A Cu-Cr-Zr-TiB2 copper matrix composite material, its preparation method and application

Abstract

The present invention discloses a Cu-Cr-Zr-TiB₂ copper-based composite material, its preparation method and application. A billet containing TiB₂ particles is subjected to rotary forging to obtain a rotary forging piece, the rotary forging piece is subjected to the first aging treatment, and then subjected to electro-pulse drawing to obtain a drawn piece, and then the drawn piece is subjected to the second aging treatment to obtain the Cu-Cr-Zr-TiB₂ copper-based composite material; the Cu-Cr-Zr-TiB₂ copper-based composite material prepared by the above preparation method has a gradient structure with a surface layer of 50-200 nm nanocrystalline layer and a core of 0.5-1 μm fine crystal in the copper matrix, the TiB₂ particle reinforcement phase is distributed in the copper matrix in a fibrous shape along the axial direction, and the Cr / Zr nano-precipitation phase is dispersed in the gaps between the TiB₂ particle reinforcement phases and in the copper matrix crystal; thus having both high hardness, high strength, high conductivity, high softening temperature, excellent high-temperature performance and excellent arc extinguishing performance.

Description

Technical Field

[0001] The present invention relates to the field of metal matrix composites, and particularly to a Cu-Cr-Zr-TiB2 copper matrix composite material, a preparation method thereof, and an application thereof. Background Art

[0002] Copper-based materials are widely used in the fields of electronics, electric power, aerospace, etc. due to their excellent electrical conductivity, thermal conductivity, and processing performance. At present, high-performance copper materials mainly include copper alloys (such as Cu-Cr-Zr, Cu-Ni-Co-Si, etc.) and copper matrix composites (such as A12O3 / Cu, TiB2 / Cu, CNTs / Cu, etc.). Among them, copper alloys will show the coarsening and re-dissolution of precipitation phases with the increase of service temperature, resulting in inevitable deterioration of electrical and mechanical properties, and poor high-temperature performance of copper alloys. In addition, high-performance copper alloys have strict requirements for the selection of alloying elements: the solubility at high temperature is required to be relatively high while the solubility at relatively low temperature is relatively small, so as to ensure sufficient precipitation of other phases while improving the electrical conductivity and strength. However, the upper limit of the solubility of most alloying elements that meet such requirements in copper is relatively low, resulting in insufficient content of precipitation phases, and their performance has reached a bottleneck. In addition, existing research mainly focuses on single-reinforcement-phase composites or alloy systems, so the improvement of performance is limited. Summary of the Invention

[0003] Aiming at the deficiencies of the existing technology, the first object of the present invention is to provide a preparation method of a Cu-Cr-Zr-TiB2 copper matrix composite material. The preparation method of the present invention is simple and controllable, and is suitable for large-scale industrial production.

[0004] The second object of the present invention is to provide a Cu-Cr-Zr-TiB2 copper matrix composite material prepared by the above preparation method. The Cu-Cr-Zr-TiB2 copper matrix composite material provided by the present invention realizes synergistic strengthening through nano-ceramic particle reinforcement phases and nano-precipitation phases, and has high hardness, high strength, high electrical conductivity, high softening temperature, excellent high-temperature performance, and excellent arc extinguishing performance.

[0005] The third object of the present invention is to provide an application of the Cu-Cr-Zr-TiB2 copper matrix composite material prepared by the above preparation method.

[0006] In order to achieve the above objects, the present invention adopts the following technical solutions:

[0007] A preparation method of a Cu-Cr-Zr-TiB2 copper matrix composite material of the present invention comprises subjecting a blank containing TiB2 particles to rotary forging to obtain a rotary forging piece, subjecting the rotary forging piece to a first aging treatment, then performing electro-pulse drawing to obtain a drawn piece, and then subjecting the drawn piece to a second aging treatment to obtain the Cu-Cr-Zr-TiB2 copper matrix composite material;

[0008] During rotary swaging, a conical die is used, the single-pass deformation amount is 4-8%, the total deformation amount is 75-90%, and the strain rate is 200-400 s -1 , the die rotation speed is 800-1200 rpm, and the feed rate is 0.2-0.5 mm / pass;

[0009] The Cu-Cr-Zr-TiB2 copper matrix composite material includes a copper matrix, as well as a TiB2 particle reinforcement phase and a Cr / Zr nano-precipitation phase. The copper matrix has a gradient structure with a surface layer of 50-200 nm nanocrystalline layer and a core of 0.5-1 μm fine grains. The TiB2 particle reinforcement phase is distributed in the copper matrix in a fibrous shape along the axial direction, and the Cr / Zr nano-precipitation phase is dispersed in the gaps between the TiB2 particle reinforcement phases and within the copper matrix crystal grains;

[0010] In the Cu-Cr-Zr-TiB2 copper matrix composite material, by mass percentage, the composition is as follows: TiB2: 0.3-3%, Cr: 0.3-2.5%, Zr: 0.05-0.2%, M: 0-0.5%, and the balance is Cu. The M is selected from at least one of Fe, Y, Mg, Zn, Sc, La, Ag, Yb, In, and Te. The TiB2 particles are formed by in-situ reaction of Ti element and B element.

[0011] For the Cu-Cr-Zr-TiB2 copper matrix composite material provided by the present invention, first, the blank containing TiB2 particles is rotary swaged. During the rotary swaging process, TiB2, as a hard particle, forms a fibrous distribution (aspect ratio >10) by flowing along the axial direction under the high-strain shear force of rotary swaging, providing anisotropic strengthening; at the same time, TiB2 hinders the movement of dislocations, generating a high dislocation density region, providing more nucleation sites for subsequent aging precipitation. More importantly, the present invention uses a conical die (entrance angle 15°, exit angle 3°) during rotary swaging; a gradient strain field is generated, the surface layer metal experiences shear-dominated deformation (shear strain ratio >70%); the core is mainly compressive strain (axial strain ratio >60%), and the strain rate is 200-400 s - ¹ (the local strain rate of the surface layer can reach 800 s - ¹); the die rotation speed is 800-1200 rpm (the flow velocity of the surface layer metal is 3-5 times higher than that of the core); the feed rate is 0.2-0.5 mm / pass (the cumulative true strain of the surface layer reaches 4-5, and that of the core is only 2-3); under the coordination of the above parameters, the rotary swaging die and the material experience intense friction to generate a shear stress >800 MPa, the surface layer metal experiences shear folding + compression composite deformation (true strain reaches 4-5), and the dislocation density breaks through 10 16 m -2The critical value triggers dynamic recrystallization. The hard TiB2 particles act as strain concentration points, generating a large amount of distortion energy at the interface, promoting discontinuous dynamic recrystallization, and generating nanocrystals. The Cr / Zr precipitates pin the sub-boundaries, inhibiting the growth of nanograins. The effective strain in the core is only 1 / 2 - 1 / 3 of that in the surface layer (ε≈2 - 3), and the dislocation density remains at 10 14 -10 15 m -2 , which does not reach the complete recrystallization threshold, thus retaining part of the original equiaxed crystal structure. Therefore, a gradient nanostructure with a nanocrystalline layer on the surface and fine grains in the core is formed by rotary forging. The surface layer acts as a diffusion barrier, raising the anti-softening temperature to above 600 °C.

