A copper-nickel-tin alloy and a method for producing the same

Abstract

The application discloses a copper-nickel-tin alloy and a preparation method thereof. The copper-nickel-tin alloy comprises at least a matrix phase and a first precipitated phase. The maximum width of the first precipitated phase is 0.5-5 microns, and 20%-60% of the first precipitated phase in a unit volume is located at the grain boundary of the matrix phase. By forming the first precipitated phase at the grain boundary of the matrix phase, and controlling the maximum width of the first precipitated phase to be 0.5-5 microns and 20%-60% of the first precipitated phase in a unit volume to be located at the grain boundary of the matrix phase, the first precipitated phase preferentially occupies the nucleation site of discontinuous precipitation, effectively hinders the continuous precipitation of discontinuous precipitation from the grain boundary during the heat treatment process, and can hinder the dislocation movement and prevent the crack propagation, thereby improving the mechanical properties and corrosion resistance of the copper-nickel-tin alloy.

Description

Technical Field

[0001] This invention relates to the field of metal alloy materials technology, and in particular to a high-strength, high-elasticity, and corrosion-resistant copper-nickel-tin alloy and its preparation method. Background Technology

[0002] With the rapid development of modern industry, the performance requirements for alloy materials are increasing. Among numerous alloy materials, copper-nickel-tin alloys have attracted widespread attention due to their non-toxicity, production safety, and excellent mechanical properties, and are considered a potential alternative to beryllium bronze alloys. Copper-nickel-tin alloys are an important copper-based alloy, and as an important engineering material, they have wide applications in many fields such as marine engineering, aerospace, and electronics.

[0003] In many fields of modern industry, such as electronics, electrical engineering, aerospace, and high-end equipment manufacturing, the demand for high-performance metallic materials continues to grow and the requirements are becoming increasingly stringent. Existing copper-nickel-tin alloys have the problem of discontinuous precipitation and continuous exudation, which prevents further improvement in the mechanical properties and corrosion resistance of copper-nickel-tin alloys, thus limiting their application in key components.

[0004] Therefore, developing a copper-nickel-tin alloy with excellent mechanical properties and corrosion resistance, and its preparation method, has significant practical implications and broad market prospects. Summary of the Invention

[0005] Based on this, the main objective of this application is to provide a copper-nickel-tin alloy and its preparation method. By forming a first precipitated phase at the grain boundary of the matrix phase and controlling the maximum width of the first precipitated phase and its amount at the grain boundary of the matrix phase, the precipitation of precipitates from the grain boundary is suppressed, thereby solving the problem of discontinuous precipitation and continuous precipitation inside the copper-nickel-tin alloy, and thus improving the mechanical properties and corrosion resistance of the copper-nickel-tin alloy.

[0006] To achieve the above objectives, the first aspect of the present invention provides a copper-nickel-tin alloy, comprising at least a matrix phase and a first precipitated phase, wherein the maximum width of the first precipitated phase is 0.5-5 μm, and 20%-60% of the first precipitated phase per unit volume is located at the grain boundaries of the matrix phase.

[0007] In one embodiment, more than 50% of the first precipitated phase per unit volume has a maximum width of 1-3 μm.

[0008] In one embodiment, the first precipitated phase is Ni. 6.67 SnB2.

[0009] In one embodiment, the copper-nickel-tin alloy further includes DO. 22 The precipitated phase and the L12 precipitated phase, wherein the DO22 The ratio of the proportion of precipitated phase to the proportion of L12 precipitated phase is 0.6-1.5.

[0010] In one embodiment, the DO 22 The maximum width of the precipitated phase is 15-30 nanometers, and the maximum width of the L12 precipitated phase is 30-50 nanometers.

[0011] In one embodiment, more than 70% of the DO 22 The precipitated phase is located on the surface of the copper-nickel-tin alloy, and more than 70% of the L12 precipitated phase is located in the core of the copper-nickel-tin alloy.

[0012] In one embodiment, the average grain size of the matrix phase is 15-40 μm.

[0013] In one embodiment, the copper-nickel-tin alloy comprises the following elements in weight percentages: 15.0-15.2 wt% nickel, 8.0-8.2 wt% tin, 0.05-0.15 wt% boron, and the balance copper and unavoidable impurities.

[0014] In a second aspect, the present invention provides a method for preparing a copper-nickel-tin alloy as described in the first aspect, the method comprising the following steps:

[0015] 1) Raw material preparation: The raw materials are prepared according to the following weight percentages of elements: 15.0-15.2wt% nickel, 8.0-8.2wt% tin, 0.05-0.15wt% boron and balance copper and unavoidable impurities.

[0016] 2) Vacuum melting: Place the raw materials from step 1) into a vacuum melting furnace. The pressure inside the vacuum melting furnace should be ≤1×10⁻⁶. 3 Pa, then a protective gas is introduced.

[0017] 3) Casting: The alloy liquid from step 2) is poured into a preheated cast iron mold at 300-400℃ using a bottom-pouring casting method.

[0018] 4) Homogenization treatment: Place the ingot from step 3) into a heating furnace for homogenization treatment.

[0019] 5) Hot rolling: The alloy block after homogenization is hot rolled.

[0020] 6) Solution treatment: The rolled copper-nickel-tin alloy is subjected to solution treatment.

[0021] 7) Aging treatment: The copper-nickel-tin alloy after solution quenching is subjected to aging treatment.

