Preparation method of raw material bar for W-Nb alloy single crystal

Abstract

The invention discloses a preparation method of a raw material bar for a W-Nb alloy single crystal. The method comprises the following steps: 1, mixing W powder and FNb-1 powder, pressing, and carrying out vacuum high-temperature sintering to obtain a W-Nb alloy sintered bar; secondly, a W-Nb alloy cast ingot is obtained after electron beam smelting; thirdly, a W-Nb alloy extrusion bar is obtained through extrusion machining; fourthly, a W-Nb alloy electrode bar is manufactured after heating and forging; and 5, carrying out pre-purification and grain amplification by adopting an electron beam zone melting furnace to prepare the raw material bar for the W-Nb alloy single crystal. The method combining electron beam melting, extrusion and forging hot working and electron beam zone melting is provided for the first time, alloying of a material system and removal of impurity elements in the material are achieved, material grain breaking and uniform distribution of structures are promoted, deep purification is conducted again, grain inoculation and growth are promoted, subsequent growth is facilitated, and a single crystal structure is formed. The preparation process is simple, easy to implement and suitable for the fields of spaceflight, nuclear energy and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy preparation, and in particular relates to a method for preparing a raw material bar for a W-Nb alloy single crystal. Background Art

[0002] Electron beam levitation zone melting (EBLM) is a classic method for producing single crystals of refractory metals and their alloys. Requirements for the raw material bar used for alloy single crystal production are: 1) the total impurity content in the raw material bar must be controlled within 100 ppm; 2) the raw material bar's microstructure must be uniform, free of defects such as cracks or pores; 3) if the raw material bar is a multicomponent alloy, the internal grain size must be large to facilitate grain annealing during single crystal growth, facilitating the formation of a single crystal structure; and 4) the raw material bar's straightness must be no greater than 1 mm / m.

[0003] W-Nb alloy sintered rods produced using conventional powder metallurgy methods struggle to meet the raw material requirements for W-Nb alloy single crystals produced by electron beam levitation zone melting (EBLM). For example, sintered alloy rods produced by PLM methods often contain high levels of gaseous impurities such as oxygen, hydrogen, nitrogen, and carbon. Polycrystalline W-Nb alloy electrode rods also exhibit defects such as cracks, pores, and inclusions. The rods also exhibit an uneven microstructure, and the small grains within them cannot support the growth or annealing of grains during single crystal growth, leading to the formation of polycrystalline structures. This significantly hinders subsequent EBLM production of alloy single crystals.

[0004] Currently, there are no publicly available reports on the processing and preparation methods for high-quality raw material bars specifically used to produce W-Nb alloy single crystals. Therefore, in order to produce W-Nb alloy single crystals that meet the requirements, it is urgently necessary to develop an economically feasible processing technology for preparing raw material bars for W-Nb alloy single crystals. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the shortcomings of the above-mentioned prior art and provide a method for preparing raw material bars for W-Nb alloy single crystals. This method proposes, for the first time, a method for preparing raw material bars for W-Nb alloy single crystals by combining electron beam melting, extrusion and forging hot working, and electron beam zone melting. Electron beam melting achieves alloying of the material system and removal of impurity elements within the material. Hot working achieves grain breakage and uniform microstructure distribution. Electron beam zone melting further purifies the material system and allows for grain growth, preparing for subsequent single crystal growth. This method solves the problem of high impurity element content, uneven microstructure, and small grains in existing W-Nb alloy sintered bars, which make it difficult to prepare alloy single crystals.

[0006] To solve the above technical problems, the present invention adopts a technical solution: a method for preparing a raw material bar for a W-Nb alloy single crystal, characterized in that the method comprises the following steps: Step 1: After W powder and FNb-1 powder are mixed in a mixer, they are pressed into billets using a hydraulic press and a rectangular mold. The billets are then placed in a vacuum sintering furnace and sintered at a high temperature under vacuum to obtain W-Nb alloy sintered bars. Step 2: placing the W-Nb alloy sintered bar obtained in step 1 in an electron beam bombardment furnace, subjecting it to electron beam melting to form a W-Nb alloy billet, and then subjecting it to turning and sawing to obtain a W-Nb alloy ingot; Step 3: placing the W-Nb alloy ingot obtained in step 2 on an extruder for extrusion processing to obtain a W-Nb alloy extruded rod; Step 4: The W-Nb alloy extruded rod obtained in step 3 is heated and forged by a die on an air hammer and straightened to obtain a W-Nb alloy forged rod blank, which is then surface-machined to produce a W-Nb alloy electrode rod; Step 5: The W-Nb alloy electrode rod obtained in step 4 is pre-purified and grain-enlarged in an electron beam zone furnace to prepare a W-Nb alloy rod, which is then surface-machined to prepare a raw material rod for W-Nb alloy single crystal.

