Preparation method of large-size aluminum-chromium-boron alloy target material

Abstract

The invention discloses a preparation method of a large-size aluminum-chromium-boron alloy target material. The method comprises the following steps: 1, pretreating chromium powder, boron powder and aluminum particle raw materials; 2, mixing the chromium powder and the boron powder, and performing cold isostatic pressing to obtain a chromium-boron cold-pressed blank; 3, preparing an aluminum-chromium-boron alloy ingot by adopting an aluminum control and gradient magnetic suspension primary smelting method; 4, preparing a semi-solid blank; 5, carrying out semi-solid forging forming; 6, vacuum annealing; and 7, carrying out subsequent machining, straightening, vacuum annealing and cleaning treatment to obtain the aluminum-chromium-boron alloy target material. According to the method, aluminum control and gradient magnetic suspension primary smelting are adopted, the cast ingot with uniform, stable and controllable components and no internal defect is obtained, the low-oxygen aluminum-chromium-boron alloy target material with the uniform and fine structure is obtained by combining the semi-solid forging and annealing treatment process, the utilization rate and the production efficiency of the cast ingot are improved, and the method is suitable for batch production of the large-size aluminum-chromium-boron target material.

Description

Technical Field

[0001] The invention belongs to the technical field of high-performance material forming and processing, and specifically 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, China's bridges, China's high-speed rail and China's nuclear power, in order to meet the rapid development of modern industrial technology, higher requirements are put forward for new materials and mechanical processing methods. Correspondingly, more stringent requirements are also put forward for machining tools to achieve high-precision, high-efficiency, green and low-cost machining needs for ultra-high strength and ultra-high hardness parts.

[0003] At present, the method of coating a hard coating on the surface of high-strength and high-toughness cemented carbide is the most effective method to obtain stable and durable cutting tools. Since the 1960s, hard coatings have experienced a development from binary TiN to ternary TiAlN and even quaternary. Gradually, simple binary coatings TiN and CrN can no longer meet modern processing requirements. Studies have shown that by adding Al elements to the above binary coatings, the AlTiN and AlCrN coatings prepared have better high-temperature oxidation resistance, wear resistance, corrosion resistance and low friction coefficient. A large number of studies and industrial applications have found that the oxidation resistance of AlCrN coating is better than that of AlTiN coating, and the oxidation resistance temperature can reach 900℃, making it a widely used hard coating. When B element is added to AlCrN coating, Al-Cr-BN nanocomposite structure is formed, which contains Al-Cr-(B)-N crystal phase and amorphous BNx phase, which significantly improves the hardness, wear resistance and bonding strength of the film layer with the substrate, reduces the residual stress of the film layer, and is particularly suitable for high-speed dry machining. At present, the most mainstream method for preparing hard coatings is physical vapor deposition (PVD), which makes the quality of the target material directly determine the stability and performance of the hard coating film. In recent years, in order to meet the development needs of modern industrial technology and new quality productivity, the target material has been continuously developed in the direction of large size, high purity, high sputtering rate, etc., which further increases the difficulty of precise control of target material composition, composition uniformity, organizational uniformity and low defect rate. Therefore, it is particularly important to develop new technologies to prepare large-size, high-purity, high-density, high-uniformity and fine-grained aluminum-chromium-boron alloy targets.

[0004] The main preparation methods of the target material are powder metallurgy and smelting. Powder metallurgy is limited by equipment and process, and it is difficult to obtain large-sized targets with high density, high purity and low oxygen. At the same time, the preparation process of the powder is complicated and difficult, which increases the preparation cost of the entire target material. The melting points of chromium and aluminum differ by 1247°C, and the melting points of boron and aluminum differ by 1416°C. In the preparation process using powder metallurgy, it is difficult to ensure that the three are completely alloyed, which in turn affects the performance of the hard coating obtained by sputtering deposition. For example, patent CN110527957A obtains an aluminum-boron alloy block by sintering aluminum powder and boron powder, and then crushes it to obtain aluminum-boron alloy powder, and finally mixes chromium powder with the prepared aluminum-boron powder and hot isostatically presses to prepare an aluminum-chromium-boron alloy target blank. Patent CN114262872A uses pre-prepared CrB2 alloy powder to improve the alloying of Cr and B, and then prepares an AlCrB alloy target blank by hot isostatic pressing of mixed Cr, Al powder and CrB2 alloy powder. Both methods involve the preparation of alloy powders, which inevitably introduce metal and non-metal impurities due to processing, thus affecting the overall performance and stability of the target material; the hot isostatic pressing temperature in both methods is not higher than 600°C, making it difficult to obtain a dense, fully alloyed aluminum-chromium-boron alloy target material; at the same time, the process is cumbersome and the cycle is long.

