A method of making a multi-alloy casting for aerospace solder

Abstract

This invention relates to the field of casting and homogenization technology of multi-element alloys, and discloses a method for preparing multi-element alloy castings for aerospace solders. The method includes: weighing five raw materials—Cu, Ni, Mn, Co, and Fe—in a predetermined ratio; placing them in a crucible and then evacuating to 10°C. ‑ The process involves heating the metal to a temperature below ¹Pa and filling it with a protective atmosphere. The temperature is first raised to a medium temperature for preheating, then raised to a high temperature to completely melt the metal. Subsequently, the temperature is lowered to a medium temperature for initial homogenization and holding. The temperature is then lowered again and vacuumed to remove gas. After the metal solidifies, the vacuuming process is stopped. A protective atmosphere is refilled, and the temperature is raised again to a medium temperature to liquefy the surface, then raised to a high temperature. Once all the residual metal on the crucible wall has melted, the temperature is lowered to the casting temperature for casting. After cooling, a cast ingot is obtained. This invention, through a multi-stage temperature control and vacuum degassing synergistic process, effectively eliminates component segregation in multi-element alloys during casting, resulting in a Cu-Ni-Mn-Co-Fe alloy ingot with highly uniform composition and no surface cracks or pores, suitable for aerospace solder applications.

Description

Technical Field

[0001] This invention relates to the field of casting and homogenization technology of multi-element alloys, specifically a method for preparing multi-element alloy castings for aerospace solders. Background Technology

[0002] Multi-element alloys used in aerospace solders possess excellent strength, corrosion resistance, and good electrical and thermal conductivity, showing significant application prospects in the aerospace solder field. As the requirements for high-temperature reliability, creep resistance, and thermal fatigue resistance of solders in aero-engines and aircraft electronic systems continue to increase, traditional ternary or quaternary alloy solders are gradually becoming unable to meet the demands of these stringent operating conditions. Pentium alloys, through multi-component alloying strategies, can significantly improve the relative stability, wettability, and high-temperature mechanical properties of solders.

[0003] However, this pentagonal alloy generally suffers from severe compositional segregation and uneven microstructure during the smelting and casting process. Due to the large differences in melting points and limited mutual solubility of the constituent elements, dendritic segregation and non-equilibrium phases are easily formed, which in turn leads to local brittle fracture of the solder and a decrease in welding reliability.

[0004] Currently, the homogenization treatment of multi-component alloys mainly relies on high-temperature homogenization annealing after casting. However, this method has shortcomings such as long processing cycle, high energy consumption, and easy coarsening of the microstructure. It is also difficult to completely eliminate the compositional inhomogeneity at the microscale. Although vacuum induction melting can effectively reduce oxide inclusions, existing processes still lack an integrated homogenization casting process for Cu-Ni-Mn-Co-Fe pentagonal alloys. Therefore, developing a casting process that can achieve uniform composition and dense microstructure in this pentagonal alloy has important engineering application value. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for preparing multi-alloy castings for aerospace solders, the specific steps of which are as follows: (1) Five metals, Cu, Ni, Mn, Co and Fe, are placed in a container for two-stage vacuum induction melting.

[0006] (2) After vacuum melting is completed, the temperature is lowered to 1150℃~1250℃ and kept at this temperature to achieve preliminary homogenization of the alloy liquid.

[0007] (3) After the initial homogenization treatment is completed, the temperature is reduced to 950℃~1050℃ and vacuum is applied for degassing until no bubbles are generated on the surface of the alloy liquid. Then, the heating of the alloy liquid is stopped and the vacuum is continued until the alloy liquid solidifies. Then, the vacuum is stopped to obtain the alloy block.

[0008] (4) Refill with inert gas as a protective atmosphere, first raise the temperature to 1150℃~1250℃, and after the surface of the alloy block liquefies, raise it to 1650℃~1750℃. After all the metal remaining on the container wall melts, lower the temperature to 950℃~1050℃ for casting. Keep the casting speed uniform. After the alloy cools and solidifies naturally in the mold, take it out to obtain the multi-alloy casting for aerospace solder.

[0009] Preferably, the percentage content of Cu, Ni, Mn, Co and Fe in step (1) is 35%, 34%, 25%, 5% and 1% by mass, and the total percentage content is 100%.