[0007] Different from the existing powder metallurgy method for preparing tungsten alloy polycrystalline rods, the impurity elements, especially C, N, O and other impurity elements, still exist in the form of simple substances or compounds in the material due to the heating temperature not exceeding 2300℃, and cannot be completely removed. In addition, there are gaps between the powder particles, resulting in low material density and a certain proportion of cracks and holes inside the material. As a result, when the polycrystalline raw material rods prepared by the powder metallurgy method are directly used to grow single crystals, the impurity elements existing in the defects (segregated at the grain boundaries) will diffuse and escape rapidly in the molten state, seriously destroying the balance between the surface tension and gravity of the molten zone. , which causes the melt zone to collapse and results in the failure of single crystal growth. The present invention uses electron beam melting of W-Nb alloy sintered bars to make W-Nb alloy ingots. The W-Nb alloy is heated to a liquid molten state using a high-energy-density electron beam. The solubility of impurity elements in the W-Nb alloy, including C, N, O and other impurity elements, is greatly reduced under high temperature, causing them to rapidly diffuse from the melt and escape to the outside of the melt for removal; at the same time, the compounds formed by tungsten, niobium, C, N, and O decompose under high temperature and diffuse to the surface of the melt for escape and removal, thereby achieving deep purification of the W-Nb alloy material. In addition, since the W-Nb alloy is first melted into a liquid state and then condensed into a solid ingot, the density of the W-Nb alloy ingot is significantly better than that of materials prepared by powder metallurgy, and there are no defects such as cracks and holes inside the ingot, which is extremely beneficial for subsequent single crystal growth.

[0008] Unlike the prior art in which tungsten alloy polycrystalline rods are processed by free forging, which is extremely unfavorable for the deformation of tungsten alloy polycrystalline materials with poor ductility due to the stress state of compressive stress in one direction and tensile stress in two directions, and is prone to uneven deformation, resulting in defects such as a large number of cracks. In addition, the radial grain crushing degree of the W-Nb alloy rod is uneven, resulting in a non-uniform fibrous structure that is not conducive to the subsequent single crystal growth needs. The present invention adopts a combination of extrusion and forging to change the structure of the W-Nb alloy ingot. During the extrusion process, the W-Nb alloy ingot is deformed under a three-way compressive stress state. On the one hand, it ensures that the deformed structure is a fibrous structure, thereby improving the machinability of the extruded rod. On the other hand, a uniform deformed structure is obtained, which is beneficial to subsequent forging processing, thereby improving the material yield rate.

[0009] Unlike the tungsten alloy polycrystalline rods prepared by powder metallurgy in the prior art, which have fine grains, it is extremely difficult for the fine grains to grow and merge to form a single crystal structure when growing single crystals, and the single crystal structure has rich subgrain network structure and poor single crystal quality. In the present invention, W-Nb alloy electrode rods are pre-purified and grain enlarged in an electron beam zone furnace to prepare raw material rods for W-Nb alloy single crystals. The polycrystalline W-Nb alloy electrode rods are heated continuously for a long time using a high-energy density electron beam. On the one hand, the fibrous structure inside the rod has a large recrystallization kinetics, and its grains grow rapidly and merge to form a large grain structure under high temperature of 2500℃~3000℃, which provides favorable conditions for subsequent application in single crystal growth. On the other hand, the impurity elements inside the rod quickly diffuse from the inside to the surface under high temperature and escape to achieve deep impurity removal, which is beneficial to the formation of single crystal structure when subsequently applied to single crystal growth.

