High-silicon high-nickel piston material and modification method thereof

Abstract

The invention discloses a high-silicon high-nickel piston material which comprises the following components in percentage by weight (wt%): 18-23% of Si, 3-5% of Ni, 0.6-1.5% of Mg, 0.8-1.4% of Cu, 0.1-0.2% of Ti, 0.1-0.2% of Zr, 0.1-0.35% of Y, 0.1-0.2% of Er, 0.015-0.025% of P, less than or equal to 0.7% of Fe and the balance of Al. The invention further provides a modification method of the high-silicon and high-nickel piston material. By adopting composite modification treatment of the aluminum-silicon-phosphorus alloy, the aluminum-yttrium alloy and the aluminum-erbium alloy, the grain size of primary silicon in the high-silicon alloy is remarkably refined, the number of crystal nucleuses of the primary silicon in the alloy is increased, the grains are refined, meanwhile, growth of a nickel-rich phase, the primary silicon and eutectic silicon is inhibited, and the performance of the high-silicon alloy is improved. The nickel-rich phase is promoted to still have good morphology and distribution when existing in a large mass fraction, and the piston material has excellent high-temperature performance, good wear resistance and volume thermal stability and has important application prospects in the field of unmanned aerial vehicle engine piston materials.

Description

Technical Field

[0001] The present invention relates to the technical field of piston internal combustion engine materials, and particularly to a high-silicon and high-nickel piston material and its modification method. Background Art

[0002] Aviation power has always been one of the key and difficult technologies in aviation technology. With the further development of unmanned aerial vehicle (UAV) technology, higher requirements are put forward for the power systems of UAVs. Currently, the following several types of power devices are adopted for different types of UAVs: piston internal combustion engines suitable for low-speed and medium-low-altitude flight, turbojet internal combustion engines for high-altitude and high-speed UAVs, turboshaft internal combustion engines for short-distance vertical takeoff and landing unmanned helicopters, turbofan internal combustion engines for high-altitude long-endurance UAVs, etc. According to the different requirements of UAVs for flight speed, flight altitude, takeoff and landing mode, endurance, range, and economic indicators, etc., power devices suitable for performing corresponding different tasks have been developed at home and abroad. Among many UAV power systems, piston internal combustion engines are favored by small and medium-sized UAVs due to their many advantages such as high power density, small volume, light weight, and low price. In particular, low-speed and low-altitude UAVs still mainly use piston internal combustion engines as their power. Moreover, after the opening of general aviation in China, piston internal combustion engines for UAVs will also obtain sufficient development and have a huge potential technology market. Piston internal combustion engines for aviation UAVs are very different from traditional piston internal combustion engines for vehicles and must break through the key short boards faced by requirements such as high power-to-weight ratio, high reliability, and high economy, and meet strict airworthiness requirements.

[0003] With the continuous improvement of the high rotational speed and high power density of piston internal combustion engines for UAVs, the working conditions of existing piston materials have become more severe. In the field of aviation UAVs, piston materials must meet the high requirements for high strength, low friction coefficient, and wear resistance. There is an urgent need for a piston material with excellent high strength ratio, good wear resistance, and good volume stability, which can reduce the structural weight while ensuring high strength and high rotational speed, thereby reducing energy consumption and improving operating efficiency. Currently, traditional diesel engine piston materials (such as ZL109 piston material and AlSiCuMgNi material) have problems such as large thermal deformation, poor volume stability, and poor wear resistance. When operating at a high rotational speed (rotational speed ≥ 6500 rpm) of an aviation UAV internal combustion engine, there are serious problems of abnormal wear, resulting in defects such as piston scuffing and causing the internal combustion engine to stop working.

