Copper-titanium alloy and preparation method thereof

Abstract

The invention provides a preparation method of a copper-titanium alloy, which comprises the following steps: S1, mixing copper particles and TiH2 powder according to the composition proportion of the copper-titanium alloy, and forming the TiH2 powder on the surfaces of the copper particles to obtain composite copper particles; s2, the composite copper particles are placed in a crucible, and a directional solidification furnace is vacuumized and then filled with carbon-containing reducing gas; and S3, the crucible in the step S2 is heated so that the composite copper particles can reach the melting temperature, then the crucible is immersed into a cooling medium to be subjected to directional solidification cooling, and the copper-titanium alloy is obtained. The invention further provides the copper-titanium alloy prepared through the preparation method. According to the preparation method provided by the invention, TiH2 micro powder is uniformly adhered to the surfaces of copper particles in a mixing manner, and then directional solidification and cooling of the composite copper particles are carried out under micro-negative-pressure reducing gas; the copper-titanium alloy obtained by the process weakens the negative influence of titanium on the conductivity of copper, so that the copper-titanium alloy has the advantages of strength and conductivity.

Description

Technical Field

[0001] This invention relates to the field of high-strength, high-conductivity materials technology, and in particular to a copper-titanium alloy and its preparation method. Background Technology

[0002] With the continuous improvement of product performance and the development of functional segmentation in the fields of electrical, communication and electronic devices, the demand for conductive materials has shifted from pursuing high conductivity to comprehensive optimization of multiple properties, specifically focusing on the synergistic control of mechanical properties and electrical conductivity, which is usually manifested as strength improvement while maintaining a high level of electrical conductivity.

[0003] From a performance perspective, copper-beryllium alloys are typical materials that meet this requirement. However, they suffer from high production costs, high toxicity during manufacturing, and difficulties in recycling and disposal. Therefore, the production and use of copper-beryllium alloys have been gradually restricted. Copper-titanium alloys are considered the most promising alternatives to copper-beryllium alloys. Copper-titanium alloys combine the effects of Ti solid solution and precipitation strengthening in copper alloys. The effect of Ti is mainly reflected in improving mechanical properties. When added in small amounts, it dissolves in the copper lattice through atomic substitution, generating lattice distortion energy and slightly increasing the alloy strength. When the addition amount is greater than the solid solubility, reinforcing phase structures such as Cu4Ti and Cu3Ti precipitate, significantly improving the alloy strength. However, Ti is detrimental to maintaining the material's electrical conductivity. Its large atomic radius causes significant volume distortion in the copper lattice, increasing the difficulty of electron migration. Furthermore, the further precipitated strengthening phases are distributed at the grain boundaries of copper grains, hindering electron transport and causing a sharp decrease in the alloy's electrical conductivity, generally below 20% IACS. The aforementioned difficulty in balancing electrical conductivity and mechanical properties severely restricts the development and use of copper-titanium alloys.

[0004] Currently, the modification and improvement of copper-titanium alloys often involve adding other alloying elements to transform them into multi-element alloy systems. For example, adding elements such as Sn, Ni, and Al, which have a relatively small impact on the electrical conductivity of Cu, can replace part of the solid solution of Ti in the copper lattice. This reduces the difficulty of electron scattering and migration caused by lattice distortion, resulting in a slight improvement in the electrical conductivity of the alloy material (still below 30% IACS). However, this also leads to a decrease in the strength of the alloy due to the weakening of the copper lattice distortion energy.

[0005] Therefore, it is of great significance to provide a method for preparing copper-titanium alloys that simultaneously possess both mechanical properties and electrical conductivity. Summary of the Invention

[0006] The technical problem solved by this invention is to provide a method for preparing copper-titanium alloys, which improves strength while maintaining high electrical conductivity.