[0010] The above-mentioned method for preparing a raw material bar for a W-Nb alloy single crystal is characterized in that the mass ratio of the W powder and the FNb-1 powder in step 1 is 97:3, and the mixing time is 16h~20h; the hydraulic press is a 600-ton hydraulic press; the vacuum degree of the vacuum high-temperature sintering is 2×10 -3 Pa~5×10 -3 Pa, the temperature is 2000° C. to 2200° C., and the time is 10 h to 20 h; the total mass content of the gaseous impurity elements C, N, H and O and other impurity elements in the W—Nb alloy sintered bar is not greater than 500 ppm.

[0011] The above-mentioned method for preparing a raw material bar for a W-Nb alloy single crystal is characterized in that the electron beam bombardment furnace in step 2 is a 300 kW electron beam bombardment furnace, and the electron beam melting is performed twice. By performing two electron beam melting cycles, the W-Nb alloy ingot is fully alloyed and impurities are removed.

[0012] The above-mentioned method for preparing a raw material bar for a W-Nb alloy single crystal is characterized in that, during the extrusion process described in step 3, the W-Nb alloy ingot is first heated to 1500°C~1600°C using an induction heating furnace, the cogging deformation rate of the extrusion process is 56.2%~81.4%, and the extrusion ratio is 5.4~2.3. The present invention controls the temperature, cogging deformation rate and extrusion ratio of the extrusion process to perform cogging processing on the ingot, so that the W-Nb alloy ingot with poor plastic deformation can better break its grains under the three-way compression force state and large deformation amount, so that it has certain workability, obtains a fibrous structure with good uniformity, improves the deformation ability of the W-Nb alloy extruded bar, is conducive to the subsequent processing, and helps to improve the material yield.

[0013] The above-mentioned method for preparing a raw material bar for a W-Nb alloy single crystal is characterized in that the total deformation rate of the heated forging in step 4 is 32.5% to 71.4%. By controlling the total deformation rate during heated forging, the present invention transforms the internal grain structure of the extruded bar from fibrous to equiaxed. Simultaneously, the forging deformation is slower than the extrusion deformation rate, eliminating defects and stress generated within the bar during extrusion deformation. It also ensures uniform external dimensions and improved straightness, facilitating further processing.

[0014] The above-mentioned method for preparing a raw material bar for a W-Nb alloy single crystal is characterized in that the total impurity element content of the raw material bar for the W-Nb alloy single crystal in step 5 does not exceed 50 ppm, the microstructure is uniform, and the grain size is 0.1 mm to 3 mm. Pre-growth of grains is a prerequisite for the successful subsequent single crystal production. By controlling the grain size in the raw material bar for the W-Nb alloy single crystal, grain annealing during single crystal growth is facilitated, single crystal formation is more easily achieved, and subsequent single crystal material production is guaranteed.

[0015] The above-mentioned method for preparing a raw material bar for a W-Nb alloy single crystal is characterized in that the diameter × height of the W-Nb alloy billet described in step 2 is 70 mm × 1000 mm, and the diameter × height of the W-Nb alloy ingot is 650 mm × 200 mm; the diameter of the W-Nb alloy extruded bar described in step 3 is 28 mm ~ 43 mm; the diameter of the W-Nb alloy forged bar described in step 4 is 23 mm, the diameter of the W-Nb alloy electrode bar is 20 mm ± 0.1 mm, and the straightness is not greater than 1 mm / m; the diameter of the W-Nb alloy rod described in step 5 is 23 mm ~ 25 mm, and the diameter of the raw material bar for the W-Nb alloy single crystal is 22 mm ± 0.1 mm, and the straightness is not greater than 1 mm / m.

[0016] Compared with the prior art, the present invention has the following advantages: 1. The present invention prepares W-Nb alloy ingots by electron beam melting, which promotes the discharge of impurity elements such as C, N, and O in the W-Nb alloy ingots, achieves a deep purification effect, and at the same time improves its density, avoiding defects such as cracks and holes inside the ingots, thereby preparing raw material bars for W-Nb alloy single crystals with high purity, good density, and no defects such as cracks and holes, which is conducive to subsequent application in single crystal growth.

[0017] 2. The present invention adopts a combination of extrusion and forging to prepare W-Nb alloy electrode rods. Extrusion processing is used to obtain a fibrous structure with good uniformity, which improves the deformation ability of the rod, facilitates the subsequent forging process, and improves the material yield rate.