[0004] Using high-silicon and high-nickel materials as the piston materials for aero UAV internal combustion engines, improving the morphology and distribution of the nickel-rich phase and silicon phase is the key bottleneck. Although elements such as Na and Sr have excellent modification effects, due to their own limitations, it is always difficult to obtain satisfactory modification effects on high-silicon alloys. Phosphorus is a relatively excellent high-silicon modifier. However, at home and abroad, phosphorus is mainly added to modify Al-Si alloys in the form of red phosphorus, phosphate salts or copper-phosphorus master alloys. But these phosphorus-modified alloys have the following disadvantages in high-silicon alloys: (1) Red phosphorus has a low ignition point (240 °C), which is unsafe during transportation, storage and use. Moreover, the reaction is intense during modification, releasing a large amount of P 2 O 5 toxic gas, causing serious erosion of equipment and great harm to the health of workers, and seriously polluting the environment, resulting in a large amount of aluminum consumption; the absorption rate of phosphorus is low and difficult to control, the modification effect is unstable, and the quality of castings is difficult to guarantee; (2) During the addition and use of phosphate salts, like red phosphorus, a large amount of P 2 O 5 toxic gas is released, seriously polluting the environment; and a large amount of Al 2 O 3 reaction slag is produced, corroding the furnace lining, and it is difficult to separate the slag from the aluminum, increasing aluminum consumption; the absorption rate of phosphorus is low, seriously endangering the health of workers and the modification effect is unstable; (3) The melting point of the phosphorus-copper Cu-P alloy is high, difficult to melt after addition, has a large density, is prone to precipitation segregation, the absorption rate of phosphorus is low, and the effect is unstable. If the undissolved Cu-P particles remain in the casting and during processing, placement or use by the user, extremely serious consequences such as bulging and cracking will occur. In short, these phosphorus-modified alloys have disadvantages such as low phosphorus absorption rate and unstable modification effect in high-silicon and high-nickel materials, and cannot simultaneously improve the morphology and distribution of the nickel-rich phase and silicon phase. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a high-silicon and high-nickel piston material and its modification method. Through the composite modification treatment of aluminum-silicon-phosphorus alloy (Al-12Si-5P) + aluminum-yttrium alloy (Al20Y) + aluminum- erbium alloy (Al20Er), the grain size of primary silicon in the high-silicon alloy is significantly refined, the number of crystal nuclei of primary silicon in the alloy is increased, and at the same time, the growth of the nickel-rich phase, primary silicon and eutectic silicon is inhibited, the grains are refined, and when the nickel-rich phase exists with a relatively large mass fraction, it still has good morphology and distribution. The piston material of the present invention has excellent high-temperature performance, good wear resistance and volume stability, and has important application prospects in the field of piston materials for UAV engines.

[0006] The technical solution provided by the present invention is as follows: A high-silicon and high-nickel piston material, by mass percentage (wt%), includes the following components: Si 18 - 23, Ni 3 - 5, Mg 0.6 - 1.5, Cu 0.8 - 1.4, Ti 0.1 - 0.2, Zr 0.1 - 0.2, Y 0.1 - 0.35, Er 0.1 - 0.2, P 0.015 - 0.025, Fe ≤ 0.7, and the balance is Al.

[0007] A modification method for the high-silicon and high-nickel piston material as described above, including the following operating steps: S1. Batching: Prepare corresponding pre-melted materials according to the components and contents described above. The pre-melted materials include crystalline silicon, pure magnesium ingots, industrial high-purity aluminum ingots, electrolytic nickel, cathode copper, aluminum-titanium alloy, aluminum-zirconium alloy, aluminum-yttrium alloy, and aluminum-silicon-phosphorus alloy; S2. Loading and melting: Load crystalline silicon, industrial high-purity aluminum ingots, electrolytic nickel, cathode copper, aluminum-titanium alloy, and aluminum-zirconium alloy into a melting furnace for melting; S3. Adding aluminum-yttrium alloy, aluminum- erbium alloy, and pure magnesium ingots: When the temperature of the pressed aluminum melt drops to 800 - 850 °C, add aluminum-yttrium alloy, aluminum- erbium alloy, and pure magnesium ingots, and keep warm for 30 - 60 min; S4. Skimming: Add a slag skimming agent accounting for 0.5 - 1 wt% of the total weight of each furnace on the surface of the aluminum melt in each furnace. Use a slag skimming spoon to stir the molten slag on the liquid surface and clean up the floating slag on the aluminum melt surface; S5. Rotary refining and degassing: When the temperature of the aluminum melt drops to 780 °C - 820 °C, add an environmentally friendly refining agent to the aluminum melt and start the degassing machine for rotary degassing; S6. Adding aluminum-silicon-phosphorus alloy: When the temperature of the aluminum melt is kept at 780 °C - 820 °C, add aluminum-silicon-phosphorus alloy, and continue degassing for a period of time, then clean up the floating slag on the aluminum liquid surface, and let the aluminum melt stand for 5 - 10 min; S7. Pouring: Place the specimen molds neatly on the mold rack, and pour the aluminum liquid prepared in step S6 into the specimen molds to obtain specimens; S8. Heat treatment: Perform casting solution strengthening and aging treatment on the obtained specimens.

