Homogeneous high-toughness copper-nickel-tin alloy and preparation method thereof

Abstract

The invention discloses a homogeneous high-toughness copper-nickel-tin alloy and a preparation method thereof, and relates to the technical field of non-ferrous metal alloys. The alloy comprises the following components in percentage by mass: 12.0%-15.0% of Ni, 7.5%-9.0% of Sn, 0.01%-0.10% of Y, 0.001%-0.005% of B and the balance of Cu and inevitable impurities. The preparation method comprises the steps of vacuum induction melting matched with superaudio electromagnetic stirring, homogenization treatment, hot working, multi-stage solution treatment, subzero treatment and multi-stage aging treatment. The Spinodal decomposition structure wavelength of the alloy is 3-8 nm, the grain boundary Y-rich phase size is smaller than 200 nm, the tensile strength is larger than or equal to 850 MPa, the ductility is larger than or equal to 15%, the V-shaped notch impact toughness is larger than or equal to 90 J / cm < 2 >, and the comprehensive performance is excellent.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal alloy technology, specifically relating to a homogeneous, high-toughness copper-nickel-tin alloy and its preparation method. Background Technology

[0002] Copper-nickel-tin alloys are widely used in aerospace, electronic communications, and marine engineering due to their excellent strength, corrosion resistance, and stress relaxation resistance. These alloys primarily achieve high strength through a spinodal strengthening mechanism. However, when the tin content is high (typically >6%), severe dendritic segregation easily occurs during casting, leading to the formation of brittle tin-rich phases and γ-(Ni,Cu)3Sn phases at grain boundaries. This significantly reduces the alloy's plasticity and toughness, limiting its application in high-load structural components.

[0003] To mitigate tin segregation, current technologies primarily employ powder metallurgy processes such as rapid solidification or mechanical alloying. While these methods improve compositional uniformity, they involve complex equipment, high costs, and difficulty in producing large-sized billets. Furthermore, powder processing easily introduces defects such as oxide inclusions, which negatively impact toughness. Traditional casting processes combined with conventional heat treatments (such as single-stage solution treatment and aging) have limited effectiveness in eliminating segregation and struggle to precisely control the Spinodal decomposition process, often resulting in a trade-off between strength and toughness.

[0004] Therefore, developing a method for preparing copper-nickel-tin alloys that can effectively suppress segregation, refine microstructure, and achieve a balance between high strength and high toughness through composition optimization and process innovation has become a pressing technical challenge in this field. In particular, a suitable and cost-effective preparation process for industrial production is needed to meet the growing demands for material performance in high-end applications. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, the embodiments of the present invention provide a homogeneous high-toughness copper-nickel-tin alloy with reasonable composition design and efficient process flow, and its preparation method. This solves the problems of insufficient toughness caused by severe dendrite segregation in high-tin content copper-nickel-tin alloys in the prior art, and the difficulty of balancing high strength and high toughness in traditional casting and heat treatment processes.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A homogeneous, high-toughness copper-nickel-tin alloy, comprising the following components by mass percentage: Ni 12.0%~15.0%, Sn 7.5%~9.0%, Y 0.01%~0.10%, B 0.001%~0.005%, balance Cu and unavoidable impurities.

[0007] In the aforementioned copper-nickel-tin alloy, preferably, the total amount of unavoidable impurity elements does not exceed 0.15%.

[0008] Preferably, in the microstructure of the copper-nickel-tin alloy described above, the wavelength of the Spinodal decomposition structure is between 3-8 nm, and Y-rich compound phases with a size of less than 200 nm are precipitated at the grain boundaries; the tensile strength of the alloy is ≥850 MPa, the elongation is ≥15%, and the V-notch impact toughness is ≥90 J / cm².