[0022] In one embodiment, in step 7), the aging process steps are as follows:

[0023] 1) Laser aging treatment, aging temperature 380-450℃, aging time 25-35s;

[0024] 2) Medium-frequency induction heating aging treatment, aging treatment temperature 500-520℃, aging treatment time 1.5-2.5min;

[0025] 3) Low-temperature slow aging treatment, aging temperature 580-620℃, aging time 1-1.5h.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: by setting a first precipitate at the grain boundary of the matrix phase, and controlling the maximum width of the first precipitate to be 0.5-5μm and 20%-60% of the first precipitate per unit volume to be located at the grain boundary of the matrix phase, the first precipitate preferentially occupies the nucleation sites of discontinuous precipitates. During the heat treatment process, it effectively prevents discontinuous precipitates from continuously precipitating from the grain boundary, and at the same time, it can hinder dislocation movement and prevent crack propagation, thereby improving the mechanical properties and corrosion resistance of copper-nickel-tin alloy.

[0027] On the other hand, by forming the first precipitated phase at the grain boundaries of the matrix phase, a large number of tin atoms are consumed, thus slowing down the DO process. 22 The phase transformation to L12 phase slows down the formation of DO3 phase, thereby inhibiting the discontinuous precipitation of DO3 phase at grain boundaries. At the same time, the first precipitated phase can hinder dislocation movement and prevent crack propagation, thus improving the mechanical properties and corrosion resistance of copper-nickel-tin alloy. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings are only for illustrating preferred embodiments and are not intended to limit this application. Throughout the drawings, the same reference numerals denote the same parts. In the drawings:

[0029] Figure 1 A scanning electron microscope (SEM) image (1500X) of a copper-nickel-tin alloy according to an embodiment of the present invention.

[0030] Figure 2 A scanning electron microscope (SEM) image (2500X) of a copper-nickel-tin alloy according to an embodiment of the present invention.

[0031] Figure 3 This is a flowchart illustrating the steps of the method for preparing copper-nickel-tin alloy in an embodiment of the present invention.

[0032] Figure 4 This is a flowchart illustrating the specific steps of step S70 in the preparation method of copper-nickel-tin alloy in this embodiment of the invention.

[0033] Figure 5 A scanning electron microscope image (1500X) of a copper-nickel-tin alloy for comparison.

[0034] Figure 6 A scanning electron microscope (SEM) image (2500X) of a copper-nickel-tin alloy for comparison.

[0035] Among them, 1 is the matrix phase; 2 is the first precipitated phase. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] In the description of the specification and claims, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present invention, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the embodiments of the present invention.

[0038] Furthermore, the terms "first," "second," etc., used in the specification and claims are used only to distinguish the description of the same technical features and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated, nor necessarily the order of description or chronological sequence. Where appropriate, the terms are interchangeable. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature.

[0039] Please see Figure 1 and Figure 2 , Figure 1 and Figure 2The images shown are scanning electron microscope (SEM) images of a copper-nickel-tin alloy according to an embodiment of the present invention, magnified at 1500X and 2500X. In this invention, the copper-nickel-tin alloy comprises at least a matrix phase 1 and a first precipitated phase 2. The maximum width of the first precipitated phase 2 is 0.5-5 μm, and 20%-60% of the first precipitated phase 2 per unit volume is located at the grain boundaries of the matrix phase 1. In the copper-nickel-tin alloy, the matrix phase 1 is the continuous phase and structural body of the alloy, and provides a carrier for the nucleation and growth of the precipitated phase. It has the same crystal structure as pure copper, but incorporates nickel, tin, and other atoms. By forming a first precipitate 2 at the grain boundaries of the matrix phase 1, and controlling the maximum width of the first precipitate 2 to be 0.5-5 μm and ensuring that 20%-60% of the first precipitate 2 per unit volume is located at the grain boundaries of the matrix phase 1, the first precipitate 2 preferentially occupies the nucleation sites of discontinuous precipitates. During heat treatment, this effectively prevents the continuous precipitation of discontinuous precipitates from the grain boundaries, while also hindering dislocation movement and preventing crack propagation, thereby improving the mechanical properties and corrosion resistance of the copper-nickel-tin alloy. The maximum width of the first precipitate 2 refers to the maximum width of its inner contour at any cross-section or top-view angle.

[0040] It should be noted that the maximum width of the first precipitate 2 is 0.5-5 μm. By limiting the maximum width of the first precipitate 2 to 0.5-5 μm, it is kept within a suitable range. On the one hand, if the maximum width of the first precipitate 2 is too large, stress concentration will occur when the copper-nickel-tin alloy is subjected to external forces, leading to cracking of the copper-nickel-tin alloy and affecting its quality and reliability. On the other hand, if the maximum width of the first precipitate 2 is too small, the precipitate may be directly cut by dislocations, failing to achieve the effect of enhancing the mechanical properties of the copper-nickel-tin alloy. Therefore, limiting the maximum width of the first precipitate 2 to 0.5-5 μm can avoid both stress concentration due to excessive size and easy cutting by dislocation movement due to excessive size, thereby significantly improving the mechanical properties of the copper-nickel-tin alloy. Optionally, the maximum width of the first precipitated phase 2 can be any one of the following values ​​or an interval of any two values: 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.7 μm, 3 μm, 3.4 μm, 4 μm, 4.5 μm, or 5 μm.