[0008] Preferably, the charging order of the pre-melted alloy in step S1 is: crystalline silicon → pure aluminum ingot → electrolytic nickel → cathode copper → aluminum-titanium alloy → aluminum-zirconium alloy, so that there are no obvious gaps left after each added material is compacted.

[0009] Preferably, after loading the melting furnace in step S2, the temperature should be slowly raised. After keeping warm at 550 - 600 °C for 60 - 80 min, then raise the temperature to 810 - 870 °C for melting and keep warm for 1 - 2 h.

[0010] Preferably, during the rotary degassing in step S5, ensure that the graphite rotor is located at the center of the holding furnace, with the rotor speed being 425 - 482 revolutions per minute, the compressed air flow rate being 0.6 - 0.8 m 3 / h, and the degassing time being 360 - 480 s.

[0011] Preferably, after the rotary degassing in step S5 is completed, the rotor rises. Immediately use a tool to dredge the vent holes of the rotor, turn the molten slag on the liquid surface with a slag skimmer, and then clean up the floating slag on the surface of the molten aluminum, and keep it warm for 20 - 40 min.

[0012] Preferably, the continuous degassing time in step S6 is 180 - 260 s, the rotor speed is 515 - 550 revolutions per minute, the compressed air flow rate is 0.8 - 1.2 m 3 / h. After degassing, the rotor rises. Immediately use a tool to dredge the vent holes of the rotor, turn the molten slag on the liquid surface with a slag skimmer, and then clean up the floating slag on the surface of the molten aluminum.

[0013] Preferably, the pouring temperature in step S7 is controlled within 740 - 760 °C. Pour the molten aluminum into the specimen mold with a hand-held ladle, pour it slowly and continuously. After it is completely solidified, use a clamp to turn over the specimen mold to demold the specimen.

[0014] Preferably, the solution strengthening process in step S8 includes primary solution treatment and secondary solution treatment. The heating temperature of the primary solution treatment is 475 ± 10 °C, and the holding time is 1 - 2 h; the heating temperature of the secondary solution treatment is 515 ± 10 °C, the holding time is 6 - 8 h, and the cooling method is water cooling.

[0015] Preferably, the heating temperature of the aging treatment in step S8 is 185 ± 10 °C, the holding time is 4 - 6 h, and the cooling method is air cooling.

[0016] The present invention has the following advantages over the prior art: The alloy material of the present invention is a high-silicon high-nickel aluminum alloy. High silicon endows the alloy with high fluidity, low shrinkage rate and thermal expansion coefficient. At the same time, because the silicon particles are hard and the α-Al matrix is relatively soft, it is a typical wear-resistant alloy with hard particle-reinforced soft matrix, and the wear resistance increases with the increase of silicon content.

[0017] However, a high silicon content will produce a large amount of coarse eutectic silicon and primary silicon, resulting in serious segregation of silicon and very uneven distribution. The eutectic silicon is in the form of thick needles, and at the same time, the primary silicon is also very thick, in the form of plate strips or polyhedrons, seriously disrupting the continuity of the matrix. At the same time, the edges of the silicon phase with plate strip characteristics are sharp, and under external stress, local stress concentration is easily caused at the tips and corners of the silicon phase, leading to crack initiation and fracture. Therefore, such a microstructure feature makes the overall strength, plasticity, machinability and heat resistance of the alloy very poor.

