High-elasticity ablation-resistant beryllium-copper alloy for high-voltage switch and preparation method thereof

Abstract

The application discloses a high-elasticity and ablation-resistant beryllium copper alloy for high-voltage switches and a preparation method thereof, and belongs to the technical field of electronic component manufacturing. Alloy components are as follows in terms of percentage by weight: Be 0.90%-1.30%, Co 1.35%-1.45%, Ni 1.50%-1.80%, Cr 0.60%-0.80%, W 0.10%-0.20%, Mo 0.20%-0.30%, Ta 0.05%-0.15%, Fe 0.020%-0.040%, C 0.005%-0.010%, Pb≤0.003%, Sn≤0.003%, total impurities≤0.01%, and the balance being Cu. The preparation method comprises the following steps: introducing Be, W, Mo and Ta in the form of intermediate alloy, melting at 1320-1350 DEG C, ultra-high temperature refining at 1650-1680 DEG C, then casting, homogenizing treatment, hot rolling, annealing, solid solution, twice cold rolling and intermediate annealing, two-stage aging, and finally obtaining a strip with a thickness of 0.5-2.0 mm. The product has a yield strength of greater than or equal to 1190 MPa, a tensile strength of greater than or equal to 1410 MPa, an elongation of greater than or equal to 2%, an elastic modulus of greater than or equal to 130 GPa, and an electric arc ablation amount of less than or equal to 0.04 g, and has excellent high elasticity and electric arc ablation resistance, and can meet the severe service requirements of high-voltage switch core elastic components.

Description

Technical Field

[0001] This invention relates to the field of electronic component manufacturing technology, specifically a high-elasticity, ablation-resistant beryllium copper alloy for high-voltage switches and its preparation method. Background Technology

[0002] High-voltage precision switches are indispensable key circuit control and protection units in high-reliability equipment such as new energy vehicles, commercial drones, and unmanned deep-sea submersibles. Their performance directly determines the stability and safety boundaries of the entire system. When subjected to high load conditions, these switches generate instantaneous electric arcs between their contacts, resulting in instantaneous high temperatures of thousands of degrees Celsius and intense thermal shock in the contact micro-area. This repeated transient extreme condition caused by high voltage poses a severe challenge to the core elastic conductive material (especially beryllium copper alloy). The bottleneck in its long-term service performance is concentrated in the simultaneous degradation of its elasticity maintenance capability and arc erosion resistance. On the one hand, repeated thermal shocks and stress cause microstructural evolution in the material, leading to a gradual decrease in its elastic modulus and yield strength. This prevents the elastic element from maintaining stable contact pressure and precise rebound during long-term operation, directly affecting the contact reliability and signal consistency of the switch. On the other hand, under the continuous erosion of the high-temperature arc, the material surface melts, vaporizes, and migrates and adheres to the mating material, causing increased contact resistance, deterioration of surface morphology, and ultimately contact failure. These two degradation mechanisms are coupled and exacerbate each other, together constituting the most critical factors restricting the electrical life and long-term operational reliability of high-voltage precision switches.

[0003] Therefore, to meet the stringent requirements of high-end equipment for switching devices under extreme conditions such as high load and high current, it is urgent to develop a new generation of highly elastic and erosion-resistant beryllium copper alloys, while simultaneously constructing highly consistent manufacturing processes to achieve precise control over microstructure and mechanical properties. This synergistic breakthrough in the "materials-process" system is a key path to improving the service life and operational reliability of devices, and a fundamental support for ensuring the long-term stable operation of the entire electrical system in harsh environments.

[0004] Chinese invention patent CN104282448A discloses a "copper-based electrical contact composite material resistant to arc erosion." This electrical contact composite material is mainly used to manufacture electrical devices such as power switches, relays, contactors, and starters for medium and low loads. Its chemical composition is: Zn 0.5–6 wt.%, Y₂O₃ 0.5–2.5 wt.%, RE 0.04–1 wt.%, B₄C 0.5–6 wt.%, with the balance being Cu. The material's electrical and thermal conductivity, resistance to welding, resistance to arc erosion, and friction properties are comparable to silver-based materials, meeting the basic requirements for materials used in electrical contacts and other components. However, this method uses powder metallurgy, which inevitably results in residual porosity within the material compared to traditional smelting processes. This defect significantly degrades its toughness, plasticity, and electrical conductivity. Furthermore, its high manufacturing cost is a significant drawback for the widespread application of this process.

[0005] Chinese invention patent CN118048549A discloses a "low-cost ablation-resistant copper-steel composite material and its preparation method." The preparation method is based on the high-temperature compatibility of copper and W18Cr4V high-speed steel. The copper-steel composite material is prepared through smelting, atomization powdering, pressing, and high-temperature sintering. This method can synergistically improve the material's strength, hardness, wear resistance, and ablation resistance. However, this method, like CN104282448A, falls under the category of powder metallurgy and is limited by the characteristics of this process. Specifically, insufficient toughness and plasticity due to residual porosity, difficulty in forming complex structures, and the resulting stress concentration problems constitute technical bottlenecks. At the same time, the high cost of raw materials and molds significantly limits its economic viability.

[0006] Chinese invention patent CN113005446A discloses a "Method and Apparatus for Oscillating Laser-Induction Composite Cladding of Wear-Resistant and Ablation-Resistant Copper-Based Coatings." The copper-based composite powder has the following chemical composition: Mo 10–30 wt.%, CNTs 1.0–3.0 wt.%, CeO 0.5–1.2 wt.%, TiB 3.2–8.5 wt.%, Fe 5–20 wt.%, with the balance being Cu. This method controls the molten pool size and stirring intensity by adjusting the laser amplitude, frequency, and power. It also controls the orderly flow direction of the molten pool by planning the scanning path. This method offers advantages such as eliminating porosity and cracks, reducing the molten pool temperature gradient, refining grains, and improving strength and toughness. The prepared copper-based coating exhibits excellent properties such as high strength and conductivity, wear resistance, and ablation resistance. However, this method is only applicable to the preparation of surface coatings and requires a suitable substrate material to achieve the ablation resistance of the parts. Compared with ablation-resistant copper alloy strips, its preparation process is more complex and the cost is significantly higher. At the same time, the high proportion of Mo in the coating leads to severe attenuation of conductivity, making it difficult to match the conductivity requirements of high-voltage precision switches.