[0041] It should be noted that 20%-60% of the first precipitated phase 2 per unit volume is located at the grain boundaries of the matrix phase 1. During the formation of the copper-nickel-tin alloy, aging treatment causes supersaturated tin atoms and other atoms to nucleate at matrix defects (vacancies, dislocations), improving the alloy strength through coherent strain or dislocation cutting; another portion of tin atoms and other atoms precipitate uniformly at the grain boundaries, preferentially occupying the nucleation sites of discontinuous precipitates, effectively preventing the continuous precipitation of discontinuous precipitates from the grain boundaries. Therefore, limiting the proportion of the first precipitate 2 at the grain boundaries of the matrix phase 1 to 20%-60% within a unit volume serves two purposes. Firstly, it prevents a small number of tin atoms from occupying nucleation sites and agglomerating at the grain boundaries, forming discontinuous precipitates that widen the grain boundaries and significantly reduce the mechanical properties and corrosion resistance of the copper-tin-nickel alloy. Secondly, it prevents an excessive number of first precipitates 2 at the grain boundaries of the matrix phase 1 from being too few in the matrix phase 1, thus failing to enhance the mechanical properties of the copper-tin-nickel alloy. Therefore, limiting the proportion of the first precipitate 2 at the grain boundaries of the matrix phase 1 to 20%-60% within a unit volume effectively occupies nucleation sites for discontinuous precipitates, effectively preventing continuous precipitation from the grain boundaries, while also ensuring the excellent mechanical properties and good corrosion resistance of the copper-tin-nickel alloy. This allows the copper-tin-nickel alloy to be widely used in key components in electronics, electrical engineering, aerospace, and high-end equipment manufacturing. Optionally, the proportion of the first precipitated phase 2 located at the grain boundary of the matrix phase 1 can be any one of 20%, 30%, 35%, 40%, 50%, 55% or 60% or a range of any two of these values.

[0042] Preferably, in this embodiment of the invention, the first precipitated phase 2 is Ni. 6.67 SnB2.

[0043] Preferably, in this embodiment of the invention, in the copper-nickel-tin alloy, more than 50% of the first precipitated phase 2 has a maximum width of 1-3 μm. Further limiting the maximum width of the first precipitated phase 2 to 1-3 μm reduces both the risk of stress concentration due to excessive size and the risk of dislocation movement cutting due to excessively small size, thereby further improving the mechanical properties of the copper-nickel-tin alloy. Simultaneously, limiting the proportion of the first precipitated phase 2 with a maximum width of 1-3 μm to more than 50% ensures that the enhanced effect is not compromised due to a low proportion. Therefore, limiting the proportion of the first precipitated phase 2 with a maximum width of 1-3 μm to more than 50% is beneficial for further improving the mechanical properties of the copper-nickel-tin alloy.

[0044] Furthermore, copper-nickel-tin alloys also include DO. 22 The precipitated phase and the L12 precipitated phase. Wherein, the DO... 22The ratio of the proportion of the precipitated phase to the proportion of the L12 precipitated phase is 0.6-1.5. DO 22 L12 precipitates and DO are two important ordered precipitates. 22 The precipitated phase has a tetragonal ordered structure. Under low temperature and high Sn conditions, it is generated through amplitude modulation decomposition or defect nucleation, becoming coherent with the matrix phase 1. This produces a strong strain field, hindering dislocation movement and significantly improving the strength of the copper-nickel-tin alloy. However, excessive DO... 22 Precipitated phases can lead to dislocation pile-up, causing brittle fracture and reduced plasticity. L12 precipitates have a face-centered cubic ordered structure and exhibit this structure under high temperature and low Sn or throughout the DO phase. 22 The precipitate 3, formed during reconstruction, exhibits high symmetry, with dislocation cutting forming antiphase domain boundaries. It has slightly lower strength but better ductility. Therefore, DO... 22 The ratio of the proportion of the precipitated phase in matrix phase 1 to the proportion of the L12 precipitated phase in matrix phase 1 is limited to 0.6-1.5, on the one hand, to avoid the influence of DO. 22 If the proportion of precipitated phase is too low, the effect of hindering dislocation movement will be insignificant, leading to a significant decrease in the strength of copper-nickel-tin alloys; on the other hand, it will not be effective due to DO 22 Excessive precipitate proportion and insufficient L12 precipitate proportion lead to dislocation pile-up, causing brittle fracture and reduced plasticity; therefore, by using DO... 22 The ratio of the proportion of the precipitated phase to the proportion of the L12 precipitated phase is limited to 0.6-1.5, so that DO 22 The precipitated phases and L12 precipitates are within a suitable range, which enhances the strength of the copper-nickel-tin alloy while significantly improving its plastic deformation, breaking through the performance bottleneck of copper alloys. This allows copper-nickel-tin alloys to be widely used in key components in electronics, electrical engineering, aerospace, and high-end equipment manufacturing. Optionally, the ratio can be any one value or a range of any two values ​​from 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.4, 1.5, or 1.6. Additionally, when DO... 22 The phase transformation to the L12 phase requires the consumption of tin atoms in matrix 1. Further aging causes the L12 phase to gradually transform into the DO3 phase. The DO3 phase bonds to the matrix at incoherent interfaces and preferentially nucleates at grain boundaries, growing into the grains to form lamellar, discontinuous precipitates. This precipitation weakens the grain boundaries, significantly reducing the alloy's strength and toughness. Therefore, the formation of the first precipitated phase 2 consumes a large number of tin atoms, slowing down the DO3 phase transformation. 22 The phase transformation to L12 phase slows down the formation of DO3, thereby inhibiting the discontinuous precipitation of DO3 phase at grain boundaries. At the same time, the first precipitated phase can hinder dislocation movement and prevent crack propagation, thus improving the mechanical properties and corrosion resistance of copper-nickel-tin alloy.

