A tin-copper alloy and a laser cladding process for tin-copper alloy

Abstract

This application relates to the technical field of the laser cladding forming process of tin bronze, and more specifically, it relates to a tin-copper alloy and a laser cladding process for the tin-copper alloy. A tin-copper alloy comprises raw materials in the following mass percentages: Sn 11% - 13%, P 0.05% - 2.0%, Ni 0.5% - 5.0%, Cr 0.5% - 3.5%, rare earth elements 0.2 - 2.0%, with the balance being copper and in-removable impurities. The rare earth elements are a mixture of La and Ce, and La, Ce and P are added in the form of phosphor copper balls. The particle size of the finished powder of the tin-copper alloy is between 50 - 120 μm. The tin-copper alloy and the laser cladding process for the tin-copper alloy of this application have extremely high energy utilization rate and at the same time have lower porosity.

Description

Technical Field

[0001] This application relates to the technical field of the laser cladding forming process of tin bronze, and more specifically, it relates to a tin-copper alloy and a laser cladding process for tin-copper alloy. Background Technique

[0002] The SLM method, full name Selective Laser Melting, is a metal additive manufacturing technology that uses a high-energy laser beam to melt and stack metal powders layer by layer to finally construct a complete metal part. However, there are still great challenges in using the SLM method to prepare high-density copper alloy parts. Firstly, due to the high optical reflectivity of copper to infrared, the energy required for the dense part increases exponentially, that is, a laser with a higher power is needed. At the same time, the high copper back reflection will also damage the optical components of the equipment. Secondly, the high intrinsic thermal conductivity of copper causes the absorbed heat to dissipate quickly, and in order to melt the material, more energy needs to be input.

[0003] Moreover, the high laser reflectivity and high thermal conductivity are prone to non-fusion pores in passes and between layers during the laser forming process. The excessive energy input causes the melt viscosity to decrease, and phenomena such as violent boiling and balling are likely to occur, resulting in an unstable molten pool, extremely easy to generate metallurgical defects, affecting the forming accuracy and quality, and reducing its service performance.

[0004] In summary, the traditional laser cladding process still has the defects of low energy utilization rate and easy generation of pores. Summary of the Invention

[0005] In order to improve the energy utilization rate of the laser cladding process and reduce the generation of pores at the same time, this application provides a tin-copper alloy and a laser cladding process for tin-copper alloy.

[0006] In the first aspect, this application provides a tin-copper alloy, adopting the following technical solution:

[0007] A tin-copper alloy, comprising raw materials in the following mass percentages: Sn 11%-13%, P 0.05%-2.0%, Ni 0.5%-5.0%, Cr 0.5%-3.5%, rare earth elements 0.2-2.0%, and the balance is copper and inremovable impurities. The rare earth elements are one or a mixture of two of La and Ce. La, Ce and P are added in the form of phosphor bronze balls. The particle size of the finished powder of the tin-copper alloy is between 50-120μm.

[0008] Preferably, the rare earth elements are a mixture of La and Ce.

[0009] Preferably, the tin-copper alloy comprises raw materials in the following mass percentages:

[0010] Sn 11%-13%, P 0.05%-2.0%, Ni 0.5%-5.0%, Cr 0.5%-3.5%, La 0.1%-1.0% and Ce 0.1-1.0%, the balance being copper and unavoidable impurities. La, Ce and P are added in the form of phosphor bronze balls. The particle size of the finished powder of the tin-copper alloy ranges from 50 to 120 μm.

[0011] In order to effectively improve the energy utilization rate of the laser cladding process, the applicant first considered using green laser with short wavelength as the light source to improve the energy absorption rate of copper. However, the price of green laser is relatively high, resulting in relatively low cost performance and poor precision control. Therefore, there is still room for improvement.

[0012] Therefore, the applicant thought of using powder raw materials with relatively smaller particle size, which can improve the forming accuracy while increasing the energy absorption rate. However, the preparation of fine powder will increase the porosity, which will deteriorate the mechanical properties, corrosion resistance and electrical conductivity of the tin-copper alloy.

[0013] In order to improve the defect of increased porosity of the tin-copper alloy caused by using powder raw materials with small particle size, the applicant first thought of modifying the raw material powder by PVD evaporation to reduce the porosity during the laser forming process of the tin-copper alloy. However, the PVD evaporation process is complex and not conducive to large-scale application.