[0005] The methods for preparing targets by smelting mainly include vacuum induction melting, vacuum consumable melting and vacuum electron beam melting. The main disadvantages of vacuum induction melting and vacuum consumable melting are large alloy component segregation, which cannot be eliminated by subsequent treatment, and are also fatal deficiencies of this method, which limits its use in the preparation of high-quality alloy targets; the main disadvantage of electron beam melting is that during the high-power and long-term refining process, the volatilization and burning of aluminum is relatively serious, and it is difficult to accurately control its composition. At the same time, impurities can be introduced, affecting the stability of the sputtered film; at the same time, this method is also difficult to ensure the uniformity of the alloy composition. Therefore, it is urgent to develop a new smelting method to obtain high-quality AlCrB ingots with uniform, stable and controllable chemical composition. At the same time, AlCrB alloy contains a large amount of brittle aluminum-chromium intermetallic compounds, which are very easy to crack during deformation. It is difficult to perform hot processing on it to achieve the refinement and homogenization of the cast structure and eliminate a large number of shrinkage and shrinkage defects such as shrinkage inside the aluminum-chromium-boron alloy ingot, which greatly limits the use of smelting to prepare high-quality AlCrB alloy targets. Currently, there are few literatures on aluminum-chromium-boron 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 urgent technical problems that need to be solved, 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 provide a method for preparing a large-sized aluminum-chromium-boron alloy target in view of the deficiencies of the above-mentioned prior art. The method uses chromium powder, boron powder and aluminum particles as raw materials, first mixes chromium powder and boron powder and presses them into a blank, and then adopts batch feeding and gradient power addition magnetic suspension melting combined with semi-solid forging and annealing process to avoid severe burning of aluminum, ensure the complete alloying of the aluminum-chromium-boron alloy target and improve its purity and composition uniformity, and reduce the deformation difficulty at the same time, so that the ingot is smoothly formed, and a large-sized dense aluminum-chromium-boron alloy target with stable and uniform composition, high purity, fine grains and uniform crystal orientation is obtained, which solves the problems of poor uniformity and stability of organizational composition and easy cracking in the current preparation of large-sized aluminum-chromium-boron alloy targets.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a large-size 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 the protection of argon, the chromium powder and the 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 suspension melting: The chromium-boron cold-pressed billet obtained in step 2 and part of the aluminum particles pretreated 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 -3 Pa~4×10 -4 Pa, high-purity argon is filled for magnetic suspension melting, during the magnetic suspension 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;

[0012] Step 4: Preparation of semi-solid aluminum-chromium-boron alloy billet: cutting off the bottom end and 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 blank obtained in step 4 is subjected to hot forging by first drawing and then upsetting, and the drawing ratio is 200% to 300%, and the upsetting ratio is 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 above-mentioned method for preparing a large-sized aluminum-chromium-boron alloy target is 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%, and the particle size of the chromium powder and the boron powder are both less than 100 mesh, and the mass purity is greater than 99%. The present invention uses chromium powder and boron powder of the above-mentioned size, which is conducive to improving the mixing degree of the two, and then is conducive to improving the melting uniformity of the chromium-boron cold-pressed blank during subsequent magnetic suspension melting, improving the alloying layer degree of the aluminum-chromium-boron alloy ingot, and reducing the melting power and time, saving energy and improving efficiency.

[0018] The above-mentioned method for preparing a large-size aluminum-chromium-boron alloy target is characterized in that the mixing in step 2 is carried out by a V-type powder mixer, and the mixing time is 2h to 5h, the pressure of the cold isostatic pressing is 200MPa to 300MPa, and the holding time is 10min to 20min. The present invention obtains a chromium-boron cold-pressed blank with good strength by controlling the pressure and holding time of the cold isostatic pressing, which is conducive to movement and subsequent magnetic suspension smelting.