[0009] This invention relates to a homogeneous, high-toughness copper-nickel-tin alloy. Through alloy composition design and microstructure control, it synergistically addresses the core problem of severe dendritic segregation and the difficulty in achieving both strength and toughness in high-tin-content copper-nickel-tin alloys. Specifically, 12.0%–15.0% Ni and 7.5%–9.0% Sn form the basis for Spinodal decomposition strengthening, ensuring high strength. 0.01%–0.10% Y forms fine, Y-rich compound phases (<200 nm in size) at grain boundaries, pinning grain boundaries, inhibiting grain growth, and purifying the melt. 0.001%–0.005% B segregates at grain and phase boundaries, further strengthening grain boundaries and inhibiting the formation of brittle phases, collectively improving the alloy's plasticity and toughness. Finally, by limiting the Spinodal decomposition wavelength and performance indicators, the alloy achieves a uniform nanoscale decomposition-strengthened phase and excellent overall mechanical properties.

[0010] As a general inventive concept, this invention provides a method for preparing the homogeneous, high-toughness copper-nickel-tin alloy as described above, comprising the following steps: S1. Vacuum induction melting combined with ultrasonic electromagnetic stirring is used for melting and casting to obtain ingots; S2. The ingot described in step S1 is homogenized and held at 850-950℃ for 20-30 hours, and then cooled to below 300℃ at a controlled rate of 20-30℃ / hour before being unloaded from the furnace. S3. Perform hot working on the ingot after homogenization treatment in step S2; S4. Perform multi-stage solution treatment on the material after hot working in step S3. First, hold at 820-850℃ for 1-2 hours and then quench in water; then hold at 780-800℃ for 2-4 hours and then quench in water. The quenching transfer time for both stages of solution treatment is less than 3 seconds. S5. Perform cryogenic treatment on the material after solution treatment in step S4 by holding it in liquid nitrogen at -196℃ for 1-2 hours; S6. Perform multi-stage aging treatment on the material after cryogenic treatment in step S5. First, keep it at 380-420℃ for 6-10 hours, then cool it down to 320-350℃ at a cooling rate of 40-50℃ / hour, and keep it at this temperature for 8-12 hours. Finally, air cool it to room temperature.

[0011] In the above-mentioned preparation method, preferably, the frequency of the ultrasonic electromagnetic stirring in step S1 is 15-25kHz, and the stirring power is dynamically adjusted according to the melting process; the specific procedure for dynamically adjusting the stirring power is as follows: from the start of melting to 10 minutes after melting, the stirring power is 60% of the rated power; from 10 minutes after melting to 15 minutes before casting, the stirring power is increased to 80% of the rated power; from 15 minutes before casting to the end of casting, the stirring power is increased to 100% of the rated power.

[0012] In the above preparation method, preferably, the cooling rate in step S2 is controlled at 25°C / hour.

[0013] In the above-mentioned preparation method, preferably, the hot working in step S3 is hot rolling or hot forging, the initial rolling temperature is not lower than 850°C, and the total deformation is not lower than 70%.

[0014] In the above-described preparation method, preferably, the quenching transfer time in both stages of solution treatment in step S4 is less than 2 seconds.

[0015] In the above-described preparation method, preferably, the material after cryogenic treatment in step S5 needs to undergo aging treatment in step S6 within 2 hours after returning to room temperature.

[0016] In the above preparation method, preferably, the cooling rate of the multi-stage aging treatment in step S6 is 45℃ / hour.

[0017] The preparation method of this invention employs a dynamic power control strategy of vacuum induction melting combined with ultrasonic electromagnetic stirring to effectively break dendrites and homogenize the composition; it combines homogenization treatment with controlled cooling at a specific rate to fully eliminate segregation; through a combination of multi-stage solid solution and cryogenic treatment, a matrix with high supersaturation and high defect density is prepared; finally, a multi-stage aging process with continuous cooling is used to precisely control the Spinodal decomposition process, ultimately successfully preparing a copper-nickel-tin alloy with nanoscale uniform decomposition structure and excellent strength and toughness matching.