[0014] Therefore, the applicant thought of introducing rare earth elements with the function of reducing the melt viscosity and chromium elements with the function of increasing the melt viscosity into the tin-copper alloy powder, and using the competition mechanism to adjust the viscosity of the tin bronze melt during the laser forming process, maintaining the melt stability, and then promoting the floating and discharging of the original pores to achieve the purpose of reducing the pores. At the same time, taking advantage of the characteristics that rare earth elements and chromium elements have low solubility in copper and large melting point differences, precipitation strengthening phases are in-situ precipitated to inhibit grain growth, and thus the wear resistance is improved.

[0015] When the rare earth element is a mixture of La and Ce, due to the strong affinity of La and Ce for hydrogen and oxygen, they can capture the oxygen of an oxide in the tin-copper metal liquid, thus forming a large number of La2O3, Ce2O3, La(OH)3, Ce(OH)3 particles, which refine the macroscopic structure of the tin-copper alloy.

[0016] At the same time, with the addition of La and Ce, due to their alloying effect, the supercooling degree of the tin-copper alloy increases. And the microstructure of the alloy depends on the supercooling degree during the growth process and growth conditions. That is, under this condition, the secondary dendrite arm spacing of the tin-copper alloy becomes smaller. In addition, during the growth process of the tin-copper alloy phase, La and Ce will also aggregate around the tin-copper alloy phase, reducing the solid-liquid surface tension and increasing the constitutional supercooling at the solid-liquid interface, further promoting the refinement of dendrites.

[0017] Compared with using La or Ce alone, the mixed use of La and Ce can promote the formation of more La2O3, Ce2O3, La(OH)3, and Ce(OH)3 particles, thereby promoting the refinement of the macroscopic and microscopic structures of the tin-copper alloy, and ultimately resulting in a lower porosity.

[0018] Moreover, when La and Ce are in the above mass percentages, more La2O3, Ce2O3, La(OH)3, and Ce(OH)3 particles will be formed in the tin-copper alloy, thereby promoting the refinement of the macroscopic and microscopic structures of the tin-copper alloy, and ultimately resulting in a lower porosity.

[0019] Preferably, the method for preparing the finished powder of the tin-copper alloy is as follows: First, add copper, tin, nickel, and chromium into a vacuum melting crucible, and melt the metals by induction heating. When the temperature of the metal liquid reaches 1000 - 1300 °C, add phosphor copper and rare earth elements to the metal liquid in a secondary feeding manner, then keep it warm for 5 - 30 min, and finally pour the metal liquid into an intermediate ladle crucible and prepare spherical metal powder from the metal liquid by gas atomization, and finally cool and perform air classification to obtain the finished powder of the tin-copper alloy.

[0020] When the melting temperature is between 1000 - 1300 °C, the yield of the finished powder of the tin-copper alloy is relatively higher. Since phosphorus and rare earth elements are prone to burning loss, long-term melting will lead to poor control of the element ratio. Therefore, the secondary feeding method can promote the melting of phosphorus and rare earth elements in a short time, thereby ensuring the balance of elements and ultimately obtaining a better porosity suppression effect.

[0021] Preferably, the method for preparing the phosphor copper balls is as follows: First, add phosphor copper alloy into a vacuum melting crucible, and melt the metal by induction heating. After the temperature of the metal liquid reaches 1000 - 1300 °C, add La and Ce and melt and mix them evenly to obtain a phosphor copper melt, and then cool and crystallize the phosphor copper melt into a phosphor copper rod through a continuous casting machine, and then process the phosphor copper rod through a heading machine, a polishing machine, a cleaning machine, and a packaging machine to form phosphor copper balls.

[0022] In this application, La, Ce, and P are added in the form of phosphor copper balls, which promotes the continuous protection of La, Ce, and P by the phosphor copper balls, further reducing the possibility of burning loss of La, Ce, and P, and indirectly promoting the tin-copper alloy to obtain a lower porosity.

[0023] Preferably, in the preparation of spherical metal powder by the gas atomization method, the atomizing gas is selected as high-purity argon, the pressure difference between the melting chamber and the gas atomization chamber is less than 0.3 MPa, and the pressure of the high-pressure atomizing gas is 4 - 5 MPa.

