Method for preparing Cr2Nb / Cu composite material through vacuum consumable electric arc melting

Abstract

The invention discloses a method for preparing a Cr2Nb / Cu composite material through vacuum consumable electric arc melting, which specifically comprises the following steps: step 1, carrying out two times of crushing treatment on Cu, Cr and Nb blocks subjected to ultrasonic cleaning, and screening Cu, Cr and Nb particles with different sizes; 2, Cu particles, Cr particles and Nb particles are mixed, and the mixed particles are pressed into a consumable electrode; 3, the consumable electrode is smelted, and the Cr2Nb / Cu composite material is obtained; fourthly, the Cr2Nb / Cu composite material obtained in the third step is machined into the size needed by the consumable electrode, the Cr2Nb / Cu composite material continues to serve as the consumable electrode to be smelted according to the third step, and the process is repeated for 3-6 times; and 5, densifying the alloy obtained in the step 4 by adopting different hot extrusion processes. The method solves the problems of element segregation and coarse Cr2Nb particles in the Cr2Nb / Cu composite material prepared by the existing casting process.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of composite material preparation, and relates to a method for preparing Cr2Nb / Cu composite material by vacuum self-consumption arc melting. BACKGROUND

[0002] The Cr2Nb / Cu composite material becomes a potential material for the next generation of recyclable launch vehicle engine combustion chamber liner due to its excellent high strength, high conductivity, high heat resistance and excellent low-cycle fatigue performance, but the preparation of the Cr2Nb / Cu composite material still faces many challenges.

[0003] Vacuum induction melting is one of the common methods for preparing the Cr2Nb / Cu composite material, and the paper "Solidification characteristics and precipitation behavior of the Cu-Cr-Nb alloys" prepared the Cr2Nb / Cu composite material by the vacuum induction melting method. It is found by EPMA that there is element segregation, which is attributed to the large difference in element density, the floating phenomenon of Cr occurs in the solidification process, which leads to insufficient reaction of Cr and Nb. At the same time, the cold speed is slow in the solidification stage, and large-sized Cr2Nb particles are formed in the material, which has poor strengthening effect and low material strength. At present, the Cr2Nb / Cu composite material prepared by the vacuum induction melting method has the following shortcomings: 1. The densities of Cu, Cr and Nb are greatly different, which easily leads to composition segregation and affects the uniformity of the material; 2. The cold speed is small during the ingot forming, which easily forms coarse Cr2Nb phase and reduces the comprehensive performance of the material; and 3. The prepared Cr2Nb / Cu composite material has large grains and low strengthening effect. SUMMARY

[0004] The purpose of the application is to provide a method for preparing Cr2Nb / Cu composite material by vacuum self-consumption arc melting, which solves the problems of element segregation and large-sized Cr2Nb particles in the preparation of Cr2Nb / Cu composite material by the existing casting process.

[0005] The technical scheme adopted by the application is that the method for preparing Cr2Nb / Cu composite material by vacuum self-consumption arc melting comprises the following steps: Step 1. The ultrasonic cleaned Cu, Cr and Nb blocks are subjected to twice breaking treatment, and Cu, Cr and Nb particles of different sizes are screened; Step 2. The Cu, Cr and Nb particles are mixed, and the mixed particles are pressed into a self-consumption electrode; Step 3. The self-consumption electrode is subjected to melting to obtain the Cr2Nb / Cu composite material; Step 4: Process the Cr2Nb / Cu composite material obtained in Step 3 into the size required for the consumable electrode, and continue to use it as a consumable electrode for melting according to Step 3, repeating 3-6 times. Step 5: Densification treatment is carried out on the alloy obtained in Step 4 using different hot extrusion processes.

[0006] The invention is further characterized by: The specific process of step 1 is as follows: Cu blocks, Cr blocks and Nb blocks are coarsely crushed once by a jaw crusher, and then the raw materials are finely crushed twice by a roller crusher. After the second crushing, Cu, Cr and Nb particles of different sizes are screened.

