Multi-level, multi-scale Cr2Nb / Cu composite materials and their preparation methods

Abstract

This invention discloses a method for preparing multi-level, multi-scale Cr2Nb / Cu composite materials: S1, Cu-Cr-Nb alloy is melted at high temperature to form a Cu-Cr-Nb ternary metal melt; subsequently, the Cu-Cr-Nb ternary metal melt is atomized to precipitate micron-scale Cr2Nb particles in one step, obtaining micron-scale Cr2Nb / Cu composite material powder; S2, the Cr2Nb / Cu composite material powder is subjected to gradient sintering using stepped current-assisted rapid hot pressing sintering. During high-temperature rapid hot pressing sintering, submicron-scale Cr2Nb particles are precipitated a second time, and during low-temperature rapid hot pressing sintering, nano-scale Cr2Nb particles are precipitated again, obtaining multi-level, multi-scale Cr2Nb / Cu composite materials. The method for preparing multi-level, multi-scale Cr2Nb / Cu composite materials provided by this invention solves the problem of matching ultra-high plasticity and strength of Cu-Cr-Nb alloys, achieving a synergistic improvement in the strength and plasticity of Cu-Cr-Nb alloys.

Description

Technical Field

[0001] This invention belongs to the field of copper-based composite material preparation technology, specifically relating to a method for preparing multi-level, multi-scale Cr2Nb / Cu composite materials. This invention also relates to multi-level, multi-scale Cr2Nb / Cu composite materials prepared using the above preparation method. Background Technology

[0002] With the rapid development of aerospace, energy, high-speed rail transportation and other fields, the performance requirements for copper-based materials have gradually evolved from the traditional high strength and high conductivity to high strength, high conductivity and heat resistance. That is, while ensuring excellent strength and electrical conductivity, it is necessary to have higher resistance to high temperature softening.

[0003] Cu-Cr-Nb alloys are widely used in high-temperature components such as the combustion chamber walls of rocket engines and the walls of the International Thermonuclear Experimental Reactor due to their excellent strength and resistance to high-temperature softening. This is mainly due to the formation of Cr2Nb precipitates in the Cu-Cr-Nb alloy. The Cr2Nb precipitates have a melting point as high as 1735 ℃ and exhibit excellent high-temperature strength and thermal stability.

[0004] However, the ultra-high plasticity requirements of Cu-Cr-Nb alloys under specific service conditions limit their widespread application. Numerous experimental studies have demonstrated that multi-scale microstructure design is a crucial means to achieve a synergistic improvement in the strength and plasticity of alloys. Therefore, a method for preparing multi-level, multi-scale Cr2Nb / Cu composite materials is urgently needed to achieve a synergistic improvement in the strength and plasticity of Cu-Cr-Nb alloys. Summary of the Invention

[0005] The first objective of this invention is to provide a method for preparing multi-level, multi-scale Cr2Nb / Cu composite materials, which solves the problem of matching the ultra-high plasticity and strength of Cu-Cr-Nb alloys and achieves a synergistic improvement in the strength and plasticity of Cu-Cr-Nb alloys.

[0006] The second objective of this invention is to provide a multi-level, multi-scale Cr2Nb / Cu composite material prepared using the above-described preparation method.

[0007] The first technical solution adopted in this invention is:

[0008] The preparation method of multi-level, multi-scale Cr2Nb / Cu composite material is as follows:

[0009] S1. The Cu-Cr-Nb alloy is melted at high temperature using vacuum induction melting technology to form a Cu-Cr-Nb ternary metal melt. Then, the Cu-Cr-Nb ternary metal melt is atomized and crushed, and micron-sized Cr2Nb particles are precipitated in one step during solidification to obtain micron-sized Cr2Nb / Cu composite powder.

[0010] S2. Gradient sintering of micron-sized Cr2Nb / Cu composite powder was carried out by step-current assisted rapid hot pressing sintering. First, high-temperature rapid hot pressing sintering was performed to precipitate submicron-sized Cr2Nb particles. Then, low-temperature rapid hot pressing sintering was performed to precipitate nano-sized Cr2Nb particles again, and finally, multi-level and multi-scale Cr2Nb / Cu composite material was prepared.