[0010] Preferably, in step (1), the five metals Cu, Ni, Mn, Co and Fe are placed in the bottom of the reaction vessel in the form of small particles and small blocks of metal, and large sheet metal is placed on the top layer.

[0011] Preferably, the conditions for the two-stage vacuum induction melting in step (1) are as follows: the first stage melting condition is melting at 1150℃~1250℃ for 5~10 minutes; the second stage melting condition is melting at 1650℃~1750℃ until all the metal raw materials are melted.

[0012] Preferably, the vacuum degree of the two-stage vacuum induction melting in step (1) is 10. - The pressure is below ¹Pa, and an inert gas is introduced as a protective atmosphere.

[0013] Preferably, the heat preservation time at 1150℃~1250℃ in step (2) is 10~20 minutes.

[0014] Preferably, the diameter of the liquid flow during casting in step (4) is controlled at 0.5~0.7cm.

[0015] Preferably, the casting mold in step (4) is a graphite mold.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention successfully solves the problems of compositional segregation, porosity, cracks, and oxidation that easily occur in the casting of Cu-Ni-Mn-Co-Fe multi-element alloys by using a process of "two-stage vacuum induction melting + preliminary homogenization treatment + vacuum homogenization treatment + vacuum solidification + secondary vacuum induction melting followed by casting". The final product is a cast billet with uniform composition and excellent surface quality, which significantly improves the high-temperature reliability, thermal fatigue resistance, wettability and welding strength of the alloy in aerospace solder applications. The formation of these properties is mainly due to the process. Special temperature control: First, the entire process is conducted in a vacuum environment to avoid oxidation and gas dissolution, eliminating porosity and oxide film at the source; second, a "double homogenization" temperature regime below the solidus line is adopted (the initial homogenization temperature is slightly lower, and the vacuum homogenization temperature is slightly higher), which promotes full atomic diffusion under vacuum conditions and eliminates dendrite segregation; more importantly, after the secondary vacuum induction melting, casting is carried out at a superheat lower than that of conventional casting (20~40℃ above the liquidus line), and a slow temperature gradient is controlled during vacuum solidification, thereby effectively suppressing the formation of hot cracks and micro-shrinkage porosity.

[0017] (2) The invention uses the specific mass percentages of Cu, Ni, Mn, Co and Fe as 35%, 34%, 25%, 5% and 1%, respectively. The casting prepared according to this special ratio has the core advantage of high strength. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the technical route of the present invention.

[0019] Figure 2 The images show the surface morphology of the Cu-Ni-Mn-Co-Fe alloy billets prepared in Examples 1 to 3.

[0020] Figure 3 The image shows the surface morphology of the Cu-Ni-Mn-Co-Fe alloy billet prepared in Comparative Example 2. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The purity of the Cu, Ni, Mn, Co and Fe metal raw materials used in the examples is 99.9%.

[0023] Example 1 A method for preparing a multi-alloy casting for aerospace solder, the specific steps of which are as follows: (1) According to the mass percentage, five metals, 35% Cu, 34% Ni, 25% Mn, 5% Co and 1% Fe, are placed in the alumina crucible of the vacuum induction melting furnace (model: ZG-0.01) in the manner of placing small particles and small blocks of metal at the bottom of the crucible and large sheet metal at the top. The furnace door is closed, and the mechanical pump of the vacuum induction melting furnace is started to evacuate the vacuum inside the furnace to 10. - Once the pressure drops below ¹Pa, stop evacuating and turn off the mechanical pump. Then, fill the furnace with argon gas as a protective atmosphere and raise the temperature to 1200℃. Hold the temperature for 7.5 minutes to perform the first stage of vacuum induction melting. After the first stage of vacuum induction melting is completed, raise the temperature to 1700℃ until all the metal is melted to complete the second stage of vacuum induction melting.

[0024] (2) After vacuum induction melting is completed, the temperature is lowered to 1200℃ and kept at this temperature for 15 minutes to achieve the initial homogenization treatment of the alloy liquid.