[0007] In step 1, the eccentric shaft speed of the jaw crusher is 200-300 r / min, the discharge port size of the jaw crusher is 10-30 mm, and the roller speed of the double roll crusher is 50-150 r / min; the particle sizes to be screened are: Cu particles 1-2 mm, Cr particles 700-1000 μm, and Nb particles 300-500 μm.

[0008] The specific process of step 2 is as follows: Cu particles, Cr particles and Nb particles are mixed in a mixer according to the following mass percentages: Cr content is 1.7-6.8 wt.%, Nb content is 1.4-5.4 wt.%, and the remainder is Cu. The total mass ratio of Cu, Cr and Nb is 100%. After mixing, the metal raw material is placed into a mold and pressed into a blank using a hydraulic press.

[0009] In step 2, Cu, Cr and Nb particles are mixed in a mixer at a speed of 40-50 r / min and a temperature of 30-40 ℃ for 2-15 h. The hydraulic press mold is made of steel, with a holding pressure of 600-700 MPa and a holding time of 30-40 s. After pressing, the blank is machined to cut threads.

[0010] The specific process of step 3 is as follows: The compressed bar from step 2 is used as a consumable electrode and placed in a vacuum consumable arc furnace. The ignition material is placed on the bottom of the crucible, and after evacuation, an inert protective gas is introduced. During melting, the consumable electrode is lowered above the crucible, and then an arc is ignited between the consumable electrode and the crucible. After ignition, the consumable electrode is fed at a low speed to gradually shorten the gap and stabilize the arc shape. The arc shape is constantly observed and adjusted during the process. Normal melting is carried out after a molten pool is observed to form on the crucible base. Before the alloy bar begins to melt, the built-in ultrasonic device is turned on. As the depth of the molten pool in the crucible increases, the ultrasonic working frequency is continuously increased until the working frequency reaches the preset value and continues to act until the alloy material is completely solidified. During solidification, a water-cooled copper crucible is used for cooling.

[0011] In step 3, the starting material is copper foil, and the inert gas is helium or argon; the height of the consumable electrode to the crucible is 5-15 mm, the low-speed feeding speed is 0.1-0.5 mm / s, the smelting current is 50-70 A, and the ultrasonic working frequency is 20-25 kHz.

[0012] In step 4, the Cr2Nb / Cu composite material obtained in the crucible in step 3 is processed into a consumable electrode size, and after threading is turned, it is again used as a consumable electrode for smelting, and the smelting is repeated for 3-6 times.

[0013] In step 5, the Cr2Nb / Cu composite material obtained in step 4 is subjected to hot extrusion treatment, the holding temperature is 800-900 DEG C, the holding time is 30-60 min, the extrusion cylinder temperature is 400-500 DEG C, and the extrusion ratio is 9:1.

[0014] The beneficial effects of the present application are as follows: 1. The preparation process of the traditional consumable electrode bar is relatively complicated, the uniformly mixed powder is pressed into a bar by a cold isostatic press, then vacuum sintering is performed, and finally the consumable electrode is machined. In the present application, different sizes of metal particles are used as raw materials, and the bar is directly pressed by a hydraulic machine, and the requirements of the consumable electrode can be met by machining. The raw material cost is low, the preparation process is simple, the processing cost is reduced, the processing efficiency is improved, and low-cost industrialization is realized.

[0015] 2. In the present application, an ultrasonic device is used in the material solidification stage to realize grain refinement, effectively improve the segregation phenomenon existing in the molten pool, promote the nucleation of Cr2Nb particles, make the Cr2Nb particles uniformly and dispersedly distributed, and improve the microstructure of the material.