[0011] The invention is further characterized by:

[0012] The specific method for high-temperature melting of Cu-Cr-Nb alloy in S1 is as follows:

[0013] The Cu-Cr-Nb alloy was placed in the melting crucible of the atomization chamber, and the melting chamber was evacuated to 5.0 × 10⁻⁶ using a three-stage pump system. -3 Pa is heated to 1300 ℃~1700 ℃ by a medium-frequency induction heating system and held for 10 min~30 min to form a uniform Cu-Cr-Nb ternary metal melt.

[0014] The specific method for atomizing and crushing Cu-Cr-Nb ternary metal melt in S1 is as follows:

[0015] The inert gas atomization system is activated, and a tightly coupled annular atomizing nozzle is used to atomize and break up the Cu-Cr-Nb ternary metal melt under an atomizing gas pressure of 3 MPa to 5 MPa. The atomized droplets solidify rapidly during the high-speed cooling process, and micron-sized Cr2Nb particles are precipitated in one step, thereby obtaining micron-sized Cr2Nb / Cu composite powder.

[0016] The specific method for high-temperature rapid hot pressing sintering in S2 is as follows:

[0017] Micron-sized Cr2Nb / Cu composite powder was filled into a graphite mold and placed in an electric current-assisted rapid hot pressing sintering furnace; a three-stage pump evacuation system was used to evacuate the furnace to 10°C. -3 The temperature is set at Pa or below, heated to 850 ℃~950 ℃, and then axial pressure of 30 MPa~50 MPa is applied and held for 10 min~20 min, thereby causing submicron-scale Cr2Nb particles to precipitate again in the sintered billet.

[0018] The heating rate during high-temperature rapid hot pressing sintering in S2 is 50 ℃ / min ~ 100 ℃ / min.

[0019] The specific method for S2 low-temperature rapid hot pressing sintering is as follows:

[0020] After high-temperature rapid hot pressing sintering, the Cr2Nb / Cu composite ingot is cooled to 500~700℃ and held for 30 min~60 min, and then cooled to room temperature to obtain multi-level and multi-scale Cr2Nb / Cu composite material.

[0021] The cooling rate during the cooling process in the low-temperature rapid hot pressing sintering process is 40 ℃ / min ~ 50 ℃ / min.

[0022] The second technical solution adopted in this invention is:

[0023] The multi-level, multi-scale Cr2Nb / Cu composite material prepared according to the above preparation method has multi-level, multi-scale Cr2Nb particles of "micron-level + submicron-level + nano-level", wherein the micron-level Cr2Nb particles have a size of 1 μm ~ 2 μm, the submicron-level Cr2Nb particles have a size of 0.1 μm ~ 0.3 μm, and the nano-level Cr2Nb particles have a size of 10 nm ~ 50 nm.

[0024] The beneficial effects of this invention are:

[0025] This invention relates to a multi-level, multi-scale Cr2Nb / Cu composite material and its preparation method. It achieves multi-level, multi-scale Cr2Nb microstructure design and proposes a three-order temperature design strategy to create the multi-level, multi-scale Cr2Nb / Cu composite material. During the solidification of the molten metal, micron-sized Cr2Nb particles precipitate in the first stage; submicron-sized Cr2Nb particles precipitate in the second stage during high-temperature rapid hot pressing sintering; and nano-sized Cr2Nb particles precipitate again during low-temperature rapid hot pressing sintering. The micron-sized Cr2Nb particles generated during solidification pin grain boundaries, refine grains, and improve the strength and plasticity of the Cr2Nb / Cu composite material. The submicron-sized Cr2Nb particles help alleviate stress concentration and promote uniform deformation, mainly improving the plasticity of the Cr2Nb / Cu composite material. Meanwhile, the nano-sized Cr2Nb particles enhance the resistance to dislocation movement, mainly improving the strength of the Cr2Nb / Cu composite material. The multi-level, multi-scale Cr2Nb / Cu composite material prepared by this invention has excellent strength-plasticity matching, which solves the problem of matching ultra-high plasticity and strength of Cu-Cr-Nb alloy and significantly improves the comprehensive mechanical properties of Cu-Cr-Nb alloy. Attached Figure Description

[0026] Figure 1 The morphology of micron-sized Cr2Nb particles prepared in Example 3 of the multi-level, multi-scale Cr2Nb / Cu composite material and its preparation method of the present invention;