[0007] In view of this, this application also provides a method for preparing a copper-titanium alloy, comprising the following steps:

[0008] S1. Copper particles and TiH2 powder are mixed according to the composition ratio of copper-titanium alloy, so that TiH2 powder is formed on the surface of copper particles to obtain composite copper particles; the particle size of TiH2 powder is from micrometer to nanometer, and the particle size of copper particles is millimeter.

[0009] S2. Place the composite copper particles in a crucible, evacuate the directional solidification furnace, and then fill it with a carbon-containing reducing gas.

[0010] S3. The crucible from step S2 is heated to bring the composite copper particles to their melting temperature. The crucible is then immersed in a cooling medium for directional solidification cooling to obtain a copper-titanium alloy, wherein the copper-titanium alloy includes Cu. x Ti phase.

[0011] In some specific embodiments, in step S1, the TiH2 powder has a particle size of 1~2μm, and the copper particles have a diameter of 1~5mm and a length of 2~3mm.

[0012] In some specific embodiments, in step S1, the mixing time is ≥12h, and the mixing is carried out in a pendulum mixer, a high-speed ball mixer, or an axial rotary mixer.

[0013] In some specific embodiments, in step S2, the crucible is a copper-bottomed graphite crucible, and the volume ratio of the copper-bottomed graphite crucible to the volume of the graphite in the crucible wall is (0.3~2):1.

[0014] In some specific embodiments, in step S2, the vacuum level after evacuation is 0.3*10. -3 ~0.8*10 -3 Pa, and / or, the carbon-containing reducing gas is a mixture of hydrogen and methane, wherein the partial pressure ratio of hydrogen to methane is 1:(4~5).

[0015] In some specific embodiments, in step S3, the heating is induction heating, the distance between the heating coil of the induction heating and the outer wall of the crucible is 3~8mm, and / or the cooling medium is gallium or gallium-indium alloy.

[0016] In some specific embodiments, in step S3, the descent speed of the crucible for directional solidification cooling is 0.1~0.6 mm / s.

[0017] In some specific embodiments, in step S3, the crucible wall temperature at which the melting temperature is reached is 1100~1600℃.

[0018] This application also provides a copper-titanium alloy prepared by the preparation method described above.

[0019] In some specific embodiments, the titanium content in the copper-titanium alloy is 0.5~5.0 wt%.

[0020] This application provides a method for preparing a copper-titanium alloy. First, copper particles and TiH2 powder are mixed according to the composition ratio of the copper-titanium alloy, causing the TiH2 powder to form on the surface of the copper particles. Then, the resulting composite copper particles are placed in a crucible. A directional solidification furnace is evacuated and then filled with a carbon-containing reducing gas. The crucible is then heated to bring the composite copper particles to their melting temperature. Finally, the crucible is immersed in a cooling medium for directional solidification cooling to obtain the copper-titanium alloy. In this method, the addition of copper particles and TiH2 powder allows the TiH2 powder to adsorb onto the surface of the copper particles, ensuring uniform Ti distribution while allowing for precise control of the addition amount. This avoids the problem of excessive Ti addition reducing electrical conductivity. Furthermore, during directional solidification, the solid solution of C reduces the solid solution of Ti, promoting the formation of nanoclusters and Cu. x The precipitation of strengthening phases such as Ti phase structure significantly improves the strength of copper-titanium alloy while effectively reducing conductivity loss, ultimately enabling the copper-titanium alloy to maintain a high level of electrical conductivity while improving strength. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the apparatus for preparing the copper-titanium alloy according to the present invention;

[0022] Figure 2 This is a photograph of the composite particles obtained by mixing copper particles and TiH2 powder in Example 1 of the present invention.

[0023] Figure 3 Optical microscope image (left) and scanning electron microscope image (right) of the copper-titanium alloy prepared in Example 1 of the present invention.

