CN107267817B

CN107267817B - A kind of high-strength anti-fatigue in-situ nano-strengthened aluminum alloy and its die-casting method

Info

Publication number: CN107267817B
Application number: CN201710376448.7A
Authority: CN
Inventors: 赵玉涛; 怯喜周; 陈刚; 殷来大; 刘海; 陈飞; 吴斌
Original assignee: DANYANG RONGJIA PRECISION MACHINERY Co Ltd; Jiangsu University
Current assignee: DANYANG RONGJIA PRECISION MACHINERY Co Ltd; Jiangsu University
Priority date: 2017-05-25
Filing date: 2017-05-25
Publication date: 2019-04-19
Anticipated expiration: 2037-05-25
Also published as: WO2018214631A1; CN107267817A; CH714442B1

Abstract

The present invention relates to aluminum matrix composites, refer in particular to the high-strength antifatigue in-situ nano reinforced aluminium alloy of one kind and its pressure casting method.By in-situ nano reinforcing and alloy elements regulation, and the non-linear high pressure die casting technique of optimization is combined to obtain die casting.By in-situ nano ZrB₂Reinforcement and nanometer Al₃Scale effect, interfacial effect, the heterogeneous forming core effect of Er precipitated phase, significantly improve intensity, anti-fatigue performance and the damping capacity of alloy；At the same time, Mg, Zn and Fe constituent content are improved, and introduces Mn and Ni element, while improving hardening constituent content, obtaining high-intensitive, refine the harmful coarse precipitated phase such as Al-Fe effectively and circle change, and ensure the good die casting performance of alloy；Thus the characteristics of showing high-strength plasticity, high antifatigue, high damping properties and good die casting performance using alloy of the present invention and its pressure casting method component produced.

Description

The high-strength antifatigue in-situ nano reinforced aluminium alloy of one kind and its pressure casting method

Technical field

The present invention relates to aluminum matrix composites, refer in particular to the high-strength antifatigue in-situ nano reinforced aluminium alloy of one kind and its die casting side Method.

Background technique

With the development of economy and society, automobile has progressed into common people house, becomes the indispensability of people's trip life Tool.China Association for Automobile Manufacturers's statistics display, Chinese Brand passenger car sells 1052.86 ten thousand altogether within 2016, increases by a year-on-year basis 20.50%.Heart of the engine as automobile, high efficiency, low cost and the high-performance of critical component production have become major The core of automobile vendor's promotion product competitiveness.

High-pressure casting is gradually replaced with its high production efficiency, good economy performance, the advantage that casting accuracy is high, surface smoothness is good For high-cost low pressure, gravitational casting, become the automobile engines such as aluminium engine cylinder body, oil pump case, cushioning members key The main manufacture of components.However, high-pressure casting is since liquid Metal Filling type chamber speed is high, fluidised form is unstable, is produced Casting be easy to generate stomata, cannot be heat-treated, leading to precipitated phase in casting is usually in coarse needle-shaped or laminated structure, reinforcing Effect is unobvious, is easy to generate stress concentration, keeps its strong plasticity, anti-fatigue performance relatively low.To make high pressure die castings be difficult to Full substitution low pressure casting, gravitational casting part, are especially dfficult to apply to middle-to-high end car engine with high performance requirements.

Summary of the invention

The object of the invention is that inclined for the existing die casting strong plasticity of typical aluminium alloy AlSi9Cu3, anti-fatigue performance It is low, it is not able to satisfy the deficiency of high-performance enginer component high-intensitive, antifatigue, high-damping technical requirements to it especially, leads to It crosses alloy elements regulation and in-situ nano is strengthened, and combine the non-linear pressure injection casting processes of optimization, improving alloy precipitated phase Content, circle are changed and are refined simultaneously, realize that transgranular and crystal boundary in-situ nano ceramic phase reinforcement is strengthened, significantly improve die cast product Strong plasticity, fatigue resistance and damping capacity.