[0024] In a second aspect, the present application provides a laser cladding process for tin-copper alloy, adopting the following technical solution:

[0025] A laser cladding process for tin-copper alloy attaches the finished powder of the above-mentioned tin-copper alloy to a component by means of laser cladding;

[0026] The laser cladding uses a narrow light spot, the laser spot diameter is 5 mm, the laser power is 1500 - 3000 kW, and the cladding speed is 400 - 800 mm / min;

[0027] After the forming is completed, the component is subjected to cutting, grinding, and polishing treatments.

[0028] A laser cladding process for tin-copper alloy attaches the finished powder of the above-mentioned tin-copper alloy to a component by means of laser cladding;

[0029] The laser cladding uses a wide light spot, the laser spot size is 20 mm × 4 mm, the laser power is 8000 - 15000 kW, and the cladding speed is 200 - 600 mm / min;

[0030] After the forming is completed, the component is subjected to cutting, grinding, and polishing treatments.

[0031] In terms of laser cladding, if the laser power is too small, the molten pool is not obvious, resulting in the generation of pores, but there is not enough time to discharge the pores. If the laser power is too large, too many pores are generated and cannot be discharged. If the cladding speed is too slow, the efficiency is reduced and the dilution rate is too high; if the cladding speed is too fast, it affects the pore discharge efficiency and results in the generation of pores.

[0032] Therefore, the applicant conducted a large number of tests and found that for a device with a 5 mm diameter light spot, a laser power of 1500 - 3000 kW and a cladding speed of 400 - 800 mm / min are more appropriate; for a device with a 20 mm × 4 mm rectangular light spot, a laser power of 8000 - 15000 kW and a cladding speed of 200 - 600 mm / min are more appropriate.

[0033] In summary, the present application has the following beneficial effects:

[0034] 1. The present application introduces rare earth elements with the function of reducing the melt viscosity and chromium elements that increase the melt viscosity into the tin-copper alloy powder, and uses a competition mechanism to regulate the viscosity of the tin bronze melt during the laser forming process, maintaining the melt stability, and then promoting the floating and discharging of the original pores, achieving the purpose of reducing pores. At the same time, taking advantage of the characteristics that rare earth elements and chromium elements have low solubility in copper and a large melting point difference, precipitation strengthening phases are in-situ precipitated to inhibit grain growth, thereby improving the wear resistance;

[0035] At the same time, when the smelting temperature is between 1000-1300℃, the yield of the finished powder of tin-copper alloy is relatively higher. However, since phosphorus and rare earth elements are easily burned, long-term smelting will make the ratio of elements difficult to control. Therefore, the secondary feeding method can promote the melting of phosphorus and rare earth elements in a short time, thereby ensuring the balance of elements and finally obtaining a better pore inhibition effect.

[0036] Furthermore, La, Ce and P are added in the form of phosphor copper balls, which enable the phosphor copper balls to continuously protect La, Ce and P, further reducing the possibility of burning of La, Ce and P, and indirectly enabling the tin-copper alloy to obtain a lower porosity.

[0037] 2. When the rare earth element is a mixture of La and Ce, La and Ce have a strong affinity for hydrogen and oxygen, so they can take away the oxygen of an oxide in the tin-copper metal liquid, thereby forming a large number of La2O3, Ce2O3, La (OH) 3, Ce (OH) 3 particles, thereby refining the macroscopic structure of the tin-copper alloy;

[0038] At the same time, with the addition of La and Ce, the supercooling of the tin-copper alloy increases due to its alloying effect, and the microstructure of the alloy depends on the supercooling of its growth process and growth conditions, that is, under this condition, the secondary dendrite spacing of the tin-copper alloy becomes smaller;

[0039] In addition, during the growth of the tin-copper alloy phase, La and Ce will also gather around the tin-copper alloy phase, reducing the solid-liquid surface tension, increasing the supercooling of the components at the solid-liquid interface front, and further promoting the refinement of the dendrites.

[0040] 3. In laser cladding, if the laser power is too small, the molten pool is not obvious, resulting in the generation of pores, but there is not enough time to discharge the pores. If the laser power is too large, too many pores will be generated and cannot be discharged. The cladding speed is too slow, the efficiency is reduced and the dilution rate is too high; the cladding speed is too fast, which affects the efficiency of pore discharge and causes pores.