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

[0020] The present invention adopts high power to melt the chromium-boron cold-pressed billet and part of the pretreated aluminum particles, thereby 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 overall molten pool is reduced. At this time, low power is adopted to ensure the alloying of aluminum with chromium and boron, avoid the burning of aluminum caused by high power, and improve the overall metallurgical quality and component stability. Finally, after the pretreated aluminum particles are completely added, the melting power is increased again to improve the magnetic suspension 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 component uniformity of the aluminum-chromium-boron alloy by adopting a magnetic suspension melting method of 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 suspension smelting, 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 above-mentioned method for preparing a large-size aluminum-chromium-boron alloy target is 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, and then 304 stainless steel is used for vacuum encapsulation, and then the temperature is brought to the furnace and heated for 20 minutes to 50 minutes; the forging temperature of the hot forging is 680°C to 800°C. The present invention controls the heating and insulation method, time and forging temperature of the semi-solid aluminum-chromium-boron alloy blank to ensure the smooth progress of semi-solid forging deformation.

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

[0023] The above-mentioned method for preparing a large-size 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 50μm, the mass purity of the aluminum-chromium-boron alloy target is above 99.9%, and the oxygen content is lower than 180ppm. 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 uniformity of its thickness distribution 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 chromium powder and boron powder and presses them into blanks, which is conducive to promoting their rapid melting and subsequent alloying with aluminum particles, and realizing stable control of the metallurgical quality of aluminum-chromium-boron alloy ingots. Then, the blanks and part of the aluminum particles are first added, and the remaining aluminum particles are added in batches to perform gradient magnetic suspension melting with gradient power addition, which avoids severe burning of aluminum, promotes the alloying process, and improves the overall metallurgical quality and composition uniformity, stability and purity of the aluminum-chromium-boron alloy ingots. Therefore, an aluminum-chromium-boron alloy ingot with high uniform 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, which solves 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, and 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 smelting 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 protection of argon ensures a higher pressure in the smelting chamber, effectively reduces the splashing and volatilization of the molten pool, thereby improving the metallurgical quality, which is conducive to obtaining 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: placing chromium powder, boron powder and aluminum particle raw materials 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 size of the aluminum particles is 1cm to 3cm, and the mass purity is 99.99%, and the particle size of the chromium powder and the boron powder are both 120 mesh, and the mass purity is 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 for 3 hours using a V-type powder mixer to obtain a chromium-boron mixed powder, the chromium-boron mixed powder is put into a sleeve mold and vibrated, and then pressed by 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 suspension 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 particle raw material 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, high-purity argon gas protection is filled for smelting, and the smelting power is stabilized at 240kW, 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 5 batches through a feeder for smelting, and each time 15% to 25% of the total mass of the pretreated aluminum particle raw material is added. The smelting power of each batch of aluminum particles after addition is 150kW, and 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, and the smelting power is increased to 300kW, and the power is maintained for 10min. 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 2min, and cooled to room temperature to obtain an aluminum-chromium-boron alloy ingot with uniform chemical composition;

[0038] Step 4: Preparation of semi-solid aluminum-chromium-boron alloy billet: Cut off the bottom end and riser portion of the aluminum-chromium-boron alloy ingot obtained in step 3, and clean the uneven parts and defects on the surface of the ingot with 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 uniformly coated with a glass protective lubricant for high-temperature deformation and air-dried, and then vacuum-encapsulated with 304 stainless steel, heated to 680° C. and kept warm for 50 minutes by entering the furnace at a temperature, first stretched to 200% of the original length, and then upset to 40% of the length after stretching, and the stretching and upsetting treatments are repeated twice to obtain an aluminum-chromium-boron alloy semi-finished product;

[0040] Step 6: vacuum annealing: vacuum annealing the aluminum-chromium-boron alloy semi-finished product obtained in step 5 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 diagram 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: placing chromium powder, boron powder and aluminum particle raw materials 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 size of the aluminum particles is 1cm to 3cm, and the mass purity is 99.99%, and the particle size of the chromium powder and the boron powder are both 120 mesh, and the mass purity is 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 for 3 hours using a V-type powder mixer to obtain a chromium-boron mixed powder, the chromium-boron mixed powder is put into a sleeve mold and vibrated, and then pressed by 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 suspension smelting: 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, high-purity argon gas was filled for protection for smelting, and the smelting power was stabilized at 240 kW, the smelting time was 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, and cooled to room temperature to obtain an aluminum-chromium-boron alloy ingot with uniform chemical composition;

[0048] Step 4: Preparation of semi-solid aluminum-chromium-boron alloy billet: Cut off the bottom end and riser portion of the aluminum-chromium-boron alloy ingot obtained in step 3, and clean the uneven parts and defects on the surface of the ingot by 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 uniformly coated with a glass protective lubricant for high-temperature deformation and air-dried, and then vacuum-encapsulated with 304 stainless steel, heated to 680° C. and kept warm for 50 minutes by entering the furnace at a temperature, first stretched to 200% of the original length, and then upset to 40% of the length after stretching, and the stretching and upsetting treatments are repeated twice to obtain an aluminum-chromium-boron alloy semi-finished product;