[0027] Figure 2 The morphology of submicron-sized Cr2Nb particles prepared in Example 3 of the multi-level, multi-scale Cr2Nb / Cu composite material and its preparation method of the present invention;

[0028] Figure 3 The morphology of nanoscale Cr2Nb particles prepared in Example 3 of the multi-level, multi-scale Cr2Nb / Cu composite material and its preparation method of the present invention. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0030] The preparation method of the multi-level, multi-scale Cr2Nb / Cu composite material of the present invention is as follows:

[0031] S1. The Cu-Cr-Nb alloy is melted at high temperature using vacuum induction melting technology to form a Cu-Cr-Nb ternary metal melt. Then, the Cu-Cr-Nb ternary metal melt is atomized and crushed, and micron-sized Cr2Nb particles are precipitated in one step during solidification to obtain micron-sized Cr2Nb / Cu composite powder.

[0032] Furthermore, the specific method for high-temperature smelting of the Cu-Cr-Nb alloy is as follows:

[0033] The Cu-Cr-Nb alloy was placed in the melting crucible of the atomization chamber, and the melting chamber was evacuated to 5.0 × 10⁻⁶ using a three-stage pump system. -3 At Pa, the temperature is raised to 1300℃~1700℃ using a medium-frequency induction heating system, and held for 10 min~30 min to form a uniform Cu-Cr-Nb ternary metal melt.

[0034] The specific method for atomizing and crushing Cu-Cr-Nb ternary metal melt is as follows:

[0035] An inert gas atomization system is activated, employing a tightly coupled annular atomizing nozzle. Under an atomizing gas pressure of 3 MPa to 5 MPa, the Cu-Cr-Nb ternary metal melt is atomized and broken up. The atomized droplets undergo rapid solidification during high-speed cooling, precipitating micron-sized Cr2Nb particles in one step, thereby obtaining micron-sized Cr2Nb / Cu composite powder. The micron-sized Cr2Nb / Cu composite powder includes the precipitated micron-sized Cr2Nb particles and a supersaturated copper-based solid solution, while the unprecipitated Cr and Nb are dissolved in the Cu matrix.

[0036] During the rapid solidification of the atomized droplets, micron-sized Cr2Nb particles are precipitated from the molten metal. Due to the high cooling rate during atomization, Cr and Nb in the powder do not completely react to form Cr2Nb particles, and the remaining Cr and Nb elements exist in the copper matrix as a supersaturated solid solution.

[0037] S2. Gradient sintering of micron-sized Cr2Nb / Cu composite powder using stepped current-assisted rapid hot pressing: First, the Cr2Nb / Cu composite powder is subjected to high-temperature rapid hot pressing sintering. During the high-temperature rapid hot pressing sintering process, submicron-sized Cr2Nb particles are precipitated again in the supersaturated copper-based solid solution. Since the copper matrix still contains incompletely precipitated Cr and Nb during the high-temperature rapid hot pressing sintering process, low-temperature rapid hot pressing sintering is then performed. During the low-temperature rapid hot pressing sintering process, nano-sized Cr2Nb particles are precipitated again, resulting in a multi-level, multi-scale Cr2Nb / Cu composite material.

[0038] The specific method for secondary precipitation of submicron-scale Cr2Nb particles by high-temperature rapid hot-pressing sintering is as follows:

[0039] Micron-sized Cr2Nb / Cu composite powder was filled into a graphite mold and placed in an electric current-assisted rapid hot pressing sintering furnace; a three-stage pump evacuation system was used to evacuate the furnace to 10°C. -3 The material is heated to 850 ℃~950 ℃ at a heating rate of 50 ℃ / min~100 ℃ / min, and then an axial pressure of 30 MPa~50 MPa is applied and held for 10 min~20 min, thereby causing submicron-sized Cr2Nb particles to precipitate again in the sintered billet.

[0040] The specific method for precipitating nanoscale Cr2Nb particles by low-temperature rapid hot-pressing sintering is as follows:

[0041] After high-temperature rapid hot pressing sintering, the temperature is then reduced to 500~700 ℃ at a rate of 40 ℃ / min~50 ℃ / min, held for 30 min~60 min, and then cooled to room temperature to obtain a multi-level, multi-scale Cr2Nb / Cu composite material.

