Cu-Ni-Sn alloy with excellent comprehensive performance and preparation method thereof

Abstract

The invention discloses a Cu-Ni-Sn alloy with excellent comprehensive performance and a preparation method thereof, the Cu-Ni-Sn alloy comprises Cu, Ni, Sn, doping elements and unavoidable impurities, the total mass percentage of all the elements is 100%, the Ni accounts for 0.6-2.5 wt%, the Sn accounts for 0.3-1.1 wt%, the doping elements comprise 0.02-0.2 wt% of an X element, at least one selected from Si and Fe, 0.05-0.3 wt% of a Y element, at least one selected from P, Zn and Zr, and the balance is Cu. And the mass percent of the element X and the element Y meets the condition that X / Y is greater than or equal to 0.2 and less than or equal to 3.0. The Cu-Ni-Sn alloy disclosed by the invention has relatively high stress relaxation resistance, relatively high bending property and relatively high conductivity.

Description

Technical Field

[0001] The invention belongs to the technical field of copper alloys, and in particular relates to a Cu-Ni-Sn alloy with excellent comprehensive performance and a preparation method thereof. Background Art

[0002] Automotive connectors are the link that ensures the transmission of current and signals in automotive wiring harnesses. With the vigorous development of automotive intelligent driving technology in recent years, the requirements for the stability of signal transmission are increasing, so the performance requirements for the base material are also gradually increasing. Not only are materials required to have good conductivity to transmit signals, but they are also required to have good elasticity and stress relaxation resistance to ensure that the connectors always remain connected under bumpy working conditions. At the same time, the material must have good bending properties to meet the current requirements of high integration and multi-bending processing.

[0003] At present, the mainstream connector copper alloy materials are bronze series alloys and copper-nickel-silicon series alloys. The invention patent application with publication number CN114908270A discloses a high-tin phosphor bronze strip, the mass percentage composition of which is Sn: 9.0-12.0wt%, P: 0.03-0.4wt%, Fe: 0.05-0.15wt%, Zn: 0.1-0.25wt%, and the remainder is Cu and unavoidable impurities; the internal texture ratio of the strip satisfies 0.04≤a / (b+c)≤0.3, where a is the cubic texture area ratio, b is the copper texture area ratio, and c is the S-type texture area ratio. By adding 0.1-0.25wt% Zn element, the reverse segregation of high-tin phosphor bronze strip is improved, and the difference in tin content in the grain and at the grain boundary of the strip is ≤0.3wt%; the cubic texture area ratio (a), copper texture area ratio (b), and S-type texture area ratio (c) are controlled at 0.04≤a / (b+c)≤0.3, which not only makes the yield strength of the strip reach more than 690MPa, but also under the condition of 180° bending, R / t≤1.0 in the good direction and R / t≤1.5 in the bad direction, and improves the uniformity of residual stress inside the strip. The strip warps ≤1mm after etching, ensuring the stability of the base material when processed into a board-to-board connector. Although the bronze alloy has high elasticity and strength, it has low conductivity and poor stress relaxation resistance.

[0004] The invention patent application with publication number CN105385890A discloses a bronze alloy containing nickel and silicon, belonging to the technical field of alloy materials. The microstructure of the bronze alloy is mainly a matrix phase and a precipitate phase dispersed on the matrix phase, the matrix phase is a face-centered cubic solid solution, the matrix phase accounts for 94.5-99.9% by mass, the precipitate phase accounts for 0.1-5.5% by mass, and the precipitate phase is mainly Ni2Si, Cr3Si and Cu3Zr, and 2≤Ni2Si / Cr3Si≤25. The composition of the bronze alloy includes, by mass percentage: nickel: 2.5-4.5%, silicon: 0.5-1.5%, chromium: 0.1-0.5%, zirconium: 0.05-0.3%, and the balance is copper and unavoidable impurities, wherein the total content of copper, nickel and silicon is ≥99%. Although the copper-nickel-silicon alloy has high electrical conductivity and good stress relaxation resistance, the presence of precipitated nickel-silicon secondary phase inside is not conducive to large-angle bending processing.