[0012] After the first aging treatment, the fibrous distribution of TiB2 and the nanoscale dispersion distribution of the precipitates jointly hinder dislocation slip, achieving dual strengthening of "the precipitates pin the dislocations within the crystal, and TiB2 hinders grain boundary migration". The two jointly form a composite structure of "fiber channels + dislocation walls". Then, the diffusion ability of Cr / Zr atoms is activated by electro-pulse drawing, enabling the incomplete precipitation of Cr / Zr to rapidly nucleate during the pulse interval to form ultra-fine precipitates. As a good conductive phase, TiB2 evenly disperses the pulsed current, preventing local overheating of the matrix from causing coarsening of the precipitates or damage to the TiB2 / matrix interface. Finally, the second aging treatment promotes the further precipitation of the remaining supersaturated solid solution of Cr / Zr, improving the conductivity and replenishing the nanoscale precipitates. The Cr / Zr precipitates preferentially distribute along the surface of the TiB2 fibers, filling the gaps between the TiB2 particles to form a dense dislocation hindrance network.

[0013] Under the synergy of the above processes and compositions, a gradient structure with a 50 - 200 nm nanocrystalline layer on the surface and 0.5 - 1 μm fine grains retained in the core is formed in the matrix. TiB2 is distributed in the matrix in a fibrous shape along the axis, and the Cr / Zr precipitates are dispersed in the fiber gaps and within the crystal. The two jointly constitute a synergistic strengthening network of "the precipitates pin the dislocations within the crystal, and TiB2 divides the grain boundaries"; thus, the material provided by the present invention has both high strength (≥600 MPa), high conductivity (≥80% IACS), and high-temperature anti-softening ability.

[0014] In the invention, the synergy between the composition and the process is crucial. If only relying on the precipitation strengthening of Cr / Zr, the coarsening of the precipitates at high temperatures leads to performance degradation; TiB2, as a thermally stable phase, provides persistent strengthening, and its interface induces the refinement of the precipitates. More importantly, only under the synergy of (TiB2 + Cr / Zr) and the rotary forging parameters of the present invention can a 50 - 200 nm nanocrystalline layer be formed on the surface of the material by rotary forging, and fine grains (0.5 - 1 μm) be retained in the core. In the absence of TiB2 in the traditional process, even with the same rotary forging parameters, only uniform micron-sized grains (3 - 5 μm) can be obtained.

[0015] In addition, during the experimental exploration process, attempts were also made to in-situ generate ceramic particles such as Al2O3, TiO2, TiC, and ZrB2. However, the properties of the finally obtained composite materials were all lower than those of the composite materials obtained in the present invention.

[0016] Of course, in the present invention, the content of each component needs to be controlled within the scope of the present invention to achieve better synergy. If too much Cr, Zr, and other trace elements are added, not only will the strength increase be limited, but the conductivity will also be reduced. If the addition amount of TiB2 is too large, it will lead to particle agglomeration, increased porosity, and weakened interfacial bonding. Stress concentration is likely to occur at the interface between the agglomerates and the matrix, becoming a crack source, and the interfacial bonding becomes poor, resulting in premature fracture of the material. In addition, the addition of excessive TiB2 will also cause a significant attenuation of the electrical / thermal conductivity. Excessive TiB2 will also consume Cr or Zr atoms through interfacial adsorption, inhibiting its solution-precipitation strengthening effect.

[0017] In a preferred embodiment, the process for obtaining the blank containing TiB2 particles is as follows: pure copper, a Cr source, a Zr source, a Ti source, a B source, and an M source are weighed according to the designed composition as raw materials, melted to obtain an alloy liquid containing TiB2 particles, the alloy liquid is cast into an ingot, the ingot is subjected to homogenization treatment to obtain a homogenized blank, the homogenized blank is hot-extruded to obtain a hot-extruded blank, the hot-extruded blank is subjected to solution treatment to obtain a solution-treated blank, and the solution-treated blank is subjected to pre-aging treatment to obtain the blank containing TiB2 particles.

[0018] In the present invention, pure copper, a Cr source, a Zr source, a Ti source, a B source, and an M source are respectively weighed as raw materials. During the melting process, the Ti source and the B source will in-situ form nano-sized TiB2 ceramic particles with a particle size of only 50-200 nm. During this process, the Cr / Zr elements and the microalloying element M synergistically assist in the in-situ generation of TiB2, refine the particle size of TiB2, and improve its distribution, laying a foundation for the synergistic distribution of the subsequent Cr / Zr-based precipitation phase and TiB2 ceramic particles.

[0019] After melting is completed, the obtained ingot is subjected to homogenization treatment. Through the homogenization treatment, the Cr / Zr elements are fully diffused and homogenized, while TiB2 remains stable during the homogenization process due to its high-temperature stability. TiB2 inhibits the migration of grain boundaries at high temperatures, hinders grain growth, and induces recrystallization of the matrix near the interface, refining the grains and avoiding local grain coarsening.