[0050] Step 6: vacuum annealing: vacuum annealing the aluminum-chromium-boron alloy semi-finished product obtained in step 5 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, which adopts 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, and 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: placing chromium powder, boron powder and aluminum particle raw materials 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 size of the aluminum particles is 1cm to 3cm, and the mass purity is 99.994%, and the particle size of the chromium powder and the boron powder are both 120 mesh, and the mass purity is both 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 for 5 hours using a V-type powder mixer to obtain a chromium-boron mixed powder, the chromium-boron mixed powder is loaded into a sleeve mold and vibrated, and then pressed by a cold isostatic press 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 suspension 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 particle raw material 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, high-purity argon gas protection is filled for smelting, and the smelting power is stabilized at 320kW, the smelting time is 5min, 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, and each time 20% to 30% of the total mass of the pretreated aluminum particle raw material is added. The smelting power after each batch of aluminum particles is 100kW, and the smelting time is 5min. 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 240kW, and the power is maintained for 5min. After the smelting is completed, the power is 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 semi-solid aluminum-chromium-boron alloy billet: Cut off the bottom end and riser portion of the aluminum-chromium-boron alloy ingot obtained in step 3, and clean the uneven parts and defects on the surface of the ingot by 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 uniformly coated with a glass protective lubricant for high-temperature deformation and air-dried, and then vacuum-encapsulated with 304 stainless steel, heated to 800° C. and kept warm for 20 minutes by entering the furnace at a temperature, first stretched to 300% of the original length, and then upset to 50% of the length after stretching, and the stretching and upsetting treatments are repeated twice to obtain an aluminum-chromium-boron alloy semi-finished product;

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

[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 is 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, and 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: placing chromium powder, boron powder and aluminum particle raw materials 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 size of the aluminum particles is 1cm to 3cm, and the mass purity is 99.994%, and the particle size of the chromium powder and the boron powder are both 120 mesh, and the mass purity is both 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 for 5 hours using a V-type powder mixer to obtain a chromium-boron mixed powder, the chromium-boron mixed powder is loaded into a sleeve mold and vibrated, and then pressed by a cold isostatic press 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 suspension melting: Add 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 particle raw material in step 1 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 evacuate to a vacuum degree of 9×10 -3 Pa, high-purity argon gas is filled for protection for smelting, and the smelting power is stabilized at 320 kW, the smelting time is 5 min, after the chromium-boron cold-pressed billet and the aluminum particles are completely melted, the remaining pretreated aluminum particles are added into a water-cooled copper crucible in 4 batches through a feeder for smelting, and each time aluminum particles accounting for 20% to 30% of the total mass of the pretreated aluminum particle raw material are added, and the smelting power after each batch of aluminum particles is added is 100 kW, and the smelting time is 5 min, 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 smelting: The primary ingot obtained in step 3 is turned over with the bottom facing upward and placed in a water-cooled copper crucible, and then evacuated to a vacuum degree of 9×10 -3 Pa, high-purity argon gas was filled for protection for smelting, and the smelting power was stabilized at 320 kW, the smelting time was 5 min, and after the smelting was completed, the power was reduced to 50 kW at a rate of not less than 90 kW / s, and then the power was reduced from 50 kW to 0 kW at an average speed within 1 min, and cooled to room temperature to obtain an aluminum-chromium-boron alloy ingot with uniform chemical composition;

[0071] Step 5: Preparation of semi-solid aluminum-chromium-boron alloy billet: cutting off the bottom end and riser portion of the aluminum-chromium-boron alloy ingot obtained in step 4, and using a lathe to clean the uneven parts and defects on the surface of the ingot 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 uniformly coated with a glass protective lubricant for high-temperature deformation and air-dried, and then vacuum-encapsulated with 304 stainless steel, heated to 800° C. and kept warm for 20 minutes by entering the furnace at a temperature, first stretched to 300% of the original length, and then upset to 50% of the length after stretching, and the stretching and upset treatments are repeated twice to obtain an aluminum-chromium-boron alloy semi-finished product;

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

[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 aluminum-chromium-boron alloy target material has relatively serious macroscopic structural segregation.