[0007] Chinese invention patent CN120465000A discloses a method for preparing an ablation-resistant copper alloy using a blue laser cladding process, and the resulting ablation-resistant copper alloy. This method utilizes the high absorption rate of copper to blue laser light, using CuCr, CuW, ODS-Cu, SiO2 / Cu, or C / Cu mixed powders as raw materials to prepare a cladding coating on a copper substrate. This avoids problems such as heat input accumulation, porosity, and inclusions under low absorption rate and high energy density conditions. A high-performance cladding layer is formed, thereby modifying the surface of the copper substrate and improving its performance. This method, along with CN113005446A, belongs to the field of laser cladding. Its application is limited by poor interfacial bonding reliability, uneven microstructure and properties, insufficient service stability, processing limitations, and manufacturing economics, making it difficult to meet the stringent safety and reliability requirements of high-end precision electronic devices. Furthermore, this method does not restrict the powder ratio; the added SiO2 powder is a typical insulating material, and its content determines the overall conductivity of the coating. Therefore, it is impossible to accurately assess the impact of this method on the electrical conductivity of Cu alloys.

[0008] Currently, beryllium copper alloys face continuous performance degradation under frequent electrothermal cycles, and the problem of simultaneous decline in their high elasticity and resistance to arc erosion has not yet been solved. This constitutes the core bottleneck restricting the realization of ultra-long life and maintenance-free operation of high-end switches. Summary of the Invention

[0009] The purpose of this invention is to provide a novel high-elasticity, ablation-resistant beryllium copper alloy and its preparation method. This alloy can maintain excellent elastic recovery and arc erosion resistance even under extreme conditions of high load and multiple cycles, fundamentally meeting the stringent requirements of high-voltage precision switches for the comprehensive service performance of core elastic components.

[0010] The technical solution of this invention: A high-elasticity, ablation-resistant beryllium copper alloy for high-voltage switches, comprising the following essential components by weight percentage: Be: 0.90%–1.30%, Co: 1.35%–1.45%, Ni: 1.50%–1.80%, Cr: 0.60%–0.80%, W: 0.10%–0.20%, Mo: 0.20%–0.30%, Ta: 0.05%–0.15%, Fe: 0.020%–0.040%, C: 0.005%–0.010%, Pb ≤ 0.003%, Sn ≤ 0.003%, and the total amount of other unavoidable impurity elements ≤ 0.01%, with the balance being Cu.

[0011] Furthermore, the beryllium copper alloy is processed into a thin strip suitable for use in the elastic components of high-voltage switches, the thickness of which is 0.5 mm to 2.0 mm.

[0012] Furthermore, the strip meets the following performance indicators under aging conditions: yield strength ≥1190MPa, tensile strength ≥1410MPa, elongation ≥2%, elastic modulus ≥130GPa, and arc erosion resistance test according to international standard ASTM B576-94 (2021), arc erosion amount ≤0.04g.

[0013] A method for preparing a high-elasticity, erosion-resistant beryllium copper alloy for high-voltage switches includes the following steps: Step 1: Ingredients: Weigh the raw materials according to the weight percentages described in claim 1, wherein Be is introduced in the form of Cu-Be master alloy, and W, Mo, and Ta are introduced in the form of Ni-W, Ni-Mo, and Ni-Ta master alloys, respectively. Step 2: Melting and casting. After pretreatment, the raw materials from Step 1 are placed in a vacuum induction furnace. They are first melted at a medium temperature of 1320-1350℃, then heated to 1650-1680℃ for high-temperature refining, and finally cast to obtain beryllium copper alloy billets. Step 3: Homogenization treatment. The billet obtained in Step 2 is heated to 880-900℃ in the homogenization zone of the furnace and held for 16-20 hours for homogenization treatment before quenching. Step 4: Hot rolling, annealing and solution treatment. The homogenized billet is hot rolled, followed by annealing, solution treatment and quenching. Step 5: Cold rolling, subjecting the solution-treated sheet to at least two cold rolling processes and intermediate annealing; Step 6: Secondary aging treatment. The cold-rolled strip is subjected to secondary aging treatment, which includes low-temperature primary aging and high-temperature secondary aging, to obtain the finished strip.

[0014] Furthermore, in step 1, Co, Ni, and Cr are introduced in the form of electrolytic cobalt, electrolytic nickel, and electrolytic chromium, respectively, while Fe and C are introduced in the form of high-purity iron powder and high-purity carbon powder, respectively. The specific specifications of the master alloys are: Cu-25%Be master alloy, Ni-35%W master alloy, Ni-45%Mo master alloy and Ni-35%Ta master alloy.

[0015] Further, step 2 specifically involves: first, smelting at 1320–1350°C until the raw material is completely melted; then, refining at 1650–1680°C for 15–20 minutes; and finally, casting into a water-cooled mold at 1180–1200°C to obtain a beryllium copper alloy billet.

[0016] Further, the hot rolling in step 4 specifically involves: holding the homogenized billet in a heating furnace at 930±20℃ for 40 to 80 minutes, then removing it from the furnace for hot rolling; wherein the rough rolling temperature is 880 to 910℃, the finish rolling temperature is 770 to 790℃, and the total hot rolling rate is 90% to 95%; after hot rolling, the billet is cooled to room temperature in air.

[0017] Further, the annealing process in step 4 is as follows: the hot-rolled copper plate is placed in the uniform temperature zone of the heat treatment furnace, heated to 820-850°C, held for 4-6 hours, and then the copper plate is air-cooled to room temperature. The solution treatment is as follows: after annealing, the copper plate is placed in the uniform temperature zone of the heat treatment furnace, heated to 900-940℃, held for 1-2 hours, and then the copper plate is placed in the quenching solution for forced cooling. After the copper plate temperature drops to room temperature, it is taken out for use.