[0020] After homogenization treatment, hot extrusion is carried out to induce dynamic recrystallization (the TiB2 hard particles hinder the movement of dislocations, increase the deformation resistance, and force more external energy to be used for grain refinement), refining the grains to 5-20 μm; TiB2 is arranged along the deformation direction to form a preliminary fibrous structure. Subsequently, solution treatment is carried out to fully dissolve Cr / Zr to form a supersaturated solid solution, while TiB2 is insoluble in the Cu matrix. Through the Zener pinning effect, it inhibits grain boundary migration and coarsening, ensuring that the grains are uniformly fine, providing a fine-grained matrix for the high-temperature solid solution of Cr / Zr, and avoiding the solute diffusion channels being blocked by coarse grain boundaries; at the same time, due to the large difference in thermal expansion coefficients between TiB2 and the Cu matrix, a local stress field is generated during cooling, inducing dislocation proliferation. The dislocation structure induced by TiB2 guides the pre-enrichment of Cr / Zr atoms, avoiding the uneven distribution and size of the precipitated phases caused by random nucleation, and promoting the uniform nucleation of fine precipitated phases during the subsequent pre-aging process.

[0021] During the pre-aging process, the surface of TiB2 serves as a low-energy nucleation site, inducing the preferential precipitation of Cr / Zr precipitated phases (5-20 nm) around it to form a TiB2-precipitated phase "pinning-bearing" composite strengthening structure. The precipitated phases are smaller in size and more densely distributed, enhancing the strengthening effect.

[0022] Further optimization: The Cr source is selected from Cu-Cr master alloy, the Zr source is selected from Cu-Zr master alloy, the Ti source is selected from Cu-Ti master alloy, and the B source is selected from Cu-B master alloy; in the prepared raw materials, the molar ratio of Ti to B is 1:2.

[0023] Even further optimization: In the Cu-Ti master alloy, the mass fraction of Ti ≤ 50%, preferably 20-30%; in the Cu-B master alloy, the mass fraction of B ≤ 6%, preferably 4-5%.

[0024] Experiments have found that using master alloys with the above component contents can minimize the burn-off rate of each metal.

[0025] Even further optimization: The pure copper is electrolytic copper, and the purity of the pure copper ≥ 99.9 wt.%.

[0026] Further optimization: The melting process is as follows: First, melt the pure copper, then raise the temperature to 1200-1300 °C. After adding the Cu-Ti master alloy and completely melting it, lower the temperature to 1100-1180 °C, preferably 1100-1150 °C. Add the Cu-B master alloy, stir for 0.5-5 min, then raise the temperature to 1200-1400 °C, add the M source, Cu-Cr master alloy, and Cu-Zr master alloy, and keep warm for 1-5 min to obtain the melt. After the melting is completed, continue to cool down to 1150-1300 °C, preferably 1170-1230 °C, while stirring, and then cast it into a water-cooled mold.

[0027] In the present invention, after the Cu-Ti alloy is completely melted, the temperature of the melt is cooled to 1100 - 1180 °C, preferably in the range of 1100 - 1150 °C, and then the Cu-B alloy is added. Within the above range, it can not only ensure the formation of TiB2 particles, but also ensure the fineness of TiB2 particles, enhancing the strengthening effect. Then, after the TiB2 particles are formed, other metal raw materials are added in sequence, so as to ensure the uniform dispersion of TiB2 particles in the ingot finally. After the melting is completed, it is cooled to the range of the present invention for casting to obtain an ingot with uniformly dispersed TiB2 particles. In the present invention, the casting temperature cannot be too high. If casting at too high a temperature, it will affect the capture of TiB2 particles at the front of the liquid-solid interface, which is not conducive to particle dispersion. While casting at too low a temperature will affect the fluidity of the melt and it is difficult to ensure the continuity of the casting process.

[0028] During the solidification process of the copper-based alloy, TiB2 mainly improves the tissue properties through heterogeneous nucleation and grain refinement. Pure copper has a face-centered cubic (FCC) structure, while TiB2 has a hexagonal crystal system. The lattice misfit degree of their low-index crystal planes (such as Cu(111) and TiB2(0001)) is about 3% - 4%, which is an effective heterogeneous nucleation core. During the solidification of copper, TiB2 particles can be adsorbed on the solid-liquid interface, hindering the extension of the dendrite trunk, promoting the formation of equiaxed crystals. The refined equiaxed crystal structure can enhance the melt feeding ability, reduce the segregation tendency of low-melting eutectic phases such as Cu-O and Cu-S, and reduce the porosity of the cast copper alloy by 40% - 60%. TiB2 improves the high-temperature stability. The melting point of TiB2 particles is as high as 3225 °C and remains stable in the copper matrix. By pinning the grain boundaries, it inhibits the grain coarsening at high temperatures (>500 °C), and increases the high-temperature strength retention rate of the material by 30% - 50%.

[0029] Further preferably, the melting is non-vacuum melting. During the non-vacuum melting process, graphite is covered on the melt. Using non-vacuum melting can not only reduce costs, but also be more suitable for industrial production, and covering graphite can reduce the burning loss rate.

[0030] Further preferably, the temperature of the homogenization treatment is 920 - 980 °C, the time of the homogenization treatment is 2 - 12 h, and water quenching is carried out after the homogenization treatment is completed.

[0031] Further preferably, before the hot extrusion, it is preheated at 880 - 920 °C for 1 - 4 h, and then hot extrusion is carried out, controlling the extrusion ratio to be 9 - 17, and air cooling is carried out after the hot extrusion.

[0032] Under the action of high temperature and high pressure through hot extrusion, casting pores and microcracks are welded together, and the material density is increased to more than 99.5%. During the hot extrusion process, strain-induced dynamic recrystallization generates fine equiaxed grains. The TiB2 particles inhibit grain growth through the Zener pinning effect, and the grain size is reduced by 50-80% compared with the as-cast state. The flow of the matrix metal elongates the TiB2 particles along the extrusion direction to form directional strengthening fibers, increasing the longitudinal (extrusion direction) strength by 20-30% while reducing the loss of transverse properties.

[0033] Further preferably, the solution treatment temperature is 940-960 °C, the solution treatment time is 2-4 h, and water quenching is carried out after the solution treatment is completed.

[0034] Further preferably, the pre-aging treatment temperature is 425-475 °C, and the pre-aging treatment time is 30-240 min.