[0025] (3) After the initial homogenization treatment is completed, the temperature is reduced to 1000℃ and vacuum is drawn for degassing treatment until no bubbles are generated on the surface of the alloy liquid. Then, heating is stopped and the vacuum is stopped after the alloy liquid solidifies to obtain the alloy block.

[0026] (4) Argon gas is refilled as a protective atmosphere. The temperature is first raised to 1200℃. After the surface of the alloy block is liquefied, the temperature is further raised to 1700℃. After all the metal remaining on the container wall is melted, the temperature is lowered to 1000℃ for casting. The casting speed is kept uniform. The casting mold is a graphite mold with a liquid flow diameter of 0.6cm. After the alloy liquid cools and solidifies naturally in the mold, it is taken out to obtain a multi-element alloy casting for aerospace solder.

[0027] The ingot head, ingot middle and ingot tail of the obtained casting were sampled and analyzed respectively. The content of each element fluctuated within ±0.02%, and the composition uniformity was excellent. The specific composition test results are shown in Table 1.

[0028] Surface morphology of castings as follows Figure 2 As shown in (a), the surface of the cast billet is smooth and free of visible cracks, pores and other defects.

[0029] Table 1 Comparison of compositional analysis results at three locations: the ingot head, middle, and tail of the Cu-Ni-Mn-Co-Fe alloy casting. Example 2 (1) According to the mass percentage, five metals, 35% Cu, 34% Ni, 25% Mn, 5% Co and 1% Fe, are placed in the alumina crucible of the vacuum induction melting furnace (model: ZG-0.01) in the manner of placing small particles and small blocks of metal at the bottom of the crucible and large sheet metal at the top. The furnace door is closed, and the mechanical pump of the vacuum induction melting furnace is started to evacuate the vacuum inside the furnace to 10. - Once the pressure drops below ¹Pa, stop evacuating and turn off the mechanical pump. Then, fill the furnace with argon gas as a protective atmosphere and raise the temperature to 1150℃. Hold the temperature for 5 minutes to perform the first stage of vacuum induction melting. After the first stage of vacuum induction melting is completed, raise the temperature to 1650℃ until all the metal is melted to complete the second stage of vacuum induction melting.

[0030] (2) After vacuum induction melting is completed, the temperature is lowered to 1150℃ and kept at this temperature for 10 minutes to achieve the initial homogenization treatment of the alloy liquid.

[0031] (3) After the initial homogenization treatment is completed, the temperature is reduced to 950℃ and vacuum is applied for degassing until no bubbles are generated on the surface of the alloy liquid; heating is stopped and the vacuum is stopped after the alloy liquid solidifies to obtain the alloy block.

[0032] (4) Argon gas is refilled as a protective atmosphere. The temperature is first raised to 1150℃. After the surface of the alloy block is liquefied, the temperature is further raised to 1650℃. After all the metal remaining on the container wall is melted, the temperature is lowered to 950℃ for casting. The casting speed is kept uniform. The casting mold is a graphite mold with a liquid flow diameter of 0.5cm. After the alloy liquid cools and solidifies naturally in the mold, it is taken out to obtain a multi-element alloy casting for aerospace solder.

[0033] Samples were taken from the ingot head, ingot middle and ingot tail of the obtained castings for analysis. The content of each element fluctuated within ±0.10%, and the composition uniformity was excellent. The specific composition test results are shown in Table 2.

[0034] Surface morphology of castings as follows Figure 2 As shown in (b), the surface of the cast billet is smooth and free of visible cracks, porosity and other defects.

[0035] Table 2 Comparison of compositional analysis results at three locations: the ingot head, middle, and tail of the Cu-Ni-Mn-Co-Fe alloy casting. Example 3 A method for preparing a multi-alloy casting for aerospace solder, the specific steps of which are as follows: (1) According to the mass percentage, five metals, 35% Cu, 34% Ni, 25% Mn, 5% Co and 1% Fe, are placed in the alumina crucible of the vacuum induction melting furnace (model: ZG-0.01) in the manner of placing small particles and small blocks of metal at the bottom of the crucible and large sheet metal at the top. The furnace door is closed, and the mechanical pump of the vacuum induction melting furnace is started to evacuate the vacuum inside the furnace to 10. - Once the pressure drops below ¹Pa, stop evacuating and turn off the mechanical pump. Then, fill the furnace with argon gas as a protective atmosphere and raise the temperature to 1250℃. Hold the temperature for 10 minutes to perform the first stage of vacuum induction melting. After the first stage of vacuum induction melting is completed, raise the temperature to 1750℃ until all the metal is melted to complete the second stage of vacuum induction melting.