[0016] 3. In the present application, the hot extrusion process is used to prepare the Cr2Nb / Cu composite material after repeated consumable consumption, which effectively eliminates defects such as pores and porosity in the hot extrusion process, and further improves the density of the material. At the same time, the alloy undergoes dynamic recrystallization in the extrusion process, breaks the coarse grains, realizes grain refinement, improves the uniformity of the structure, and improves the mechanical properties of the alloy. DETAILED DESCRIPTION

[0017] Figure 1 The present application is a vacuum consumable arc smelting method for preparing a Cr2Nb / Cu composite material, and the distribution of metal particles in the steel mold inside the hydraulic machine for preparing the consumable metal bar is shown in the schematic diagram. Figure 2 The flow chart of the present application is shown in the flow chart of the present application. Figure 3Figure 4 is a microstructure morphology diagram of the 7% Cr2Nb / Cu composite material after vacuum self-consumption arc melting according to the method for preparing the Cr2Nb / Cu composite material by vacuum self-consumption arc melting of the present application; Figure 4 Figure 5 is a microstructure morphology diagram of the 7% Cr2Nb / Cu composite material in the vertical extrusion direction after hot extrusion according to the method for preparing the Cr2Nb / Cu composite material by vacuum self-consumption arc melting of the present application; Figure 5 Figure 6 is a microstructure morphology diagram of the 7% Cr2Nb / Cu composite material in the parallel extrusion direction after hot extrusion according to the method for preparing the Cr2Nb / Cu composite material by vacuum self-consumption arc melting of the present application; Figure 6 Figure 7 is a stress-strain curve of the 7% Cr2Nb / Cu composite material after vacuum self-consumption arc melting and after hot extrusion according to the method for preparing the Cr2Nb / Cu composite material by vacuum self-consumption arc melting of the present application. DETAILED DESCRIPTION

[0018] The present application will be described in detail below in combination with the drawings and specific embodiments.

[0019] The present application adopts the method for preparing the Cr2Nb / Cu composite material by vacuum self-consumption arc melting, as shown in Figure 1, which specifically comprises the following steps: Figure 2 Step 1, respectively ultrasonic cleaning the Cu, Cr and Nb blocks. Step 2, twice breaking treatment is performed on the cleaned Cu, Cr and Nb blocks, and Cu, Cr and Nb particles of different sizes are screened, specifically as follows: the Cu block, the Cr block and the Nb block are respectively subjected to once coarse crushing by a jaw crusher, and then twice fine crushing by a roller crusher, and Cu, Cr and Nb particles of different sizes are respectively screened after the twice fine crushing.

[0020] In step 2, the eccentric shaft rotation speed of the jaw crusher is 200-300 r / min, the size of the discharge port of the jaw crusher is 10-30 mm, and the roller rotation speed of the roller crusher is 50-150 r / min; the particle sizes screened are as follows: Cu particle size 1-2 mm, Cr particle size 700-1000 μm, and Nb particle size 300-500 μm.

[0021]

[0022] ​Step 3, Cu particles, Cr particles, Nb particles are mixed in a mixer according to the following mass percentage: Cr content is 1.7-6.8 wt.%, Nb content is 1.4-5.4 wt.%, and the rest is Cu, the total mass ratio of the three elements is 100%. Large and small particles are mixed, small particles fill the gaps of large particles, reduce the porosity of raw materials, improve the compactness of the mixture, which is beneficial to reduce gas residues or molten pool fluctuations caused by loose structure during smelting, and at the same time avoid local melting too fast or too slow during consumable electrode smelting. After mixing, the raw materials are put into the mold and pressed into a rod by a hydraulic machine.

[0023] In step 3, Cu, Cr and Nb particles are mixed in a mixer, the vacuum degree of the mixer is-0.1 Pa, the rotation speed of the mixer is 40-50 r / min, the temperature of the mixer is 30-40 ℃, and the mixing time is 2-15 h. The mold material of the hydraulic machine is steel, the holding pressure is 600-700 MPa, the holding time is 30-40 s, and the machined rod is machined and threaded.