[0024] Figure 4 Here are high-magnification scanning electron microscope images and elemental energy dispersive spectroscopy (EDS) spectra of the copper-titanium alloy prepared in Example 1 of this invention;

[0025] Figure 5 Cu, the copper-titanium alloy prepared in Example 1 of this invention x Surface scan spectrum of elements in the Ti phase and adjacent regions. Detailed Implementation

[0026] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0027] Given that existing copper-titanium alloys cannot simultaneously possess both strength and electrical conductivity, this application provides a method for preparing a copper-titanium alloy. The method involves uniformly adhering TiH2 powder to the surface of copper particles using a mixing process, followed by directional melting and solidification of the composite copper particles in a liquid-cooled crucible under a slightly negative pressure carbon-containing reducing gas. In this process, a copper-titanium alloy is prepared by synergistic addition of C and Ti. The interstitial solid solution of C only causes minor distortion of the copper lattice and does not significantly affect electron transport. Simultaneously, the solid solution sites of C compress the precipitation of Ti, allowing Cu to precipitate from Ti at a relatively low addition level. x Ti-reinforced phases and nanoclusters effectively improve the mechanical properties of copper-titanium alloys while ensuring high electrical conductivity. Specifically, this invention discloses a method for preparing a copper-titanium alloy, comprising the following steps:

[0028] S1. Copper particles and TiH2 powder are mixed according to the composition ratio of copper-titanium alloy, so that TiH2 powder is formed on the surface of copper particles to obtain composite copper particles; the particle size of TiH2 powder is from micrometer to nanometer, and the particle size of copper particles is millimeter.

[0029] S2. Place the composite copper particles in a crucible, evacuate the directional solidification furnace, and then fill it with a carbon-containing reducing gas.

[0030] S3. The crucible from step S2 is heated to bring the composite copper particles to their melting temperature. The crucible is then immersed in a cooling medium for directional solidification cooling to obtain a copper-titanium alloy, wherein the copper-titanium alloy includes Cu. x Ti phase.

[0031] In the preparation method of copper-titanium alloy, in step S1, copper particles and TiH2 powder are mixed according to the composition ratio of copper-titanium alloy, so that TiH2 powder forms on the surface of copper particles to obtain composite copper particles; in the above process, the particle size of copper particles is on the millimeter scale, further, the copper particles are regular or nearly regular in shape, such as cylindrical or spherical, and even further, the diameter of the copper particles is 1~5mm and the length is 2~3mm; the size of copper particles determines their surface area and specific surface area (S). 表面The amount of TiH2 powder adsorbed on the surface is also determined by the particle size ( / V). The particle size of TiH2 powder ranges from micrometers to nanometers, with good size uniformity. Specifically, the particle size of the TiH2 powder is 1~2μm. The above-mentioned small-particle-size TiH2 powder can rapidly decompose into Ti and H during the smelting process. Moreover, the small particle size has the advantage of high elemental dispersion uniformity during raw material mixing and melting. H, as a reducing agent, can also weaken the oxidation during the mixing process and reduce the oxygen element in the material, further improving the purity of the material. Furthermore, after the copper particles and the TiH2 powder are mixed, the amount of TiH2 powder that can adhere to the surface of the copper particles is fixed. Thus, the mass ratio of Ti to copper (i.e., the fixed amount of Ti added) can be quantitatively controlled. The smaller the size of the copper particles, the greater the amount of Ti added. The change in the amount of Ti added is adjusted by the mixing ratio of copper particles of different sizes. In this application, the mass ratio of Cu to Ti is determined by changing the size of the copper particles while keeping the particle size of TiH2 powder constant. The larger the size of the copper particles, the smaller the specific surface area, and the less TiH2 powder can adhere after mixing.