[0045] Furthermore, in this embodiment of the invention, the DO 22The maximum width of the precipitated phase is 15-30 nanometers. Nanoscale DO 22 The superposition of the precipitated phase and the matrix coherent strain field significantly hinders dislocation motion, and the strength can reach the theoretical limit. By using DO... 22 The maximum width of the precipitated phase is limited to 15-30 nanometers. On the one hand, this will not be affected by DO. 22 If the precipitated phase is too small, it will be directly cut by dislocations, slowing down or even reducing the strength increase, and at the same time, it will not be affected by DO. 22 If the precipitated phase is too small, it directly transforms into a non-equilibrium phase instead of an L12 precipitate, and even nano-sized DO precipitates at the grain boundaries. 22 Precipitated phases may induce grain boundary slip or creep, leading to a significant decrease in the increase in strength and affecting the widespread application of copper-nickel-tin alloys. On the other hand, it will not be affected by DO 22 Excessively large precipitate size leads to loss of coherence with matrix phase 1, weakening the strain field and reducing the force hindering dislocation movement, thus decreasing the strength of the copper-nickel-tin alloy. Therefore, DO... 22 The maximum width of the precipitated phase is limited to 15-30 nanometers. This avoids direct cutting by dislocations, which would slow down or even reduce the strength increase. It also prevents loss of coherence with the matrix phase 1, which would weaken the strain field and reduce the force hindering dislocation movement, thus maintaining a high strength level in the copper-nickel-tin alloy. Optionally, DO... 22 The maximum width of the precipitated phase can be any one of 15nm, 20nm, 25nm or 30nm, or any range of two of these values.

[0046] Furthermore, in this embodiment of the invention, the maximum width of the L12 precipitate is 30-50 nanometers. By limiting the maximum width of the L12 precipitate to 30-50 nanometers, on the one hand, excessive cutting resistance due to excessively small size will not cause the alloy to become brittle; on the other hand, loss of coherence with matrix phase 1 due to excessively large size will not weaken the strengthening effect of the alloy. Therefore, limiting the maximum width of the L12 precipitate to 30-50 nanometers can balance the strength and plasticity of the alloy, giving the alloy excellent mechanical properties. Optionally, the maximum width of the L12 precipitate can be any one or a range of any two values ​​from 30 nm, 35 nm, 40 nm, 45 nm, or 50 nm.

[0047] It is worth noting that, in the embodiments of the present invention, more than 70% of the DO 22 The precipitated phases are located on the surface of the copper-nickel-tin alloy, with over 70% of the L12 precipitates located in the core. This can be achieved by adjusting the DO concentration in the surface and core. 22 The ratio of precipitated phase to L12 precipitated phase can achieve a gradient performance of "hard on the outside and tough on the inside". Surface DO 22With a precipitate phase accounting for more than 70%, it forms a coherent structure with the matrix phase 1, resulting in strain strengthening and resistance to abrasive wear. In the core, the L12 precipitate phase accounts for more than 70%, and dislocation cutting forms anti-phase domain boundaries, resulting in better plasticity and inhibiting fatigue crack propagation. This allows the copper-nickel-tin alloy to break through the performance bottleneck of traditional homogeneous materials and achieve cross-scale performance control of "external hardness and internal toughness", making it particularly suitable for the needs of multi-functional components under complex working conditions.

[0048] It should be noted that over 70% of the aforementioned DO 22 The precipitated phases are located on the surface of the copper-nickel-tin alloy, with over 70% of the L12 precipitates located in the core of the alloy. This is achieved through at least one of gradient aging, surface tinning, or selective cooling. Surface tinning involves depositing a 2-5 μm Sn layer on the alloy surface using magnetron sputtering, followed by diffusion annealing at 350°C for 1 hour to create a Sn concentration gradient: surface Sn ≈ 9 wt%, core Sn ≈ 5 wt%. Selective cooling involves rapid cooling of the surface layer with liquid nitrogen at a rate > 1000°C / s, and air cooling of the core at a rate of 10°C / s. The specific steps of gradient aging are as follows:

[0049] 1) Laser aging: Local heating with a high-energy beam at 380-450℃, aging time 25-35s, rapidly forming nano-DO. 22 The phase has a depth of 50-100μm. The temperature control accuracy of laser heating needs to be ±5℃, and the layer depth fluctuation should be <10μm.

[0050] 2) Induction heating: Medium-frequency induction aging treatment temperature 500-520℃, aging treatment time 1.5-2.5min, forming DO. 22 / L12 hybrid transition layer 200-300μm. Temperature control accuracy for induction heating needs to be ±5℃, and layer depth fluctuation <10μm.

[0051] 3) Furnace aging: The core is treated at a low temperature of 580-620℃ for 1-1.5 hours to generate a uniform L12 phase.