[0024] Step 4, the rod after pressing in step 3 is used as a consumable electrode and is put into a vacuum consumable arc smelting furnace, the arc starting material is placed at the bottom of the water-cooled copper crucible, the furnace door is closed, the required vacuum degree is extracted, and then the inert protective gas is filled. Turn on the power and adjust the current size, lower the consumable electrode to the top of the crucible, ignite the arc between the electrode and the crucible, start melting, and feed the consumable electrode at a low speed to stabilize the arc shape. At the same time, the built-in ultrasonic device is turned on before the consumable electrode starts to melt, the initial ultrasonic working frequency is 20 kHz, and the ultrasonic working frequency is increased with the increase of the depth of the molten pool in the crucible until the working frequency reaches 25 kHz and continues to act until the material completely solidifies.

[0025] In step 4, the arc starting material is copper foil, the vacuum degree of the smelting furnace is 10 -2 Pa, the inert gas is helium or argon; the height of the consumable electrode to the crucible is 5-15 mm, the low-speed feeding speed is 0.1-0.5 mm / s, the smelting current is 50-70 A, and the ultrasonic working frequency is 20-25 kHz.

[0026] Step 5, the Cr2Nb / Cu composite material obtained in step 4 is machined to the size of the consumable electrode, and then the threaded rod is used as a consumable electrode for smelting again, and the smelting is repeated for 3-6 times. The remaining material after machining can be reused.

[0027] Step 6, the Cr2Nb / Cu composite material obtained in step 5 is subjected to hot extrusion treatment, the holding temperature is 800-900℃, the holding time is 30-60 min, the extrusion cylinder temperature is 400-500℃, and the extrusion ratio is 9:1.

[0028] Example 1 Step 1, the Cu, Cr and Nb blocks are respectively subjected to ultrasonic cleaning for 10 min.

[0029] Step 2, the blocks are first coarsely crushed by a jaw crusher with an eccentric shaft rotating speed of 200 r / min and a discharge port size of 15 mm, and then finely crushed by a roll crusher with a roller rotating speed of 80 r / min, and after the second crushing, fine particles are formed. The particle sizes are screened to be: Cu particles of 1 mm, Cr particles of 700 μm, and Nb particles of 300 μm.

[0030] Step 3, the Cu, Cr and Nb particles are mixed in a mixer with a vacuum degree of -0.1 Pa for 8 h, the mixer rotating speed is 40 r / min, and the mixer temperature is 40℃, the Cr content is 1.7 wt.%, the Nb content is 1.4 wt.%, and the balance is copper, the total mass percentage of Cu, Cr and Nb is 100%. The mixed particles are placed in a steel mold and pressed into a rod required for the consumable electrode by a hydraulic press, the compacting pressure is 600 MPa, and the holding time is 35 s, and then the consumable electrode is processed by turning threads for subsequent use; Step 4, the rod after compacting in step 3 is loaded into a vacuum consumable arc melting furnace as a consumable electrode, a copper foil arc starter is placed at the bottom of a water-cooled copper crucible, the furnace door is closed, the vacuum degree is extracted to 10 -2 Pa, and then helium or argon inert gas is filled to a gas pressure of 0.1 Pa. The power is turned on, the current is adjusted to 50 A, the consumable electrode is lowered to 10 mm above the bottom of the crucible, the arc is ignited between the electrode and the crucible, after the melting starts, the consumable electrode is fed at a low speed of 0.2 mm / s, the arc shape is stabilized, and the arc shape is observed and adjusted at all times. At the same time, the built-in ultrasonic device is turned on before the consumable electrode starts to melt, the initial ultrasonic working frequency is 20 kHz, and as the depth of the molten pool in the crucible increases, the ultrasonic working frequency is continuously increased until the working frequency reaches 25 kHz, and the ultrasonic wave is always applied until the material completely solidifies.

[0031] Step 5, the Cr2Nb / Cu composite material obtained in the crucible in step 4 is processed to the size of the consumable electrode, the threads are turned, and then the consumable electrode is melted again, the melting is repeated 4 times, and the remaining material after machining can be reused.