[0032] The mixing of the copper particles and the TiH2 powder can be carried out in a sealed container to avoid oxidation of the copper particles during the mixing process. The mixing equipment can be a pendulum mixer, a high-speed ball mixer, or an axial rotary mixer. In a specific embodiment, the mixing equipment is a pendulum mixer, and the mixing time is ≥12 hours, specifically 13~16 hours. The above mixing is a process of collision and stirring between copper particles and TiH2 powder. The copper particles with higher density and larger particle size play a dominant role, while the TiH2 powder with lower density and smaller particle size passively adheres to the surface of the copper particles. The flow of copper particles plays an overall stirring role in the material, promoting the overall uniformity of material distribution in the sealed container. The collision of copper particles during the flow generates friction, preventing the agglomeration of TiH2 powder and promoting adhesion to the surface of copper particles. As the mixing time increases, the amount of TiH2 micro powder that can adhere to the surface of copper particles tends to a stable value, which, from another perspective, ensures the uniformity of Ti and the precise controllability of the added amount.

[0033] After obtaining the composite copper particles, in step S2, the composite copper particles are placed in a crucible, and the directional solidification furnace is evacuated and then filled with a carbon-containing reducing gas. Specifically, the crucible is a copper-bottomed graphite crucible, a composite structure combining the high-temperature resistance and chemical stability of graphite with the high thermal conductivity of copper. Its main body is made of high-purity graphite or graphite composite material, and its bottom is a liquid-cooled copper base. Further, the position of the copper-bottomed graphite crucible is adjusted so that the copper base is close to the cooling medium but not in contact with it, and it is placed at the position of the electromagnetic induction heating coil. The distance between the outer wall of the copper-bottomed graphite crucible and the electromagnetic induction heating coil is 3-8 mm, specifically 4-5 mm. The volume ratio of the crucible to the graphite volume of the crucible wall is (0.3-2):1, specifically (0.8-1.2):1. The cooling medium is gallium or a gallium-indium alloy, which is liquid at room temperature.

[0034] Afterwards, the directional solidification furnace is evacuated and then filled with a carbon-containing reducing gas. Specifically, the directional solidification furnace is evacuated to a specific vacuum level, the vacuum air valve is closed, and a carbon-containing reducing gas is introduced into the furnace. The inlet valve is then closed, creating a slight negative pressure inside the directional solidification furnace, which facilitates the reduction and removal of oxygen from the raw materials. During this process, the vacuum level after evacuation is 0.3*10. -3 ~0.8*10 -3 Pa, specifically, the vacuum level after evacuation is 0.4*10 Pa. -3 ~0.5*10 -3 Pa. The carbon-containing reducing gas is a mixture of hydrogen and methane, specifically, the partial pressure ratio of hydrogen to methane is 1:(4~5), more specifically, the partial pressures of hydrogen and methane are 0.05 MPa and 0.025 MPa, respectively. In this application, the copper-bottomed graphite crucible and methane provide the carbon source, and hydrogen provides the reducing atmosphere to remove oxygen from the alloy.

[0035] This application then performs induction melting and directional solidification of the composite copper particles, as shown in the schematic diagram. Figure 1As shown, in step S3, the crucible from step S2 is heated to bring the composite copper particles to their melting temperature. The crucible wall temperature at the melting temperature is detected to be 1100~1600℃, specifically 1300~1500℃, and more specifically 1350~1400℃. As described above, when the composite copper particles reach the melting temperature, the crucible is slowly lowered, allowing the copper bottom of the crucible to begin immersing in the cooling medium for directional solidification cooling, thus enhancing cooling. The directional solidification crucible descends at a speed of 0.1~0.6 mm / s, specifically 0.2~0.5 mm / s, and more specifically, 0.3~0.4 mm / s. In the aforementioned induction melting and directional solidification processes, copper has extremely low carbon solubility after equilibrium solidification. However, high-temperature gradient directional solidification, far from equilibrium, promotes the dispersion of carbon atoms into the melt. The presence of Ti increases the chemical potential gradient of the Cu melt, further enhancing the diffusion efficiency of carbon atoms, ultimately resulting in a high carbon content in the solidified copper-titanium alloy. Meanwhile, Ti is dissolved atomically in the copper lattice, and when solid solution saturation is reached, it precipitates as a second phase (Cu). x The Ti phase exists outside the copper grains. Atomic solid solution causes lattice distortion of the grains, but its maximum distortion capability is limited. When C dissolves in the copper lattice, it reduces the amount of Ti that can be dissolved in the copper lattice, thus encouraging more Ti to participate in Cu. x The formation and precipitation of the Ti phase. Therefore, C reduces the amount of Ti added and allows Cu to precipitate. x The Ti phase is beneficial for improving strength without affecting electrical conductivity. In summary, the high-temperature gradient directional solidification technology under a reducing atmosphere achieves effective dispersion and solid solution of C in the material, enabling Ti to exert its solid solution and precipitation strengthening effects at a relatively low addition amount, thus maintaining a high level of electrical conductivity while improving strength.