[0052] It should be noted that, in this embodiment of the invention, the average grain size of the matrix phase 1 is 15-40 μm. By limiting the average grain size of the matrix phase 1 to 15-40 μm, on the one hand, the alloy will not become embrittled due to excessively large grain size, thus reducing its mechanical properties and affecting its use. On the other hand, the total grain boundary area per unit volume will not increase significantly due to excessively small grain size, leading to insufficient contact between the corrosive medium and the alloy interface, thereby reducing the corrosion resistance of the copper-nickel-tin alloy. Therefore, limiting the average grain size of the matrix phase 1 to 15-40 μm significantly reduces the total grain boundary area per unit volume, thereby effectively reducing the contact area between the corrosive medium and the alloy interface. This significantly inhibits the ion migration process in the electrochemical reaction, slows down the anodic dissolution rate and the cathodic reduction rate, and achieves a significant reduction in the alloy corrosion rate, thus significantly improving the corrosion resistance of the material. Optionally, the average grain size of the matrix phase 1 can be any one or a range of any two values ​​from 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, or 40 μm.

[0053] In one embodiment, the copper-nickel-tin alloy comprises, by weight percentage, 15.0-15.2 wt% nickel, 8.0-8.2 wt% tin, 0.05-0.15 wt% boron, and the balance copper and unavoidable impurities. The addition of nickel and tin to copper allows for the formation of amplitude-modulated decomposition and ordered phase structures within the copper-nickel-tin alloy, thereby improving its mechanical properties. Simultaneously, the addition of boron allows for the precipitation of a first precipitate 2, Ni, at grain boundaries and within grains. 6.67 By controlling the SnB2 phase and the boron content within the aforementioned range, the precipitation behavior of each precipitated phase during the aging process of copper-nickel-tin alloy can be effectively regulated, the nucleation of discontinuous precipitates on grain boundaries can be effectively suppressed, and the mechanical properties of the alloy can be improved.

[0054] See Figure 3 , Figure 3 The flowchart illustrates the steps of a method for preparing a copper-nickel-tin alloy according to the present invention. The embodiment of the present invention provides a method for preparing a copper-nickel-tin alloy, which includes the following steps:

[0055] S10: Raw material preparation: Prepare the raw materials according to the following weight percentages of elements: 15.0-15.2wt% nickel, 8.0-8.2wt% tin, 0.05-0.15wt% boron and balance copper and unavoidable impurities.

[0056] S20: Vacuum melting: Place the raw material from step S10 into a vacuum melting furnace, with the pressure inside the furnace ≤ 1×10⁻⁶. 3 Pa, then a protective gas is introduced.

[0057] S30: Casting: Using the bottom-pouring casting method, the alloy liquid from step S20 is poured into a preheated cast iron mold at 300-400℃.

[0058] S40: Homogenization treatment: The ingot from step S30 is placed in a heating furnace for homogenization treatment.

[0059] S50: Hot rolling: Hot rolling of alloy blocks that have undergone homogenization treatment.

[0060] S60: Solution treatment: The rolled copper-nickel-tin alloy is subjected to solution treatment.

[0061] S70: Aging treatment: The copper-nickel-tin alloy after solution quenching is subjected to aging treatment.

[0062] In step S10, the raw materials are copper with a purity of 99.95%, nickel with a purity of 99.95%, tin with a purity of 99.95%, and Cu-5B master alloy.

[0063] In step S20, the raw materials include copper, nickel, and tin. The vacuum melting process involves first adding the raw materials to a vacuum melting furnace, then adding a Cu-5B master alloy at a furnace temperature of 1300°C. The melting temperature is 1400-1500°C, and the melting time is 10-15 minutes. By controlling the melting temperature and time within the above ranges, the uniform distribution of each element in the melt can be ensured, thereby improving the strength of the reinforced copper-nickel-tin-boron alloy.

[0064] In step S40, the heating rate of the homogenization treatment is 5-8℃ / min, the homogenization treatment temperature is 800℃-900℃, and the treatment time is 5-6h. By controlling the homogenization treatment temperature and time within the above range, the microscopic composition inhomogeneity generated during solidification or high-temperature processing can be eliminated, resulting in more consistent mechanical properties of the material as a whole. Simultaneously, it reduces the formation of harmful phases and lowers the risk of localized galvanic corrosion or intergranular corrosion.

[0065] It should be noted that the homogenization process uses a protective or controlled atmosphere to prevent oxidation. The homogenization process is cooled to room temperature using furnace cooling or air cooling.

[0066] In step S50, the hot rolling temperature is 800℃-920℃, and the hot rolling reduction rate is 50%-70%. By controlling the hot rolling temperature and reduction rate within the above range, internal pores can be closed, the material density can be improved, and the grains can be extended along the rolling direction, recrystallized, and the anisotropy caused by casting can be reduced. This further promotes the diffusion and homogenization of residual segregated elements, improving the mechanical properties of the alloy. At the same time, the hot rolling process promotes significant grain coarsening through a dynamic recrystallization mechanism. Grain coarsening significantly reduces the total grain boundary area per unit volume, thereby effectively reducing the contact area between the corrosive medium and the alloy interface. This can significantly inhibit the ion migration process in the electrochemical reaction, slow down the anodic dissolution rate and the cathodic reduction rate, and achieve a significant reduction in the alloy corrosion rate, thus significantly improving the corrosion resistance of the material. For example, a reduction rate of 70% is achieved through a series of rolling channels: 13mm→11mm→9mm→7mm→5mm→3.9mm.

[0067] In step S60, the solution treatment temperature is 850-900℃, and the holding time is 4-5 hours. By controlling the solution treatment temperature and time within the above range, the elements are fully dissolved into the matrix, coarse precipitates formed during processing are eliminated, the microstructure is reset, and stress is relieved. The solution treatment uses a protective atmosphere or a controlled atmosphere to prevent oxidation, avoid surface tin depletion, and prevent affecting the transformation of the microstructure.