Using the automobile engine shock bracket of the technology of the present invention production and the tensile strength of shell up to 352MPa, bend It takes intensity and reaches 285MPa, elongation percentage is up to 10.6%.Final products carry out durability test through Special-purpose bench, minimum circulation time Number has reached 1,000,000 times, much higher than 500,000 times of customer requirement, has reached germany volkswagen (shock bracket) DIN EN1706- 1998 standards and Japan's Mazda (shock-absorbing casing) MES MM 621-ADC12 standard, while having also exceeded using low pressure casting Shock bracket performance (the tensile strength 300MPa, yield strength 210MPa, elongation percentage of (after solid solution+aging strengthening model) production 7.5%).

A kind of die casting in-situ nano reinforced aluminium alloy and its die casting that high-strength antifatigue and damping capacity is good of the invention Method is strengthened by alloy elements regulation and in-situ nano, and the non-linear high pressure die casting of optimization is combined to obtain transgranular and crystal boundary Include a large amount of and finely dispersed nanometer ZrB₂Ceramic phase reinforcement, transgranular includes nanometer Al₃Er precipitated phase, including common reciever, Mg2Si phase, alloy precipitated phase including Al2Cu phase and phase containing Fe is tiny, circle die casting.By nanometer reinforcement and nanometer The Al that the Er element of the dispersion-strengtherning of precipitated phase, interfacial damping effect and low solid solubility is generated in alloy melt₃Er phase crystal grain Refining effect significantly improves the strong plasticity of alloy components, antifatigue and damping capacity；At the same time, Mg, Zn and Fe constituent content Raising and Mn and Ni element introduce, while ensureing good die casting performance, improving alloy strengthening phase content, make Al-Fe Equal alloy strengthenings mutually change by effectively refinement and circle；To make alloy of the present invention component produced show high-strength plasticity, highly resistance The characteristics of fatigability and excellent damping performance.

Preparation method of the invention the following steps are included:

(1) AlSi9Cu3 alloy melting to 750-780 DEG C and alloy melting: is kept the temperature into 10min.The AlSi9Cu3 is closed Gold is commercial alloy, the element mass percent of specific chemical composition are as follows: Si 8.0~11.0, Cu 2.0~3.5, Zn 1.0 ~1.5, Mg 0.3~0.5, Fe≤0.8, Mn 0.1~0.5, surplus Al.

(2) fabricated in situ nanometer ZrB₂Nano ceramics reinforcement: it is molten that step (1) is added in Al-Zr and Al-B intermediate alloy It refines and in the melt that keeps the temperature and is brought rapidly up to 840-860 DEG C, while using graphite stirring rotator agitation melt to promote alloy Be sufficiently mixed, soaking time 10-15min keeps Zr in alloy and B element in situ anti-under the driving force that free energy reduces A nanometer ZrB should be synthesized₂Then ceramic phase reinforcement is cooled to 730-750 DEG C and keeps the temperature.So that zirconium boron element in step (2) alloy Mass percent reach Zr:3.0-5.0, B:0.5-1.0.

(3) Er and Ni element is introduced, the content of Fe and Mn element in alloy is adjusted and refines degasification: by Al-Er, Al-Fe Be added in step (2) compounding flux obtained with Al-Mn intermediate alloy and pure Ni, and use graphite stirring rotator to stir with Promote being sufficiently mixed for alloy, the insulated and stirred time is 10-15min；Then the powdered composite refining by granularity less than 500 μm Agent is blown into melt with inert gas by the hollow channel of graphite rotator, carries out refining degasification to melt, to remove alloy height The hydrogen dissolved in the slag inclusion and melt generated in warm melting and reaction process, refining temperature are 730-750 DEG C, refine soaking time For 25-30min.Finally erbium ferro-nickel element content in step (3) alloy is made to reach Er:0.1-0.15, Fe:1.0~1.5, Mn: 0.5~1.0, Ni 0.5~1.0.