[0005] Therefore, it is urgent to develop a Cu-Ni-Sn series material that takes into account strength, bending performance and conductivity, while improving the stress relaxation resistance of the base material to meet the higher requirements of automotive connectors and lead terminals. Summary of the invention

[0006] The invention provides a copper alloy with strong stress relaxation resistance, strong bending performance and high electrical conductivity.

[0007] The invention provides a Cu-Ni-Sn alloy with excellent comprehensive performance. The alloy comprises Cu, Ni, Sn, doping elements and inevitable impurities, wherein the total mass percentage of all elements is 100%, wherein Ni is 0.6-2.5wt%, Sn is 0.3-1.1wt%, the doping elements comprise X element: 0.02-0.2wt%, selected from at least one of Si and Fe, and Y element: 0.05-0.3wt%, selected from at least one of P, Zn and Zr, and the mass percentage of X element and Y element meets 0.2≤X / Y≤3.0.

[0008] The present invention adds X element and Y element to the Cu-Ni-Sn alloy, and adjusts the content of X element and Y element, so as to achieve the synergistic strengthening effect of fine grain strengthening and precipitation strengthening, significantly improve the strength and stress relaxation resistance of the copper alloy strip, and at the same time ensure that the material has good electrical conductivity and meets the requirements of bending processing.

[0009] The present invention provides an appropriate amount of Sn element so that a small amount of Sn element can be evenly distributed at the grain boundaries to inhibit the migration of dislocations in the strip, thereby improving the strength of the material to a certain extent. At the same time, the appropriate amount of Sn element can form a composite phase with the Ni element and the Cu element, further improving the strength and stress relaxation resistance of the material. If the Sn element is excessive, since the melting point of the Sn element is lower than that of the Cu element, it is easy to aggregate at the grain boundaries, resulting in the alloy provided by the present invention cracking along the grain during bending processing, and the electrical conductivity decreases significantly, which does not meet the electrical conductivity requirements of substrates such as automotive connectors. When the Sn content is too little, the Sn element can no longer be evenly distributed at the grain boundaries, but instead becomes an impurity element at the grain boundaries, increasing the risk of bending and cracking of the strip.

[0010] The present invention provides an appropriate amount of Ni element, which can form a second phase precipitation with the Sn element. When the Sn content remains unchanged, the strength of the alloy continues to increase with the increase of the Ni element. While the strength is improved, the electrical conductivity and bending performance are both good. When the Ni element content is too high, although the Ni element can still improve the matrix strength through solid solution strengthening, the electrical conductivity of the material will begin to decrease. When the Ni element content is too low, fewer nickel-tin second phase particles are precipitated. Although the bending performance and electrical conductivity of the material are good, the strength is low and the stress relaxation resistance is also poor.

[0011] The appropriate amount of X element provided by the present invention can be used as a precipitation strengthening element to form a compound precipitation phase with the nickel element, further improving the strength of the material, while a small amount of Y element can be precipitated at the grain boundary as a pinning point to inhibit the growth of grains during the recrystallization process.

[0012] Preferably, the content ratio of the X element to the Y element satisfies 0.2≤X / Y≤3.0. Under the above content ratio conditions, the effects of precipitation strengthening and fine grain strengthening can be achieved to a large extent, and the strength and stress relaxation resistance of the copper alloy strip can be significantly improved, while ensuring that the material has good electrical conductivity and bending processing requirements.

[0013] Preferably, the mass percentages of Si and Fe are Si: 0.01-0.05wt%, Fe: 0.01-0.15wt%. The X element is an auxiliary precipitation strengthening element. An appropriate amount of the X element can play an auxiliary strengthening role. If too much is added, it will have an adverse effect on the formation and distribution of the nickel-tin second phase, resulting in a weakened strengthening effect.