[0041] To this end, the applicant conducted a large number of tests and found that for equipment with a 5mm diameter spot, the laser power is 1500-3000 kilowatts and the cladding speed is 400-800mm / min, which is more suitable; for equipment with a 20mm×4mm rectangular spot, the laser power is 8000-15000 kilowatts and the cladding speed is 200-600mm / min, which is more suitable.

[0042] 4. The tin-copper alloy of the present application has good adaptability to laser cladding. At the same time, the parameter window of the laser cladding process is wide, which can effectively improve the impact of equipment noise or environmental changes on the uniformity of coating quality. Moreover, the elements of the tin-copper alloy are environmentally friendly and harmless. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is the pore condition diagram of Example 1;

[0044] Figure 2 It is the pore condition diagram of Comparative Example 1;

[0045] Figure 3 It is the pore condition diagram of Example 2;

[0046] Figure 4 It is the pore condition diagram of Comparative Example 2. Detailed implementation manners

[0047] The following further elaborates on this application in conjunction with Figures 1-4 , Examples 1 - 9 and Comparative Examples 1 - 2.

[0048] Raw materials:

[0049] Cu pure copper, P - Cu phosphor bronze, Sn tin, Ni nickel, Cr chromium, La lanthanum, and Ce cerium are all commercially available.

[0050] Example 1

[0051] A tin - copper alloy, comprising raw materials in the following mass percentages: Sn 12.0%, P 1.0%, Ni 2.0%, Cr 1.0%, La 0.3%, Ce 0.3%, with the balance being copper and unavoidable impurities;

[0052] The preparation method of the finished tin - copper alloy powder is as follows: First, 78.9 kg of pure copper, 12 kg of tin, 2 kg of nickel, and 1 kg of chromium are added to a vacuum melting crucible, and the vacuum is pumped to 10 Pa. Medium - frequency induction melting is used, with a melting power of 150 kW. After melting for 90 min, all the metals are melted, and the temperature of the metal liquid is measured using an infrared double - color pyrometer;

[0053] When the temperature of the molten liquid reaches 1150 °C, phosphor - bronze balls are added to the metal liquid in a secondary feeding manner, and then it is held for 15 min. After the metal liquid is clarified, the metal liquid is poured into an intermediate - ladle crucible with a temperature of 1000 °C. At the same time, high - pressure gas is turned on for atomization, and the metal liquid is atomized into spherical metal droplets and rapidly cooled and solidified. After complete cooling, the powder is subjected to air classification, and the fraction with a particle size of 50 - 120 μm is selected, which is the finished tin - copper alloy powder;

[0054] In the preparation of spherical metal powder by the aerosol method, the atomizing gas is high - purity argon, the pressure difference between the melting chamber and the aerosol chamber is less than 0.3 MPa, and the pressure of the high - pressure atomizing gas is 5 MPa.

[0055] Among them, the phosphor - bronze balls are composed of phosphor bronze, lanthanum, and cerium, with the contents being: 5.5 kg of phosphor bronze, 0.3 kg of lanthanum, and 0.3 kg of cerium;

[0056] The preparation method of phosphor copper balls is as follows:

[0057] First, add the phosphor copper alloy into a vacuum melting crucible, and use induction heating to melt the metal. After the temperature of the metal liquid reaches 1150 °C, add lanthanum and cerium and melt and mix them evenly to obtain a phosphor copper melt. Then, cool and crystallize the phosphor copper melt into a phosphor copper rod through a continuous casting machine, and then process the phosphor copper rod into phosphor copper balls through a heading machine, a polishing machine, a cleaning machine and a packaging machine in sequence.

[0058] A laser cladding process for a tin copper alloy, which attaches the finished powder of the above tin copper alloy to a component by laser cladding;

[0059] The laser cladding uses a narrow light spot, the diameter of the laser light spot is 5 mm, the laser power is 2100 kW, and the cladding speed is 600 mm / min;

[0060] After the forming is completed, cut, grind and polish the component.