(4) Mg is adjusted, the content of Zn element: the melt that step (3) obtain is cooled to 660-700 DEG C and is kept the temperature, then By pure Mg and pure Zn using in the melt after bell jar indentation refining degasification, start graphite stirring rotator, and mix slowly, heat preservation is stirred > 15min is mixed the time, so that Mg, Zn dissolve in alloy and avoid melt air-breathing, and reaches magnesium Zn-ef ficiency content in step (4) alloy To Mg:0.5~1.0, Zn:1.5~2.5.

(5) non-linear high pressure die casting: in the insulated bag for the compounding flux merging die casting machine that step (4) are obtained, use is excellent The non-linear die-casting process changed carries out die casting and obtains nano crystalline compounding die casting, and wherein injection speed is parabolic from small to large Wire type injection slowly fills type 2.5-3m/s early period to realize, final instants high speed fills the non-linear of type and fills type (maximum injection speed Reach 40-50m/s, die casting pressure reaches 100-150MPa).

(6) ageing treatment: the die casting that step (5) are obtained carries out ageing treatment (natrual ageing or artificial aging), with Obtain the good in-situ nano reinforced aluminium alloy die casting of high-strength antifatigue and damping capacity.

Al-Zr, Al-B, Al-Er, Al-Fe and Al-Mn intermediate alloy, during preferred alloy constituent content is high Between alloy, such as Al-10Zr, Al-10B, Al-20Er, Al-20Fe and Al-10Mn.

The fabricated in situ nanometer ZrB₂Nano ceramics reinforcement refers to and utilizes ZrB in the multi-element alloy system₂Ji Buss free energy is low, and Zr has thermodynamics-kinetic characteristics of low solubility and low thermal diffusivity coefficient in Al, in the alloy Introduce Zr, after B element, in the melt fabricated in situ nanoscale ZrB₂Ceramic particle, having a size of 20-80nm, content is to close The 2-6wt.% of golden amount, synthesis temperature are 840-860 DEG C.To in alloy melt process of setting: on the one hand, in-situ nano ZrB₂Ceramic particle can be used as the nucleation rate that heterogeneous forming core core improves alloy, refine crystal grain, and finally comprising being scattered in alloy Intra-die significantly improves intensity, the anti-fatigue performance of alloy；On the other hand, do not become the nanometer ZrB of forming core core₂Ceramics Particle can be scattered in crystal boundary during crystal grain is grown up, and effectively pin crystal boundary and can hinder the migration of crystal boundary, it is strong to improve alloy While spending, performance interfacial damping effect is maximized, improves the damping capacity of alloy.

Introducing Er and the Ni element adjusts the content of Fe and Mn element in alloy and refines degasification, refers in alloy The Er of the 0.1-0.15wt.% of middle introducing, it is molten in alloy on the one hand by solubility (0.1wt.%) Er low in aluminium solution Al is precipitated in body₃The heterogeneous forming core core of Er improves the nucleation rate of aluminium, on the other hand refining alloy is solid-solution in Er element in alloy, Can in alloy aging it is transgranular be precipitated it is tiny and with the good L1 of aluminum substrate Lattice Matching₂Type nanometer Al₃Er precipitated phase, significantly Improve the aging strength and anti-fatigue performance of alloy pressuring casting；The purpose for increasing the content of Fe element in the alloy is to improve alloy Middle Fe precipitated phase content further increases the anti-stick mould performance of alloy, alloy precipitated phase is avoided to contain while improving alloy strength It measures and increases, expands demoulding hardly possible and considerable sticking problems caused by system's reduction, introduce Ni element and the purpose for improving Mn constituent content is logical β-Fe the phase transition of gill shape in Ni, Mn and alloy is crossed into blocky or Chinese character shape α-Al (Mn, Fe) Si and α-Al (Ni, Fe) Si Phase avoids the raising of Fe content from generating a large amount of acicular beta-Fe and mutually drops low-alloyed plasticity and toughness.