[0018] Compared with the prior art, the advantages of the present invention are as follows: (1) This invention achieves a nanoscale Spinodal decomposition structure (wavelength 3-8nm) by combining the reasonable ratio of Ni and Sn main elements with the composite addition of trace Y and B elements, and by multi-stage heat treatment process, thus achieving an excellent strength and toughness match of tensile strength ≥850MPa, elongation ≥15%, and impact toughness ≥90J / cm². (2) The present invention uses ultrasonic electromagnetic stirring and dynamically adjusts the power, combined with long-term high-temperature homogenization and controlled cooling, to eliminate intracrystalline Sn segregation and brittle phase, resulting in high compositional uniformity and a macroscopic segregation index of less than 1.2. (3) The addition of rare earth element Y in this invention forms a fine Y-rich compound phase (size <200nm), pins grain boundaries, and inhibits grain growth; cryogenic treatment introduces high-density dislocations and twins, providing more nucleation points for subsequent aging, and obtaining a fine-grained structure of ASTM grade 7 or above. (4) The present invention adopts a multi-stage aging process with continuous cooling. By precisely controlling the cooling rate (40-50℃ / hour), the strengthening phase is precipitated in a finer and more uniform manner in different temperature ranges, thereby achieving precise control of the Spinodal decomposition process. The process has high stability and good reproducibility. Detailed Implementation

[0019] To facilitate understanding of the present invention, the invention will be described more fully and in detail below with reference to preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0020] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0021] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0022] Example 1 A homogeneous, high-toughness copper-nickel-tin alloy of the present invention is composed of the following components by mass percentage: Ni 14.0%, Sn 8.2%, Y 0.05%, B 0.003%, with the balance being Cu and unavoidable impurities.

[0023] The preparation method of the homogeneous high-toughness copper-nickel-tin alloy in this embodiment includes the following steps: S1. The alloy is batched according to its composition. Vacuum induction melting combined with ultrasonic electromagnetic stirring is used for melting and casting at a frequency of 20kHz. The stirring power is dynamically adjusted. From the start of melting to 10 minutes after the melt is clear, the power is 60% of the rated power. From 10 minutes after the melt is clear to 15 minutes before casting, the power is increased to 80%. From 15 minutes before casting to the end, the power is increased to 100%. Finally, the ingot is cast. S2. The obtained ingot is homogenized at 900℃ and held for 25 hours, then cooled to below 300℃ at a controlled rate of 25℃ / hour before being unloaded from the furnace. S3 heats the homogenized ingot to 880℃ and holds it for 1 hour, then hot rolls it with an initial rolling temperature of 870℃ and a total deformation of 80% to obtain the sheet material of the required specifications. S4. Perform multi-stage solution treatment on the hot-rolled plate. First, hold at 830℃ for 1.5 hours and then quickly water quench with a transfer time of <2 seconds; then hold at 790℃ for 3 hours and then quickly water quench again. S5. Immediately place the solution-treated material in liquid nitrogen at -196℃ for cryogenic treatment, keep it at this temperature for 1.5 hours, then remove it and leave it at room temperature for no more than 1 hour. S6. Perform multi-stage aging treatment on the cryogenically treated material. First, hold it at 400℃ for 8 hours, then cool it down to 340℃ at a cooling rate of 45℃ / hour, and hold it at 340℃ for 10 hours. Finally, air cool it to room temperature.

[0024] Testing revealed that the homogeneous, high-toughness copper-nickel-tin alloy prepared in this embodiment exhibited a tensile strength of 875 MPa, an elongation of 16.5%, and a V-notch impact toughness of 95 J / cm². The Spinodal decomposition structure was uniform and fine, with an average wavelength of only 4.5 nm and a grain size meeting ASTM 8.5 standards. Furthermore, γ-rich phases with a size of 50-150 nm were dispersed at the grain boundaries. The compositional system employed in this invention, combined with dynamic electromagnetic stirring and multi-stage heat treatment, successfully achieved the synergistic effect of nanoscale strengthening phases and grain refinement, resulting in optimal overall alloy performance.

[0025] Example 2 A homogeneous, high-toughness copper-nickel-tin alloy of the present invention comprises, by mass percentage, 13.0% Ni, 8.5% Sn, 0.03% Y, 0.002% B, with the balance being Cu and unavoidable impurities.