[0035] By performing a pre-aging treatment once before deformation, the precipitation of the Cr-rich phase can be made more sufficient, and the precipitation strengthening effect is more significant. Finally, combined with subsequent deformation and aging treatments, a better precipitation effect can be obtained. During the pre-aging process, the TiB2 surface serves as a low-energy nucleation site, inducing the preferential precipitation of Cr / Zr precipitation phases (5-20 nm) around it to form a TiB2-precipitation phase "pinning-bearing" composite strengthening structure, enhancing the interfacial bonding strength between the precipitation phase and TiB2 and avoiding the debonding of hard particles and the matrix during subsequent deformation. During subsequent high-strain processing (such as rotary forging and drawing) of the material, dislocation can be pinned by the Cr / Zr precipitation phase, and the integrity of the fiber structure can be maintained by TiB2, realizing the simultaneous improvement of strength and plasticity.

[0036] During the pre-aging process, the temperature needs to be effectively controlled. If the pre-aging temperature is too low: the diffusion ability of Cr / Zr atoms is insufficient, and it is difficult to break through the nucleation barrier, resulting in a small number of precipitation phases and uneven sizes. The size of the pre-precipitation phase is too small or not formed, and longer time or higher temperature compensation is required during the subsequent first aging, leading to an increased risk of grain coarsening; if the pre-aging temperature is too high, the diffusion rate of Cr / Zr atoms increases rapidly, resulting in the rapid nucleation and excessive growth of precipitation phases (such as CrCu2 and ZrCu3) at the TiB2 interface (size > 50 nm), losing the nano-scale strengthening effect; over-aging causes the premature depletion of Cr / Zr solute atoms, and no precipitation can be replenished during the subsequent first aging treatment, limiting the strength improvement.

[0037] In a preferred scheme, during rotary forging, the single-pass deformation amount is 5-6%, the total deformation amount is 80-85%, and the strain rate is 300-350 s -1. The rotational speed of the die is 1000 - 1100 rpm, and the feed rate is 0.3 - 0.4 mm per pass. With the rotary forging parameters within this preferred range, the properties of the final composite material are better.

[0038] In a preferred embodiment, the temperature of the first aging treatment is 425 - 475 °C, the time of the first aging treatment is 30 - 360 min, and water quenching is carried out after the first aging treatment.

[0039] By controlling the aging temperature within the above range, the properties of the final material are optimal. If the aging temperature is too low, the precipitation driving force is insufficient, and Cr / Zr cannot be effectively precipitated, and the conductivity and strength of the material cannot reach excellent levels after aging. If the aging temperature is too high, recrystallization and grain growth of the matrix will occur before the solution elements are completely precipitated, and the work hardening and grain boundary strengthening effects will decrease sharply.

[0040] In a preferred embodiment, during the electro - pulse drawing, the electro - pulse frequency is controlled to be 100 - 300 Hz, the current density is 50 - 200 A / mm², and the pulse width is 0.6 - 3 ms.

[0041] During electro - pulse drawing, the electro - pulse frequency and current density need to be effectively controlled. The applied electro - pulse frequency is slightly higher than the dislocation relaxation frequency (200 - 300 Hz) to ensure that the pulse interval is shorter than the dislocation re - annihilation period, continuously promoting dislocation slip. If the electro - pulse frequency is too high, heat accumulation will occur and grain boundaries will be weakened; if the electro - pulse frequency is too low (<50 Hz), dislocation motion cannot be effectively activated. The current density is controlled at 50 - 200 A / mm 2 ² to balance the Joule heat and the electron wind force effect, avoid interface damage, and at the same time drive the electron - dislocation interaction and reduce the flow stress. If the current density is too large, the interface will overheat and the precipitated phase will coarsen; if the current density is too low, the energy cannot activate dynamic precipitation, resulting in insufficient strengthening effect.

[0042] During electro - pulse drawing, the pulse width is controlled to match the dislocation slip time scale of the Cu matrix to achieve efficient local energy utilization. If the pulse width is too short, the dislocation response is insufficient; if the pulse width is too long, the temperature rise range will be too large, increasing the risk of grain coarsening.

[0043] In the present invention, it is crucial to use electro - pulse drawing. If cold drawing is carried out directly after aging, lacking the electro - pulse to reduce the matrix flow stress and lacking the Cr / Zr nano - phase of dynamic precipitation to pin dislocations, the deformation is extremely likely to localize and the wire is prone to fracture.

[0044] In a preferred embodiment, the electro - pulse drawing is multi - pass drawing, the total number of passes is 12 - 16 passes, the total deformation amount is 60% - 90%, and the drawing speed is 5 - 20 m / min.

[0045] In the present invention, a forming strategy of small deformation amount and multi-pass accumulation is adopted. By gradually introducing strain and combining with the dynamic regulation effect of electric pulse, the gradient optimization of the microstructure and the synergistic improvement of the performance are realized. The dislocation density is gradually increased by small deformation in each pass, avoiding excessive entanglement of dislocations. The combination of high strain rate and small deformation amount triggers discontinuous dynamic recrystallization at the TiB2 particle interface, refining the grains. At the same time, through multi-pass drawing, the TiB2 particles are distributed axially to form a continuous fiber network, strengthening the anisotropy. And a short diffusion window is provided for Cr / Zr during the pulse interval of each pass, promoting the precipitation of the previously incompletely precipitated Cr / Zr nano-precipitates at the TiB2 interface. At the same time, the combination of multi-pass small deformation and pulse interval reduces the residual stress and avoids the risk of interface debonding.

[0046] Further preferably, during the electric pulse drawing, the current density in the initial passes is 150 - 200 A / mm², and the current density in the subsequent passes is 50 - 100 A / mm². The number of initial passes is 50 - 60% of the total number of passes. In this preferred scheme, a high current density is adopted in the initial passes to quickly activate the dislocation source and break through the pinning at the TiB2 interface; while in the subsequent passes (the passes after the initial passes), the current density is reduced to inhibit the temperature rise and refine the precipitates.

[0047] In a preferred scheme, the temperature of the second aging treatment is 400 - 450 °C, the time of the second aging treatment is 30 - 360 min, and water quenching is carried out after the second aging treatment.

[0048] In a preferred scheme, in the Cu-Cr-Zr-TiB2 copper matrix composite, by mass percentage, the composition is as follows: TiB2: 0.5 - 1%, Cr: 0.5 - 1%, Zr: 0.05 - 0.1%, M 0 - 0.3%, and the balance is Cu.

[0049] In a preferred scheme, the particle size of the TiB2 particle reinforcement phase is 50 - 200 nm, and the size of the Cr / Zr nano-precipitates is <20 nm.

[0050] The present invention also provides a Cu-Cr-Zr-TiB2 copper matrix composite prepared by the above preparation method.