[0014] Preferably, the mass percentages of P, Zn and Zr are P: 0.02-0.08wt%, Zn: 0.02-0.17wt%, and Zr: 0.01-0.05wt%. The above Y elements are all easily burned elements. When the amount added is too small, the effective precipitation amount at the grain boundary is reduced, resulting in a weakened pinning effect; and when the amount added is too large, it becomes an impurity element, resulting in an increased risk of intergranular cracking of the alloy material.

[0015] Preferably, the structure of the Cu-Ni-Sn alloy includes nickel-tin second phase particles, and the distribution number of the nickel-tin second phase particles is ≥ 12 / μm 2 The morphology of the nickel-tin second phase particles is spherical or ellipsoidal.

[0016] The Cu-Ni-Sn alloy provided by the present invention mainly utilizes the nickel-tin second phase particles precipitated from the parent phase on the rolled surface of the alloy strip to achieve the strengthening effect. Compared with the Cu-Ni-Sn alloy disclosed in the prior art in which the precipitated phase is an elongated phase, the spherical or ellipsoidal nickel-tin second phase particles provided by the present invention have higher stress relaxation resistance and are suitable for use under higher temperature working conditions.

[0017] Further preferably, the aspect ratio of the nickel-tin second phase particles is l / w: 1≤l / w≤4, where l and w are the major diameter and minor diameter of the nickel-tin second phase particles, respectively. Most of the nickel-tin second phase particles provided by the present invention have a suitable aspect ratio, that is, most of the nickel-tin second phase particles are spherical or ellipsoidal with a suitable size, thereby further improving the stress relaxation resistance.

[0018] Preferably, the structure of the Cu-Ni-Sn alloy further includes a nickel-silicon phase and a copper-iron phase. The present invention controls the content of the X element so that the second phase in the structure is mainly nickel-tin second phase particles with a strengthening effect, and the formed nickel-silicon phase and copper-iron phase play an auxiliary strengthening role.

[0019] Preferably, the tensile strength of the Cu-Ni-Sn alloy is 500-620 MPa, the conductivity is 40-50% IACS, and the initial stress R p0.2 Under the condition of 80% of the stress, after heating at 150°C for 1000h, the stress relaxation rate is ≤20%. Under the condition of 180° bending, the bending direction perpendicular to the rolling direction is R / t≤1.0, and the bending direction parallel to the rolling direction is R / t≤1.5, where R is the bending radius and t is the strip thickness.

[0020] On the other hand, the present invention also provides a method for preparing the Cu-Ni-Sn alloy with excellent comprehensive performance, and the process flow of the preparation method includes: smelting → horizontal continuous casting → homogenization annealing → milling → rough rolling → first intermediate annealing → intermediate rolling → second intermediate annealing → finishing rolling → stress relief annealing → cold drawing and straightening;

[0021] The ingredients are prepared and smelted according to the mass percentage of the Cu-Ni-Sn alloy with excellent comprehensive performance;

[0022] The temperature of the second intermediate annealing is 430-480°C.

[0023] The present invention can uniformly form high-density nickel-tin second phase particles in the copper matrix by controlling the temperature of the second intermediate annealing, and the distribution number of the nickel-tin second phase particles is ≥12 / μm 2 , fully realizing the effect of precipitation strengthening.

[0024] The present invention controls the temperature of the second intermediate annealing so that the material reaches the aging temperature for the formation of nickel-tin second phase particles, and the nickel-tin second phase particles are gradually and uniformly precipitated in the copper matrix. The Ni element with a combined content of 0.6-2.5wt% causes the aspect ratio of the formed nickel-tin second phase particles to be mainly 1≤l / w≤4, and a small amount of Ni element is still dissolved in the matrix. If the temperature of the second intermediate annealing is too low, the Ni element will still be dissolved in the copper matrix, or only a small part will form the second phase, which greatly weakens the strengthening effect on the material; on the contrary, if the temperature of the second intermediate annealing is too high, the elliptical nickel-tin second phase particles precipitated will gradually elongate, and when the aspect ratio is greater than 4, the nickel-tin second phase particles will tend to be connected end to end, and finally form a slender lath or strip distribution. In addition, due to the high temperature, the fine crystal effect of the Y element is weakened, and the grains grow rapidly. Although the conductivity of the material will be improved, the strength is significantly reduced.