[0068] It should be noted that after the high-temperature solution treatment, cooling should be performed immediately, including at least one of water quenching or air cooling. For example, after the high-temperature solution treatment, the solution is immediately placed in hot water at 60°C for quenching for 5 minutes to lock in the high-temperature composition and obtain a metastable supersaturated solid solution. This forces the solute atoms to remain in the matrix, ensuring good solution effect and microstructure.

[0069] In step S70, the aging treatment temperature is 350-400℃, and the aging treatment time is 1.5-2.5h. By controlling the aging treatment temperature and time within the above range, the supersaturated solid solution can smoothly precipitate nanoscale strengthening phases and suppress the precipitation of harmful phases, thereby improving the strength, hardness, and fatigue performance of the alloy.

[0070] In one embodiment, see Figure 4 In step S70, the timeliness processing steps are as follows:

[0071] S71: Laser aging treatment, aging treatment temperature 380-450℃, aging treatment time 25-35s;

[0072] S72: Medium frequency induction heating aging treatment, aging treatment temperature 500-520℃, aging treatment time 1.5-2.5min;

[0073] S73: Low-temperature slow aging treatment, aging treatment temperature 580-620℃, aging treatment time 1-1.5h.

[0074] By employing a stepped, graded aging treatment method, the dissolved oxygen (DO) levels in the surface and core layers were regulated. 22 The ratio of the precipitated phase to the L12 precipitated phase makes the surface DO 22 With a precipitate phase accounting for over 70%, it forms a coherent structure with the matrix phase, resulting in strain strengthening and resistance to abrasive wear. In the core, the L12 precipitate phase accounts for over 70%, and dislocation cutting forms antiphase domain boundaries, resulting in better plasticity and inhibiting fatigue crack propagation. This allows the copper-nickel-tin alloy to break through the performance bottleneck of traditional homogeneous materials and achieve cross-scale performance control of "external hardness and internal toughness," making it particularly suitable for the needs of multifunctional components under complex working conditions.

[0075] It should be noted that after the aging treatment is completed, the material is cooled to room temperature in the furnace to obtain the final copper-nickel-tin alloy material.

[0076] The copper-nickel-tin alloy and its preparation method provided in this invention have the following advantages: by forming a first precipitate at the grain boundary of the matrix phase, and controlling the maximum width of the first precipitate to be 0.5-5 μm and the first precipitate per unit volume to be located at the grain boundary of the matrix phase, the first precipitate preferentially occupies the nucleation sites of discontinuous precipitates. During heat treatment, it effectively prevents discontinuous precipitates from continuously precipitating from the grain boundary, and at the same time, it can hinder dislocation movement and prevent crack propagation, thereby improving the mechanical properties and corrosion resistance of the copper-nickel-tin alloy.

[0077] On the other hand, by forming the first precipitated phase at the grain boundaries of the matrix phase, a large number of tin atoms are consumed, thus slowing down the DO process. 22 The phase transformation to L12 phase slows down the formation of DO3 phase, thereby inhibiting the discontinuous precipitation of DO3 phase at grain boundaries. At the same time, the first precipitated phase can hinder dislocation movement and prevent crack propagation, thus improving the mechanical properties and corrosion resistance of copper-nickel-tin alloy.

[0078] To demonstrate the beneficial effects of the copper-nickel-tin alloy and its preparation method provided in the embodiments of the present invention, the following description is provided in conjunction with several embodiments and comparative examples.

[0079] Example 1:

[0080] A copper-nickel-tin alloy comprising the following components in weight percentages: 15.0 wt% nickel, 8.0 wt% tin, 0.05 wt% boron, and balance copper and unavoidable impurities, including the matrix phase, the first precipitated phase, and DO. 22 The precipitated phases are L12 and Ni. 6.67SnB2, with a maximum width of 3 μm, accounts for 50% of the volume, and 20% of the first precipitated phase per unit volume is located at the grain boundaries of the matrix phase; DO 22 The maximum width of the precipitated phase is 20 nm, the maximum width of the L12 precipitated phase is 30 nm, and DO 22 The ratio of the proportion of precipitated phase to the proportion of L12 precipitated phase is 0.6, and the average grain size of the matrix phase is 25 μm.

[0081] Example 2:

[0082] The copper-nickel-tin alloy in this embodiment is the same as that in Example 1, except that 40% of the first precipitated phase with a maximum width of 3 μm per unit volume is located at the grain boundary of the matrix phase.

[0083] Example 3:

[0084] The copper-nickel-tin alloy in this embodiment is the same as that in Embodiment 1, except that: the maximum width is 3μm, accounting for 70% of the unit volume, and 60% of the first precipitated phase in the unit volume is located at the grain boundary of the matrix phase.

[0085] Example 4:

[0086] The copper-nickel-tin alloy in this embodiment is the same as that in Embodiment 1, except that: the maximum width is 3μm, accounting for 90% of the unit volume, and 60% of the first precipitated phase in the unit volume is located at the grain boundaries of the matrix phase.

[0087] Example 5:

[0088] The copper-nickel-tin alloy in this embodiment is the same as that in Example 1, except that: DO 22 The ratio of the proportion of precipitated phase to the proportion of L12 precipitated phase is 1.

[0089] Example 6:

[0090] The copper-nickel-tin alloy in this embodiment is the same as that in Example 1, except that: DO 22 The ratio of the proportion of precipitated phase to the proportion of L12 precipitated phase is 1.2.