[0051] The present invention also provides an application of the Cu-Cr-Zr-TiB2 copper matrix composite prepared by the above preparation method, and the Cu-Cr-Zr-TiB2 copper matrix composite is applied to one of resistance welding electrodes, heat dissipation devices, and aerospace wires.

[0052] Beneficial effects

[0053] (1)Multi-scale collaborative strengthening mechanism: On the one hand, TiB2 particles are generated through in-situ reaction to achieve tight interfacial bonding with the Cu matrix (lattice misfit degree ≈ 3% - 4%), reduce the electron scattering barrier, maintain high conductivity (electrical conductivity ≥ 80% IACS) while enhancing strength, and optimize the interface of the nano-ceramic reinforcement phase; on the other hand, Cr / Zr alloying elements form nano-precipitates (size < 20nm) through multi-stage aging, and cooperate with sub-micron / nano-scale TiB2 particles. Through the Orowan bypass mechanism and dislocation pinning effect, the precipitation phase and particle coupling dual-scale strengthening are realized.

[0054] (2)High-temperature stability regulation: Through rotary forging processing combined with multi-stage deformation heat treatment, a gradient nanostructure with a 50 - 200 nm nanocrystalline layer on the material surface and 0.5 - 1 μm fine grains retained in the core is formed. The surface layer acts as a diffusion barrier, raising the anti-softening temperature to above 600°C.

[0055] (3)Low-energy consumption processing technology: Through electro-pulse assisted drawing, the electron wind effect promotes dislocation slip, eliminates dislocation tangles, reduces the processing energy consumption by 40%, and simultaneously retains a high density of mobile dislocations (density > 10 14 m -2 ), achieving the collaborative optimization of strength and conductivity.

[0056] In summary, through the coordination of processes and preparation methods, the present invention breaks through the inverted relationship of "strength - conductivity - thermal stability" in copper-based composites. The final product is applicable to extreme working conditions such as resistance welding electrodes (the arc extinguishing performance is improved by 30%), high-power heat dissipation devices (thermal conductivity ≥ 350 W / m·K), and aerospace wires. The service life is increased by 3 - 5 times compared with traditional materials. Brief Description of the Drawings

[0057] Figure 1 Scanning images of the as-cast sample of the Cu-Cr-Zr-TiB2 copper-based composite material prepared in Example 1 of the present invention at different magnifications, where, Figure 1 (a)is at a lower magnification; Figure 1 (b)is at a higher magnification.

[0058] Figure 2 Macrophotograph of the sample after hot extrusion in Example 1 of the present invention.

[0059] Figure 3 Macrophotograph of the sample after rotary forging in Example 1 of the present invention.

[0060] Figure 4 Scanning images of the sample after secondary aging in Example 1 of the present invention at different magnifications, where, Figure 4 (a)is at a lower magnification, Figure 4 (b)is at an intermediate magnification, Figure 4(c) is at a higher magnification.

[0061] Figure 5 This is the transmission image of the sample after secondary aging in Example 1 of the present invention, where Figure 5 (a) is the transmission image of the surface area of the sample, Figure 5 (b) is the transmission image of the core area of the sample.

[0062] Figure 6 This is the distribution diagram of TiB2 particles and Cr / Zr precipitation phases of the sample after secondary aging in Example 1 of the present invention, where Figure 6 (a) is the distribution diagram of the TiB2 particle reinforcement phase, Figure 6 (b) is the distribution diagram of the Cr / Zr precipitation phase.

[0063] Figure 7 This is the fracture surface scanning image of the wire after secondary aging in Example 1 of the present invention.

[0064] Figure 8 This is the macroscopic photograph of the wire after cleaning after secondary aging in Example 1 of the present invention. Specific implementation manners

[0065] The present invention will be described in detail below with reference to the accompanying drawings and specific implementation manners.

[0066] Example 1:

[0067] The Cu-Cr-Zr-TiB2 copper matrix composite material, by mass percentage, includes TiB2: 0.5%, Cr: 0.5%, Zr: 0.1%, Zn: 0.03%, In: 0.03%, Mg: 0.05%, and the balance is Cu.

[0068] The preparation process includes:

[0069] Step (1): Use an intermediate frequency induction melting furnace for non-vacuum melting and in-situ reaction to obtain an ingot. The raw materials added during melting include electrolytic copper (99.9 wt.%), Cu-10 wt.% Cr master alloy, Cu-30 wt.% Zr master alloy, Cu-25 wt.% Ti master alloy, Cu-4 wt.% B master alloy, and pure Mg (99.9 wt.%). Before melting, the raw materials, crucible, and mold are dried. During the melting process, first melt the pure copper (1083 °C). When the melt temperature reaches 1300 °C, add the Cu-Ti master alloy. After it is fully melted, cool the temperature to 1150 °C and add the Cu-B master alloy. Stir the melt thoroughly to ensure sufficient in-situ reaction between Ti and B, with a duration of about 3 min. Then raise the temperature to 1350 °C, add the Cu-Cr master alloy in 3 batches, stir for 30 s after holding for 2.5 minutes. Subsequently, add pure Zn, pure In, pure Mg, and Cu-Zr master alloy, continue to hold for 1 minute while stirring, and reduce the power of the induction furnace. When the melt temperature drops to 1200 °C, pour the melt into a cylindrical water-cooled mold to solidify. The diameter of the ingot is about 90 mm and the height is about 200 mm.

[0070] Step (2): Homogenize the ingot. The homogenization temperature is 960 °C, the homogenization time is 8 h, and the cooling method is water quenching. Then, machine process to remove the surface defects of the ingot to ensure that there is no oxide layer, shrinkage cavity, etc. on the ingot surface.

[0071] Step (3): Hot extrude the homogenized billet. The hot extrusion ratio is 17:1. Before hot extrusion, the billet is held at a temperature of 900 °C for 1 h, and the extrusion die is held at a temperature of 450 °C for 1 h. During the extrusion process, the average pressure of the press is 700 MPa and the maximum pressure is 900 MPa. After hot extrusion, air cooling is carried out. The diameter of the bar is about 21 mm.

[0072] Step (4): Solution treat the bar after blooming. The solution temperature is 960 °C, the solution time is 4 h, and the cooling method is water quenching.