[0018] Furthermore, the two cold rolling and intermediate annealing processes in step 5 are as follows: the total processing rate of the first cold rolling is 70% to 90%, the annealing temperature after rolling is 350 to 380℃, and the holding time is 2 to 4 hours; the total processing rate of the second cold rolling is 50% to 65%, the annealing temperature after rolling is 420 to 460℃, and the holding time is 6 to 8 hours.

[0019] Furthermore, the secondary aging treatment in step 6 specifically comprises: a primary aging temperature of 300–340℃ and a holding time of 2–4 hours; a secondary aging temperature of 420–460℃ and a holding time of 6–8 hours; and air cooling to room temperature after the aging treatment to obtain the finished strip. The beneficial effects of this invention are: 1. This invention adopts a design concept of "medium Be content + precipitation / dispersion composite strengthening + microalloying control" to design a high-strength, ablation-resistant beryllium copper alloy for high-voltage switches, specifically as follows: The core of the medium Be content design is to enable the alloy to possess both excellent high-temperature elasticity and good electrical conductivity; by jointly introducing refractory elements such as W, Mo, and Ta, the high-melting-point solid solution particles or intermetallic compounds formed by them improve the high-temperature strength and elastic properties of the alloy. At the same time, it promotes the formation of a dense composite oxide layer on the alloy surface, effectively inhibiting alloy evaporation and melting, significantly reducing the arc erosion rate, and extending service life; the synergistic addition of Co, Ni, and Cr elements further contributes to the solid solution and precipitation strengthening of the alloy, among which Cr element also effectively improves the structure and stability of the oxide layer on the alloy surface; in addition, the precise control of Fe and C microalloying elements not only refines the grain structure but also forms high-melting-point carbides, jointly improving the alloy's comprehensive resistance to arc erosion.

[0020] 2. The high-strength, ablation-resistant beryllium copper alloy strip for high-voltage switches prepared by the method of this invention has a yield strength ≥1190MPa, tensile strength ≥1410MPa, elongation ≥2%, elastic modulus ≥130GPa, and arc ablation amount ≤0.04g under the condition of a thickness specification of 0.5mm~2.0mm. It successfully overcomes the problem in the prior art that it is difficult to synergistically improve the elasticity and arc ablation resistance of alloys, and provides an ideal material selection solution for high-voltage precision switches that require high elasticity and long electrical contact life. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a design strategy diagram for the beryllium copper alloy of the present invention. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should not be construed that the scope of the subject matter of the present invention is limited to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0024] The high-elasticity, ablation-resistant beryllium copper alloy for high-voltage switches described in this invention comprises, by weight percentage: Be: 0.90%–1.30%, Co: 1.35%–1.45%, Ni: 1.50%–1.80%, Cr: 0.60%–0.80%, W: 0.10%–0.20%, Mo: 0.20%–0.30%, Ta: 0.05%–0.15%, Fe: 0.020%–0.040%, C: 0.005%–0.010%, Pb ≤ 0.003%, Sn ≤ 0.003%, total amount of other impurity elements ≤ 0.01%, balance is Cu.

[0025] This invention optimizes the chemical composition of beryllium copper alloy, referring to... Figure 1 The details are as follows: (1) Be is a key strengthening element in beryllium copper alloys. Through solid solution strengthening and the formation of Be-Cu intermetallic compounds (mainly γ'', γ' and γ phases), it significantly improves the elastic limit and relaxation resistance of the alloy, ensuring its stable elastic response under long-term dynamic load. At the same time, the precipitates formed by Be can effectively refine the grains, improve the alloy strength and arc erosion resistance, and slow down surface melting and alloy loss during arcing, thus enhancing the service reliability of the alloy. However, excessive Be content can easily lead to grain boundary embrittlement, reduce cold working performance, and may cause stress concentration, which in turn weakens the overall performance of the alloy. To this end, this invention proposes a composition design scheme with "medium Be content" to effectively balance the high elasticity, arc erosion resistance, good electrical conductivity, and machinability of the alloy, and strictly control the Be content within the range of 0.90% to 1.30%.

[0026] (2) Co, as an important strengthening element in copper alloys, plays a significant role in improving the elasticity and arc erosion resistance of the alloy. Through solid solution strengthening and the formation of fine, dispersed Co-rich precipitates, the strength and elastic limit of the matrix can be effectively improved, thereby enhancing the elastic recovery ability of the alloy under dynamic loads. In terms of arc erosion resistance, the addition of Co helps to improve the thermal stability and high-temperature strength of the alloy. The stable precipitates formed can effectively inhibit the local melting of the alloy under the high temperature of the arc, slow down the depth of arc erosion, and improve the ablation resistance durability of the alloy surface. However, excessive Co will promote the formation of coarse or brittle intermetallic compounds. These phases are prone to become microcrack sources under the thermal-mechanical coupling effect of the arc, reducing the toughness and thermal shock resistance of the material, and thus impairing its elasticity retention and ablation resistance. Therefore, the Co content in this invention is strictly controlled within the range of 1.35% to 1.45%.

[0027] (3) Ni is another important strengthening element in copper alloys. By combining with Be to form fine, dispersed Be-Ni precipitates, these precipitates can effectively hinder dislocation movement, strengthen the strength and elasticity of the alloy matrix, and thus ensure that the alloy has stable elastic recovery capability under dynamic loads. In addition, the addition of Ni enhances the high-temperature strength and thermal stability of the alloy, making it less prone to local structural degradation and softening under the instantaneous high temperature of an electric arc, and significantly delaying the arc erosion process. However, excessively high Ni content will promote the coarsening of precipitates, and even form large-sized Ni-rich brittle phases, which will not only damage the elasticity and toughness of the alloy, but also reduce its ablation resistance. Therefore, the present invention strictly controls the Ni content within the range of 1.50% to 1.80%.