[0032] Step 6, the Cr2Nb / Cu composite material obtained in step 5 is subjected to hot extrusion treatment, and the obtained Cr2Nb / Cu composite material is heated to 800 ℃ for 1 h and kept for 40 min before hot extrusion to homogenize the internal structure. The extrusion cylinder mold is heated to 400 ℃ and then the metal material is put in, and the 9:1 extrusion ratio process is used to prepare the Cr2Nb / Cu composite material by forward extrusion.

[0033] Example 2 In this embodiment, in step 2, the eccentric shaft rotation speed of the jaw crusher is 300 r / min, the discharge port size of the jaw crusher is 10 mm, and the roller rotation speed of the roller crusher is 50 r / min; the screened particle sizes are: Cu particles of 2 mm, Cr particles of 1000 μm, and Nb particles of 500 μm. In step 3, the mixing time is 15 h, the mixer rotation speed is 50 r / min, and the mixer temperature is 30 ℃, The hydraulic machine green compact pressure holding pressure is 700 MPa; the pressure holding time is 40 s; in step 4, the melting current is 70 A; the consumable electrode to crucible height is 15 mm, and the low speed feeding speed is 0.5 mm / s; in step 5, the melting is repeated for 3 times.

[0034] In step 6, the material heating temperature is 900 ℃, the extrusion cylinder mold temperature is 500 ℃, and the holding time is 30 min; the other steps are the same as in example 1.

[0035] The electrical property test and the mechanical property test of the 3.5% Cr2Nb / Cu composite material prepared in example 2 are performed, and the measured conductivity is 88.33% IACS, and the Brinell hardness is 99.5 HBW.

[0036] Example 3 In this embodiment, in step 2, the eccentric shaft rotation speed of the jaw crusher is 300 r / min, the discharge port size of the jaw crusher is 10 mm, and the roller rotation speed of the roller crusher is 50 r / min; the screened particle sizes are: Cu particles of 2 mm, Cr particles of 1000 μm, and Nb particles of 500 μm. In step 3, the mixing time is 15 h, the mixer rotation speed is 50 r / min, and the mixer temperature is 30 ℃,

[0037] Example 4 In this embodiment, the particle size screened in step 2 is: Cu particles of 2 mm, Cr particles of 1000 μm, and Nb particles of 500 μm. The particle content in step 3 is: Cr content of 3.4 wt.%, Nb content of 2.8 wt.%, and the balance being copper, with the total mass ratio of the three elements being 100%; the mixing time is 10 h, the speed of the mixer is 50 r / min; and the pressure holding pressure of the hydraulic press is 700 MPa. In step 4, the height of the consumable electrode to the crucible is 5 mm, the low-speed feeding speed is 0.1 mm / s, and the smelting current is 70 A. In step 6, the material heating temperature is 850 ℃, the extrusion cylinder mold temperature is 450 ℃, and the holding time is 60 min; and the other steps are the same as in Example 1.

[0038] The electrical property test and the mechanical property test of the 7%Cr2Nb / Cu composite material prepared in Example 4 are performed, and the conductivity is measured to be 82.47% IACS, and the Brinell hardness is measured to be 109 HBW. After vacuum consumable arc smelting, the tensile strength is measured to be 278 MPa, and the elongation is measured to be 35%; and after hot extrusion, the tensile strength is measured to be 336 MPa, and the elongation is measured to be 46%.

[0039] Example 5 In this embodiment, the particle size screened in step 2 is: Cu particles of 1 mm, Cr particles of 700 μm, and Nb particles of 300 μm. The particle content in step 3 is: Cr content of 4.8 wt.%, Nb content of 5.4 wt.%, and the balance being copper, with the total mass ratio of the three elements being 100%; the mixing time is 8 h, the speed of the mixer is 40 r / min; and the pressure holding pressure of the hydraulic press is 600 MPa. In step 4, the smelting current is 60 A. In step 6, the material heating temperature is 800 ℃, and the extrusion cylinder mold temperature is 400 ℃. The other steps are the same as in Example 1.