[0025] Preferably, the holding time of the second intermediate annealing is 5 to 12 hours, and the atmosphere is argon. The second annealing in argon atmosphere avoids the introduction of impurities such as oxygen, and by controlling the holding time, the nickel-tin second phase particles have enough time to precipitate and avoid agglomeration or overburning.

[0026] Preferably, the order of adding materials for smelting is: first add the electrolytic copper plate, then add the nickel plate and the tin ingot, then heat up to 1200-1300° C., after all of them are melted, cover the surface with charcoal, then add the master alloy containing the X element, and finally add the master alloy containing the Y element.

[0027] The reason why the intermediate alloy of element X is added first is to fully melt it in the copper water. However, the intermediate alloy of element Y is severely burned at high temperature, so it is added last to reduce the loss of quality.

[0028] Preferably, the casting temperature of the horizontal continuous casting is 1150-1250° C., the drawing speed is 100-180 mm / min, the drawing pitch is 8-20 mm, and secondary cooling water spraying is used at the outlet.

[0029] Preferably, the homogenization annealing temperature is 680-780° C., the holding time is 6-12 hours, and the atmosphere is argon.

[0030] In order to ensure that the Ni element is fully dissolved in the copper matrix and reduce the Sn element in the grain boundary, the present invention adopts a high temperature of 680°C or above for homogenization annealing, and this temperature is also conducive to the solid solution of the X element in the copper matrix. If the temperature is higher than 780°C, the inhibitory effect of the Y element on the grain growth begins to weaken, and it is difficult to refine the grains through subsequent processing, and the bending performance of the large-grained strip will drop sharply.

[0031] Preferably, the rough rolling processing amount is 85-94%. Through cold working with large deformation, the recrystallized grains after homogenization annealing are completely broken, laying the foundation for subsequent grain refinement. However, if the processing amount is too large, the strip is prone to cracking after work hardening, and the plate shape is difficult to control. Therefore, the final rough rolling processing amount range is 85-94%.

[0032] Preferably, the temperature of the first intermediate annealing is 500-580°C, the holding time is 4-12 hours, and the atmosphere is argon. Annealing at a temperature above the recrystallization temperature can soften the material to facilitate further processing by intermediate rolling.

[0033] Preferably, the processing amount of the finish rolling is 55-70%. The finish rolling of the present invention also adopts cold processing with a large deformation amount to achieve the work hardening effect of the material and improve the strength of the material.

[0034] Preferably, the stress relief annealing temperature is 200-260°C, the holding time is 2-5 hours, and the atmosphere is argon. After the finish rolling process, the internal residual stress of the strip is large, which will lead to poor plate shape and bending performance of the strip. After the above stress relief annealing, the bending performance of the strip will be improved.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present invention controls the amount of Ni, Sn, X and Y, adopts the synergistic strengthening method of fine grain and precipitation phase, improves the material strength, takes into account the electrical conductivity and stress relaxation resistance, and realizes the copper alloy strip with a tensile strength of 500-620MPa and a conductivity of 40-50%IACS. p0.2 Under the condition of 80% of the stress relaxation rate, after heating at 150°C for 1000h, the stress relaxation rate is ≤20%, and under the condition of 180° bending, the bending R / t in the vertical rolling direction is ≤1.0, and the bending R / t in the vertical rolling direction is ≤1.5. Therefore, the Cu-Ni-Sn alloy provided by the present invention is suitable for electronic components such as automotive connectors, lead terminals, and electronic packaging materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a scanning electron microscope analysis image of the Cu-Ni-Sn alloy prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below with reference to the accompanying drawings.

[0039] The present invention selects 10 embodiments and 12 comparative examples for illustration, and the weight percentage of the chemical components of each embodiment and comparative example is shown in Table 1.