[0042] The present invention provides a multi-level, multi-scale Cr2Nb / Cu composite material prepared by the above preparation method. The multi-level, multi-scale Cr2Nb / Cu composite material simultaneously possesses "micron-level + submicron-level + nano-level" multi-level, multi-scale Cr2Nb particles, wherein the micron-level Cr2Nb particles have a size of 1 μm to 2 μm, the submicron-level Cr2Nb particles have a size of 0.1 μm to 0.3 μm, and the nano-level Cr2Nb particles have a size of 10 nm to 50 nm.

[0043] This invention relates to a multi-level, multi-scale Cr2Nb / Cu composite material and its preparation method. By rationally designing the powder metallurgy preparation process and heat treatment regime, and controlling the precipitation kinetics of the Cr2Nb phase at different temperatures, a multi-level, multi-scale Cr2Nb / Cu composite material of "micron-scale + submicron-scale + nano-scale" was successfully prepared.

[0044] Using Cu-Cr-Nb alloy as raw material, a Cu-Cr-Nb ternary metal melt was obtained through vacuum induction melting. The high-temperature melt was then atomized to prepare micron-sized Cr2Nb particle-reinforced Cu-based composite material powder. Due to the high cooling rate during atomization, Cr and Nb in the powder did not completely react to form Cr2Nb particles; the remaining Cr and Nb elements existed in the copper matrix as supersaturated solid solutions. Further, step-current assisted rapid hot pressing sintering was used to simultaneously densify the composite powder and precipitate submicron-sized and nano-sized Cr2Nb particles in the matrix.

[0045] The micron-sized Cr2Nb particles generated during solidification pin grain boundaries, refine the grains, and improve the strength and plasticity of the Cr2Nb / Cu composite material. Submicron-sized Cr2Nb particles help alleviate stress concentration and promote uniform deformation, primarily improving the plasticity of the Cr2Nb / Cu composite material. Meanwhile, nanoscale Cr2Nb particles enhance dislocation movement resistance, mainly improving the strength of the Cr2Nb / Cu composite material. The multi-level, multi-scale Cr2Nb / Cu composite material prepared by this invention exhibits excellent strength-plasticity matching, solving the problem of matching ultra-high plasticity and strength in Cu-Cr-Nb alloys, and significantly improving the comprehensive mechanical properties of Cu-Cr-Nb alloys.

[0046] The multi-level, multi-scale microstructure of Cr2Nb prepared by this invention helps to solve the problem of matching ultra-high plasticity and strength in Cu-Cr-Nb alloys.

[0047] Example 1

[0048] The preparation method of the multi-level, multi-scale Cr2Nb / Cu composite material in this embodiment is as follows:

[0049] Step 1: Place the Cu-Cr-Nb alloy into the melting crucible of the atomization chamber, and use a three-stage pump system to evacuate the melting chamber to a vacuum level of 5.0 × 10⁻⁶. -3 At a pressure of 3 MPa, the melting temperature was raised to 1300 °C using a medium-frequency induction heating system and held for 10 min to form a uniform Cu-Cr-Nb ternary metal melt. Subsequently, an inert gas atomization system was activated, employing a tightly coupled annular atomizing nozzle to atomize and break up the Cu-Cr-Nb ternary metal melt under an atomizing gas pressure of 3 MPa. During rapid cooling, the atomized droplets solidified quickly, precipitating micron-sized Cr2Nb particles in the metal melt in a single step, thus forming micron-sized Cr2Nb / Cu composite powder.

[0050] Step 2: First, the micron-sized Cr2Nb / Cu composite powder prepared in Step 1 is filled into a graphite mold and placed in an electric current-assisted rapid hot pressing sintering furnace. Next, a three-stage pump system is used to evacuate the furnace to 10... -3 The sintered ingot was heated to 850 °C at a heating rate of 50 °C / min. Then, an axial pressure of 30 MPa was applied, and the ingot was held for 10 min to induce secondary precipitation of submicron-sized Cr₂Nb particles. Finally, the ingot was cooled to 500 °C at a cooling rate of 40 °C / min, held for 30 min, and then cooled to room temperature to induce the re-precipitation of nano-sized Cr₂Nb particles, resulting in a multi-level, multi-scale Cr₂Nb / Cu composite material.