[0018] 3. The present invention adopts an electron beam zone melting furnace to prepare raw material rods for W-Nb alloy single crystals, and utilizes electron beam heating to promote the recrystallization of the fibrous structure of the rods to form a large-grain structure, while promoting the discharge of impurity elements to achieve deep impurity removal and storage, which is beneficial to the subsequent growth to form a single crystal structure.

[0019] 4. The raw material bar for W-Nb alloy single crystal prepared by the present invention has no defects such as cracks, pores and inclusions on the surface, a straightness of no more than 1 mm / m, a total content of impurity elements of no more than 50 ppm, a uniform microstructure, a grain size of 0.1 mm to 3 mm, and larger grains along the axial direction, which facilitates grain annealing during single crystal growth, more easily forms a single crystal structure, and ensures the successful preparation of subsequent single crystals. This single crystal material is used for core components in cutting-edge fields such as aerospace and nuclear energy.

[0020] 5. The preparation process of the present invention is simple, low-cost, and easy to implement.

[0021] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a physical picture of the W-Nb alloy extruded rod prepared in Example 1 of the present invention.

[0023] Figure 2 This is a transverse metallographic structure diagram of the raw material bar for the W-Nb alloy single crystal prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] Example 1 This embodiment includes the following steps: Step 1: After W powder and FNb-1 powder with a mass ratio of 97:3 were mixed in a mixer for 16 hours, they were pressed into billets with a width × height × length of 16 mm × 16 mm × 400 mm using a 600-ton hydraulic press and a rectangular mold. The billets were then placed in a vacuum sintering furnace at a vacuum degree of 2 × 10 -3Pa~3.8×10 -3 Pa, vacuum high-temperature sintering at a temperature of 2000°C to 2100°C for 10 hours, and cooling with the furnace to obtain a W-Nb alloy sintered bar; the total mass content of gaseous impurity elements C, N, H and O and other impurity elements in the W-Nb alloy sintered bar is 475ppm, as shown in Table 1; Step 2: Place the W-Nb alloy sintered bar obtained in step 1 in a 300kW electron beam bombardment furnace and perform electron beam melting twice to form a W-Nb alloy billet with a diameter × height of 70 mm × 1000 mm. The vacuum degree of electron beam melting is better than 5.0 × 10 -2 Pa, the melting rate is 15kg / h~30kg / h, the electron beam current is 3.5A~4.5A, and a W-Nb alloy ingot with a diameter × height of 65mm × 200mm is obtained by turning and sawing; Step 3: The W-Nb alloy ingot obtained in step 2 is heated to 1500°C~1600°C in an induction heating furnace, and then placed on a 1000-ton extruder for extrusion processing. The extrusion process has a blanking deformation rate of 81.4% and an extrusion ratio of 5.4, and a W-Nb alloy extruded rod with a diameter of 28mm±1mm is obtained. Figure 1 As shown; Step 4: The W-Nb alloy extruded rod obtained in step 3 is heated and forged using a die on an air hammer and straightened. The total deformation rate of the heated forging is 32.53%, and a W-Nb alloy forged rod with a diameter of 23 mm is obtained. The rod is then centerlessly ground into a W-Nb alloy electrode rod with a diameter of 20 mm ± 0.1 mm and a straightness of no more than 1 mm / m. Step 5: The W-Nb alloy electrode rod obtained in step 4 is pre-purified and the grains are enlarged in an electron beam zone furnace with a vacuum degree of less than 8.0×10 -3 Pa, the zone melting speed is 3mm / min~5mm / min, the electron beam current is 1A~2A, and a W-Nb alloy rod with a diameter of 24mm±1mm is prepared. Then, the surface is subjected to centerless grinding to prepare a raw material rod for W-Nb alloy single crystal with a diameter of 22mm±0.1mm and a straightness of no more than 1mm / m.

[0025] Figure 2 This is the transverse metallographic structure diagram of the raw material bar for the W-Nb alloy single crystal prepared in this embodiment. Figure 2 It can be seen that the microstructure of the raw material bar for the W-Nb alloy single crystal is uniform, and the grain size is 0.1 mm to 3 mm. After testing, the total content of impurity elements in the raw material bar for the W-Nb alloy single crystal is 40.855 ppm, as shown in Table 2.