[0018] This invention adopts aluminum silicon phosphorus alloy (Al-12Si-5P) + aluminum yttrium alloy (Al20Y) to couple the silicon phase, especially the coarse hypereutectic silicon and primary silicon. Table 1 below is a comparison of the phosphorus absorption rate of aluminum silicon phosphorus alloy in high silicon and high nickel piston materials. It can be seen from Table 1 that the phosphorus absorption rate in aluminum silicon phosphorus alloy is much higher than that in other alloys in the prior art. The reasons are as follows: Al-12Si-5P intermediate alloy has a low melting point and is close to the composition of high silicon melt, has good wettability, is easy to melt after addition, has low density, has a high phosphorus absorption rate, is easy to form AlP nucleation center, has a good modification effect, increases the number of primary silicon nuclei in the alloy, inhibits the growth of primary silicon, reduces the grain size, increases the number, and makes the distribution more uniform, reducing the adverse effect of primary silicon on alloy deformation.

[0019] Table 1 Comparison of phosphorus absorption rate

[0020] The yttrium element in the present invention is not only an effective α-Al matrix refiner, but also an effective silicon phase modifier. The modification of the silicon phase by the yttrium element mainly works by preferentially adsorbing on the silicon phase growth step and enriching at the silicon phase front to affect the growth mode of the silicon phase. The yttrium element inhibits the anisotropic growth of the silicon phase in the preferred direction by "poisoning" the twin concave angle, forcing the silicon phase to produce multiple twins and grow isotropically along other directions to grow into an equiaxed shape. It can cooperate with the AlP nucleation center to play the role of a heterogeneous nucleation substrate for primary silicon, thereby greatly improving the nucleation rate and promoting the refinement of primary silicon. For eutectic silicon, the addition of yttrium makes the silicon phase no longer a leading phase, thereby breaking its symbiotic growth mode and generating branches. The yttrium element is enriched at the end of the dendrite, causing the dendrite to fuse, making the eutectic silicon short rod-shaped or even independent equiaxed.

[0021] The present invention is also a high-nickel aluminum alloy. Nickel is the most indispensable element for enhancing the high-temperature strength of the piston alloy of the present invention, and the nickel-rich phase is the most important high-temperature strengthening phase. 3 The phase always tends to be in the form of long strips. 3 CuNi phase exchange is stripe morphology, Al 7 Cu 4 The Ni phase is in block form. These three nickel-rich phases can still maintain better high-temperature performance and excellent volume stability at high temperatures. Among them, nickel exists in a small amount in high-silicon alloys. When the nickel-rich phase exists in a large mass fraction, it still has good morphology and distribution. However, when Ni (wt) ≥ 2%, the morphology deteriorates sharply, which is not conducive to the improvement of performance. When the content increases, NiA1 3 It turns into long needles, cuts the matrix and loses its strengthening effect.

[0022] The present invention uses an aluminum- erbium alloy (Al20Er). The erbium element can form constitutional supercooling at the solidification front, and the erbium element can promote the transformation of the NiA 13 phase into fine short rod-shaped ErNi 3 A1 16 phase. At the same time, the ErA 13 formed with the matrix has a strong binding energy with vacancies, inhibits the diffusion of nickel atoms and silicon atoms, reduces the size of the NiA 13 phase and the growth of primary silicon, and the erbium element enables the nickel-rich phase to still have good morphology and distribution when it exists with a relatively large mass fraction. Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 It is the metallographic structure diagram (100×) of the specimen obtained in Embodiment 1 of the present invention; Figure 2 It is the microstructural diagram (500×) of the specimen obtained in Embodiment 1 of the present invention; Figure 3 It is the metallographic structure diagram (100×) of the specimen obtained in Embodiment 2 of the present invention; Figure 4 It is the metallographic structure diagram (100×) of the specimen obtained in Embodiment 3 of the present invention; Figure 5 It is the metallographic structure diagram (100×) of the specimen obtained in Embodiment 4 of the present invention; Figure 6 It is the metallographic structure diagram (100×) of the specimen obtained in Embodiment 5 of the present invention; Figure 7 It is the metallographic structure diagram (100×) of the specimen obtained in Comparative Example 1 of the present invention; Figure 8 It is the metallographic structure diagram (100×) of the specimen obtained in Comparative Example 2 of the present invention; Figure 9 It is the metallographic structure diagram (100×) of the specimen obtained in Comparative Example 3 of the present invention. Detailed Embodiments

[0025] To enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] The embodiment of the present invention provides a high-silicon and high-nickel piston material, which includes the following components by mass percentage (wt%): Si 18-23, Ni 3-5, Mg 0.6-1.5, Cu 0.8-1.4, Ti 0.1-0.2, Zr 0.1-0.2, Y 0.1-0.35, Er 0.1-0.2, P 0.015-0.025, Fe≤0.7, and the balance is Al.