[0051] Example 2

[0052] The preparation method of the multi-level, multi-scale Cr2Nb / Cu composite material in this embodiment is as follows:

[0053] Step 1: Place the Cu-Cr-Nb alloy into the melting crucible of the atomization chamber, and use a three-stage pump system to evacuate the melting chamber to a vacuum level of 5.0 × 10⁻⁶. -3 At a pressure of 4 MPa, the melting temperature was raised to 1700 ℃ using a medium-frequency induction heating system and held for 20 min to form a uniform Cu-Cr-Nb ternary metal melt. Subsequently, an inert gas atomization system was activated, employing a tightly coupled annular atomizing nozzle to atomize and break up the Cu-Cr-Nb ternary metal melt under an atomizing gas pressure of 4 MPa. During rapid cooling, the atomized droplets solidified quickly, precipitating micron-sized Cr2Nb particles in the metal melt in a single step, thus forming micron-sized Cr2Nb / Cu composite powder.

[0054] Step 2: First, the micron-sized Cr2Nb / Cu composite powder prepared in Step 1 is filled into a graphite mold and placed in an electric current-assisted rapid hot pressing sintering furnace. Next, a three-stage pump system is used to evacuate the furnace to 10... -3 The ingot was heated to 900 °C at a heating rate of 100 °C / min. Then, an axial pressure of 50 MPa was applied, and the ingot was held for 20 min to induce secondary precipitation of submicron-sized Cr2Nb particles. Finally, the ingot was cooled to 700 °C at a cooling rate of 50 °C / min, held for 40 min, and then cooled to room temperature to induce the re-precipitation of nano-sized Cr2Nb particles, resulting in a multi-level, multi-scale Cr2Nb / Cu composite material.

[0055] Example 3

[0056] The preparation method of the multi-level, multi-scale Cr2Nb / Cu composite material in this embodiment is as follows:

[0057] Step 1: Place the Cu-Cr-Nb alloy into the melting crucible of the atomization chamber, and use a three-stage pump system to evacuate the melting chamber to a vacuum level of 5.0 × 10⁻⁶. -3 The melting temperature was raised to 1600 °C using a medium-frequency induction heating system and held for 30 min to form a uniform Cu-Cr-Nb ternary metal melt. Subsequently, an inert gas atomization system was activated, employing a tightly coupled annular atomizing nozzle, to atomize and break up the Cu-Cr-Nb ternary metal melt at a gas pressure of 5 MPa. During rapid cooling, the atomized droplets solidified quickly, precipitating micron-sized Cr2Nb particles in the metal melt, thus forming micron-sized Cr2Nb / Cu composite powder.

[0058] Step 2: First, the micron-sized Cr2Nb / Cu composite powder prepared in Step 1 is filled into a graphite mold and placed in an electric current-assisted rapid hot pressing sintering furnace. Next, a three-stage pump system is used to evacuate the furnace to 10... -3 The ingot was heated to 950 °C at a heating rate of 75 °C / min. Then, an axial pressure of 40 MPa was applied, and the ingot was held for 15 min to induce secondary precipitation of submicron-sized Cr2Nb particles. Finally, the ingot was cooled to 600 °C at a cooling rate of 45 °C / min, held for 60 min, and then cooled to room temperature to induce the re-precipitation of nano-sized Cr2Nb particles, resulting in a multi-level, multi-scale Cr2Nb / Cu composite material.

[0059] Example 4

[0060] The preparation method of the multi-level, multi-scale Cr2Nb / Cu composite material in this embodiment is as follows:

[0061] Step 1: Place the Cu-Cr-Nb alloy into the melting crucible of the atomization chamber, and use a three-stage pump system to evacuate the melting chamber to a vacuum level of 5.0 × 10⁻⁶. -3 The melting temperature was raised to 1400 °C using a medium-frequency induction heating system and held for 15 min to form a uniform Cu-Cr-Nb ternary metal melt. Subsequently, an inert gas atomization system was activated, employing a tightly coupled annular atomizing nozzle to atomize and break up the Cu-Cr-Nb ternary metal melt at an atomizing gas pressure of 3.5 MPa. During rapid cooling, the atomized droplets solidified quickly, precipitating micron-sized Cr2Nb particles in the metal melt in a single step, thus forming micron-sized Cr2Nb / Cu composite powder.