[0036] The solidification process of composite copper particles involves a phase transformation, with supercooling (the difference between the actual solidification temperature and the theoretical melting point) being the core driving force. Greater supercooling results in finer grains in the solidified microstructure. This application employs directional solidification, where the temperature field of the melt and the solidified microstructure is gradient-distributed along the crucible axis, resulting in a directional microstructure with columnar grain growth. High-heat-capacity liquid metal is used as the cooling medium, which helps to increase the supercooling during solidification and stabilizes the orientation and grain refinement of the solidified microstructure. The microstructure of the copper-titanium alloy obtained through induction melting and directional solidification includes copper grains with dissolved C and Ti atoms and Cu. x The Ti phase is a mixture of these two phases.

[0037] Finally, heating is stopped after all the composite copper particles in the copper-bottomed graphite crucible have melted. The copper particles solidify sequentially under the dual cooling effect of the copper bottom and the cooling medium to obtain a copper-titanium alloy.

[0038] The method for preparing copper-titanium alloys provided in this application employs a synergistic addition of C and Ti to prepare the copper-titanium alloy material. Specifically, C atoms do not form chemical bonds with Cu atoms, and the interstitial solid solution mode of C only causes minor distortion of the copper lattice without significantly affecting electron transport. Simultaneously, the solid solution occupancy of C forces the precipitation of Ti, allowing Ti to precipitate as Cu even at relatively low addition levels. x Ti-reinforced phases and nanocluster particles effectively enhance the mechanical properties of copper-titanium alloys. Therefore, the preparation method provided in this application reduces the amount of Ti added by adjusting the C solid solution content and promotes the formation of nanoclusters and Cu... x The precipitation of reinforcing agents such as the Ti phase structure significantly improves the material's strength properties while effectively reducing conductivity loss. Furthermore, the preparation method provided in this application is highly operable, and the low-pressure atmosphere during the melting process effectively deoxidizes the material to stabilize its overall performance range.

[0039] This application also provides copper-titanium alloys prepared by the above method.

[0040] Furthermore, the titanium content in the copper-titanium alloy is 0.5~5.0 wt%, specifically, the titanium content in the copper-titanium alloy is 0.6~2.4 wt%, and more specifically, the titanium content in the copper-titanium alloy is 1.0~2.0 wt%.

[0041] To further understand the present invention, the copper-titanium alloy and its preparation method provided by the present invention will be described in detail below with reference to the embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0042] Example 1

[0043] Copper particles with a diameter of 3 mm and a length of 3 mm and TiH2 powder with a particle size of 1~2 μm were mixed at a mass ratio of 95:1 using a pendulum mixer for 13 hours to obtain composite copper particles with TiH2 powder adhering to the surface of the copper particles; Figure 2 As shown, TiH2 powder is uniformly adhered to the surface of the copper particles;