[0026] The preparation method of the homogeneous high-toughness copper-nickel-tin alloy in this embodiment includes the following steps: S1. Prepare the alloy components according to the proportions, and follow the same melting and casting steps as in Example 1, using the same dynamic electromagnetic stirring. S2 homogenizes the obtained ingot at 890℃ and holds it at that temperature for 28 hours. Then, it is cooled to below 300℃ at a controlled rate of 22℃ / hour before being unloaded from the furnace. S3. The hot working steps are the same as in Example 1, with a total deformation of 80%; S4. Perform multi-stage solution treatment on the hot-worked material. First, hold at 835℃ for 1.2 hours, then quickly water quench, with a transfer time of <2 seconds; then hold at 795℃ for 2.5 hours, and then quickly water quench again. S5. The cryogenic treatment procedure is the same as in Example 1, and the sample is kept in liquid nitrogen at -196°C for 1.5 hours; S6. Perform multi-stage aging treatment on the cryogenically treated material. First, hold it at 405℃ for 7 hours, then cool it down to 335℃ at a cooling rate of 48℃ / hour, and hold it at 335℃ for 11 hours. Finally, air cool it to room temperature.

[0027] Testing revealed that the homogeneous, high-toughness copper-nickel-tin alloy prepared in this embodiment exhibited a tensile strength of 862 MPa, an elongation increased to 17.2%, an impact toughness of 92 J / cm², a Spinodal decomposition wavelength of 5.0 nm, a grain size refined to ASTM 8.0 grade, and a finer Y-phase size at grain boundaries (30-120 nm). By adjusting the proportions of the main elements within the compositional range of this invention and employing the same optimized process, a balance of high strength, high plasticity, and high toughness can still be achieved.

[0028] Example 3 A homogeneous, high-toughness copper-nickel-tin alloy of the present invention comprises, by mass percentage, 12.5% ​​Ni, 7.8% Sn, 0.08% Y, 0.004% B, with the balance being Cu and unavoidable impurities.

[0029] The preparation method of the homogeneous high-toughness copper-nickel-tin alloy in this embodiment includes the following steps: S1. Prepare the alloy components according to the proportions, and follow the same melting and casting steps as in Example 1, using the same dynamic electromagnetic stirring. S2. The obtained ingot is homogenized at 910℃ and held for 22 hours, then cooled to below 300℃ at a controlled rate of 28℃ / hour before being unloaded from the furnace. S3. The hot working steps are the same as in Example 1, with a total deformation of 80%; S4. Perform multi-stage solution treatment on the heat-treated material. First, hold at 825℃ for 1.8 hours, then quickly water quench with a transfer time of <2 seconds; then hold at 785℃ for 3.5 hours, and then quickly water quench again. S5. The cryogenic treatment procedure is the same as in Example 1, and the sample is kept in liquid nitrogen at -196°C for 1.5 hours; S6. Perform multi-stage aging treatment on the cryogenically treated material. First, hold it at 395℃ for 9 hours, then control the temperature drop to 345℃ at a cooling rate of 42℃ / hour, and hold it at 345℃ for 9 hours. Finally, air cool it to room temperature.

[0030] Testing revealed that the homogeneous, high-toughness copper-nickel-tin alloy prepared in this embodiment exhibited a tensile strength of 855 MPa, an elongation increased to 18.0%, an impact toughness of 98 J / cm², a Spinodal decomposition wavelength of 6.0 nm, and a grain size conforming to ASTM 7.5. Although the content of the main alloying element was slightly lower, the high Y content resulted in the formation of more and slightly larger (80-180 nm) Y-rich phases at grain boundaries. This effectively pinned the grain boundaries while significantly enhancing plasticity and toughness, demonstrating the role of trace rare earth element Y in optimizing the overall performance of the alloy.

[0031] Comparative Example 1 A copper-nickel-tin alloy, by mass percentage, consists of the following components: Ni 14.0%, Sn 8.2%, with the balance being Cu and unavoidable impurities.

[0032] The preparation method of the copper-nickel-tin alloy in this comparative example includes the following steps: S1. The alloy components are proportioned, without adding Y and B elements. Vacuum induction melting combined with ultrasonic electromagnetic stirring is used for melting and casting at a frequency of 20kHz. The stirring power is dynamically adjusted in the same way as in Example 1. S2. The obtained ingot is homogenized at 900℃ and held for 25 hours, then cooled to below 300℃ at a controlled rate of 25℃ / hour before being unloaded from the furnace. S3. The heat treatment steps are exactly the same as in Example 1; S4. The multi-stage solution treatment steps are exactly the same as in Example 1; S5. The cryogenic treatment process is exactly the same as in Example 1; S6. The multi-level aging process is exactly the same as in Example 1.