[0040] Example 6 In this embodiment, the particle size screened in step 2 is: Cu particles of 2 mm, Cr particles of 1000 μm, and Nb particles of 500 μm. The particle content in step 3 is: Cr content of 4.8 wt.%, Nb content of 5.4 wt.%, and the balance being copper, with the total mass ratio of the three elements being 100%; the mixing time is 10 h, the speed of the mixer is 50 r / min; and the pressure holding pressure of the hydraulic press is 700 MPa. In step 4, the smelting current is 70 A. In step 6, the material heating temperature is 900 ℃, and the extrusion cylinder mold temperature is 500 ℃. The other steps are the same as in Example 1.

[0041] The electrical property test and the mechanical property test of the 14%Cr2Nb / Cu composite material prepared in Example 6 are performed, and the conductivity is measured to be 76.12% IACS, and the Brinell hardness is measured to be 121 HBW.

[0042] Table 1 Performance of Cr2Nb / Cu composite materials with different contents

[0043] Figure 1 The self-consumption metal rod is prepared by a hydraulic machine, and the schematic diagram of the uniform distribution of different metal particles in the mold of the hydraulic machine is shown.

[0044] Figure 2 The preparation method flow chart of the Cr2Nb / Cu composite material prepared by the vacuum self-consumption arc melting is adopted, the process is simple, the processing time is shortened, and the processing efficiency is improved.

[0045] Figure 3 The microstructure morphology diagram of the 7% Cr2Nb / Cu composite material after the vacuum self-consumption arc melting of Example 4 is shown, and it can be seen from the diagram that the average size of the second phase of the prepared material is 2.8 μm, the size is small and the distribution is uniform.

[0046] Figure 4 The microstructure morphology diagram of the 7% Cr2Nb / Cu composite material in the vertical extrusion direction after the hot extrusion of Example 4 is shown.

[0047] Figure 5 The microstructure morphology diagram of the 7% Cr2Nb / Cu composite material in the parallel extrusion direction after the hot extrusion of Example 4 is shown.

[0048] Figure 6 The stress-strain curve of the 7% Cr2Nb / Cu composite material after the vacuum self-consumption arc melting and the hot extrusion of Example 4 is shown, and it can be seen from the diagram that the tensile strength and the elongation of the prepared material after the hot extrusion are improved.

[0049] The present application is based on self-consumption arc melting, adopts graded different sizes of Cu, Cr and Nb particles as raw materials, and is pressed into a self-consumption electrode by a cold press, improves the composition segregation problem, and greatly improves the processing efficiency; the solidification rate of the material is rapidly improved by using water-cooled copper mold, which hinders the ripening behavior of Cr2Nb particles; at the same time, ultrasonic assisted melting is used to refine the grains and improve the microstructure of the material; finally, the material is dynamically recrystallized by hot extrusion, further realizing grain refinement and improving the comprehensive mechanical properties of the material.

Claims

1. A method for preparing Cr2Nb / Cu composite materials by vacuum consumable arc melting, characterized in that: Specifically, the steps include the following: Step 1: The Cu, Cr and Nb blocks after ultrasonic cleaning are subjected to two crushing processes to screen Cu, Cr and Nb particles of different sizes. Step 2: Mix Cu, Cr and Nb particles, and press the mixed particles into a consumable electrode. Step 3: Melt the consumable electrode to obtain a Cr2Nb / Cu composite material; Step 4: Process the Cr2Nb / Cu composite material obtained in Step 3 into the size required for the consumable electrode, and continue to melt it again as a consumable electrode, repeating 3-6 times. Step 5: Densification treatment is carried out on the alloy obtained in Step 4 using different hot extrusion processes.