[0073] Step (5): Pre-age the bar after solution treatment. The pre-ageing temperature is 450 °C, the pre-ageing time is 60 min, and the cooling method is water quenching.

[0074] Step (6): Cold rotary forging is carried out on the bar after pre-ageing treatment. A conical die (inlet angle 15°, outlet angle 3°) is used during rotary forging. The single-pass deformation amount is 5%, and the total rotary forging deformation amount is 80%. The strain rate is 300 s -1 , the die rotation speed is 1000 rpm, the feed rate: 0.4 mm / pass. After rotary forging, the bar is aged. The ageing temperature is 450 °C, the ageing time is 60 min, and the cooling method is water quenching. The diameter of the bar is about 5 mm.

[0075] Step (7): Conduct electro-pulse assisted drawing. The final state of the drawn wire is achieved through multiple passes, with a total deformation of 80%. Pulse parameters: frequency 200 Hz (matched with the relaxation time of dislocation movement), current density 60 A / mm 2 , pulse width 1 ms (ensuring the balance between dislocation slip and dynamic recovery). The drawing is carried out in 14 passes, from 5 mm to 0.2 mm. Specific drawing passes:

[0076] 5 mm → 4.2 mm → 3.5 mm → 2.9 mm → 2.4 mm → 2.0 mm → 1.6 mm → 1.3 mm → 1.0 mm → 0.8 mm → 0.6 mm → 0.5 mm → 0.4 mm → 0.3 mm → 0.2 mm. Use lubricant to reduce friction and prevent surface defects. The drawing speed is 10 m / min.

[0077] Step (8): Conduct aging treatment of the wire after electro-pulse assisted drawing under a protective atmosphere. The aging temperature is 400 °C, the aging time is 120 min, and the cooling method is water quenching. After cleaning the wire after secondary aging, the finished product is obtained.

[0078] Figure 1 These are scanning images of the as-cast sample of the Cu-Cr-Zr-TiB2 composite material prepared in Example 1 of the present invention at different magnifications. From Figure 1 it can be seen that the TiB2 particles are dispersed and fine, with an average size of 126 nm, presenting regular hexagonal or approximately circular shapes, and the size distribution is uniform without obvious agglomeration.

[0079] Figure 2 This is the macroscopic photo of the sample after hot extrusion in Example 1 of the present invention. From Figure 2 it can be seen that there are no obvious cracks or defects on the surface of the sample. There are slight extrusion lines, linearly distributed along the extrusion direction. The cross-section is a regular circle, with clear edges, no obvious deformation or burrs.

[0080] Figure 3 This is the macroscopic photo of the sample after rotary forging in Example 1 of the present invention. From Figure 3 it can be seen that the surface of the sample is smooth, showing a metallic luster, without obvious cracks, scratches or defects. The sample is cylindrical, with uniform dimensions, clear edges, no burrs or warping, and the overall color of the sample is uniform without oxide scale or discolored areas.

[0081] Figure 4 These are scanning images of the sample after secondary aging in Example 1 of the present invention at different magnifications. From Figure 4It can be seen that TiB2 particles are clearly visible in the matrix, presenting regular hexagons or approximate circles, and the size distribution is more uniform than that in the as-cast state. The interface between the particles and the matrix is well-bonded, and no obvious interface cracks or debonding phenomena are observed.

[0082] Figure 5 This is the transmission image of the sample after secondary aging in Example 1 of the present invention. In the figure, TiB2 particles are clearly visible in the matrix, presenting regular hexagons or approximate circles, with uniform size distribution. The interface between the particles and the matrix is tightly bonded, and no obvious interface reactions or defects are observed. A certain number of dislocations and substructures are observed, the dislocation density is moderate, and no excessive dislocation tangles or pile-ups are observed; from Figure 5 (a), it can be seen that the grain size of the copper matrix in the surface area is 50 - 200 nm; from Figure 5 (b), it can be seen that the grain size in the core area is 0.5 - 1 μm, showing a gradient structure.

[0083] Figure 6 This is the distribution diagram of TiB2 particles and Cr / Zr precipitation phases of the sample after secondary aging in Example 1 of the present invention, where Figure 6 (a) is the distribution diagram of the TiB2 particle reinforcement phase. From Figure 6 (a), it can be seen that the TiB2 particle reinforcement phase is distributed in the matrix along the axial direction in a fibrous shape. From Figure 6 (b), it can be seen that the Cr / Zr nano-precipitation phases (black parts) are dispersed in the fiber gaps and within the matrix grains, and their average size < 20 nm.

[0084] Figure 7 This is the fracture surface scanning image of the wire after secondary aging in Example 1 of the present invention. From the figure, it can be seen that the interface between the particles and the matrix is well-bonded, and no obvious debonding or interface cracks are observed, indicating that the TiB2 particles play a good strengthening role on the material. The fracture morphology is mainly ductile fracture, and the dimple-like characteristics are obvious, indicating that the material has experienced significant plastic deformation during the fracture process. A small amount of cleavage planes may be observed in local areas, but the overall is dominated by ductile fracture, the fracture morphology is uniform, and the distribution of dimples and TiB2 particles is consistent, reflecting the uniformity of the material and the good interface bonding performance.

[0085] Figure 8 This is the macroscopic photograph of the wire after cleaning after secondary aging in Example 1 of the present invention. From Figure 8 it can be seen that the surface of the wire is smooth, presenting a uniform metallic luster, without obvious scratches, cracks or defects. The diameter of the wire is uniform, without obvious non-uniform thickness or deformation phenomena, indicating that the processing technology is well-controlled.

[0086] Example 2:

[0087] Other preparation processes and parameters are the same as those in Example 1, except that the current density parameter in step (7) is different. Specifically: the current density in the initial passes (5 mm → 4.2 mm → 3.5 mm → 2.9 mm → 2.4 mm → 2.0 mm → 1.6 mm → 1.3 mm) is 160 A / mm², and the current density in the later passes (1.3 mm → 1.0 mm → 0.8 mm → 0.6 mm → 0.5 mm → 0.4 mm → 0.3 mm → 0.2 mm) is 70 A / mm².

[0088] Comparative Example 1:

[0089] Other preparation processes and parameters are the same as those in Example 1. Only in step (7), traditional cold drawing is used for processing, and the drawing passes and total deformation amount are the same as those in Example 1.