[0026] Example 2 This embodiment includes the following steps: Step 1: After W powder and FNb-1 powder with a mass ratio of 97:3 were mixed in a mixer for 18 hours, they were pressed into billets with a width × height × length of 16mm × 16mm × 400mm using a 600-ton hydraulic press and a rectangular mold. The billets were then placed in a vacuum sintering furnace at a vacuum degree of 3.0×10 -3 Pa~4.6×10 -3 Pa, vacuum high-temperature sintering at a temperature of 2100° C. to 2200° C. for 14 hours, and cooling in the furnace to obtain a W-Nb alloy sintered bar; the total mass content of gaseous impurity elements C, N, H and O and other impurity elements in the W-Nb alloy sintered bar is 415 ppm, as shown in Table 1; Step 2: Place the W-Nb alloy sintered bar obtained in step 1 in a 300kW electron beam bombardment furnace and perform electron beam melting twice to form a W-Nb alloy billet with a diameter × height of 70 mm × 1000 mm. The vacuum degree of electron beam melting is better than 5.0 × 10 -2 Pa, the melting rate is 15kg / h~30kg / h, the electron beam current is 3.5A~4.5A, and a W-Nb alloy ingot with a diameter × height of 65mm × 200mm is obtained by turning and sawing; Step 3: The W-Nb alloy ingot obtained in step 2 is heated to 1500° C. to 1600° C. in an induction heating furnace, and then extruded on a 1000-ton extruder. The extrusion deformation rate is 74.2%, the extrusion ratio is 3.9, and a W-Nb alloy extruded rod with a diameter of 33 mm ± 1 mm is obtained; Step 4: The W-Nb alloy extruded rod obtained in step 3 is heated and forged using a die on an air hammer and straightened. The total deformation rate of the heated forging is 51.42%, and a W-Nb alloy forging rod with a diameter of 23 mm is obtained. The W-Nb alloy electrode rod with a diameter of 20 mm ± 0.1 mm and a straightness of no more than 1 mm / m is obtained by centerless grinding. Step 5: The W-Nb alloy electrode rod obtained in step 4 is pre-purified and the grains are enlarged in an electron beam zone furnace with a vacuum degree of less than 8.0×10 -3 Pa, the zone melting speed is 3mm / min~5mm / min, and the electron beam current is 1A~2A, and a W-Nb alloy rod with a diameter of 24mm±1mm is prepared. Then, the surface is centerless ground to prepare a raw material rod for W-Nb alloy single crystal with a diameter of 22mm±0.1mm and a straightness of not more than 1mm / m. After testing, the microstructure of the raw material rod for W-Nb alloy single crystal is uniform, the grain size is 0.1mm~3mm, and the total content of impurity elements in the raw material rod for W-Nb alloy single crystal is 38.395ppm, as shown in Table 3.

[0027] Example 3 This embodiment includes the following steps: Step 1: After W powder and FNb-1 powder with a mass ratio of 97:3 were mixed in a mixer for 20 hours, they were pressed into billets with a width × height × length of 16mm × 16mm × 400mm using a 600-ton hydraulic press and a rectangular mold. The billets were then placed in a vacuum sintering furnace at a vacuum degree of 3.0 × 10 -3 Pa~5.0×10 -3 Pa, vacuum high-temperature sintering at a temperature of 2100° C. to 2200° C. for 18 hours, and cooling in the furnace to obtain a W-Nb alloy sintered bar; the total mass content of gaseous impurity elements C, N, H and O and other impurity elements in the W-Nb alloy sintered bar is 465 ppm, as shown in Table 1; Step 2: Place the W-Nb alloy sintered bar obtained in step 1 in a 300kW electron beam bombardment furnace and perform electron beam melting twice to form a W-Nb alloy billet with a diameter × height of 70 mm × 1000 mm. The vacuum degree of electron beam melting is better than 5.0 × 10 -2 Pa, the melting rate is 15kg / h~30kg / h, the electron beam current is 3.5A~4.5A, and a W-Nb alloy ingot with a diameter × height of 65mm × 200mm is obtained by turning and sawing; Step 3: The W-Nb alloy ingot obtained in step 2 is heated to 1500° C. to 1600° C. in an induction heating furnace, and then extruded on a 1000-ton extruder. The extrusion deformation rate is 65.8%, the extrusion ratio is 2.9, and a W-Nb alloy extruded rod with a diameter of 38 mm ± 1 mm is obtained; Step 4: The W-Nb alloy extruded rod obtained in step 3 is heated and forged using a die on an air hammer and straightened. The total deformation rate of the heated forging is 63.4%, and a W-Nb alloy forging rod with a diameter of 23 mm is obtained. The W-Nb alloy electrode rod with a diameter of 20 mm ± 0.1 mm and a straightness of no more than 1 mm / m is obtained by centerless grinding. Step 5: The W-Nb alloy electrode rod obtained in step 4 is pre-purified and the grains are enlarged in an electron beam zone furnace with a vacuum degree of less than 8.0×10 -3 Pa, the zone melting speed is 3mm / min~5mm / min, and the electron beam current is 1A~2A, and a W-Nb alloy rod with a diameter of 24mm±1mm is prepared. Then, the surface is centerless ground to prepare a raw material rod for W-Nb alloy single crystal with a diameter of 22mm±0.1mm and a straightness of not more than 1mm / m. After testing, the microstructure of the raw material rod for W-Nb alloy single crystal is uniform, the grain size is 0.1mm~3mm, and the total content of impurity elements in the raw material rod for W-Nb alloy single crystal is 37.305ppm, as shown in Table 4 for details.