[0062] Step 2: First, the micron-sized Cr2Nb / Cu composite powder prepared in Step 1 is filled into a graphite mold and placed in an electric current-assisted rapid hot pressing sintering furnace. Next, a three-stage pump system is used to evacuate the furnace to 10... -3The ingot was heated to 900 °C at a heating rate of 60 °C / min. Then, an axial pressure of 45 MPa was applied, and the ingot was held for 18 min, resulting in secondary precipitation of submicron-sized Cr2Nb particles in the sintered ingot. Finally, the ingot was cooled to 650 °C at a cooling rate of 45 °C / min, held for 60 min, and then cooled to room temperature, causing nano-sized Cr2Nb particles to precipitate again in the sintered ingot, yielding a multi-level, multi-scale Cr2Nb / Cu composite material.

[0063] Example 5

[0064] The preparation method of the multi-level, multi-scale Cr2Nb / Cu composite material in this embodiment is as follows:

[0065] Step 1: Place the Cu-Cr-Nb alloy into the melting crucible of the atomization chamber, and use a three-stage pump system to evacuate the melting chamber to a vacuum level of 5.0 × 10⁻⁶. -3 The melting temperature was raised to 1500 °C using a medium-frequency induction heating system and held for 25 min to form a uniform Cu-Cr-Nb ternary metal melt. Subsequently, an inert gas atomization system was activated, employing a tightly coupled annular atomizing nozzle to atomize and break up the Cu-Cr-Nb ternary metal melt at a gas pressure of 4.5 MPa. The atomized droplets rapidly solidified during high-speed cooling, precipitating micron-sized Cr2Nb particles in the metal melt in a single step, thus forming micron-sized Cr2Nb / Cu composite powder.

[0066] Step 2: First, the micron-sized Cr2Nb / Cu composite powder prepared in Step 1 is filled into a graphite mold and placed in an electric current-assisted rapid hot pressing sintering furnace. Next, a three-stage pump system is used to evacuate the furnace to 10... -3 The ingot was heated to 900 °C at a heating rate of 90 °C / min. Then, an axial pressure of 35 MPa was applied, and the ingot was held for 15 min, resulting in secondary precipitation of submicron-sized Cr2Nb particles in the sintered ingot. Finally, the ingot was cooled to 500 °C at a cooling rate of 42 °C / min, held for 50 min, and then cooled to room temperature, causing nano-sized Cr2Nb particles to precipitate again in the sintered ingot, yielding a multi-level, multi-scale Cr2Nb / Cu composite material.

[0067] Example 6

[0068] The preparation method of the multi-level, multi-scale Cr2Nb / Cu composite material in this embodiment is as follows:

[0069] Step 1: Place the Cu-Cr-Nb alloy into the melting crucible of the atomization chamber, and use a three-stage pump system to evacuate the melting chamber to a vacuum level of 5.0 × 10⁻⁶. -3The melting temperature was raised to 1550 °C using a medium-frequency induction heating system and held for 30 min to form a uniform Cu-Cr-Nb ternary metal melt. Subsequently, an inert gas atomization system was activated, employing a tightly coupled annular atomizing nozzle to atomize and break up the Cu-Cr-Nb ternary metal melt at a gas pressure of 4 MPa. During rapid cooling, the atomized droplets solidified quickly, precipitating micron-sized Cr2Nb particles in the metal melt, thus forming micron-sized Cr2Nb / Cu composite powder.

[0070] Step 2 is the same as in Example 1, resulting in a multi-level, multi-scale Cr2Nb / Cu composite material.

[0071] Figure 1 This figure shows the morphology of micron-sized Cr2Nb particles precipitated during the atomization of Cu-Cr-Nb ternary metal melt in inert gas according to Embodiment 3 of the present invention. As can be seen from the figure, the Cr2Nb particles are spherical with a size of 1μm to 2μm.

[0072] Figure 2 This figure shows the morphology of submicron-sized Cr2Nb particles that precipitated secondary during high-temperature rapid hot-pressing sintering in Example 3 of the present invention. As can be seen from the figure, the Cr2Nb particle size is 0.1 μm ~ 0.3 μm.