[0027] A modification method for the high-silicon and high-nickel piston material as described above includes the following operating steps: S1. Batching: Prepare the corresponding pre-melted materials according to the components and contents described above. The pre-melted materials include crystalline silicon, pure magnesium ingot, industrial high-purity aluminum ingot, electrolytic nickel, cathode copper, aluminum-titanium alloy and aluminum-zirconium alloy, aluminum-yttrium alloy, aluminum-silicon-phosphorus alloy, as specifically shown in Table 2 below; Table 2 Pre-melted material alloys and specification models

[0028] S2. Loading and melting: After loading the melting furnace, the temperature should be slowly raised. After the crystalline silicon, industrial high-purity aluminum ingot, electrolytic nickel, cathode copper, aluminum-titanium alloy and aluminum-zirconium alloy are kept at 550°C - 600°C for 60 - 80 minutes, then the temperature is raised to 810 - 870°C for melting and kept for 1 - 2 h to ensure the melting of the high-silicon alloy. The loading order of the pre-melted alloy is: crystalline silicon → pure aluminum ingot → electrolytic nickel → cathode copper → aluminum-titanium alloy → aluminum-zirconium alloy, etc., and try to make each added material compact without obvious gaps; S3. Adding aluminum-yttrium alloy, aluminum- erbium alloy and pure magnesium ingot: When the temperature of the aluminum melt drops to 800 - 850°C, add aluminum-yttrium alloy, aluminum- erbium alloy and pure magnesium ingot and keep warm for 30 - 60 min; S4. Skimming: Add 0.5 - 1 wt% of skimming agent based on the total weight of each furnace of aluminum water to the surface of each furnace of aluminum water, stir the molten slag on the liquid surface with a slag skimming ladle, and scoop up the floating slag on the aluminum water surface clean; S5. Rotary refining and degassing: When the temperature of the aluminum melt drops to 780 - 820°C, adjust the position of the holding furnace to ensure that the graphite rotor is located at the center of the holding furnace, add an environmental protection refining agent, and turn on the degassing machine. The rotor and baffle will automatically sink and enter the automatic stage. The rotor speed is 425 - 482 revolutions per minute, and the compressed air flow rate is 0.6 - 0.8 m 3 / h, degassing for 360 - 480 s; after degassing is completed, the rotor rises. Immediately use tools to dredge the ventilation holes of the rotor, stir the molten slag on the liquid surface with a slag ladle, and then clean up the floating slag on the surface of the aluminum liquid. Keep warm for 20 - 40 min; S6. Add aluminum-silicon-phosphorus alloy: When the temperature of the aluminum melt is kept at 780 - 820 °C, add aluminum-silicon-phosphorus alloy, continue degassing for 180 - 260 s, the rotor speed is 515 - 550 revolutions per minute, and the compressed air flow rate is 0.8 - 1.2 m 3 / h; after degassing, the rotor rises. Immediately use tools to dredge the ventilation holes of the rotor, stir the molten slag on the liquid surface with a slag ladle, and then clean up the floating slag on the surface of the aluminum liquid. Let the aluminum melt stand for 5 - 10 min; S7. Pouring: Arrange the specimen molds neatly on the mold rack, pour the aluminum liquid obtained in step S6 into the specimen molds. Control the pouring temperature within 740 - 760 °C. Use a hand-held ladle to pour the aluminum liquid into the specimen molds, pour slowly and continuously. After complete solidification, use pliers to turn over the specimen molds to demold the specimens and obtain the specimens; S8. Heat treatment: Conduct casting solution strengthening and aging treatment on the obtained specimens, as shown in Table 3 below.

[0029] Table 3 Heat treatment process

[0030] The following are specific examples and comparative examples.