[0040] Table 1 Chemical composition of the embodiments and comparative examples / wt%

[0041]

[0042]

[0043] The embodiments provided by the present invention are prepared according to the following steps:

[0044] 1) Smelting: First add electrolytic copper plate, then add nickel plate and tin ingot with required composition, then heat to 1200-1300℃, after all are melted, cover the surface with red-hot charcoal, then add one or several metals containing element X, and finally add one or several intermediate alloys containing elements P, Zn, Ca and Zr. During the smelting process, always keep the smelting furnace copper liquid covered with red-hot charcoal, and replenish it every 3-4 hours to suppress the absorption of copper liquid at high temperature.

[0045] 2) Horizontal continuous casting: The casting temperature is 1150-1250°C, the casting speed is 100-180 mm / min, the casting pitch is 8-20 mm, and secondary cooling water spraying is used at the outlet.

[0046] 3) Homogenization annealing: the heating temperature is 680-780°C, the holding time is 6-12h, and the atmosphere is argon.

[0047] 4) Milling surface: The upper and lower milling surfaces are 0.3 to 1 mm to eliminate oxides and other impurities on the surface of the material after annealing.

[0048] 5) Rough rolling: The processing volume of rough rolling ranges from 85 to 94%.

[0049] 6) First annealing: annealing temperature is 500-580°C, annealing time is 4-12h.

[0050] 7) Medium rolling: The processing volume range is 15% to 30%.

[0051] 8) Second annealing: the annealing temperature is 430-480°C, the holding time is 5-12h, and the atmosphere is argon.

[0052] 9) Finishing rolling: The processing amount of finishing rolling is 55-70%.

[0053] 10) Low temperature annealing: The annealing temperature is 200-260°C, the annealing time is 2-5 hours, and the strip is subjected to stress relief annealing to improve its bending performance.

[0054] Cold drawing and straightening: The strip is drawn and straightened at an elongation of 0.1 to 0.5%.

[0055] The difference between the comparative example provided by the present invention and Example 1 is as follows:

[0056] The difference between Comparative Example 1 and Example 1 is that the Ni element content is 3.0 wt %.

[0057] The difference between Comparative Example 2 and Example 1 is that the Sn element content is 5.0 wt %.

[0058] The difference between Comparative Example 3 and Example 1 is that no X element is added.

[0059] The difference between Comparative Example 4 and Example 1 is that no Y element is added.

[0060] The difference between Comparative Example 5 and Example 1 is that the Si element content is 1.2 wt %.

[0061] The difference between Comparative Example 6 and Example 1 is that the P element content is 0.8 wt %.

[0062] The difference between Comparative Example 7 and Example 1 is that the content ratio of the X element to the Y element is 4.0.

[0063] The difference between Comparative Example 8 and Example 1 is that the homogenization annealing temperature is 650°C.

[0064] The difference between Comparative Example 9 and Example 1 is that the rough rolling processing amount is 70%.

[0065] The difference between Comparative Example 10 and Example 1 is that the second annealing temperature is 550°C.

[0066] The difference between Comparative Example 11 and Example 1 is that the processing amount of finishing rolling is 50%.

[0067] The difference between Comparative Example 12 and Example 1 is that no low-temperature annealing is performed.

[0068] The process parameters of the key steps and other steps in the embodiments and comparative examples provided by the present invention are detailed in Tables 2 and 3.

[0069] Table 2 Key process parameters of the embodiments and comparative examples

[0070]

[0071] Table 3 Other process parameters of the embodiments and comparative examples

[0072]

[0073] The tensile strength, electrical conductivity, morphology and distribution of the nickel-tin second phase particles, stress relaxation resistance and bending performance of the above-mentioned embodiments and comparative examples were analyzed.

[0074] The tensile strength test provided in the specific embodiment of the present invention is carried out on an electronic universal mechanical properties testing machine according to the standard requirements of "GB / T 228.1-2010 Tensile test of metallic materials Part 1: Room temperature test method". The test specimen is dumbbell-shaped and the width of the tensile specimen is 20 mm.