[0033] Testing revealed that the copper-nickel-tin alloy prepared in this comparative example exhibited a tensile strength of 830 MPa, an elongation of only 9.5%, and an impact toughness of 45 J / cm². Due to the absence of added Y and B elements, the grain size was ASTM 5.0 grade, indicating coarse grains and the presence of Sn dendritic segregation. The Spinodal decomposition wavelength was coarsened to 10.5 nm. This demonstrates the crucial role of trace amounts of Y and B in refining grain size, suppressing Sn segregation, and purifying grain boundaries; their absence leads to reduced plasticity and toughness of the alloy.

[0034] Comparative Example 2 A copper-nickel-tin alloy, by mass percentage, consists of the following components: Ni 14.0%, Sn 8.2%, Y 0.05%, B 0.003%, with the balance being Cu and unavoidable impurities.

[0035] The preparation method of the copper-nickel-tin alloy in this comparative example includes the following steps: S1. The alloy components are proportioned and the melting and casting are carried out using vacuum induction melting combined with ultrasonic electromagnetic stirring at a frequency of 20kHz; however, the stirring power is kept constant at 80% of the rated power without dynamic adjustment. S2. The homogenization process is exactly the same as in Example 1; S3. The heat treatment steps are exactly the same as in Example 1; S4. The multi-stage solution treatment steps are exactly the same as in Example 1; S5. The cryogenic treatment process is exactly the same as in Example 1; S6. The multi-level aging process is exactly the same as in Example 1.

[0036] Testing revealed that the copper-nickel-tin alloy prepared in this comparative example exhibited a tensile strength of 848 MPa, an elongation of 12.0%, and an impact toughness of 65 J / cm². Although its grain size (ASTM 7.0 grade) and Spinodal wavelength (7.0 nm) were superior to those of Comparative Example 1, they still lagged behind the examples. This is due to the lack of dynamic power control via electromagnetic stirring, resulting in incomplete homogenization of the melt composition and residual microsegregation. This limited the full effectiveness of subsequent heat treatment, highlighting the importance of dynamic stirring strategies for obtaining an extremely homogeneous microstructure.

[0037] Comparative Example 3 A copper-nickel-tin alloy, by mass percentage, consists of the following components: Ni 14.0%, Sn 8.2%, Y 0.05%, B 0.003%, with the balance being Cu and unavoidable impurities.

[0038] The preparation method of the copper-nickel-tin alloy in this comparative example includes the following steps: S1. The alloy components are proportioned and the smelting and casting steps are exactly the same as in Example 1; S2. The obtained ingot is homogenized at 900℃ and held for 25 hours. Then the power is turned off and the ingot is cooled with the furnace at a cooling rate of 50℃ / hour until it is removed from the furnace at a temperature below 300℃. S3. The heat treatment steps are exactly the same as in Example 1; S4. The multi-stage solution treatment steps are exactly the same as in Example 1; S5. The cryogenic treatment step is omitted, and the material is directly subjected to aging treatment after solution treatment; S6. The multi-level aging process is exactly the same as in Example 1.

[0039] Testing revealed that the copper-nickel-tin alloy prepared in this comparative example had a tensile strength of 860 MPa, an elongation of 13.5%, and an impact toughness of 75 J / cm². The rapid furnace cooling following homogenization resulted in insufficient diffusion of alloying elements during cooling, leading to inadequate microstructural uniformity and premature precipitation of some brittle phases. This limited the full potential of subsequent processing and heat treatment, ultimately preventing the material from achieving an optimal balance between strength and toughness.

[0040] Comparative Example 4 A copper-nickel-tin alloy, by mass percentage, consists of the following components: Ni 14.0%, Sn 8.2%, Y 0.05%, B 0.003%, with the balance being Cu and unavoidable impurities.

[0041] The preparation method of the copper-nickel-tin alloy in this comparative example includes the following steps: S1. The alloy components are proportioned and the smelting and casting steps are exactly the same as in Example 1; S2. The homogenization process is exactly the same as in Example 1; S3. The heat treatment steps are exactly the same as in Example 1; S4. The multi-stage solution treatment steps are exactly the same as in Example 1; S5. The cryogenic treatment step is omitted. After solution treatment, the material is placed at room temperature and then directly subjected to subsequent aging. S6. The multi-level aging process is exactly the same as in Example 1.