[0090] Perform performance tests on the Cu-0.5Cr-0.1Zr-0.5TiB2 copper matrix composites prepared in Example 1, Example 2, and Comparative Example 1. The test results are shown in Table 1.

[0091]

[0092] It can be seen from the table that Example 2 exhibits better performance than Example 1 and Comparative Example 1. The main reason is that Example 2 optimized the electro-pulse current density in the initial passes and the later passes. A high current density was used in the initial passes to quickly activate the dislocation source and break through the TiB2 interface pinning; while the current density was reduced in the later passes to suppress the temperature rise, refine the precipitated phase, and improve the strengthening effect.

[0093] Example 3:

[0094] For the Cu-1Cr-0.1Zr-1TiB2 copper matrix composite, in terms of mass percentage, the material components include TiB2: 1.0%, Cr: 1.0%, Zr: 0.1%, Mg: 0.05%, Sc: 0.03%, La: 0.03%, Y: 0.03%, and the balance is Cu.

[0095] The specific preparation process includes:

[0096] Step (1): Use a medium frequency induction melting furnace to perform non-vacuum melting and in-situ reaction to obtain an ingot, and the raw materials added during melting include electrolytic copper (99.9wt.%), Cu-10wt.%Cr master alloy, Cu-30wt.%Zr master alloy, Cu-25wt.%Ti master alloy, Cu-4wt.%B master alloy, pure Mg (99.9wt.%), pure Sc (99.9wt.%), pure La (99.9wt.%), and pure Y (99.9wt.%). Before melting, the raw materials, crucible, and mold are dried. During the melting process, pure copper is first melted (1083℃). When the melt temperature is 1320℃, the Cu-Ti master alloy (added in an amount of 3.2kg / 100kg raw material) is added. After it is fully melted, the temperature is lowered to 1140℃, and the Cu-B master alloy (added in an amount of 8.5kg / 100kg raw material) is added. The melt is stirred thoroughly to ensure a full in-situ reaction between Ti and B for 3 minutes. The temperature is then raised to 1350°C, and the Cu-Cr master alloy is added in three batches. The temperature is then maintained for 3 minutes. Pure Mg, pure Sc, pure La, pure Y, and a Cu-Zr master alloy are then added. The temperature is maintained for another 1.5 minutes while stirring. The induction furnace power is reduced. Once the melt temperature drops to 1250°C, the melt is cast into a cylindrical water-cooled mold and solidified. The ingot is approximately 90 mm in diameter and 200 mm in height.

[0097] Step (2): homogenizing the ingot at a homogenizing temperature of 960°C for 10 h, cooling by water quenching, and machining to remove the surface oxide layer and defects.

[0098] Step (3): The homogenized billet is hot extruded to form a blank, the extrusion ratio is 17:1, the billet is kept at 900℃×1.5h, the mold is kept at 450℃×1.5h, the average pressure of the press is 750MPa, the maximum pressure is 950MPa, and after extrusion, it is air-cooled to obtain a rod with a diameter of about 21mm.

[0099] Step (4): Solution treatment parameters are 960°C × 4h, and water quenching.

[0100] Step (5): pre-aging process is 450°C × 90min, followed by water quenching.

[0101] Step (6): The pre-aged bar is cold forged using a conical die (entry angle 15°, exit angle 3°), with a single-pass deformation of 5.5% and a total forging deformation of 85% at a strain rate of 350 s. -1 The die speed was 1100 rpm, the feed rate was 0.35 mm / pass, and the bars were aged at 450°C for 90 minutes. The cooling method was water quenching. The bar diameter was approximately 3 mm.

[0102] Step (7): Carry out electro-pulse assisted drawing. The final state wire is achieved through multiple passes, and the total deformation is 90%. Pulse parameters: frequency 220 Hz, current density 80 A / mm², pulse width 0.8 ms. The number of drawing passes is 16: 3 mm → 2.7 mm → 2.4 mm → 2.1 mm → 1.9 mm → 1.7 mm → 1.5 mm → 1.3 mm → 1.1 mm → 0.9 mm → 0.7 mm → 0.55 mm → 0.3 mm → 0.25 mm → 0.2 mm → 0.15 mm → 0.1 mm. Use lubricant to reduce friction and prevent surface defects. The drawing speed is 8 m / min.

[0103] Step (8): Carry out aging treatment on the wire after electro-pulse assisted drawing under a protective atmosphere. The aging temperature is 400 °C, the aging time is 180 min, and the cooling method is water quenching. After cleaning the wire after secondary aging, the finished product is obtained.

[0104] Comparative Example 2:

[0105] Other preparation processes and parameters are the same as those in Example 2, only different in step (5). Specifically: Do not perform pre-aging treatment on the sample.

[0106] Example 4:

[0107] Other preparation processes and parameters are the same as those in Example 2, only different in the cold rotary forging parameters in step (6). Specifically: The strain rate is set to 200 s -1 , the die rotation speed is 800 rpm, the feed rate: 0.2 mm / pass, and the others are the same.

[0108] Example 5:

[0109] Other preparation processes and parameters are the same as those in Example 2, only different in the current density parameters in step (7). Specifically: The current density in the initial passes (3 mm → 2.7 mm → 2.4 mm → 2.1 mm → 1.9 mm → 1.7 mm → 1.5 mm → 1.3 mm → 1.1 mm) is 180 A / mm², and the current density in the later passes (1.1 mm → 0.9 mm → 0.7 mm → 0.55 mm → 0.3 mm → 0.25 mm → 0.2 mm → 0.15 mm → 0.1 mm) is 80 A / mm².

[0110] Perform performance tests on the Cu-Cr-Zr-TiB2 copper matrix composites prepared in Example 3, Example 4, Example 5, and Comparative Example 2. The test results are shown in Table 2.

[0111]

[0112] As can be seen from Table 2, Example 5 exhibits better performance than Example 3, Example 4, and Comparative Example 2. The main reason is that in Example 5, the electric pulse current density in the initial pass and the final pass is optimized. A high current density is adopted in the initial pass to quickly activate the dislocation source and break through the TiB2 interface pinning; while in the final pass, the current density is reduced to suppress the temperature rise, refine the precipitated phase, and improve the strengthening effect.