[0044] Composite copper particles were placed into a copper-bottomed graphite crucible with an inner diameter of 29 mm and a wall thickness of 5.5 mm, and positioned at the location of the electromagnetic induction heating coil. The furnace vacuum was then evacuated to 0.5*10. -3 Pa, then H2 and CH4 mixed gas are introduced at a partial pressure ratio of 2:1 until the total pressure is 0.075 MPa, and the copper bottom of the copper-bottomed graphite crucible is adjusted to be close to but not in contact with the surface of the gallium-indium alloy liquid;

[0045] When electromagnetic induction heating is started and the temperature of the graphite crucible wall reaches 1450℃, the crucible is lowered at a speed of 0.3mm / s, so that the copper bottom and the graphite crucible wall are successively immersed in the gallium indium alloy, and the copper liquid in the crucible is directionally solidified to obtain a copper-titanium alloy with a Ti content of 0.9wt%.

[0046] Figure 3 The images show optical microscope (left) and scanning electron microscope (right) images of the copper-titanium alloy prepared in this embodiment. As can be seen from the images, the metallographic structure of the copper-titanium alloy prepared in this embodiment consists of dendritic structure and Cu distributed in the interdendritic arm interstices. x Ti precipitates phase.

[0047] Figure 4 The images shown are high-magnification scanning electron microscope (SEM) images and elemental energy dispersive spectroscopy (EDS) spectra of the copper-titanium alloy prepared in this embodiment. The upper left image is a high-magnification SEM image of the copper-titanium alloy, the upper right two images are point scan spectra of the copper-titanium alloy, from which the elemental composition of Ti atomic-level Ti nanoclusters can be obtained, and the bottom three images are surface scan spectra of the copper-titanium alloy, from which the distribution of each element C, Ti, and Cu in the entire field of view can be observed.

[0048] Figure 5 The elemental surface scan spectrum of the precipitated phase and adjacent region of the copper-titanium alloy prepared in this embodiment is obtained from... Figure 5 It can be seen that the Ti content in the precipitated phase is significantly higher than the solid solution content in the copper matrix, while the copper content in the precipitated phase is slightly lower than that in the matrix, confirming that it is Cu. x Ti precipitates phase.

[0049] The electrical conductivity of the copper-titanium alloy prepared in this embodiment was 57% IACS, and the microhardness was 243 HV, as determined by the van der Bauer method.

[0050] Example 2

[0051] Copper particles with a diameter of 2 mm and a length of 2 mm and TiH2 powder with a particle size of 1~2 μm were mixed at a mass ratio of 40:1 using a pendulum mixer for 16 hours to obtain composite copper particles with TiH2 powder adhering to the surface of the copper particles.

[0052] Composite copper particles were placed into a copper-bottomed graphite crucible with an inner diameter of 24 mm and a wall thickness of 8 mm, and then placed at the position of the electromagnetic induction heating coil. The vacuum level in the furnace was then evacuated to 0.5*10. -3 Pa, then H2 and CH4 mixed gas were sequentially introduced in a partial pressure ratio of 2:1 until the total pressure was 0.075 MPa. The copper bottom of the graphite crucible was adjusted to be close to but not in contact with the surface of the gallium-indium alloy liquid.

[0053] Electromagnetic induction heating is initiated until the temperature of the graphite crucible wall at the coil position reaches 1350℃. The crucible is then lowered at a speed of 0.2mm / s, allowing the copper bottom and graphite crucible wall of the copper-bottomed graphite crucible to be successively immersed in the gallium-indium alloy, thus achieving directional solidification of the copper liquid inside the crucible and obtaining a copper-titanium alloy with a Ti element content of 2.1wt%.

[0054] The metallographic structure of the copper-titanium alloy prepared in this embodiment consists of copper dendrites, intragranular Ti atom nanoclusters, and Cu atoms at dendrite arm interstices and grain boundaries. x Ti phase; the electrical conductivity of the copper-titanium alloy prepared in this embodiment was 18% IACS, and the microhardness was 283 HV, as tested by the van der Bauer method.