[0028] Example 4 This embodiment includes the following steps: Step 1: After W powder and FNb-1 powder with a mass ratio of 97:3 were mixed in a mixer for 20 hours, they were pressed into billets with a width × height × length of 16mm × 16mm × 400mm using a 600-ton hydraulic press and a rectangular mold. The billets were then placed in a vacuum sintering furnace at a vacuum degree of 3.0 × 10 -3 Pa~5.0×10 -3 Pa, vacuum high-temperature sintering at a temperature of 2100° C. to 2200° C. for 20 hours, and cooling in the furnace to obtain a W-Nb alloy sintered bar; the total mass content of gaseous impurity elements C, N, H and O and other impurity elements in the W-Nb alloy sintered bar is 465 ppm, as shown in Table 1; Step 2: Place the W-Nb alloy sintered bar obtained in step 1 in a 300kW electron beam bombardment furnace and perform electron beam melting twice to form a W-Nb alloy billet with a diameter × height of 70 mm × 1000 mm. The vacuum degree of electron beam melting is better than 5.0 × 10 -2 Pa, the melting rate is 15kg / h~30kg / h, the electron beam current is 3.5A~4.5A, and a W-Nb alloy ingot with a diameter × height of 65mm × 200mm is obtained by turning and sawing; Step 3: The W-Nb alloy ingot obtained in step 2 is heated to 1500° C. to 1600° C. in an induction heating furnace, and then extruded on a 1000-ton extruder. The extrusion deformation rate is 56.2%, the extrusion ratio is 2.3, and a W-Nb alloy extruded rod with a diameter of 43 mm ± 1 mm is obtained; Step 4: The W-Nb alloy extruded rod obtained in step 3 is heated and forged using a die on an air hammer and straightened. The total deformation rate of the heated forging is 71.4%, and a W-Nb alloy forged rod with a diameter of 23 mm is obtained. The W-Nb alloy electrode rod with a diameter of 20 mm ± 0.1 mm and a straightness of no more than 1 mm / m is obtained by centerless grinding. Step 5: The W-Nb alloy electrode rod obtained in step 4 is pre-purified and the grains are enlarged in an electron beam zone furnace with a vacuum degree of less than 8.0×10 -3Pa, the zone melting speed is 3mm / min~5mm / min, and the electron beam current is 1A~2A, and a W-Nb alloy rod with a diameter of 24mm±1mm is prepared, and then the surface is centerless ground to prepare a raw material rod for W-Nb alloy single crystal with a diameter of 22mm±0.1mm and a straightness of not more than 1mm / m. After testing, the microstructure of the raw material rod for W-Nb alloy single crystal is uniform, the grain size is 0.1mm~3mm, and the total content of impurity elements in the raw material rod for W-Nb alloy single crystal is 38.415ppm, as shown in Table 5 for details.

[0029] Table 1 Content of gaseous impurity elements in W-Nb alloy sintered bars prepared in Examples 1 to 4

[0030] Table 2 Impurity element content in the raw material bar for W-Nb alloy single crystal prepared in Example 1

[0031] "Matrix" in Table 2 represents the matrix element.