2. The method for preparing Cr2Nb / Cu composite materials by vacuum consumable arc melting according to claim 1, characterized in that: The specific process of step 1 is as follows: Cu blocks, Cr blocks and Nb blocks are coarsely crushed once by a jaw crusher, and then the raw materials are finely crushed twice by a roller crusher. After the second crushing, Cu, Cr and Nb particles of different sizes are screened.

3. The method for preparing Cr2Nb / Cu composite materials by vacuum consumable arc melting according to claim 2, characterized in that: In step 1, the eccentric shaft speed of the jaw crusher is 200-300 r / min, the discharge port size of the jaw crusher is 10-30 mm, and the roller speed of the double roll crusher is 50-150 r / min; the particle sizes to be screened are: Cu particles 1-2 mm, Cr particles 700-1000 μm, and Nb particles 300-500 μm.

4. The method for preparing Cr2Nb / Cu composite materials by vacuum consumable arc melting according to claim 3, characterized in that: The specific process of step 2 is as follows: Cu particles, Cr particles, and Nb particles are mixed in a mixer at the following mass percentages: Cr content is 1.7-6.8 wt.%, Nb content is 1.4-5.4 wt.%, and the remainder is Cu. The total mass ratio of Cu, Cr, and Nb is 100%. After mixing, the metal raw material is placed into a mold and pressed into a blank using a hydraulic press.

5. The method for preparing Cr2Nb / Cu composite materials by vacuum consumable arc melting according to claim 4, characterized in that: In step 2, Cu, Cr and Nb particles are mixed in a mixer at a speed of 40-50 r / min and a temperature of 30-40 ℃ for 2-15 h. The hydraulic press mold is made of steel, with a holding pressure of 600-700 MPa and a holding time of 30-40 s. After pressing, the blank is machined to cut threads.

6. The method for preparing Cr2Nb / Cu composite materials by vacuum consumable arc melting according to claim 5, characterized in that: The specific process of step 3 is as follows: The compressed bar from step 2 is used as a consumable electrode and placed in a vacuum consumable arc furnace. The ignition material is placed on the bottom of the crucible, and after evacuation, an inert protective gas is introduced. During melting, the consumable electrode is lowered above the crucible, and then an arc is ignited between the consumable electrode and the crucible. After ignition, the consumable electrode is fed at a low speed to gradually shorten the gap and stabilize the arc shape. The arc shape is constantly observed and adjusted during the process. Normal melting is carried out after a molten pool is observed to form on the crucible base. Before the alloy bar begins to melt, the built-in ultrasonic device is turned on. As the depth of the molten pool in the crucible increases, the ultrasonic working frequency is continuously increased until the working frequency reaches the preset value and continues to act until the alloy material is completely solidified. During solidification, a water-cooled copper crucible is used for cooling.

7. The method for preparing Cr2Nb / Cu composite materials by vacuum consumable arc melting according to claim 6, characterized in that: In step 3, the arc-igniting material is copper foil, the inert gas is helium or argon, the height from the consumable electrode to the crucible is 5-15 mm, the low-speed feed rate is 0.1-0.5 mm / s, the melting current is 50-70 A, and the ultrasonic working frequency is 20-25 kHz.

8. The method for preparing Cr2Nb / Cu composite materials by vacuum consumable arc melting according to claim 7, characterized in that: In step 4, the Cr2Nb / Cu composite material obtained in the crucible in step 3 is processed to the size of a consumable electrode, and after threading, it is melted again as a consumable electrode. The melting process is repeated 3-6 times.

9. The method for preparing Cr2Nb / Cu composite materials by vacuum consumable arc melting according to claim 8, characterized in that: In step 5, the Cr2Nb / Cu composite material obtained in step 4 is subjected to hot extrusion treatment, with a holding temperature of 800-900℃, a holding time of 30-60 min, an extrusion cylinder temperature of 400-500℃, and an extrusion ratio of 9:1.

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