[0042] Testing revealed that while the copper-nickel-tin alloy prepared in this comparative example achieved a tensile strength of 865 MPa, its elongation and impact toughness were only 13.5% and 75 J / cm², respectively, significantly lower than those of Example 1. The omission of the crucial cryogenic treatment step resulted in insufficient formation of high-density crystal defects (dislocations and twins) in the solid solution alloy, reducing the nucleation sites for Spinodal decomposition during subsequent aging. This led to insufficiently fine and dispersed precipitation of the strengthening phase, ultimately affecting the improvement of the alloy's toughness.

[0043] Comparative Example 5 A copper-nickel-tin alloy, by mass percentage, consists of the following components: Ni 14.0%, Sn 8.2%, Y 0.05%, B 0.003%, with the balance being Cu and unavoidable impurities.

[0044] The preparation method of the copper-nickel-tin alloy in this comparative example includes the following steps: S1. The alloy components are proportioned and the smelting and casting steps are exactly the same as in Example 1; S2. The homogenization process is exactly the same as in Example 1; S3. The heat treatment steps are exactly the same as in Example 1; S4. The multi-stage solution treatment steps are exactly the same as in Example 1; S5. The cryogenic treatment process is exactly the same as in Example 1; S6. The material after cryogenic treatment is aged by first holding it at 400℃ for 8 hours, then air-cooling it to room temperature; then the material is put back into the aging furnace and held at 340℃ for 10 hours, and finally air-cooled to room temperature. That is, there is no controlled cooling process between the two stages of aging. Testing revealed that the copper-nickel-tin alloy prepared in this comparative example exhibited a high tensile strength of 890 MPa, but its elongation plummeted to 8.0%, and its impact toughness was only 50 J / cm². Although its Spinodal decomposition wavelength was small (~3.0 nm), its distribution was extremely uneven, with numerous coarsened clusters present. The lack of a continuous cooling process of 45 °C / hour between the two aging stages prevented the gradual transformation and homogenization of the precipitated phases, leading to microstructural instability and embrittlement. This demonstrates the necessity of temperature control sequence for obtaining a uniform nanostructure.

[0045] Comparative Example 6 A copper-nickel-tin alloy, by mass percentage, consists of the following components: Ni 14.0%, Sn 8.2%, Y 0.05%, B 0.003%, with the balance being Cu and unavoidable impurities.

[0046] The preparation method of the copper-nickel-tin alloy in this comparative example includes the following steps: S1. The alloy components are proportioned and the smelting and casting steps are exactly the same as in Example 1; S2. The homogenization process is exactly the same as in Example 1; S3. The heat treatment steps are exactly the same as in Example 1; S4. The multi-stage solution treatment steps are exactly the same as in Example 1; S5. The cryogenic treatment process is exactly the same as in Example 1; S6. Perform a single-stage aging treatment on the cryogenically treated material, hold it at 400℃ for 10 hours, and then air-cool it to room temperature.

[0047] Testing revealed that while the copper-nickel-tin alloy prepared in this comparative example achieved a tensile strength of 890 MPa, its elongation and impact toughness were as low as 8.0% and 50 J / cm², respectively. The traditional single-stage aging process resulted in an overly violent and uncontrollable Spinodal decomposition process, forming a fine but extremely uneven decomposition structure (wavelength 3.5 nm), accompanied by premature coarsening of harmful phases, leading to reduced plasticity. This highlights the advantages of the multi-stage aging process of this invention in coordinating the contradiction between strength and toughness.

[0048] In summary, the embodiments of this invention, through innovative compositional design (introducing trace amounts of Y and B elements) and optimized preparation processes (dynamic electromagnetic stirring, controlled-speed homogenization cooling, multi-stage solid solution treatment + deep cryogenic treatment + continuous cooling aging), successfully prepared a copper-nickel-tin alloy with high strength (≥850MPa), high elongation (≥15%), and high impact toughness (≥90J / cm²). The comparison results between the embodiments and comparative examples show that omitting any key steps (such as dynamic stirring, deep cryogenic treatment, or controlled-temperature aging) will lead to problems such as segregation, coarsening of the microstructure, or mismatch between strength and toughness in the alloy. This fully demonstrates the synergistic effect between the various technical features of this invention and effectively solves the technical bottleneck of difficulty in achieving both strength and toughness in traditional processes.