[0076] contrast Figure 3 and Figure 4 It is found that the present invention adopts a one-time 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 organizational uniformity and small grain size, which is beneficial 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 organizational characteristics of aluminum-chromium-boron alloys. The solid solubility of chromium in its matrix aluminum is very low, its melting point is low, its magnetic permeability is poor, and its melting point is quite different from that of the aluminum-chromium phase, which makes the entire ingot prone to severe organizational segregation during the secondary melting.

[0077] Example 3

[0078] This embodiment includes the following steps:

[0079] Step 1, pretreatment: placing chromium powder, boron powder and aluminum particle raw materials 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 size of the aluminum particles is 1cm to 3cm, and the mass purity is 99.999%, and the particle size of the chromium powder and the boron powder are both 120 mesh, and the mass purity is both 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 for 2 hours using a V-type powder mixer to obtain a chromium-boron mixed powder, the chromium-boron mixed powder is put into a sleeve mold and vibrated, and then pressed by a cold isostatic press 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 suspension 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 particle raw material 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, high-purity argon gas protection is filled for smelting, and the smelting power is stabilized at 240kW, the smelting time is 15min, 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 3 batches through a feeder for smelting, and each time 25% to 35% of the total mass of the pretreated aluminum particle raw material is added. The smelting power of each batch of aluminum particles after addition is 150kW, and 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, and the power is maintained for 10min. After the smelting is completed, the power is 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 semi-solid aluminum-chromium-boron alloy billet: Cut off the bottom end and riser portion of the aluminum-chromium-boron alloy ingot obtained in step 3, and clean the uneven parts and defects on the surface of the ingot by 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 uniformly coated with a glass protective lubricant for high-temperature deformation and air-dried, and then vacuum-encapsulated with 304 stainless steel, heated to 780° C. and kept warm for 30 minutes by entering the furnace at a temperature, first stretched to 240% of the original length, and then upset to 48% of the length after stretching, and the stretching and upsetting treatments are repeated twice to obtain an aluminum-chromium-boron alloy semi-finished product;

[0084] Step 6: vacuum annealing: vacuum annealing the aluminum-chromium-boron alloy semi-finished product obtained in step 5 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 is 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, and 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: placing chromium powder, boron powder and aluminum particle raw materials 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 size of the aluminum particles is 1cm to 3cm, and the mass purity is 99.999%, and the particle size of the chromium powder and the boron powder are both 120 mesh, and the mass purity is both 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 for 2 hours using a V-type powder mixer to obtain a chromium-boron mixed powder, the chromium-boron mixed powder is put into a sleeve mold and vibrated, and then pressed by a cold isostatic press 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 suspension 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 particle raw material 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, high-purity argon gas protection is filled for smelting, and the smelting power is stabilized at 240kW, the smelting time is 15min, 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 3 batches through a feeder for smelting, and each time 25% to 35% of the total mass of the pretreated aluminum particle raw material is added. The smelting power of each batch of aluminum particles after addition is 150kW, and 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, and the power is maintained for 10min. After the smelting is completed, the power is 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: Preparation of aluminum-chromium-boron alloy billet for hot deformation: Cut off the bottom end and the riser portion of the aluminum-chromium-boron alloy ingot obtained in step 3, and clean the uneven parts and defects on the surface of the ingot by lathe to obtain an aluminum-chromium-boron 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 kept warm for 30 minutes by entering the furnace at a temperature, first stretched to 240% of the original length, then upset to 48% of the stretched length, and the stretching and upset treatments are repeated twice to obtain an aluminum-chromium-boron alloy semi-finished product;

[0094] Step 6: vacuum annealing: vacuum annealing the aluminum-chromium-boron alloy semi-finished product obtained in step 5 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: placing the raw materials of chromium powder, boron powder and aluminum particles 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 size of the aluminum particles is 1cm to 3cm, and the mass purity is 99.998%, the particle size of the chromium powder and the boron powder are both 200 mesh, and the mass purity is both 99.3%;

[0099] Step 2, powder mixing and cold isostatic pressing: under argon protection, the chromium powder and boron powder pretreated in step 1 are mixed for 3.5 hours using a V-type powder mixer to obtain a chromium-boron mixed powder, the chromium-boron mixed powder is put into a sleeve mold and vibrated, and then pressed by a cold isostatic press 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 suspension 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 particle raw material 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, high-purity argon gas protection is filled for smelting, and the smelting power is stabilized 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, and each time 20% to 30% of the total mass of the pretreated aluminum particle raw material is added. The smelting power of each batch of aluminum particles after addition is 120kW, and 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, and 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 semi-solid aluminum-chromium-boron alloy billet: Cut off the bottom end and riser portion of the aluminum-chromium-boron alloy ingot obtained in step 3, and clean the uneven parts and defects on the surface of the ingot by 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 uniformly coated with a glass protective lubricant for high-temperature deformation and air-dried, and then vacuum-encapsulated with 304 stainless steel, heated to 720° C. and kept warm for 35 minutes by entering the furnace at a temperature, first stretched to 220% of the original length, and then upset to 45% of the length after stretching, and the stretching and upsetting treatments are repeated twice to obtain an aluminum-chromium-boron alloy semi-finished product;