[0032] Table 3 Impurity element content in the raw material bar for W-Nb alloy single crystal prepared in Example 2

[0033] "Matrix" in Table 3 represents the matrix element.

[0034] Table 4 Impurity element contents in the raw material rod for W-Nb alloy single crystal prepared in Example 3

[0035] "Matrix" in Table 4 represents a matrix element.

[0036] Table 5 Impurity element contents in the raw material bar for W-Nb alloy single crystal prepared in Example 4

[0037] "Matrix" in Table 5 represents a matrix element.

[0038] 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 raw material bar for a W-Nb alloy single crystal, characterized in that: The method comprises the following steps: Step 1: W powder and FNb-1 powder are mixed in a mixer, and then pressed into billets using a hydraulic press and a rectangular mold. The billets are then placed in a vacuum sintering furnace and sintered at a high temperature under vacuum to obtain W-Nb alloy sintered bars. Step 2: placing the W-Nb alloy sintered bar obtained in step 1 in an electron beam bombardment furnace, subjecting it to electron beam melting to obtain a W-Nb alloy billet, and then subjecting it to turning and sawing to obtain a W-Nb alloy ingot; Step 3: placing the W-Nb alloy ingot obtained in step 2 on an extruder for extrusion processing to obtain a W-Nb alloy extruded rod; Step 4: The W-Nb alloy extruded rod obtained in step 3 is heated and forged by a die on an air hammer and straightened to obtain a W-Nb alloy forged rod blank, which is then surface-machined to produce a W-Nb alloy electrode rod; Step 5: The W-Nb alloy electrode rod obtained in step 4 is pre-purified and grain-enlarged in an electron beam zone furnace to prepare a W-Nb alloy rod, which is then surface-machined to prepare a raw material rod for W-Nb alloy single crystal.

2. The method for preparing a raw material bar for a W-Nb alloy single crystal according to claim 1, characterized in that: The mass ratio of W powder to FNb-1 powder in step 1 is 97:3, and the mixing time is 16h~20h; the hydraulic press is a 600-ton hydraulic press; the vacuum degree of the vacuum high-temperature sintering is 2×10 -3 Pa~5×10 -3 Pa, the temperature is 2000° C. to 2200° C., and the time is 10 h to 20 h; the total mass content of the gaseous impurity elements C, N, H and O and other impurity elements in the W—Nb alloy sintered bar is not greater than 500 ppm.

3. The method for preparing a raw material bar for a W-Nb alloy single crystal according to claim 1, characterized in that: The electron beam bombardment furnace in step 2 is a 300kW electron beam bombardment furnace; the electron beam melting times are 2 times.

4. The method for preparing a raw material bar for a W-Nb alloy single crystal according to claim 1, characterized in that: During the extrusion process in step 3, the W-Nb alloy ingot is first heated to 1500° C. to 1600° C. using an induction heating furnace. The cogging deformation rate of the extrusion process is 56.2% to 81.4%, and the extrusion ratio is 5.4 to 2.

3.

5. The method for preparing a raw material bar for a W-Nb alloy single crystal according to claim 1, characterized in that: The total deformation rate of the heating forging in step 4 is 32.5% to 71.4%.

6. The method for preparing a raw material bar for a W-Nb alloy single crystal according to claim 1, characterized in that: The total content of impurity elements in the raw material bar for the W-Nb alloy single crystal in step 5 does not exceed 50 ppm, the microstructure is uniform, and the grain size is 0.1 mm to 3 mm.

7. The method for preparing a raw material bar for a W-Nb alloy single crystal according to claim 1, characterized in that: The diameter × height of the W-Nb alloy billet described in step 2 is 70 mm × 1000 mm, and the diameter × height of the W-Nb alloy ingot is 650 mm × 200 mm; the diameter of the W-Nb alloy extruded rod described in step 3 is 28 mm ~ 43 mm; the diameter of the W-Nb alloy forged rod described in step 4 is 23 mm, the diameter of the W-Nb alloy electrode rod is 20 mm ± 0.1 mm, and the straightness is not greater than 1 mm / m; the diameter of the W-Nb alloy rod described in step 5 is 23 mm ~ 25 mm, and the diameter of the raw material bar for the W-Nb alloy single crystal is 22 mm ± 0.1 mm, and the straightness is not greater than 1 mm / m.

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