Claims

1. A homogeneous high-toughness copper-nickel-tin alloy, characterized by: consists of, by mass percentage, Ni 12.0%~15.0%, Sn 7.5%~9.0%, Y 0.01%~0.10%, B 0.001%~0.005%, balance Cu and inevitable impurities.

2. The homogeneous high-toughness copper-nickel-tin alloy of claim 1, wherein: The total amount of inevitable impurity elements is not more than 0.15%.

3. The homogeneous high-toughness copper-nickel-tin alloy of claim 1, wherein: In the microstructure of the alloy, the wavelength of the spinodal decomposition structure is between 3-8nm, and a Y-rich compound phase with a size less than 200nm is precipitated at the grain boundary; the tensile strength of the alloy is ≥850MPa, the elongation is ≥15%, and the V-notch impact toughness is ≥90J / cm².

4. A method of producing a homogeneous high-toughness copper-nickel-tin alloy, characterized by: Comprising the following steps, S1. Vacuum induction melting with ultra-audio frequency electromagnetic stirring is used for melting and casting to obtain an ingot; S2. The ingot of step S1 is subjected to homogenization treatment, and is kept at 850-950℃ for 20-30 hours, and then is controlled to cool at a rate of 20-30℃ / hour to below 300℃ before discharging; S3. The ingot after the homogenization treatment of step S2 is subjected to hot working; S4. The material after the hot working of step S3 is subjected to multi-stage solid solution treatment, first kept at 820-850℃ for 1-2 hours, water quenched, then kept at 780-800℃ for 2-4 hours, water quenched, and the quenching transfer time of the two-stage solid solution treatment is less than 3 seconds; S5. The material after the solid solution treatment of step S4 is subjected to cryogenic treatment, kept at -196℃ for 1-2 hours; S6. The material after the cryogenic treatment of step S5 is subjected to multi-stage aging treatment, first kept at 380-420℃ for 6-10 hours, then cooled at a rate of 40-50℃ / hour to 320-350℃, kept at this temperature for 8-12 hours, and finally air cooled to room temperature.

5. The method for preparing a homogeneous, high-toughness copper-nickel-tin alloy according to claim 4, characterized in that: The frequency of the ultra-audio frequency electromagnetic stirring in step S1 is 15-25kHz, and the stirring power is dynamically adjusted during the melting process; the specific procedure of the dynamic adjustment of the stirring power is that, from the beginning of melting to 10 minutes after the melting is clear, the stirring power is 60% of the rated power; from 10 minutes after the melting is clear to 15 minutes before casting, the stirring power is increased to 80% of the rated power; from 15 minutes before casting to the end of casting, the stirring power is increased to 100% of the rated power.

6. The method of claim 4, wherein the homogeneous high-toughness copper-nickel-tin alloy is prepared by the following steps of: The rate of the controlled cooling in step S2 is 25℃ / hour. ​ 7. The method for preparing a homogeneous, high-toughness copper-nickel-tin alloy according to claim 4, characterized in that: The hot working in step S3 is hot rolling or hot forging, and the open rolling temperature is not less than 850℃, and the total deformation is not less than 70%.

8. The method of claim 4, wherein the homogeneous high-toughness copper- nickel-tin alloy is prepared by the steps of: The quenching transfer time of the two-stage solid solution treatment in step S4 is less than 2 seconds. ​ 9. The method of claim 4, wherein the homogeneous high-toughness copper- nickel-tin alloy is prepared by the steps of: After the cryogenic treatment in step S5, the material needs to be subjected to the aging treatment of step S6 within 2 hours after returning to room temperature. ​ 10. The method of claim 4, wherein the homogeneous high-toughness copper- nickel-tin alloy is prepared by the steps of: The cooling rate of the multi-stage aging treatment in step S6 is 45℃ / hour. ​