[0075] The conductivity test provided by the specific embodiment of the present invention: according to the standard requirements of "GB / T 32791-2016 Eddy Current Test Method for Electrical Conductivity of Copper and Copper Alloys", the test sample size is 100mm×100mm.

[0076] The nickel-tin second phase particle detection provided by the specific embodiment of the present invention is tested using a JSM-IT700HR scanning electron microscope, and the test sample size is 10 mm×10 mm.

[0077] The anti-stress relaxation performance test provided in the specific embodiment of the present invention is tested according to the standard requirements of "GB / T39152-2020 Test Method for Bending Stress Relaxation of Copper and Copper Alloys", with a test temperature of 150°C and a heating time of 1000h.

[0078] The bending performance test provided by the specific embodiment of the present invention is as follows: according to the standard requirements of "GB / T 232-2010 Metal Material Bending Test Method", 180° bending is performed in the perpendicular rolling direction and parallel rolling direction through the corresponding bending die, and the sample width is 10 mm and the length is 50 mm.

[0079] Table 4 Performance table of embodiments and comparative examples

[0080]

[0081]

[0082] As shown in Table 1, Table 2, Table 3 and Table 4, it can be seen from Comparative Example 1 that when the Ni element content is 3.0wt%, the strength of the material is slightly improved, but due to the excessive addition of Ni, the conductivity decreases significantly and the bending performance also decreases slightly.

[0083] It can be seen from Comparative Example 2 that when the Sn element content is 5.0wt%, the strength of the material is significantly increased, but the conductivity and bending performance are significantly reduced. The strip is bent 180° parallel to the rolling direction, and the R / t value reaches 3.0.

[0084] It can be seen from Comparative Example 3 that since no auxiliary precipitation strengthening phase is formed in the matrix, the strength of the strip is low and the stress relaxation resistance is poor.

[0085] It can be seen from Comparative Example 4 that without adding grain refining elements such as P, the tensile strength and bending performance of the material are reduced. After analyzing the second annealing structure, it is found that the grain size of the embodiment is about 0.020 mm, while the grain size of Comparative Example 4 reaches 0.035 mm. Due to the large grain size, the hindering effect of dislocation slip is enhanced, which ultimately leads to the easy cracking of the strip.

[0086] From Comparative Example 5, it can be seen that when the Si content increases, the tensile strength of the alloy material will increase, but the conductivity will decrease to 35% IACS. In addition, since a large amount of nickel and silicon elements will form a nickel-silicon phase, the growth of the nickel-tin phase will be inhibited, and the bending performance of the material will also decrease.

[0087] It can be seen from Comparative Example 6 that when the P content increases, the conductivity of the alloy material decreases significantly, and excessive addition of the P element cannot play the effect of precipitating the phase, but instead becomes an impurity element, resulting in poor bending performance of the material.

[0088] It can be seen from Comparative Example 7 that when the content ratio of X element to Y element is 20, the size of the nickel-tin second phase particles is longer and the stress relaxation resistance of the material decreases.

[0089] It can be seen from Comparative Example 8 that due to the low homogenization annealing temperature, the homogenization effect of the Sn element is poor and the bending performance of the strip is poor.

[0090] It can be seen from Comparative Example 9 that when the processing amount of rough rolling is 70%, the strength of the strip is relatively low.

[0091] It can be seen from Comparative Example 10 that when the second annealing temperature is 550°C, the strip is over-aged, the grains grow abnormally along the rolling direction, presenting an elongated grain structure, and the nickel-tin second phase particles aggregate, the precipitation strengthening effect is significantly weakened, and the strength and stress relaxation resistance are significantly reduced.

[0092] It can be seen from Comparative Example 11 that when the processing amount of the finish rolling is 50%, the strength of the strip is low.

[0093] It can be seen from Comparative Example 12 that the bending performance of the strip is significantly reduced due to the lack of stress relief annealing.

