~150kW, and the smelting time is 2min~5min. The smelting power after all pretreated aluminum particles are added is 240kW~300kW, and the smelting time is 5min~10min. After the smelting is completed, the power is first rapidly reduced to 50kW within 1s~2s, and then uniformly reduced from 50kW to 0kW within 1min~2min. Step 4: preparing a semi-solid aluminum-chromium-boron alloy billet: removing the bottom end and the riser portion of the aluminum-chromium-boron alloy ingot obtained in step 3, and cleaning the surface defects to obtain a semi-solid aluminum-chromium-boron alloy billet; Step 5, semi-solid forging: The semi-solid aluminum-chromium-boron alloy billet obtained in step 4 is subjected to hot forging by first drawing and then upsetting, with the drawing ratio being 200% to 300% and the upsetting ratio being 40% to 50%, and the drawing and upsetting processes are repeated twice to obtain an aluminum-chromium-boron alloy semi-finished product; Step 6: Vacuum annealing: vacuum annealing the aluminum-chromium-boron alloy semi-finished product obtained in step 5; Step 7, subsequent processing: machining, straightening, vacuum annealing and cleaning the aluminum-chromium-boron alloy semi-finished product after vacuum annealing in step 6 to obtain an aluminum-chromium-boron alloy target; the diameter of the aluminum-chromium-boron alloy target is more than 6 inches.

2. The method for preparing a large-size aluminum-chromium-boron alloy target according to claim 1, characterized in that: The size of the aluminum particles in step 1 is 1 cm to 3 cm, and the mass purity is above 99.99%. The particle size of the chromium powder and the boron powder are both less than 100 mesh, and the mass purity is both greater than 99%.

3. The method for preparing a large-size aluminum-chromium-boron alloy target according to claim 1, characterized in that: The mixing in step 2 is performed using a V-type powder mixer, and the mixing time is 2h~5h. The pressure of the cold isostatic pressing is 200MPa~300MPa, and the holding time is 10min~20min.

4. The method for preparing a large-size aluminum-chromium-boron alloy target according to claim 1, characterized in that: In step 5, a glass protective lubricant for high-temperature deformation is evenly coated on the surface of the semi-solid aluminum-chromium-boron alloy blank and air-dried. Then, 304 stainless steel is used for vacuum encapsulation. Then, the blank is heated and kept warm for 20 to 50 minutes by heating it to the temperature in a furnace. The forging temperature of the hot forging is 680 to 800°C.

5. The method for preparing a large-size aluminum-chromium-boron alloy target according to claim 1, characterized in that: The vacuum annealing temperature in step six is ​​240° C. to 450° C., and the time is 1 h to 3 h.

6. The method for preparing a large-size aluminum-chromium-boron alloy target according to claim 1, characterized in that: The metallographic structure of the aluminum-chromium-boron alloy target described in step seven consists of an aluminum matrix and a uniformly distributed aluminum-chromium phase, with an average grain size not exceeding 50 μm. The mass purity of the aluminum-chromium-boron alloy target is above 99.9%, and the oxygen content is lower than 180 ppm.

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