[0061] Example 2

[0062] A tin copper alloy, comprising raw materials in the following mass percentages: Sn 12.0%, P 1.0%, Ni 2.0%, Cr 1.5%, La 0.5%, Ce 0.5%, and the balance is copper and impurities that cannot be removed;

[0063] The preparation method of the finished powder of the tin copper alloy is as follows: First, add 78 kg of electrolytic copper, 12 kg of tin, 2 kg of nickel, and 1.5 kg of chromium into a vacuum melting crucible, evacuate to 10 Pa, and use medium-frequency induction melting with a melting power of 150 kW. After melting for 90 min, all the metal is melted, and the temperature of the metal liquid is measured by an infrared double-color pyrometer;

[0064] After the temperature of the melt reaches 1150 °C, add phosphor copper balls to the metal liquid in a secondary feeding manner, and then keep it warm for 15 min. After the metal liquid is clarified, pour the metal liquid into an intermediate ladle crucible with a temperature of 1000 °C, and at the same time, turn on high-pressure gas for atomization to atomize the metal liquid into spherical metal droplets and quickly cool and solidify. After complete cooling, perform air classification on the powder, and select the part with a particle size of 50 - 120 μm, which is the finished powder of the tin copper alloy;

[0065] Among them, the phosphor copper balls are composed of phosphor copper, lanthanum and cerium, and the contents are: 5.5 kg of phosphor copper, 0.5 kg of lanthanum, and 0.5 kg of cerium;

[0066] The preparation method of phosphor copper balls is as follows:

[0067] First, add the phosphor bronze alloy into a vacuum melting crucible, and melt the metal by induction heating. After the temperature of the molten metal reaches 1150 °C, add lanthanum and cerium and melt them to mix evenly to obtain a phosphor bronze melt. Then, cool and crystallize the phosphor bronze melt into a phosphor bronze rod through a continuous casting machine, and then process the phosphor bronze rod through a heading machine, a polishing machine, a cleaning machine and a packaging machine to form phosphor bronze balls.

[0068] A laser cladding process for a tin-copper alloy, which attaches the finished powder of the above-mentioned tin-copper alloy to a component by laser cladding;

[0069] The laser cladding uses a wide spot, the laser spot size is 20mm×4mm, the laser power is 8500 kW, and the cladding speed is 400mm / min;

[0070] After the forming is completed, the component is cut, ground and polished.

[0071] Example 3

[0072] The difference from Example 1 is that the phosphor bronze balls are directly added without secondary addition treatment.

[0073] Example 4

[0074] The difference from Example 1 is that the phosphor bronze, lanthanum and cerium are directly added without phosphor bronze ball treatment.

[0075] Example 5

[0076] The difference from Example 4 is that lanthanum is no longer added, and the missing part is supplemented with copper.

[0077] Example 6

[0078] The difference from Example 4 is that cerium is no longer added, and the missing part is supplemented with copper.

[0079] Examples 7 - 8

[0080] The difference from Example 4 is that the mass percentages of lanthanum and cerium are different, as shown in Table 1 specifically.

[0081] Table 1 Mass percentage table of each component of rare earth elements in Example 4 and Examples 7 - 8

[0082]

[0083] Example 9

[0084] The difference from Example 4 is that the rare earth elements lanthanum and cerium are no longer added.

[0085] Comparative Example 1

[0086] The difference from Example 1 is that Cr, La, and Ce are no longer added to the tin-copper alloy, and the missing part is supplemented with copper.

[0087] Comparative Example 2

[0088] The difference from Example 2 is that Cr, La, and Ce are no longer added to the tin-copper alloy, and the missing part is supplemented with copper.

[0089] Performance detection test

[0090] Porosity test of tin-copper alloy

[0091] Three samples were taken from Examples 1 - 9 and Comparative Examples 1 - 2 respectively, and then the porosity of the above samples was tested and averaged with reference to ASTM B276 - 05 (2015) "Standard Test Method for Apparent Porosity of Cemented Carbides".

[0092] The test data is shown in Table 2.

[0093] Table 2 Test data table of Examples 1 - 9 and Comparative Examples 1 - 2

[0094]

[0095] In order to effectively improve the energy utilization rate of the laser cladding process, the applicant first considered using green laser with short wavelength as the light source to improve the energy absorption rate of copper. However, the price of green laser is relatively high, resulting in relatively low cost performance and poor precision control. Therefore, there is still room for improvement.

[0096] For this reason, the applicant also thought of using powder raw materials with relatively smaller particle size, which can improve the forming accuracy while increasing the energy absorption rate. However, the preparation of fine powder will increase the porosity, and then deteriorate the mechanical properties, corrosion resistance and electrical conductivity of the tin-copper alloy.

[0097] In order to improve the defect of increased porosity of the tin-copper alloy caused by using small particle size powder raw materials, the applicant first thought of modifying the raw material powder by PVD evaporation to reduce the porosity during the laser forming process of the tin-copper alloy. However, the PVD evaporation process is complex and not conducive to large-scale application.