[0091] Example 7:

[0092] The copper-nickel-tin alloy in this embodiment is the same as that in Example 1, except that: 70% of the DO... 22 The precipitated phase is located on the surface of the copper-nickel-tin alloy, and 70% of the L12 precipitated phase is located in the core of the copper-nickel-tin alloy.

[0093] Example 8:

[0094] The copper-nickel-tin alloy in this embodiment is the same as that in Example 1, except that: 90% of the DO...22 The precipitated phase is located on the surface of the copper-nickel-tin alloy, and 90% of the L12 precipitated phase is located in the core of the copper-nickel-tin alloy.

[0095] Example 9:

[0096] The copper-nickel-tin alloy in this embodiment is the same as that in Example 1, except that the copper-nickel-tin alloy is composed of the following components by mass percentage: 15.0 wt% nickel, 8 wt% tin, 0.1 wt% boron and balance copper and unavoidable impurities.

[0097] Example 10:

[0098] The copper-nickel-tin alloy in this embodiment is the same as that in Example 1, except that the copper-nickel-tin alloy is composed of the following components by mass percentage: 15.0 wt% nickel, 8 wt% tin, 0.15 wt% boron and balance copper and unavoidable impurities.

[0099] Example 11:

[0100] The copper-nickel-tin alloy in this embodiment is the same as that in Example 1, except that the copper-nickel-tin alloy is composed of the following components by mass percentage: 15.1 wt% nickel, 8 wt% tin, 0.1 wt% boron and balance copper and unavoidable impurities.

[0101] Example 12:

[0102] The copper-nickel-tin alloy in this embodiment is the same as that in Example 1, except that the copper-nickel-tin alloy is composed of the following components by mass percentage: 15.1 wt% nickel, 8.2 wt% tin, 0.1 wt% boron and balance copper and unavoidable impurities.

[0103] Comparative Example 1:

[0104] A copper-nickel-tin alloy comprising the following components in weight percentages: 15.0 wt% nickel, 8.0 wt% tin, and the balance copper and unavoidable impurities, including the matrix phase and DO. 22 Precipitated phase and L12 precipitated phase, DO 22 The maximum width of the precipitated phase is 20 nm, the maximum width of the L12 precipitated phase is 30 nm, and DO 22 The ratio of precipitated phase to L12 precipitated phase is 0.6, and the average grain size of the matrix phase is 25 μm. See also Figure 5 and Figure 6 , Figure 5 and Figure 6 The images shown are 1500X and 2500X magnifications of a copper-nickel-tin alloy from this comparative example. No obvious precipitates were observed in this comparative example, and relatively obvious discontinuous precipitates could be observed at the grain boundaries, with the thickness of the discontinuous precipitate layer being about 6.5 micrometers.

[0105] Comparative Example 2:

[0106] A copper-nickel-tin alloy comprising the following components in weight percentages: 15.0 wt% nickel, 8.0 wt% tin, and the balance copper and unavoidable impurities, including the matrix phase and DO. 22 Precipitated phase and L12 precipitated phase, DO 22 The maximum width of the precipitated phase is 20 nm, the maximum width of the L12 precipitated phase is 30 nm, and DO 22 The ratio of the precipitated phase to the L12 precipitated phase is 0.6, and the average grain size of the matrix phase is 5 μm.

[0107] Comparative Example 3:

[0108] The copper-nickel-tin alloy in this embodiment is the same as that in Example 1, except that the maximum width of the first precipitated phase is 10 μm.

[0109] Comparative Example 4:

[0110] The copper-nickel-tin alloy in this embodiment is the same as that in Example 1, except that 5% of the first precipitated phase per unit volume is located at the grain boundary of the matrix phase.

[0111] Comparative Example 5:

[0112] The copper-nickel-tin alloy in this embodiment is the same as that in Example 1, except that: DO 22 The maximum width of the precipitated phase is 5 nm, and the maximum width of the L12 precipitated phase is 5 nm.

[0113] Comparative Example 6:

[0114] The copper-nickel-tin alloy in this embodiment is the same as that in Example 1, except that: DO 22 The maximum width of the precipitated phase is 70 nm, and the maximum width of the L12 precipitated phase is 80 nm.

[0115] Mechanical properties and corrosion resistance were tested on the copper-tin-nickel alloys of Examples 1-12 and Comparative Examples 1-6.

[0116] Mechanical property testing: Tensile test data are shown in Table 1.

[0117] Corrosion resistance test: Electrochemical test data are shown in Table 1.

[0118] Table 1. Mechanical properties and corrosion resistance of copper-tin-nickel alloys of Examples 1-12 and Comparative Examples 1-6.

[0119]

[0120] As can be seen from Table 1, the copper-tin-nickel alloy of the present invention has excellent mechanical properties and corrosion resistance, which enables the copper-nickel-tin alloy to be widely used in key components of electronics, electrical engineering, aerospace and high-end equipment manufacturing.

[0121] In summary, by forming a first precipitate at the grain boundaries of the matrix phase, and controlling the maximum width of the first precipitate to be 0.5-5 μm (3 μm) and the fact that 20%-60% (20%, 40%, 60%) of the first precipitate per unit volume is located at the grain boundaries of the matrix phase, the first precipitate preferentially occupies the nucleation sites of discontinuous precipitates. During heat treatment, this effectively prevents discontinuous precipitates from continuously precipitating from the grain boundaries, while also hindering dislocation movement and preventing crack propagation, thereby improving the mechanical properties and corrosion resistance of copper-nickel-tin alloys.