[0073] Figure 3 This figure shows the morphology of nano-sized Cr2Nb particles that were re-precipitated during low-temperature rapid hot-pressing sintering in Example 3 of the present invention. As can be seen from the figure, the size of the Cr2Nb particles is 10 nm to 50 nm.

[0074] As can be seen from the figure above, the multi-level, multi-scale Cr2Nb / Cu composite material prepared by the method of this application can simultaneously possess Cr2Nb particles of different sizes. The multi-level, multi-scale Cr2Nb microstructure characteristics prepared by this invention help to solve the problem of matching ultra-high plasticity and strength of Cu-Cr-Nb alloy.

[0075] Comparative Example 1

[0076] The comparative method for preparing CuCrNb alloy by rapid hot pressing sintering is as follows:

[0077] S1. Place Cr blocks and Nb blocks in a CaO crucible for vacuum induction melting. Fill the melting furnace with nitrogen gas. Start melting when the furnace pressure reaches 0.015 MPa. The heating rate is 10 KW / min and the melting power is 300 KW. Cr2Nb alloy is obtained.

[0078] S2. The Cr2Nb alloy is subjected to vacuum atomization treatment in an argon environment with a gas pressure of 2.5 MPa and a feed rate of 50 mm / min, and solidified into Cr2Nb powder at a cooling rate of 110 K / s.

[0079] S3. The obtained blank is placed in a rapid hot pressing sintering furnace for sintering. First, the temperature is raised from room temperature to 725°C within 13 minutes and held for 10 minutes; then the temperature is raised to 925°C within 8 minutes and held for 8 minutes to obtain the sintered alloy.

[0080] S4. The sintered alloy obtained in step S3 is subjected to solution aging treatment in a tube furnace under Ar protective atmosphere to obtain CuCrNb alloy. The solution treatment temperature is 750 ℃, the heating time is 1.5 h, the holding time is 1.2 h, and the alloy is cooled by water quenching. The aging treatment temperature is 450 ℃, the heating time is 0.8 h, the holding time is 1.8 h, and the alloy is cooled with the furnace.

[0081] Compared with Example 1, the Cu-Cr-Nb alloy obtained in Comparative Example 1 has a uniformly distributed Cr2Nb reinforcing phase, and cannot obtain the multi-level, multi-scale Cr2Nb / Cu composite material with different sizes of Cr2Nb in this application.

[0082] Comparative Example 2

[0083] The preparation method of this comparative high-strength and high-conductivity Cu-Cr-Zr-Nb alloy is as follows:

[0084] S1. Preparation of Cu-Cr-Zr-Nb alloy ingots by vacuum casting: The composition of the Cu-Cr-Zr-Nb alloy is controlled as follows: 0.93 wt.% Cr, 0.15 wt.% Cr, 0.15 wt.% Zr, with the balance being Cu; the melting power is 100 KW, and the vacuum degree is 6.6 × 10⁻⁶. -2 Pa, melting temperature is 1700 ℃.

[0085] S2. Hot forging of the melted and cast Cu-Cr-Zr-Nb alloy ingot; furnace loading temperature is 750 ℃, holding temperature is 910 ℃, holding time is 80 min, and final forging temperature is 650 ℃.

[0086] S3. The hot-forged Cu-Cr-Zr-Nb alloy ingot is subjected to solution treatment; the solution temperature is 980 ℃ and the holding time is 1 h.

[0087] S4. The Cu-Cr-Zr-Nb alloy casting after solution treatment is cold forged, with a deformation of 37.5%.

[0088] S5. The cold-forged Cu-Cr-Zr-Nb alloy ingot is subjected to aging treatment.

[0089] Compared with Example 1, the Cu-Cr-Zr-Nb alloy obtained in Comparative Example 1 has a uniformly distributed and extremely low content of the Cr2Nb reinforcing phase, which cannot produce the multi-level, multi-scale Cr2Nb / Cu composite material with high content of Cr2Nb of different sizes as described in this application. Furthermore, Cr particles readily precipitate in Cu-Cr-Zr-Nb, and their high-temperature thermal stability is significantly lower than that of Cr2Nb particles. Therefore, the high-temperature performance of the Cu-Cr-Zr-Nb alloy prepared in Comparative Example 1 is lower than that of the multi-level, multi-scale Cr2Nb / Cu composite material prepared in this application.