[0036] (2) After vacuum induction melting is completed, the temperature is lowered to 1250℃ and kept at this temperature for 20 minutes to achieve the initial homogenization treatment of the alloy liquid.

[0037] (3) After the initial homogenization treatment is completed, the temperature is reduced to 1050℃ and vacuum is applied for degassing until no bubbles are generated on the surface of the alloy liquid. Then, heating is stopped and the vacuum is stopped after the alloy liquid solidifies to obtain the alloy block.

[0038] (4) Argon gas is refilled as a protective atmosphere. The temperature is first raised to 1250℃. After the surface of the alloy block is liquefied, the temperature is further raised to 1750℃. After all the metal remaining on the container wall is melted, the temperature is lowered to 1050℃ for casting. The casting speed is kept uniform. The casting mold is a graphite mold with a liquid flow diameter of 0.7cm. After the alloy liquid cools and solidifies naturally in the mold, it is taken out to obtain a multi-element alloy casting for aerospace solder.

[0039] Sampling and analysis were performed on the ingot head, ingot middle, and ingot tail of the obtained castings. The content fluctuations of each element were all within ±0.10%, indicating excellent compositional uniformity. The specific compositional test results are shown in Table 3. The surface morphology of the cast billet is as follows: Figure 2 As shown in (c), the surface of the cast billet is smooth and free of visible cracks, pores and other defects.

[0040] Table 3 Comparison of compositional analysis results at three locations: the ingot head, middle, and tail of the Cu-Ni-Mn-Co-Fe alloy casting. Comparative Example 1 In comparison, this comparative example differs from Example 1 in that the five metals Cu, Ni, Mn, Co, and Fe are vacuum melted and then directly cast to obtain the casting. The specific steps are as follows: (1) According to the mass percentage, five metals, 35% Cu, 34% Ni, 25% Mn, 5% Co and 1% Fe, are placed in the alumina crucible of the vacuum induction melting furnace (model: ZG-0.01) in the manner of placing small particles and small blocks of metal at the bottom of the crucible and large sheet metal at the top. The furnace door is closed, and the mechanical pump of the vacuum induction melting furnace is started to evacuate the vacuum inside the furnace to 10. - Once the pressure drops below ¹Pa, stop evacuating and turn off the mechanical pump. Then, fill the furnace with argon gas as a protective atmosphere and raise the temperature to 1250℃. Hold the temperature for 10 minutes to perform the first stage of vacuum induction melting. After the first stage of vacuum induction melting is completed, raise the temperature to 1750℃ until all the metal is melted to complete the second stage of vacuum induction melting.

[0041] (2) After vacuum induction melting is completed, the temperature is reduced to 1000℃ for casting; the casting speed is kept uniform, the casting mold is a graphite mold, the liquid flow diameter is 0.6cm, and the alloy liquid is taken out after natural cooling and solidification in the mold to obtain a multi-alloy casting for aerospace solder.

[0042] Since no homogenization treatment was performed, the content of each element inside the alloy fluctuated significantly and the compositional uniformity was poor. Therefore, the surface quality was no longer of analytical value. The specific compositional test results are shown in Table 4.

[0043] Table 4 Comparison of compositional analysis results at three locations: the ingot head, middle, and tail of the Cu-Ni-Mn-Co-Fe alloy casting. Comparative Example 2 In contrast, this comparative example differs from Example 1 in that a vacuum process is not performed during step (3). The specific steps are as follows: (1) According to the mass percentage, five metals, 35% Cu, 34% Ni, 25% Mn, 5% Co and 1% Fe, are placed in the alumina crucible of the vacuum induction melting furnace (model: ZG-0.01) in the manner of placing small particles and small blocks of metal at the bottom of the crucible and large sheet metal at the top. The furnace door is closed, and the mechanical pump of the vacuum induction melting furnace is started to evacuate the vacuum inside the furnace to 10. - Once the pressure drops below ¹Pa, stop evacuating and turn off the mechanical pump. Then, fill the furnace with argon gas as a protective atmosphere and raise the temperature to 1200℃. Hold the temperature for 7.5 minutes to perform the first stage of vacuum induction melting. After the first stage of vacuum induction melting is completed, raise the temperature to 1700℃ until all the metal is melted to complete the second stage of vacuum induction melting.