[0098] By introducing rare earth elements with the function of reducing the melt viscosity and chromium elements with the function of increasing the melt viscosity into the tin-copper alloy powder, the competition mechanism is used to adjust the viscosity of the tin bronze melt during the laser forming process, maintain the melt stability, and then promote the floating and discharging of the original pores to achieve the purpose of reducing the pores. At the same time, taking advantage of the characteristics that rare earth elements and chromium elements have low solubility in copper and large melting point differences, in-situ precipitation strengthening phases are precipitated to inhibit grain growth.

[0099] Specifically, referring to Examples 1-2, Comparative Examples 1-2 and Table 2 and combining with Figures 1-2 It can be seen that, compared with Comparative Examples 1-2, the porosity of Examples 1-2 is significantly reduced, indicating that the addition of Cr, La and Ce can effectively reduce the generation of bubbles in the tin-copper alloy.

[0100] In addition, in laser cladding, if the laser power is too small, the molten pool is not obvious, resulting in the generation of pores, but there is not enough time to discharge the pores. If the laser power is too large, too many pores are generated and cannot be discharged. If the cladding speed is too slow, the efficiency is reduced and the dilution rate is too high; if the cladding speed is too fast, it affects the pore discharge efficiency and leads to the generation of pores.

[0101] Therefore, the applicant conducted a large number of tests and found that for a device with a 5mm diameter spot, a laser power of 1500-3000 kW and a cladding speed of 400-800 mm / min is more appropriate; for a device with a 20mm×4mm rectangular spot, a laser power of 8000-15000 kW and a cladding speed of 200-600 mm / min is more appropriate.

[0102] Referring to Example 1 and Example 3 and combining with Table 2, it can be seen that, compared with Example 1, the porosity of Example 3 is significantly increased, indicating that compared with directly adding phosphor copper balls, secondary addition treatment of phosphor copper balls can further reduce the generation of pores in the tin-copper alloy.

[0103] The reason is that when the melting temperature is between 1000-1300 °C, the yield of the tin-copper alloy finished powder is relatively higher. Since phosphorus and rare earth elements are easily burned out, long-term melting will lead to poor control of the element ratio. Therefore, the method of secondary feeding can promote the melting of phosphorus and rare earth elements in a short time, thus ensuring the balance of elements and finally obtaining a better pore suppression effect.

[0104] Referring to Example 1 and Example 4 and combining with Table 2, it can be seen that, compared with Example 1, the porosity of Example 4 is significantly increased, indicating that adding La, Ce and P in the form of phosphor copper balls can further reduce the generation of pores in the tin-copper alloy.

[0105] The reason is that when La, Ce and P are added in the form of phosphor copper balls, the phosphor copper balls will continuously protect La, Ce and P, effectively reducing the possibility of burning loss of La, Ce and P, and indirectly promoting the tin-copper alloy to obtain a lower porosity.

[0106] Referring to Example 4-Example 6 and combining with Table 2, it can be seen that compared with Example 4, Example 5-Example 6 has a relatively higher porosity, which shows that compared with using lanthanum or cerium alone, when lanthanum and cerium are used together, the prepared tin-copper alloy will have a lower porosity.

[0107] The reason is that when the rare earth elements are a mixture of La and Ce, La and Ce have a strong affinity for hydrogen and oxygen, so they can capture the oxygen of an oxide in the tin-copper metal liquid, thereby forming a large number of La2O3, Ce2O3, La(OH)3, Ce(OH)3 particles, thereby refining the macroscopic structure of the tin-copper alloy.

[0108] At the same time, with the addition of La and Ce, due to their alloying effect, the supercooling of the tin-copper alloy increases, and the microstructure of the alloy depends on the supercooling of the growth process and growth conditions, that is, under this condition, the secondary dendrite spacing of the tin-copper alloy becomes smaller. In addition, during the growth of the tin-copper alloy phase, La and Ce will also gather around the tin-copper alloy phase, reducing the solid-liquid surface tension, increasing the supercooling of the solid-liquid interface front component, and further promoting the refinement of the dendrite.