[0094] like Figure 1As shown, according to the alloy prepared in Example 1 of the present invention, the second phase particles are uniformly precipitated inside the matrix, such as the white particles in the figure, which are spherical or ellipsoidal in shape, and the distribution number of the nickel-tin second phase particles is ≥12 / μm 2 , suitable as a substrate for electronic components such as automotive connectors, lead terminals, and electronic packaging materials.

Claims

1. A Cu-Ni-Sn alloy with excellent comprehensive performance, characterized in that: The invention comprises Cu, Ni, Sn, doping elements and inevitable impurities, wherein the total mass percentage of all elements is 100%, wherein Ni: 0.6-2.5wt%, Sn: 0.3-1.1wt%, the doping elements include X element: 0.02-0.2wt%, selected from at least one of Si and Fe, Y element: 0.05-0.3wt%, selected from at least one of P, Zn and Zr, and the mass percentage of X element and Y element satisfies 0.2≤X / Y≤3.

0.

2. The Cu-Ni-Sn alloy with excellent comprehensive performance according to claim 1, characterized in that: The mass percentages of Si and Fe are Si: 0.01-0.05wt%, Fe: 0.01-0.15wt%.

3. The Cu-Ni-Sn alloy with excellent comprehensive performance according to claim 1, characterized in that: The mass percentages of P, Zn and Zr are P: 0.02-0.08wt%, Zn: 0.02-0.17wt%, and Zr: 0.01-0.05wt%.

4. The Cu-Ni-Sn alloy with excellent comprehensive performance according to claim 1, characterized in that: The structure of the Cu-Ni-Sn alloy includes nickel-tin second phase particles, and the distribution number of the nickel-tin second phase particles is ≥12 / μm 2 The morphology of the nickel-tin second phase particles is spherical or ellipsoidal.

5. The Cu-Ni-Sn alloy with excellent comprehensive performance according to claim 4, characterized in that: The aspect ratio l / w of the nickel-tin second phase particles is: 1≤l / w≤4, wherein l and w are the major diameter and minor diameter of the nickel-tin second phase particles, respectively.

6. A method for preparing a Cu-Ni-Sn alloy with excellent comprehensive properties according to any one of claims 1 to 5, characterized in that: The process flow of the preparation method includes: smelting → horizontal continuous casting → homogenization annealing → milling → rough rolling → first intermediate annealing → medium rolling → second intermediate annealing → finishing rolling → stress relief annealing → cold drawing and straightening; The ingredients are prepared and smelted according to the mass percentage of the Cu-Ni-Sn alloy with excellent comprehensive performance as described in any one of claims 1 to 5; The temperature of the second intermediate annealing is 430-480°C.

7. The method for preparing a Cu-Ni-Sn alloy with excellent comprehensive properties according to claim 6, characterized in that: The holding time of the second intermediate annealing is 5-12 hours, and the atmosphere is argon atmosphere.

8. The method for preparing a Cu-Ni-Sn alloy with excellent comprehensive properties according to claim 6, characterized in that: The order of adding materials for smelting is: first add electrolytic copper plate, then add nickel plate and tin ingot, then heat to 1200-1300° C., after all of them are melted, cover the surface with charcoal, then add the master alloy containing element X, and finally add the master alloy containing element Y.

9. The method for preparing a Cu-Ni-Sn alloy with excellent comprehensive properties according to claim 6, characterized in that: The homogenization annealing temperature is 680-780° C., the holding time is 6-12 hours, and the atmosphere is argon gas.

10. The method for preparing a Cu-Ni-Sn alloy with excellent comprehensive properties according to claim 6, characterized in that: The processing amount of the rough rolling is 85-94%.

11. The method for preparing a Cu-Ni-Sn alloy with excellent comprehensive properties according to claim 6, characterized in that: The processing amount of the finish rolling is 55-70%.

12. The method for preparing a Cu-Ni-Sn alloy with excellent comprehensive properties according to claim 6, characterized in that: The stress relief annealing is performed at a temperature of 200 to 260° C., with a holding time of 2 to 5 hours, and an argon atmosphere.

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