[0044] (2) After vacuum induction melting is completed, the temperature is lowered to 1200℃ and kept at this temperature for 15 minutes to achieve the initial homogenization treatment of the alloy liquid.

[0045] (3) After the initial homogenization treatment is completed, the temperature is lowered to 1000℃. After the alloy liquid solidifies, argon gas is refilled as a protective atmosphere. The temperature is first raised to 1200℃. After the alloy surface is liquefied, the temperature is further raised to 1700℃. After all the metal remaining on the container wall is melted, the temperature is lowered to 1000℃ for casting. The casting speed is kept uniform. The casting mold is a graphite mold with a liquid flow diameter of 0.6cm. After the alloy liquid cools and solidifies naturally in the mold, it is taken out to obtain a multi-element alloy casting for aerospace solder.

[0046] Alloy surface morphology such as Figure 3 As shown, since no vacuum was applied during the smelting process, a large number of bubble defects appeared on the alloy surface, so no further compositional analysis is required.

[0047] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a multi-alloy casting for aerospace solder, characterized in that: The specific steps of the method are as follows: (1) Five metals, Cu, Ni, Mn, Co and Fe, are placed in a container for two-stage vacuum induction melting; (2) After vacuum melting is completed, the temperature is lowered to 1150℃~1250℃ and held at this temperature to achieve preliminary homogenization of the alloy liquid. (3) After the initial homogenization treatment is completed, the temperature is reduced to 950℃~1050℃ and vacuum is drawn for degassing treatment until no bubbles are generated on the surface of the alloy liquid. Then, the heating of the alloy liquid is stopped and the vacuum is continued until the alloy liquid solidifies. Then, the vacuum is stopped to obtain the alloy block. (4) Refill with inert gas as a protective atmosphere, first raise the temperature to 1150℃~1250℃, and after the surface of the alloy block liquefies, raise it to 1650℃~1750℃. After all the metal remaining on the container wall melts, lower the temperature to 950℃~1050℃ for casting. Keep the casting speed uniform. After the alloy cools and solidifies naturally in the mold, take it out to obtain the multi-alloy casting for aerospace solder.

2. The method for preparing multi-alloy castings for aerospace solder according to claim 1, characterized in that: The percentages of Cu, Ni, Mn, Co and Fe in step (1) are 35%, 34%, 25%, 5% and 1% by mass, respectively, with a total percentage of 100%.

3. The method for preparing multi-alloy castings for aerospace solder according to claim 1, characterized in that: In step (1), the five metals Cu, Ni, Mn, Co and Fe are placed in the bottom of the reaction vessel in the form of small particles and small blocks of metal, and large sheet metal is placed on the top layer.

4. The method for preparing multi-alloy castings for aerospace solder according to claim 1, characterized in that: The conditions for the two stages of vacuum induction melting in step (1) are as follows: the first stage of melting is melting at 1150℃~1250℃ for 5~10 minutes; the second stage of melting is melting at 1650℃~1750℃ until all the metal raw materials are melted.

5. The method for preparing multi-alloy castings for aerospace solder according to claim 1, characterized in that: The vacuum degree of the two-stage vacuum induction melting in step (1) is 10. - The pressure is below ¹Pa, and an inert gas is introduced as a protective atmosphere.

6. The method for preparing multi-alloy castings for aerospace solder according to claim 1, characterized in that: In step (2), the heat preservation time at 1150℃~1250℃ is 10~20 minutes.

7. The method for preparing multi-alloy castings for aerospace solder according to claim 1, characterized in that: In step (4), the diameter of the liquid flow during casting is controlled at 0.5~0.7cm.

8. The method for preparing multi-alloy castings for aerospace solder according to claim 1, characterized in that: In step (4), the casting mold is a graphite mold.

Images