[0122] On the other hand, by forming the first precipitated phase at the grain boundaries of the matrix phase, a large number of tin atoms are consumed, thus slowing down the DO process. 22 The phase transformation to L12 phase slows down the formation of DO3 phase, thereby inhibiting the discontinuous precipitation of DO3 phase at grain boundaries. At the same time, the first precipitated phase can hinder dislocation movement and prevent crack propagation, thus improving the mechanical properties and corrosion resistance of copper-nickel-tin alloy.

[0123] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0124] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A copper-nickel-tin alloy, characterized in that, The composition comprises, by weight percentage, 15.0-15.2 wt% nickel, 8.0-8.2 wt% tin, 0.05-0.15 wt% boron, and the balance copper and unavoidable impurities. The copper-nickel-tin alloy comprises at least a matrix phase and a first precipitated phase, wherein the average grain size of the matrix phase is 15-40 μm, and the first precipitated phase is Ni. 6.67 SnB2, wherein the maximum width of the first precipitated phase is 0.5-5 μm, and 20%-60% of the first precipitated phase per unit volume is located at the grain boundaries of the matrix phase; The preparation method of the copper-nickel-tin alloy includes the following steps: 1) Raw material preparation: The raw materials are prepared according to the following weight percentages of elements: 15.0-15.2wt% nickel, 8.0-8.2wt% tin, 0.05-0.15wt% boron and balance copper and unavoidable impurities; 2) Vacuum melting: Place the raw materials from step 1) into a vacuum melting furnace. The pressure inside the vacuum melting furnace should be ≤1×10⁻⁶. 3 Pa, then a protective gas is introduced; 3) Casting: The alloy liquid from step 2) is poured into a preheated cast iron mold at 300-400℃ using a bottom-pouring casting method. 4) Homogenization treatment: The ingot from step 3) is placed in a heating furnace for homogenization treatment. The heating rate of the homogenization treatment is 5-8℃ / min, the homogenization treatment temperature is 800℃-900℃, and the treatment time is 5-6h. 5) Hot rolling: The homogenized alloy block is hot rolled at a temperature of 800℃-920℃, and the reduction rate of the hot rolling is 50%-70%. 6) Solution treatment: The rolled copper-nickel-tin alloy is subjected to solution treatment at a temperature of 850-900℃ and a holding time of 4-5 hours. After the high-temperature solution treatment, it is cooled immediately. 7) Aging treatment: The copper-nickel-tin alloy after solution quenching is subjected to aging treatment. The aging treatment steps are as follows: ① Laser aging treatment, aging temperature 380-450℃, aging time 25-35s; ② Medium-frequency induction heating aging treatment, aging treatment temperature 500-520℃, aging treatment time 1.5-2.5min; ③ Low-temperature slow aging treatment, aging temperature 580-620℃, aging time 1-1.5h.

2. The copper-nickel-tin alloy as described in claim 1, characterized in that, The maximum width of the first precipitated phase is 1-3 μm for more than 50% of the unit volume.

3. The copper-nickel-tin alloy as described in claim 1, characterized in that, The copper-nickel-tin alloy also includes DO. 22 The precipitated phase and the L12 precipitated phase, wherein the DO 22 The ratio of the proportion of precipitated phase to the proportion of L12 precipitated phase is 0.6-1.

5.

4. The copper-nickel-tin alloy as described in claim 3, characterized in that, The DO 22 The maximum width of the precipitated phase is 15-30 nanometers, and the maximum width of the L12 precipitated phase is 30-50 nanometers.

5. The copper-nickel-tin alloy as described in claim 3, characterized in that, More than 70% of the DO 22 The precipitated phase is located on the surface of the copper-nickel-tin alloy, and more than 70% of the L12 precipitated phase is located in the core of the copper-nickel-tin alloy.

6. The method for preparing the copper-nickel-tin alloy according to any one of claims 1-5, characterized in that, Includes the following steps: 1) Raw material preparation: The raw materials are prepared according to the following weight percentages of elements: 15.0-15.2wt% nickel, 8.0-8.2wt% tin, 0.05-0.15wt% boron and balance copper and unavoidable impurities; 2) Vacuum melting: Place the raw materials from step 1) into a vacuum melting furnace. The pressure inside the vacuum melting furnace should be ≤1×10⁻⁶. 3 Pa, then a protective gas is introduced; 3) Casting: The alloy liquid from step 2) is poured into a preheated cast iron mold at 300-400℃ using a bottom-pouring casting method. 4) Homogenization treatment: The ingot from step 3) is placed in a heating furnace for homogenization treatment. The heating rate of the homogenization treatment is 5-8℃ / min, the homogenization treatment temperature is 800℃-900℃, and the treatment time is 5-6h. 5) Hot rolling: The homogenized alloy block is hot rolled at a temperature of 800℃-920℃, and the reduction rate of the hot rolling is 50%-70%. 6) Solution treatment: The rolled copper-nickel-tin alloy is subjected to solution treatment at a temperature of 850-900℃ and a holding time of 4-5 hours. After the high-temperature solution treatment, it is cooled immediately. 7) Aging treatment: The copper-nickel-tin alloy after solution quenching is subjected to aging treatment. The aging treatment steps are as follows: ① Laser aging treatment, aging temperature 380-450℃, aging time 25-35s; ② Medium-frequency induction heating aging treatment, aging treatment temperature 500-520℃, aging treatment time 1.5-2.5min; ③ Low-temperature slow aging treatment, aging temperature 580-620℃, aging time 1-1.5h.

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