[0028] (4) Cr is an important strengthening element in this invention. After non-equilibrium solidification, Cr can be partially dissolved in the Cu matrix. During subsequent aging, it precipitates fine and thermally stable Cr-rich second-phase particles (such as CuCr2), which hinder dislocation movement, enhance the strength and stiffness of the alloy, and improve the yield strength and elastic modulus of the alloy. Regarding the arc erosion resistance, the addition of Cr mainly plays a role in two aspects: on the one hand, the Cr-rich phase itself has good high-temperature strength and oxidation resistance, which helps to suppress the softening and deformation of the arc heat-affected zone; on the other hand, under the action of high-temperature arc, Cr can promote the formation of a continuous, dense and strongly adherent chromium oxide protective film on the alloy surface. This film has low thermal conductivity and high thermal stability, which can effectively block the continuous impact of arc heat flow on the matrix, reduce metal evaporation and droplet splashing, thereby delaying the formation and expansion of ablation pits and significantly improving the service life and reliability of the contact material. However, excessive Cr will accelerate the aging process, promote the rapid coarsening of the precipitated phase, lead to a decrease in plasticity and processing difficulties, and may cause a decrease in local electrical conductivity. Therefore, the Cr content is strictly controlled within the range of 0.60% to 0.80% in this invention.

[0029] (5) W is the key ablation-resistant strengthening element in this invention. A small amount of W atoms can be dissolved in the Cu matrix, causing lattice distortion and playing a certain role in solid solution strengthening. However, most W exists as an independent second phase, such as α-W solid solution or W-Be precipitates. These high-hardness, high-thermal-stability tungsten-rich precipitates can not only hinder dislocation movement through the Orowan strengthening mechanism and significantly improve the elastic properties of the alloy, but also pin grain boundaries, hinder grain boundary migration, and utilize their high melting point advantage to suppress the softening of the microstructure in the arc heat-affected zone, and promote the formation of a dense and stable high-temperature resistant surface layer on the alloy surface, effectively blocking the direct introduction of arc heat flow, slowing down material melting, evaporation and splashing, thereby significantly reducing the arc erosion rate and extending service life. However, W has very low solid solubility in the copper matrix. Excessive addition can easily lead to coarsening of the precipitates or the formation of brittle agglomerates, which can damage the toughness and machinability of the material and may induce microcracks. Therefore, the W content is strictly controlled within the range of 0.10% to 0.20% in this invention.

[0030] (6) Similar to W, Mo is another key ablation-resistant strengthening element in this invention. Through non-equilibrium cooling, some of its atoms dissolve in the Cu matrix, inducing lattice distortion and providing a certain solid solution strengthening effect; it mainly exists in the form of thermally stable Mo particles or Mo-Be intermetallic compounds. These dispersed hard phases strongly pin dislocations, inhibiting dislocation slip and proliferation, thereby significantly improving the strength and elastic limit of the alloy. In terms of arc ablation resistance, the addition of Mo can promote the formation of a dense and strongly adhered composite oxide surface layer, significantly increasing the evaporation temperature of the alloy surface, absorbing and storing arc energy, and inhibiting the expansion and flow of the micro-melt pool, thereby greatly delaying the ablation process and improving the electrical contact life. However, excessive addition of Mo will lead to coarsening and uneven distribution of precipitates, increasing matrix brittleness and deteriorating hot working performance. Therefore, the Mo content in this invention is strictly controlled within the range of 0.20% to 0.30%.

[0031] (7) Ta is also one of the key ablation-resistant strengthening elements in this invention. It can form high-hardness solid solution particles or Ta-rich precipitates in the Cu matrix. These dispersed hard particles can increase the dislocation motion threshold and ensure the elasticity retention rate of the alloy under cyclic loading. At the same time, this high-melting-point phase plays a key role in the arc ablation process. With its high melting point and high thermal stability, it can not only effectively pin grain boundaries and inhibit grain growth and microstructure deterioration under high arc temperature, but also improve the stability of the alloy surface under thermal shock and reduce the adverse effects of arc ablation on the alloy. However, excessive Ta can easily form coarse brittle phases, which can significantly reduce the elastic properties and conductivity of the alloy. Therefore, this invention strictly controls the Ta content within the range of 0.05% to 0.15%.

[0032] (8) As a key grain boundary and microstructure control element, Fe combines with residual impurities such as P and S to form stable compounds, effectively inhibiting the segregation of impurities at grain boundaries, thereby reducing high-temperature brittleness of grain boundaries and improving the elastic limit of the alloy. In addition, the fine precipitates formed by Fe can pin grain boundaries and inhibit grain growth, maintaining the fine grain strengthening effect in the arc thermo-mechanical cycle, which helps to stabilize the high-temperature elastic modulus. In terms of arc ablation resistance, Fe enhances the alloy surface's resistance to arc thermal shock by purifying grain boundaries and refining the microstructure. Its uniformly dispersed precipitates can hinder the initiation and propagation of ablation cracks, reduce splashing caused by local melting, thereby delaying the ablation process and improving the electrical contact life. However, if the Fe content is too low, the purification and refining effect will be insufficient, and if it is too high, it will easily form coarse and brittle phases, which will become stress concentration points and crack sources. Therefore, the present invention strictly controls the Fe content within the range of 0.020% to 0.040%.

[0033] (9) C, as a key microalloying element in this invention, forms a series of high-melting-point carbides in the alloy due to its strong affinity with elements such as W, Mo, and Cr, including WC, MoC, and Cr. 23 C6, etc. On the one hand, WC, MoC, and other carbides dispersed in the matrix, with their extremely high hardness and high-temperature stability, can effectively hinder dislocation movement and act as a heat-resistant skeleton under the instantaneous high temperature of the electric arc, inhibiting the local softening and melting behavior of the alloy, thereby providing continuous and reliable strengthening support for the matrix and effectively delaying the ablation process. On the other hand, Cr precipitated along the grain boundaries 23 Carbides such as C6 can significantly strengthen grain boundaries and improve their stability at high temperatures. This not only prevents grain boundary embrittlement but also inhibits grain boundary weakening and local slip processes caused by thermal activation, thereby maintaining the integrity of the surface structure during arc ablation and preventing rapid crack propagation along grain boundaries. However, excessive C can lead to carbide coarsening or the formation of a continuous brittle film, impairing the toughness and conductivity of the matrix. Therefore, this invention strictly controls the C content within the range of 0.005% to 0.010%.