[0031] Table 4 shows the aluminum alloy component tables used in Examples 1 - 5 and Comparative Examples 1 - 6.

[0032] Table 4 Compositions of Examples and Comparative Examples (wt%)

[0033] Conduct partial physical and mechanical property tests on the products obtained in Examples 1 - 5 and Comparative Examples 1 - 6. The results are shown in Table 5 below.

[0034] Table 5 Performance comparison of Examples 1 - 5 and Comparative Examples 1 - 6

[0035] It can be seen from Table 5 that: at 300 °C, the tensile strength is 102 - 112 MPa, the yield strength is 76 - 84 MPa, the elongation at fracture is 5.5 - 6%, the fatigue strength is 36 - 42 MPa, and the relative wear rate is 0.7 - 0.8; at 20 - 100 °C, the linear expansion coefficient of the aluminum alloy is 17.9 - 18.5×10 -6 m / m•K; at 20 - 200 °C, the linear expansion coefficient of the aluminum alloy is 18.5 - 19.4×10 -6m / m•K; The linear expansion coefficient of aluminum alloy under the condition of 20~300 °C is 19.4~20.3×10 -6 m / m•K.

[0036] Table 6 shows the test results of the piston volume stability of Examples 1-3 and Comparative Examples 4-6. The test method is: heat preservation at 250±5 °C, furnace cooling for 5 hours, and standing at room temperature for 24 hours), and D is the piston diameter.

[0037] Table 6 Comparison of piston volume stability performance of Examples 1-3 and Comparative Examples 4-6

[0038] With the continuous increase of the high speed of the piston internal combustion engine of the unmanned aerial vehicle, the existing piston materials require excellent volume stability. It can be seen from Table 6 that for the unmanned aerial vehicle piston with a diameter D = 80 mm, the major axis change rate of Examples 1-3 is 0.0037~0.0050%, and the minor axis change rate is 0.0050~0.0075%, meeting the requirements of the existing and future high speeds of unmanned aerial vehicle pistons (rotation speed ≥ 6500 rpm).

[0039] The products obtained from Examples 1-5 and Comparative Examples 1-3 were tested for metallographic or microstructural analysis, and the results are as Figures 1-9 shown. From Figure 1 and Figures 3-6 the metallographic structure, it can be seen that the primary silicon is fine, and the eutectic silicon is in the shape of short rods or even independent equiaxed shapes. The two are evenly distributed in the aluminum alloy matrix, greatly enhancing the wear resistance and volume stability of the matrix.

[0040] From Figure 2 the microstructural analysis, it can be seen that the Al 3 CuNi phase is in a strip morphology, the Al 7 Cu 4 Ni phase presents blocks, the fine short rod-shaped ErNi 3 A1 16 phase is in the shape of fine short rods. These nickel-rich high-temperature phases are dispersed in the aluminum alloy matrix, greatly improving the high-temperature resistance and volume stability of the alloy.

[0041] From Figure 7 , Figure 8 and Figure 9 it can be seen that the primary silicon is thick and blocky, and the tip is easy to cut the matrix to become a crack source. The eutectic silicon is in a long strip shape, and the NiA1 3 phase becomes long needle-shaped, cutting the matrix and losing the strengthening effect, seriously affecting the alloy performance.

[0042] The foregoing description of the disclosed embodiments enables those skilled in the art to practice or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-silicon and high-nickel piston material, characterized in that: The components include the following by mass percentage (wt%): Si 18-23, Ni 3-5, Mg 0.6-1.5, Cu 0.8-1.4, Ti 0.1-0.2, Zr 0.1-0.2, Y 0.1-0.35, Er 0.1-0.2, P 0.015-0.025, Fe≤0.7, and the rest is Al.