Claims

1. A preparation method of a Cu-Cr-Zr-TiB2 copper matrix composite material, characterized in that: The blank containing TiB2 particles is subjected to rotary forging to obtain a rotary forging, the rotary forging is subjected to the first aging treatment, followed by electro-pulse drawing to obtain a drawn piece, and then the drawn piece is subjected to the second aging treatment to obtain the Cu-Cr-Zr-TiB2 copper matrix composite material; When performing rotary swaging, a conical die is used, the single-pass deformation amount is 4-8%, the total deformation amount is 75-90%, the strain rate is 200-400 s -1 , the die rotation speed is 800-1200 rpm, and the feed rate is 0.2-0.5 mm / pass; The Cu-Cr-Zr-TiB2 copper matrix composite material comprises a copper matrix, as well as a TiB2 particle reinforcement phase and a Cr / Zr nano-precipitation phase. The copper matrix has a gradient structure with a surface layer of 50-200 nm nanocrystalline layer and a core of 0.5-1 μm fine grains. The TiB2 particle reinforcement phase is distributed in the copper matrix in a fibrous shape along the axial direction, and the Cr / Zr nano-precipitation phase is dispersedly distributed in the gaps between the TiB2 particle reinforcement phases and within the copper matrix crystals; In the Cu-Cr-Zr-TiB2 copper matrix composite material, by mass percentage, the composition is as follows: TiB2: 0.3-3%, Cr: 0.3-2.5%, Zr: 0.05-0.2%, M: 0-0.5%, and the balance is Cu. The M is selected from at least one of Fe, Y, Mg, Zn, Sc, La, Ag, Yb, In, and Te. The TiB2 particles are formed by in-situ reaction of Ti element and B element.

2. The preparation method of a Cu-Cr-Zr-TiB2 copper matrix composite material according to claim 1, wherein: The process for obtaining the blank containing TiB2 particles is as follows: pure copper, a Cr source, a Zr source, a Ti source, a B source, and an M source are proportioned according to the designed composition as raw materials, melted to obtain an alloy liquid containing TiB2 particles, the alloy liquid is cast into an ingot, the ingot is subjected to homogenization treatment to obtain a homogenized blank, the homogenized blank is subjected to hot extrusion to obtain a hot-extruded blank, the hot-extruded blank is subjected to solution treatment to obtain a solution-treated blank, and the solution-treated blank is subjected to pre-aging treatment to obtain the blank containing TiB2 particles.

3. The preparation method of a Cu-Cr-Zr-TiB2 copper matrix composite material according to claim 2, characterized in that: The Cr source is selected from Cu-Cr master alloy, the Zr source is selected from Cu-Zr master alloy, the Ti source is selected from Cu-Ti master alloy, the B source is selected from Cu-B master alloy. In the proportioned raw materials, the molar ratio of Ti to B is 1:2; In the Cu-Ti master alloy, the mass fraction of Ti ≤ 50%, and in the Cu-B master alloy, the mass fraction of B ≤ 6%; The pure copper is electrolytic copper, and the purity of the pure copper ≥ 99.9 wt.%; The melting process is as follows: first, the pure copper is melted, then the temperature is raised to 1200-1300 °C. After adding the Cu-Ti master alloy and melting it completely, the temperature is lowered to 1100-1180 °C, the Cu-B master alloy is added, stirred for 0.5-5 min, then the temperature is raised to 1200-1400 °C, the M source, Cu-Cr master alloy, and Cu-Zr master alloy are added, and kept warm for 1-5 min to obtain. After the melting is completed, continue to cool down to 1150-1300 °C while stirring, and then cast into a water-cooled mold; The temperature of the homogenization treatment is 920-980 °C, the time of the homogenization treatment is 2-12 h, and after the homogenization treatment is completed, water quenching is carried out; Before the hot extrusion, it is kept warm at 880-920 °C for 1-4 h, then hot extrusion is carried out, and the extrusion ratio is controlled to be 9-17. After hot extrusion, air cooling is carried out; The solution treatment temperature is 940 - 960 °C, the solution treatment time is 2 - 4 h, and water quenching is carried out after the solution treatment is completed; The pre-aging treatment temperature is 425 - 475 °C, and the pre-aging treatment time is 30 - 240 min.

4. A method for preparing a Cu-Cr-Zr-TiB2 copper matrix composite material according to claim 1, characterized in that: The temperature of the first aging treatment is 425 - 475 °C, the time of the first aging treatment is 30 - 360 min, and water quenching is carried out after the first aging treatment.

5. A method for preparing a Cu-Cr-Zr-TiB2 copper matrix composite material according to claim 1, characterized in that: During the electro-pulse drawing, the electro-pulse frequency is controlled to be 100 - 300 Hz, the current density is 50 - 200 A / mm², and the pulse width is 0.6 - 3 ms; The electro-pulse drawing is multi-pass drawing, the total number of passes is 12 - 16 passes, the total deformation is 60% - 90%, and the drawing speed is 5 - 20 m / min.

6. The preparation method of a Cu-Cr-Zr-TiB2 copper matrix composite material according to claim 5, characterized in that: During the electro-pulse drawing, the current density in the initial passes is 150 - 200 A / mm², the current density in the later passes is 50 - 100 A / mm², and the number of initial passes is 50 - 60% of the total number of passes.

7. The preparation method of a Cu-Cr-Zr-TiB2 copper matrix composite material according to claim 1, characterized in that: The temperature of the second aging treatment is 400 - 450 °C, the time of the second aging treatment is 30 - 360 min, and water quenching is carried out after the second aging treatment.

8. The preparation method of a Cu-Cr-Zr-TiB2 copper matrix composite material according to claim 1, characterized in that: In the Cu-Cr-Zr-TiB2 copper matrix composite material, by mass percentage, the composition is as follows: TiB2: 0.5 - 1%, Cr: 0.5 - 1%, Zr: 0.05 - 0.1%, M 0 - 0.3%, and the balance is Cu; The particle size of the TiB2 particle reinforcement phase is 50 - 200 nm, and the size of the Cr / Zr nano-precipitation phase is <20 nm.

9. A Cu-Cr-Zr-TiB2 copper matrix composite material prepared by the preparation method according to any one of claims 1 - 8.

10. Use of the Cu-Cr-Zr-TiB2 copper matrix composite material prepared by the preparation method according to any one of claims 1-8, characterized in that: The Cu-Cr-Zr-TiB2 copper matrix composite material is applied to one of resistance welding electrodes, heat dissipation devices, and aerospace wires.

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