Claims

1. A method for preparing multi-level, multi-scale Cr2Nb / Cu composite materials, characterized in that, The specific method is as follows: S1. The Cu-Cr-Nb alloy is melted at high temperature using vacuum induction melting technology to form a Cu-Cr-Nb ternary metal melt. Then, the Cu-Cr-Nb ternary metal melt is atomized and crushed, and micron-sized Cr2Nb particles are precipitated in one step during solidification to obtain micron-sized Cr2Nb / Cu composite powder. S2. Gradient sintering of micron-sized Cr2Nb / Cu composite powder was carried out by step-current assisted rapid hot pressing sintering. First, high-temperature rapid hot pressing sintering was performed to precipitate submicron-sized Cr2Nb particles. Then, low-temperature rapid hot pressing sintering was performed to precipitate nano-sized Cr2Nb particles again. Finally, multi-level and multi-scale Cr2Nb / Cu composite material was prepared. The specific method for high-temperature rapid hot-pressing sintering in S2 is as follows: The micron-sized Cr2Nb / Cu composite material powder is filled into a graphite mold and placed into a current-assisted rapid hot-pressing sintering furnace; a three-stage pump pumping system is used to pump vacuum to 10 -3 Pa and below, heated to 850°C~950 ℃, then an axial pressure of 30 MPa ~50 MPa is applied, and heat preservation is performed for 10 min ~20 min, thereby secondarily precipitating sub-micron-sized Cr2Nb particles in the sintered billet. The heating rate during the high-temperature rapid hot pressing sintering is 50 ℃ / min ~ 100 ℃ / min; The specific method for low-temperature rapid hot pressing sintering in S2 is as follows: After high-temperature rapid hot pressing sintering, the temperature is then lowered to 500~700 ℃, held for 30 min~60 min, and then cooled to room temperature to obtain multi-level multi-scale Cr2Nb / Cu composite material. The multi-level, multi-scale Cr2Nb / Cu composite material simultaneously possesses "micron-level + submicron-level + nano-level" multi-level, multi-scale Cr2Nb particles.

2. The method for preparing the multi-level, multi-scale Cr2Nb / Cu composite material according to claim 1, characterized in that, The specific method for high-temperature melting of the Cu-Cr-Nb alloy in S1 is as follows: The Cu-Cr-Nb alloy is placed into a smelting crucible of an atomization chamber, and a three-stage pump suction system is used to vacuumize the smelting chamber to 5.0*10 -3 Pa, and the Cu-Cr-Nb alloy is heated to 1300 ℃-1700 ℃ by a medium-frequency induction heating system, and the holding time is 10 min-30 min, so that a uniform Cu-Cr-Nb ternary metal melt is formed.

3. The method for preparing the multi-level, multi-scale Cr2Nb / Cu composite material according to claim 1, characterized in that, The specific method for atomizing and crushing the Cu-Cr-Nb ternary metal melt in S1 is as follows: The inert gas atomization system is activated, and a tightly coupled annular atomizing nozzle is used to atomize and break up the Cu-Cr-Nb ternary metal melt under an atomizing gas pressure of 3MPa~5MPa. The atomized droplets solidify rapidly during the high-speed cooling process, and micron-sized Cr2Nb particles are precipitated in one step, thereby obtaining micron-sized Cr2Nb / Cu composite powder.

4. The method for preparing the multi-level, multi-scale Cr2Nb / Cu composite material according to claim 1, characterized in that, The cooling rate during the cooling process in the low-temperature rapid hot pressing sintering process is 40 ℃ / min ~ 50 ℃ / min.

5. The multi-level, multi-scale Cr2Nb / Cu composite material prepared by any one of the preparation methods described in claims 1 to 4, wherein the multi-level, multi-scale Cr2Nb / Cu composite material simultaneously possesses "micron-level + submicron-level + nano-level" multi-level, multi-scale Cr2Nb particles, wherein the micron-level Cr2Nb particles have a size of 1 μm to 2 μm, the submicron-level Cr2Nb particles have a size of 0.1 μm to 0.3 μm, and the nano-level Cr2Nb particles have a size of 10 nm to 50 nm.

Images