2. A method for modifying a high-silicon and high-nickel piston material as claimed in claim 1, characterized in that: The steps are as follows: S1. Ingredients: prepare corresponding pre-melted materials according to the components and contents described in claim 1, the pre-melted materials including crystalline silicon, pure magnesium ingot, industrial high-purity aluminum ingot, electrolytic nickel, cathode copper, aluminum-titanium alloy and aluminum-zirconium alloy, aluminum-yttrium alloy, aluminum-erbium alloy, aluminum-silicon-phosphorus alloy; S2. Charging and melting: charging crystalline silicon, industrial high-purity aluminum ingots, electrolytic nickel, cathode copper, aluminum-titanium alloy and aluminum-zirconium alloy into a melting furnace for melting; S3, adding aluminum yttrium alloy, aluminum erbium alloy and pure magnesium ingot: when the temperature of the pressed aluminum melt drops to 800-850°C, add aluminum yttrium alloy, aluminum erbium alloy and pure magnesium ingot, and keep warm for 30-60 minutes; S4, slag removal: add 0.5-1wt% of the total weight of each furnace of slag removal agent to the surface of each furnace of aluminum liquid, use a slag scoop to turn over the slag on the liquid surface, and remove the slag on the surface of the aluminum liquid; S5, rotary refining and degassing: when the temperature of the aluminum melt drops to 780℃~820℃, add environmentally friendly refining agent to the aluminum melt, and start the degasser for rotary degassing; S6. Add aluminum-silicon-phosphorus alloy: When the temperature of aluminum melt is kept at 780℃~820℃, add aluminum-silicon-phosphorus alloy, and continue to degas for a period of time, then remove the slag on the surface of aluminum liquid, and let the aluminum melt stand for 5~10 minutes; S7, pouring: the sample mold is neatly placed on the mold frame, and the aluminum liquid obtained in step S6 is poured into the sample mold to obtain the sample; S8. Heat treatment: The obtained samples are subjected to casting solid solution strengthening and aging treatment.

3. The modification method of high silicon and high nickel piston material according to claim 2, characterized in that: The order of loading the pre-melted alloy in step S1 is: crystalline silicon → pure aluminum ingot → electrolytic nickel → cathode copper → aluminum-titanium alloy → aluminum-zirconium alloy, so that each added material is compacted without leaving obvious gaps.

4. The modification method of high silicon and high nickel piston material according to claim 2, characterized in that: In step S2, the melting furnace should be slowly heated after loading, kept at 550-600° C. for 60-80 minutes, and then heated to 810-870° C. for melting, and kept at this temperature for 1-2 hours.

5. The modification method of high silicon and high nickel piston material according to claim 2, characterized in that: In the step S5, the graphite rotor is ensured to be located at the center of the holding furnace during the degassing, the rotor speed is 425-482 rpm, and the compressed air flow rate is 0.6-0.8 m 3 / h, degassing 360-480s.

6. The modification method of high silicon and high nickel piston material according to claim 5, characterized in that: After the rotary degassing is completed in step S5, the rotor rises, and the vent holes of the rotor are immediately cleared with a tool, and the slag on the liquid surface is turned over with a slag scoop, and then the slag on the surface of the aluminum liquid is cleaned and kept warm for 20 to 40 minutes.

7. The modification method of high silicon and high nickel piston material according to claim 2, characterized in that: The degassing time in step S6 is 180-260 seconds, the rotor speed is 515-550 rpm, and the compressed air flow rate is 0.8-1.2 m 3 / h. After degassing, the rotor rises. Immediately use a tool to clear the rotor's vents. Use a slag scoop to turn over the slag on the liquid surface, and then clean the slag on the surface of the aluminum liquid.

8. The modification method of high silicon and high nickel piston material according to claim 2, characterized in that: In step S7, the pouring temperature is controlled within the range of 740-760° C., and the aluminum liquid is poured into the sample mold by using a hand-held ladle, and the pouring is slow and continuous. After the sample is completely solidified, the sample mold is flipped with tongs to demould the sample.

9. The modification method of high silicon and high nickel piston material according to claim 2, characterized in that: The solid solution strengthening process in step S8 includes primary solution treatment and secondary solution treatment. The heating temperature of the primary solution treatment is 475±10°C, and the holding time is 1 to 2 hours. The heating temperature of the secondary solution treatment is 515±10°C, and the holding time is 6 to 8 hours. The cooling method is water cooling.

10. The modification method of high silicon and high nickel piston material according to claim 9, characterized in that: The heating temperature of the aging treatment in step S8 is 185±10° C., the holding time is 4 to 6 hours, and the cooling method is air cooling.

Images