[0034] (10) Pb and Sn have a significant detrimental effect on the elasticity and arc erosion resistance of beryllium copper alloys. Pb is almost insoluble in the Cu matrix and is mostly distributed in the form of free soft particles at grain boundaries and within grains. Under dynamic loads, these particles are prone to debonding from the matrix to form micropores, which not only become stress concentration points, reduce the elastic limit and relaxation stability, but may also melt or vaporize instantaneously under the high temperature of the arc, exacerbating material splashing and surface roughening, and accelerating the ablation process. Sn tends to agglomerate at grain boundaries, weakening the grain boundary bonding force, inducing high-temperature grain boundary embrittlement and local softening, seriously damaging the elastic recovery ability and structural stability of the material; at the same time, Sn and Pb are prone to form a low-melting-point eutectic phase, which can lead to local melting or liquefaction of grain boundaries under arc thermal shock, becoming a rapid propagation channel for ablation cracks, significantly reducing the arc erosion resistance life. Therefore, in order to ensure the high elasticity and excellent ablation resistance of the alloy, the present invention strictly limits its content, requiring Pb≤0.003% and Sn≤0.003%.

[0035] To ensure the stability and consistency of the microstructure and overall properties of the alloy of this invention, the total amount of other unavoidable impurity elements should be strictly controlled to ≤0.01%. The beryllium copper alloy for elastic diaphragms with excellent fatigue performance described in this invention is characterized by a strip thickness specification of 0.5mm ≤ T ≤ 2mm.

[0036] The present invention discloses a method for manufacturing a beryllium copper alloy for elastic diaphragms with excellent fatigue performance, comprising the steps of batching, smelting, homogenization treatment, milling, hot rolling, annealing, solution treatment, pickling, cold rolling, pickling and passivation, and aging treatment, specifically including the following steps: Step 1: Raw material preparation. Oxygen-free copper, Cu-25%Be master alloy, electrolytic cobalt, electrolytic nickel, Ni-35%W master alloy, Ni-45%Mo master alloy, Ni-35%Ta master alloy, electrolytic chromium, high-purity iron powder, and high-purity carbon powder are selected as raw materials. Among these, Be is highly reactive; using master alloys instead of pure metals significantly reduces burn-off during smelting. W, Mo, and Ta have high melting points, all exceeding 2500℃, especially W and Ta, with melting points as high as 3414℃. Therefore, master alloys are used as raw materials to make them more easily soluble in Cu liquid. Subsequently, the raw material surfaces are sandblasted to remove surface impurities and rust, then degreased, cleaned, and dried for later use. The raw materials are prepared according to the mass percentages of the chemical components described in this invention.

[0037] Step 2: Smelting. Place the prepared raw materials in a vacuum induction furnace and smelt them at a temperature of 1320-1350℃ until the raw materials are completely melted. Raise the temperature to 1650-1680℃ for refining. The refining time is controlled at 15-20 minutes. Then, cast the mixture into a water-cooled mold at a temperature of 1180-1200℃ to obtain a beryllium copper alloy billet.

[0038] Step 3: Homogenization treatment. The beryllium copper alloy billet is placed in a heat treatment furnace for homogenization treatment. The billet is placed in the homogenization zone of the furnace and heated to 880-900℃. It is held for 16-20 hours. Then the billet is placed in a quenching solution for forced cooling. After the billet temperature drops to room temperature, it is taken out for use.

[0039] Step 4: Milling. The homogenized billet is milled to remove oxide scale and defects from the surface of the billet, resulting in a clean and dimensionally accurate billet to be rolled, thus providing quality assurance for subsequent rolling operations.

[0040] Step 5: Hot rolling. The billet is placed in a heating furnace at 930±20℃ and held for 40–80 minutes to ensure that both the inside and outside of the billet reach the set temperature. It is then removed from the furnace and hot rolled. The roughing temperature is 880–910℃, the finishing temperature is 770–790℃, and the total hot rolling rate is 90%–95%. It is then cooled to room temperature in air.

[0041] Step 6: Annealing treatment. Place the hot-rolled copper plate in a heat treatment furnace for annealing treatment. Place the copper plate in the uniform temperature zone of the furnace, heat it to 820-850℃, hold it for 4-6 hours, and then air cool the copper plate to room temperature.

[0042] Step 7: Solution treatment. Place the annealed copper plate in a heat treatment furnace for solution treatment. Place the copper plate in the uniform temperature zone of the furnace and heat it to 900-940℃. Hold it at that temperature for 1-2 hours. Then, place the copper plate in a quenching solution for forced cooling. Once the copper plate temperature drops to room temperature, remove it for use.

[0043] Step 8: Acid pickling. After solution treatment, the copper plate is placed in a 2% sodium carbonate cleaning solution for degreasing and cleaning at a temperature of 65℃. Subsequently, it is immersed in a 2.5% dilute sulfuric acid solution for 10 minutes, and then the surface of the copper plate is cleaned to remove the oxide scale. Finally, the surface of the copper plate is cleaned with an ethanol aqueous solution.

[0044] Step 9: Cold rolling. The pickled copper plate is cold rolled using a two-stage cold rolling process followed by intermediate annealing. The first cold rolling stage has a total processing yield of 70%–90%, with an annealing temperature of 350–380℃ and a holding time of 2–4 hours. The second cold rolling stage has a total processing yield of 50%–65%, with an annealing temperature of 420–460℃ and a holding time of 6–8 hours.

[0045] Step 10: Pickling and passivation. The cold-rolled copper strip undergoes pickling and passivation treatment. First, the copper strip is placed in a 2% sodium carbonate cleaning solution for degreasing and cleaning at a temperature of 65℃. Subsequently, it is immersed in a 2.5% dilute sulfuric acid solution for 10 minutes, and then the surface of the copper strip is cleaned again. Finally, passivation treatment is performed by spraying a 0.2% BTA (benzotriazole) aqueous solution onto the surface of the copper strip. After the Cu+ reacts with the BTA molecules, a surface passivation layer is obtained. The surface of the copper strip is then cleaned and dried for later use.

[0046] Step 11: Aging treatment. The passivated copper strip is placed in a heat treatment furnace for aging treatment, which adopts a two-stage aging process. The first-stage aging temperature is 300-340℃, and the holding time is 2-4 hours. The second-stage aging temperature is 420-460℃, and the holding time is 6-8 hours. Afterwards, the copper strip is air-cooled to room temperature to obtain the finished copper strip.