[0055] Example 3

[0056] Copper particles with a diameter of 4 mm and a length of 5 mm and TiH2 powder with a particle size of 1~2 μm were mixed at a mass ratio of 170:1 using a pendulum mixer for 12 hours to obtain composite copper particles with TiH2 powder adhering to the surface of the copper particles.

[0057] Composite copper particles were placed into a copper-bottomed graphite crucible with an inner diameter of 27 mm and a wall thickness of 6.5 mm, and then placed at the position of the electromagnetic induction heating coil. The vacuum degree of the furnace was evacuated to 0.5*10. -3 Pa, then H2 and CH4 mixed gas were sequentially introduced in a partial pressure ratio of 2:1 until the total pressure was 0.075 MPa. The copper bottom of the graphite crucible was adjusted to be close to but not in contact with the surface of the gallium-indium alloy liquid.

[0058] Electromagnetic induction heating is started until the temperature of the graphite crucible wall at the coil position reaches 1300℃. The crucible is then lowered at a speed of 0.4mm / s, so that the copper bottom and graphite crucible wall of the copper-bottomed graphite crucible are successively immersed in the gallium-indium alloy, so that the copper liquid in the crucible can be directionally solidified to obtain a copper-titanium alloy with a Ti element content of 0.5wt%.

[0059] The metallographic structure of the copper-titanium alloy prepared in this embodiment includes copper dendrite structure and intragranular dispersed nanocluster particles, containing very little Cu. x Ti precipitates; in this embodiment, Ti is only 0.5%, a low content, and the Ti element is basically dissolved in the copper lattice, participating in the formation of Cu. x The Ti precipitates are extremely rare and difficult to detect under a microscope. The electrical conductivity of the copper-titanium alloy prepared in this example was 67% IACS, and the microhardness was 156 HV, as tested by the van der Bauer method.

[0060] In the above embodiments, the amount of Ti added was adjusted to achieve a multi-scale strengthening mode of second-phase particles and second-phase structure precipitation after C and Ti composite solid solution to solid solution saturation, thus enabling the copper-titanium alloy to achieve a balance between excellent mechanical and electrical properties; due to the solid solution of C, when the Ti content is 0.9wt%, Cu can be achieved x The precipitation of Ti phase and C nanoclusters achieves multi-scale strengthening, with a microhardness of 243 HV. The discontinuous precipitation has limited segmentation of the copper grain boundaries, which can retain most of the electron transport interface, and the conductivity reaches 57% IACS.

[0061] Comparative Example 1

[0062] Copper particles with a diameter of 3 mm and a length of 3 mm were placed in a copper-bottomed graphite crucible with an inner diameter of 26 mm and a wall thickness of 7 mm. Directional solidification was carried out in a high-frequency induction heating furnace. The furnace vacuum degree during heating and solidification was 0.5*10⁻⁶. -3 Pa;

[0063] Before starting electromagnetic induction heating, the copper bottom of the graphite crucible is close to but not in contact with the surface of the gallium-indium alloy liquid below. After starting electromagnetic induction heating, the crucible wall is heated. The heat is transferred to the graphite crucible wall through thermal conduction. When the temperature reaches 1250℃, the crucible is lowered at a speed of 0.6mm / s. The copper bottom and the graphite crucible wall are successively immersed in the gallium-indium alloy, so that the copper liquid in the crucible obtains a directional solidification temperature field, and copper ingots are obtained.

[0064] The copper ingot prepared in this comparative example has a columnar crystal structure. The electrical conductivity of the copper-titanium alloy prepared in this example was 100% IACS, and the microhardness was 53 HV, as tested by the van der Bauer method.

[0065] Comparative Example 2

[0066] Spherical copper powder with a particle size of 15~53μm and TiH2 powder with a particle size of 1~2μm were mixed in a pendulum mixer at a mass ratio of 95:1 for 13 hours to obtain a mixture of copper powder and TiH2 powder.