[0103] Step 6: vacuum annealing: vacuum annealing the aluminum-chromium-boron alloy semi-finished product obtained in step 5 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 is 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, and 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: placing the raw materials of chromium powder, boron powder and aluminum particles 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 size of the aluminum particles is 1cm to 3cm, and the mass purity is 99.999%, and the particle size of the chromium powder and the boron powder are both 200 mesh, and the mass purity is both 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 for 4.5 hours using a V-type powder mixer to obtain a chromium-boron mixed powder, the chromium-boron mixed powder is put into a sleeve mold and vibrated, and then pressed by a cold isostatic press 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 suspension 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 particle raw material 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, high-purity argon gas is filled for protection for smelting, and the smelting power is stabilized 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, and each time 40% to 60% of the total mass of the pretreated aluminum particle raw material is added. The smelting power of each batch of aluminum particles after addition is 140kW, and 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, and the power is maintained for 6min. 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 semi-solid aluminum-chromium-boron alloy billet: Cut off the bottom end and riser portion of the aluminum-chromium-boron alloy ingot obtained in step 3, and clean the uneven parts and defects on the surface of the ingot by 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 uniformly coated with a glass protective lubricant for high-temperature deformation and air-dried, and then vacuum-encapsulated with 304 stainless steel, heated to 700° C. and kept warm for 45 minutes by entering the furnace at a temperature, first stretched to 260% of the original length, and then upset to 43% of the length after stretching, and the stretching and upsetting treatments are repeated twice to obtain an aluminum-chromium-boron alloy semi-finished product;

[0113] Step 6: vacuum annealing: vacuum annealing the aluminum-chromium-boron alloy semi-finished product obtained in step 5 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 is 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, and 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 is 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, and 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 with the two magnetic suspension melting processes in Comparative Example 2, the aluminum-chromium-boron alloy round targets prepared in Examples 1 to 5 of the present invention have uniform structure and no macro-segregation, which shows that the present invention adopts a one-time magnetic suspension melting method with gradient power addition, which ensures the composition uniformity of the aluminum-chromium-boron alloy ingot and avoids the serious macro-segregation of the structure caused by multiple melting. The macro-segregation is mainly related to the organizational characteristics of the aluminum-chromium-boron alloy and the characteristics of magnetic suspension melting, which cannot be solved by multiple melting.

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

[0124] The above 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 change made to the above embodiment according to the technical essence of the invention still falls within the protection scope 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 the protection of argon, the chromium powder and the 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 suspension melting: The chromium-boron cold-pressed billet obtained in step 2 and part of the aluminum particles pretreated 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 -3 Pa~4×10 -4 Pa, high-purity argon is filled for magnetic suspension melting, during the magnetic suspension 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; Step 4: Preparation of semi-solid aluminum-chromium-boron alloy billet: cutting off the bottom end and 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 blank obtained in step 4 is subjected to hot forging by first drawing and then upsetting, and the drawing ratio is 200% to 300%, and the upsetting ratio is 40% to 50%, and the drawing and upsetting treatments 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 sizes 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 by a V-type powder mixer, and the mixing time is 2h to 5h. The pressure of the cold isostatic pressing is 200MPa to 300MPa, and the holding time is 10min to 20min.

4. The method for preparing a large-size aluminum-chromium-boron alloy target according to claim 1, characterized in that: During the magnetic levitation smelting process described in step three, the smelting power of the chromium-boron cold-pressed billet and part of the pretreated aluminum particles is completely melted, and the smelting time is 5min to 15min. The smelting power of 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, it is first quickly reduced to 50kW within 1s to 2s, and then uniformly reduced from 50kW to 0kW within 1min to 2min.

5. 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, and then vacuum-encapsulated with 304 stainless steel, and then heated and kept warm for 20 minutes to 50 minutes by heating into a furnace when the temperature reaches 500°C. The hot forging temperature is 680°C to 800°C.

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

7. 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 less than 180 ppm.

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