[0047] This invention measures the tensile properties of beryllium copper alloy strips using an electronic universal testing machine, based on the national standard GB / T 34505-2017 "Tension Test Method for Copper and Copper Alloys at Room Temperature".

[0048] This invention, based on the national standard GB / T 22315-2008 "Test Methods for Elastic Modulus and Poisson's Ratio of Metallic Materials", uses a high-temperature dynamic elastic modulus tester to measure the high-temperature elastic modulus of beryllium copper alloy strip.

[0049] This invention tests the arc erosion resistance of beryllium copper alloy strip according to the international standard ASTM B576-94 (2021), "Standard Guide for Arc Erosion Testing of Electrical Contact Materials". Test conditions: 30A current, 28V voltage, arc ignition frequency 60 times / minute, and 60,000 cycles.

[0050] Example 1: This example provides a high-elasticity, ablation-resistant beryllium copper alloy for high-voltage switches and its preparation method.

[0051] The chemical composition (weight percentage) of the beryllium copper alloy is as follows: Be 0.92%, Co 1.35%, Ni 1.51%, Cr 0.62%, W 0.10%, Mo 0.21%, Ta 0.06%, Fe 0.020%, Pb 0.003%, Sn 0.001%, with other unavoidable impurities totaling ≤0.01%, and the balance being Cu. The preparation method is as follows: Step 1: Raw material preparation. Select oxygen-free copper, Cu-25%Be master alloy, electrolytic cobalt, electrolytic nickel, Ni-35%W master alloy, Ni-45%Mo master alloy, Ni-35%Ta master alloy, electrolytic chromium, high-purity iron powder, and high-purity carbon powder as raw materials, and prepare them according to the above-mentioned mass percentages. Sandblast the raw materials to remove surface impurities and rust, then degrease and clean them, and dry them for later use.

[0052] Step 2: Melting and casting. Place the raw material in a vacuum induction furnace and melt it completely at 1320℃. Then, raise the temperature to 1650℃ and refine it for 15 minutes. Finally, cast it into a water-cooled mold at 1180℃ to obtain a beryllium copper alloy billet.

[0053] Step 3: Homogenization treatment. Place the billet in a heat treatment furnace, heat it to 880℃ and hold it for 16 hours, then quench it to room temperature.

[0054] Step 4: Milling removes the oxide scale and defects from the surface of the cast billet to obtain the billet to be rolled.

[0055] Step 5: Hot rolling. Heat the billet to 910℃ and hold for 40 minutes. Remove from the furnace and perform hot rolling. The roughing temperature is 880℃ and the finishing temperature is 770℃. The total hot rolling rate is 90%. After hot rolling, cool to room temperature in air.

[0056] Step 6: Annealing treatment. Heat the hot-rolled sheet to 820℃ and hold for 4 hours, then air cool.

[0057] Step 7: Solution treatment. Heat the annealed sheet to 900℃ and hold for 1 hour, then quench.

[0058] Step 8: Pickling. After solution treatment, place the board in a 2% sodium carbonate cleaning solution at 65°C to remove oil, then soak it in 2.5% dilute sulfuric acid for 10 minutes to remove oxide scale, and finally clean it with an ethanol aqueous solution.

[0059] Step 9: Cold rolling. The pickled sheet undergoes two cold rolling processes and intermediate annealing. The first cold rolling process yields a total processing rate of 70%, with an annealing temperature of 350℃ and a holding time of 2 hours. The second cold rolling process yields a total processing rate of 50%, with an annealing temperature of 420℃ and a holding time of 6 hours.

[0060] Step 10: Pickling and passivation. The cold-rolled strip is pickled again, and then passivated by spraying a 0.2% BTA aqueous solution on the surface, followed by cleaning and drying.

[0061] Step 11: Aging treatment, using two-stage aging, with the first stage aging temperature at 300℃ and a holding time of 2 hours; the second stage aging temperature at 420℃ and a holding time of 6 hours, followed by air cooling to room temperature to obtain the finished strip.

[0062] The prepared strip has a thickness of 0.5 mm to 2.0 mm. Its properties were tested and found to be: yield strength 1194 MPa, tensile strength 1412 MPa, elongation 3.29%, elastic modulus 132.1 GPa, and arc ablation amount of 0.037 g according to ASTM B576-94 (2021) standard.

[0063] Examples 2-8 were all prepared according to the preparation method of Example 1, and their chemical composition, process parameters, and performance test results are shown in Tables 1 to 6. The chemical composition of each example falls within the scope of this invention, the key parameters of each step of the preparation method meet the process conditions of this invention, and the final strip thickness is 0.5 mm to 2.0 mm, and the performance indicators all meet the requirements set by this invention.

[0064] Comparative examples: Commercially available beryllium copper alloys QBe1.9 and C17200 were selected as comparative examples, and were prepared and tested according to their conventional processes.

[0065] The chemical composition (wt%) of comparative example QBe1.9 is: Be 2.02%, Ni 0.35%, Si 0.02%, Al 0.06%, Ti 0.22%, Fe 0.04%, total impurities ≤0.10%, balance Cu. Preparation process: Melting temperature 1200℃, refining temperature 1350℃ / 10min, casting temperature 1130℃; homogenization treatment 750℃ / 8h; hot rolling heating temperature 850℃ / 30min, rough rolling 820℃, finish rolling 700℃, processing rate 80%; annealing 500℃ / 4h; solution treatment 850℃ / 2h; cold rolling primary processing rate 75%, annealing 300℃ / 1h, secondary processing rate 45%, annealing 380℃ / 4h; aging 300℃ / 3h. The properties of the obtained strip are: yield strength 1158MPa, tensile strength 1325MPa, elongation 3.92%, elastic modulus 126.7GPa, and arc ablation 0.165g.