[0067] The mixture was placed into a copper-bottomed graphite crucible with an inner diameter of 29 mm and a wall thickness of 5.5 mm, and positioned at the location of the electromagnetic induction heating coil. The furnace vacuum was then evacuated to 0.5*10. -3 Pa, then H2 and CH4 mixed gas are introduced at a partial pressure ratio of 2:1 until the total pressure is 0.075 MPa, and the copper bottom of the copper-bottomed graphite crucible is adjusted to be close to but not in contact with the surface of the gallium-indium alloy liquid;

[0068] When electromagnetic induction heating is started and the temperature of the graphite crucible wall reaches 1450℃, the crucible is lowered at a speed of 0.3mm / s, so that the copper bottom and the graphite crucible wall are successively immersed in the gallium indium alloy, and the copper liquid in the crucible is directionally solidified to obtain a copper-titanium alloy with a Ti content of 0.7wt%.

[0069] The microstructure of the copper-titanium alloy prepared in this comparative example consists of copper dendrites, intragranular Ti atom nanoclusters, and a small amount of Cu present in the interdendritic arm interstices. x Ti phase, but Cu x The Ti phase exhibits significant size variation, ranging from 3 μm to 80 μm, and its distribution spacing within the Cu dendrite arm interstices is irregular. The electrical conductivity of the copper-titanium alloy prepared in this embodiment, measured by the van der Bauer method, is 47% IACS, and its microhardness is 206 HV.

[0070] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0071] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a copper-titanium alloy, comprising the following steps: S1. Copper particles and TiH2 powder are mixed according to the composition ratio of copper-titanium alloy, so that TiH2 powder is formed on the surface of copper particles to obtain composite copper particles; the particle size of TiH2 powder is from micrometer to nanometer, and the particle size of copper particles is millimeter. S2. Place the composite copper particles in a crucible, evacuate the directional solidification furnace, and then fill it with a carbon-containing reducing gas. S3. The crucible from step S2 is heated to bring the composite copper particles to their melting temperature. The crucible is then immersed in a cooling medium for directional solidification cooling to obtain a copper-titanium alloy, wherein the copper-titanium alloy includes Cu. x Ti phase.

2. The preparation method according to claim 1, characterized in that, In step S1, the TiH2 powder has a particle size of 1~2μm, and the copper particles have a diameter of 1~5mm and a length of 2~3mm.

3. The preparation method according to claim 1, characterized in that, In step S1, the mixing time is ≥12h, and the mixing is carried out in a pendulum mixer, a high-speed ball mixer, or an axial rotary mixer.

4. The preparation method according to claim 1, characterized in that, In step S2, the crucible is a copper-bottomed graphite crucible, and the volume ratio of the copper-bottomed graphite crucible to the volume of the graphite in the crucible wall is (0.3~2):

1.

5. The preparation method according to claim 1, characterized in that, In step S2, the vacuum level after evacuation is 0.3*10. -3 ~0.8*10 -3 Pa, and / or, the carbon-containing reducing gas is a mixture of hydrogen and methane, wherein the partial pressure ratio of hydrogen to methane is 1:(4~5).

6. The preparation method according to claim 1, characterized in that, In step S3, the heating is induction heating, the distance between the heating coil of the induction heating and the outer wall of the crucible is 3~8mm, and / or the cooling medium is gallium or gallium-indium alloy.

7. The preparation method according to claim 1, characterized in that, In step S3, the crucible for directional solidification cooling descends at a speed of 0.1~0.6 mm / s.

8. The preparation method according to claim 1, characterized in that, In step S3, the crucible wall temperature at which the melting temperature is reached is 1100~1600℃.

9. The copper-titanium alloy prepared by the preparation method according to any one of claims 1 to 8.

10. The copper-titanium alloy according to claim 9, characterized in that, The titanium content in the copper-titanium alloy is 0.5~5.0wt%.

Images