[0109] Compared with the use of La or Ce alone, the mixed use of La and Ce can promote the formation of more La2O3, Ce2O3, La(OH)3, and Ce(OH)3 particles, thereby making the macrostructure and microstructure of the tin-copper alloy more refined, ultimately resulting in a lower porosity.

[0110] Referring to Example 4 and Example 7-Example 8 and combining with Table 2, it can be seen that the porosity of Example 7-Example 8 is significantly improved compared with Example 4, which shows that when lanthanum and cerium use the mass percentage of Example 4, the prepared tin-copper alloy will have a lower porosity.

[0111] The reason may be that when La and Ce adopt the above-mentioned mass percentages, more La2O3, Ce2O3, La(OH)3, and Ce(OH)3 particles will be formed in the tin-copper alloy, thereby making the macrostructure and microstructure of the tin-copper alloy more refined, ultimately resulting in a lower porosity.

[0112] Referring to Example 4 and Example 9 and combining with Table 2, it can be seen that the porosity of Example 9 is significantly improved compared with that of Example 4, which further illustrates that the addition of lanthanum and cerium can effectively reduce the porosity of the tin-copper alloy.

[0113] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A tin-copper alloy, characterized in that, The raw materials include the following in mass percentages: Sn 11% - 13%, P 0.05% - 2.0%, Ni 0.5% - 5.0%, Cr 0.5% - 3.5%, rare earth elements 0.2 - 2.0%, and the balance is copper and impurities that cannot be removed. The rare earth elements are a mixture of La and Ce, and La, Ce, and P are added in the form of phosphor copper balls. The particle size of the finished powder of the tin - copper alloy is between 50 - 120 μm.

2. The tin-copper alloy according to claim 1, wherein, The raw materials include the following in mass percentages: Sn 11% - 13%, P 0.05% - 2.0%, Ni 0.5% - 5.0%, Cr 0.5% - 3.5%, La 0.1% - 1.0% and Ce 0.1 - 1.0%, and the balance is copper and impurities that cannot be removed. La, Ce, and P are added in the form of phosphor copper balls. The particle size of the finished powder of the tin - copper alloy is between 50 - 120 μm.

3. The tin-copper alloy according to claim 2, characterized in that, The preparation method of the finished powder of the tin - copper alloy is as follows: First, add copper, tin, nickel, and chromium into a vacuum melting crucible, and melt the metals by induction heating. When the temperature of the metal liquid reaches 1000 - 1300 °C, add phosphor copper, lanthanum, and cerium to the metal liquid in a secondary feeding manner, then keep it warm for 5 - 30 min. Finally, pour the metal liquid into an intermediate - ladle crucible and prepare spherical metal powder by gas atomization of the metal liquid, and finally cool and perform air classification to obtain the finished powder of the tin - copper alloy.

4. The tin-copper alloy according to claim 1, characterized in that, The preparation method of the phosphor copper balls is as follows: First, add the phosphor copper alloy into a vacuum melting crucible, and melt the metal by induction heating. After the temperature of the metal liquid reaches 1000 - 1300 °C, add La and Ce and melt and mix them evenly to obtain a phosphor copper melt. Then, cool and crystallize the phosphor copper melt into a phosphor copper rod through a continuous casting machine, and then process the phosphor copper rod into phosphor copper balls through a heading machine, a polishing machine, a cleaning machine, and a packaging machine in sequence.

5. The tin-copper alloy according to claim 3, wherein: In the preparation of spherical metal powder by the gas atomization method, the atomizing gas is high - purity argon, the pressure difference between the melting chamber and the gas atomization chamber is less than 0.3 MPa, and the pressure of the high - pressure atomizing gas is 4 - 5 MPa.

6. A laser cladding process for tin-copper alloy, characterized in that: It attaches the finished powder of the tin - copper alloy according to any one of claims 1 - 5 to the component by laser cladding; The laser cladding uses a narrow laser spot, the diameter of the laser spot is 5 mm, the laser power is 1500 - 3000 kW, and the cladding speed is 400 - 800 mm / min; after forming, the component is cut, ground, and polished.

7. A laser cladding process for tin-copper alloy, characterized in that: It attaches the finished powder of the tin - copper alloy according to any one of claims 1 - 5 to the component by laser cladding; The laser cladding uses a wide laser spot, the size of the laser spot is 20 mm × 4 mm, the laser power is 8000 - 15000 kW, and the cladding speed is 200 - 600 mm / min; after forming, the component is cut, ground, and polished.

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