[0066] The chemical composition (wt%) of comparative example C17200 is: Be 1.93%, Co 0.16%, Ni 0.12%, Si 0.05%, Al 0.10%, Fe 0.15%, total impurities ≤0.20%, balance Cu. Preparation process: Melting temperature 1200℃, refining temperature 1350℃ / 10min, casting temperature 1130℃; homogenization treatment 750℃ / 8h; hot rolling heating temperature 850℃ / 30min, rough rolling 820℃, finish rolling 700℃, processing rate 80%; annealing 500℃ / 4h; solution treatment 850℃ / 2h; cold rolling primary processing rate 75%, annealing 300℃ / 1h, secondary processing rate 45%, annealing 380℃ / 4h; aging 300℃ / 3h. The properties of the obtained strip are: yield strength 1146MPa, tensile strength 1294MPa, elongation 3.67%, elastic modulus 125.3GPa, and arc ablation 0.154g.

[0067] Table 1. Chemical composition and content (wt%) of beryllium copper alloys in Examples 1-8 of this invention.

[0068] As can be seen from Table 1, the chemical compositions of Examples 1 to 8 are all within the range defined by this invention, covering a wide range of Be from 0.92% to 1.27%, Co from 1.35% to 1.45%, Ni from 1.51% to 1.78%, Cr from 0.62% to 0.79%, W from 0.10% to 0.19%, Mo from 0.21% to 0.29%, Ta from 0.06% to 0.15%, and Fe from 0.020% to 0.039%. Furthermore, Pb and Sn are controlled at extremely low levels, and the total amount of other impurities is ≤0.01%. Comparative Examples QBe1.9 and C17200 have Be contents as high as 1.93% to 2.02%, and do not contain W, Mo, Ta, or other key anti-ablation elements of this invention; their composition systems are significantly different from those of this invention.

[0069] Table 2. Smelting process parameters of beryllium copper alloys in Examples 1-8 of this invention.

[0070] Table 2 shows the smelting process parameters for Examples 1-8. All examples were smelted at 1320–1350°C, followed by refining at an ultra-high temperature of 1650–1680°C for 15–20 minutes to ensure that high-melting-point elements such as W, Mo, and Ta were fully dissolved and uniformly distributed in the copper melt. Finally, casting was carried out at 1180–1200°C. As the example number increases, the temperature parameters and refining time show a gradual increasing trend, reflecting the synergistic optimization of process parameters and chemical composition. The comparative example had a smelting temperature of only 1200°C and a refining temperature of 1350°C, far lower than that of this invention, and could not effectively melt high-melting-point elements.

[0071] Table 3 Hot rolling process parameters of beryllium copper alloys in Examples 1-8 of this invention

[0072] Table 3 shows the hot rolling process parameters for Examples 1-8. The billet heating temperature was controlled at 910–950℃ (i.e., within the range of 930±20℃), held for 40–80 min, with a rough rolling temperature of 880–910℃ and a finish rolling temperature of 770–790℃, achieving a total processing rate as high as 90%–95%. With the increase of alloying elements such as Be, the heating temperature, holding time, and processing rate were correspondingly increased to optimize the hot deformation microstructure. The comparative examples showed lower hot rolling temperatures and smaller processing rates.

[0073] Table 4 Cold rolling process parameters of beryllium copper alloys in Examples 1-8 of this invention

[0074] As shown in Table 4, all embodiments employed a two-stage cold rolling and intermediate annealing process. The first cold rolling yielded 70%–90% of the material, with an intermediate annealing temperature of 350–380℃ and a holding time of 2–4 hours. The second cold rolling yielded 50%–65% of the material, with an intermediate annealing temperature of 420–460℃ and a holding time of 6–8 hours. This process design effectively eliminated work hardening, refined the grain structure, and laid a good microstructure foundation for the final aging treatment. The annealing temperature in the comparative cold rolling parameters was relatively low.

[0075] Table 5. Heat treatment process parameters of beryllium copper alloys in Examples 1-8 of this invention.

[0076] Table 5 summarizes the heat treatment process parameters for each embodiment. Homogenization treatment temperature is 880–900℃, held for 16–20 h; annealing treatment temperature is 820–850℃, held for 4–6 h; solution treatment temperature is 900–940℃, held for 1–2 h. Aging treatment employs a two-stage aging process: first-stage aging temperature is 300–340℃, held for 2–4 h; second-stage aging temperature is 420–460℃, held for 6–8 h. With increasing alloy element content, the heat treatment temperature and time are correspondingly increased to promote the uniform dispersion of precipitated phases. The heat treatment temperatures in the comparative examples differ significantly from those of this invention.

[0077] Table 6 Mechanical properties and mass loss after arc ablation of beryllium copper alloys in Examples 1-8 of this invention

[0078] As shown in Table 6, the performance indicators of all embodiments met the target requirements of the present invention. Yield strength was between 1194 and 1233 MPa, all ≥1190 MPa; tensile strength was between 1412 and 1457 MPa, all ≥1410 MPa; elongation was between 2.35% and 3.29%, all ≥2%; elastic modulus was between 132.1 and 136.4 GPa, all ≥130 GPa; and arc ablation was between 0.026 and 0.037 g, all ≤0.04 g. With the increase of alloying element content (Be, Co, Ni, Cr, W, Mo, Ta, etc.) from Examples 1 to 8, the strength and elastic modulus of the material showed a gradual upward trend, while the arc ablation gradually decreased, and the elongation decreased slightly but remained above 2%, demonstrating the synergistic optimization effect of alloy composition and process parameters. The comparative examples exhibit a yield strength of 1146–1158 MPa, a tensile strength of 1294–1325 MPa, an elongation of 3.67%–3.92%, an elastic modulus of 125.3–126.7 GPa, and an arc ablation resistance as high as 0.154–0.165 g. These comparative data fully demonstrate that, through unique compositional design and process optimization, this invention enables the alloy to possess both excellent high elasticity and resistance to arc ablation. As can be seen from Examples 1-8 above, the high-elasticity, ablation-resistant beryllium copper alloy for high-voltage switches and its preparation method described in this invention can produce beryllium copper alloy strips with both excellent mechanical properties and arc erosion resistance. These strips exhibit a yield strength ≥1190 MPa, tensile strength ≥1410 MPa, elongation ≥2%, elastic modulus ≥130 GPa, and arc erosion amount ≤0.04 g. This alloy and its preparation method successfully overcome the challenge of synergistically improving the elasticity and arc erosion resistance of alloys in existing technologies, providing an ideal material selection solution for high-voltage precision switches requiring high elasticity and long electrical contact life.

[0079] The above provides a detailed description of the high-elasticity, erosion-resistant beryllium copper alloy for high-voltage switches and its preparation method. Specific examples have been used to illustrate the structure and working principle of the invention. The descriptions of these embodiments are merely for the purpose of helping to understand the method and core ideas of the invention. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims.

Claims

1. A high-elasticity, ablation-resistant beryllium copper alloy for high-voltage switches, characterized in that: By weight percentage, it includes the following essential components: Be: 0.90%–1.30%, Co: 1.35%–1.45%, Ni: 1.50%–1.80%, Cr: 0.60%–0.80%, W: 0.10%–0.20%, Mo: 0.20%–0.30%, Ta: 0.05%–0.15%, Fe: 0.020%–0.040%, C: 0.005%–0.010%, Pb ≤ 0.003%, Sn ≤ 0.003%, and the total amount of other unavoidable impurity elements ≤ 0.01%, with the balance being Cu.

2. The high-elasticity, ablation-resistant beryllium copper alloy for high-voltage switches according to claim 1, characterized in that: The beryllium copper alloy is processed into a thin strip suitable for use in the elastic components of high-voltage switches, with a thickness of 0.5 mm to 2.0 mm.

3. The high-elasticity, ablation-resistant beryllium copper alloy for high-voltage switches according to claim 2, characterized in that: The strip meets the following performance indicators under aging conditions: yield strength ≥1190MPa, tensile strength ≥1410MPa, elongation ≥2%, elastic modulus ≥130GPa, and arc erosion resistance test according to international standard ASTM B576-94 (2021), arc erosion amount ≤0.04g.

4. A method for preparing the high-elasticity, ablation-resistant beryllium copper alloy for high-voltage switches according to any one of claims 1-3, characterized in that: Includes the following steps, Step 1: Ingredient preparation, weigh the raw materials according to the weight percentages described in claim 1, wherein Be is introduced in the form of Cu-Be master alloy, and W, Mo, and Ta are introduced in the form of Ni-W, Ni-Mo, and Ni-Ta master alloys, respectively; Step 2: Melting and casting. After pretreatment, the raw materials from Step 1 are placed in a vacuum induction furnace. They are first melted at a medium temperature of 1320-1350℃, then heated to 1650-1680℃ for high-temperature refining, and finally cast to obtain beryllium copper alloy billets. Step 3: Homogenization treatment. The billet obtained in Step 2 is heated to 880-900℃ in the homogenization zone of the furnace and held for 16-20 hours for homogenization treatment before quenching. Step 4: Hot rolling, annealing and solution treatment. The homogenized billet is hot rolled, followed by annealing, solution treatment and quenching. Step 5: Cold rolling, subjecting the solution-treated sheet to at least two cold rolling processes and intermediate annealing; Step 6: Secondary aging treatment. The cold-rolled strip is subjected to secondary aging treatment, which includes low-temperature primary aging and high-temperature secondary aging, to obtain the finished strip.

5. The method for preparing a high-elasticity, ablation-resistant beryllium copper alloy for high-voltage switches according to claim 4, characterized in that: In step 1, Co, Ni, and Cr are introduced in the form of electrolytic cobalt, electrolytic nickel, and electrolytic chromium, respectively, while Fe and C are introduced in the form of high-purity iron powder and high-purity carbon powder, respectively. The specific specifications of the master alloys are: Cu-25%Be master alloy, Ni-35%W master alloy, Ni-45%Mo master alloy and Ni-35%Ta master alloy.

6. The method for preparing a high-elasticity, ablation-resistant beryllium copper alloy for high-voltage switches according to claim 5, characterized in that: Step 2 specifically involves: first, smelting at 1320–1350°C until the raw material is completely melted; then, refining at 1650–1680°C for 15–20 minutes; and finally, casting into a water-cooled mold at 1180–1200°C to obtain a beryllium copper alloy billet.

7. The method for preparing a high-elasticity, ablation-resistant beryllium copper alloy for high-voltage switches according to claim 5, characterized in that: The hot rolling in step 4 specifically involves: holding the homogenized billet in a heating furnace at 930±20℃ for 40 to 80 minutes, then removing it from the furnace for hot rolling; wherein the rough rolling temperature is 880 to 910℃, the finish rolling temperature is 770 to 790℃, and the total hot rolling rate is 90% to 95%; after hot rolling, the billet is cooled to room temperature in air.

8. The method for preparing a high-elasticity, ablation-resistant beryllium copper alloy for high-voltage switches according to claim 5, characterized in that: The annealing process in step 4 is as follows: the hot-rolled copper plate is placed in the uniform temperature zone of the heat treatment furnace, heated to 820-850°C, held for 4-6 hours, and then the copper plate is air-cooled to room temperature. The solution treatment is as follows: after annealing, the copper plate is placed in the uniform temperature zone of the heat treatment furnace, heated to 900-940℃, held for 1-2 hours, and then the copper plate is placed in the quenching solution for forced cooling. After the copper plate temperature drops to room temperature, it is taken out for use.

9. The method for preparing a high-elasticity, ablation-resistant beryllium copper alloy for high-voltage switches according to claim 5, characterized in that: The specific process of two cold rolling and intermediate annealing in step 5 is as follows: the total processing rate of the first cold rolling is 70% to 90%, the annealing temperature after rolling is 350 to 380℃, and the holding time is 2 to 4 hours; the total processing rate of the second cold rolling is 50% to 65%, the annealing temperature after rolling is 420 to 460℃, and the holding time is 6 to 8 hours.

10. The method for preparing a high-elasticity, ablation-resistant beryllium copper alloy for high-voltage switches according to claim 5, characterized in that: The secondary aging treatment in step 6 is specifically as follows: the primary aging temperature is 300-340℃, and the holding time is 2-4h; the secondary aging temperature is 420-460℃, and the holding time is 6-8h; after the aging treatment, the material is air-cooled to room temperature to obtain the finished strip.

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