The content of adjustment Mg, the Zn element, is the content for further increasing precipitated phase in alloy, strong to improve alloy Degree, anti-fatigue performance, and by the damping capacity of increased phase boundary raising alloy.

The non-linear high pressure die casting technique refers to the novel die casting machine controlled using die-cast rotor housing speed-programmable, And optimize its acquisition non-linear high pressure die casting technique, with from avoid in melt cavity filling process turbulent flow and volume gas, be conducive to type chamber The discharge of middle gas and the infiltration and dispersion for promoting nanometer reinforcement under the instantaneous high speed and high pressure full of type chamber, to obtain tissue Defect is few, function admirable die-cast product.Wherein injection speed is parabolic injection from small to large, to realize that early period is slow Fill type 2.5-3m/s, final instants high speed fills the non-linear of type and fills type (maximum injection speed reaches 40-50m/s, and die casting pressure reaches To 100-150MPa).

Detailed description of the invention

Fig. 1 (a) is routine AlSi9Cu3 die casting metallographic structure figure, is (b) prepared by the present invention high-strength antifatigue and resistance The good in-situ nano reinforced aluminium alloy shock bracket die casting metallographic structure figure of damping properties, can be seen that from two metallographic structure figures It is disappeared using precipitated phase needle-shaped in die casting prepared by this patent, is converted into the circle precipitated phase of graininess or short-movie shape, mentions The high disperse degree of precipitated phase, conducive to the raising of workpiece strong plasticity and fatigue behaviour.

The good in-situ nano reinforced aluminium alloy shock bracket die casting of Fig. 2 high-strength antifatigue and damping capacity prepared by the present invention Part TEM organization chart, it can be seen from the figure that in-situ nano existing for transgranular and crystal boundary using die casting prepared by this patent ZrB₂Ceramic enhancement phase and more fine uniform nanometer Al₃Er nanometer precipitated phase is conducive to the strong plasticity of workpiece, anti-fatigue performance and resistance The comprehensive of damping properties is improved.

Specific embodiment

Further describe below in conjunction with attached drawing to embodiment of the present invention: following embodiment is being with technical solution of the present invention Under the premise of implemented, the detailed implementation method and specific operation process are given, but protection scope of the present invention is not limited to Following embodiments.

Embodiment 1

With Al-10Zr, Al-10B, Al-20Er, Al-20Fe, Al-10Mn intermediate alloy and pure Ni, pure Mg, pure Zn, and AlSi9Cu3 is raw material, prepares automobile engine shock bracket using the non-linear high pressure die casting technology of optimization.

The 500Kg commercialization AlSi9Cu3 alloy (760 DEG C) of melting is transferred in moderate soak furnace, then by Al-10Zr and Al-10B intermediate alloy is added in holding furnace and is warming up to 850 DEG C, while using graphite stirring rotator agitation melt to promote to close Gold is sufficiently mixed, then alloy is cooled to 750 DEG C and kept the temperature by soaking time 15min；By Al-20Er, Al-20Fe and Al-10Mn and pure Ni is added in melt, and the powdered composite refiner after stirring heat preservation 15min by partial size less than 500 μm is used Inert gas is blown into melt by the hollow channel of graphite rotator, carries out refining degasification to melt, molten to remove alloy high-temp The hydrogen dissolved in the slag inclusion and melt generated in refining and reaction process, refining time 30min, temperature are maintained at 750 DEG C, refining It is cooled to 680 DEG C after degasification and pure Mg and pure Zn bell jar is pressed into the melt after refining degasification, starting graphite stirring Rotor, and mix slowly, insulated and stirred time 18min makes the alloy ultimate constituent reach Si 9.5, Cu 3, Zr 3.5, B 0.75, Zn 1.5, Mg 0.8, Fe 1.3, Mn 1.0, Ni 0.7, Er 0.12, surplus Al, finally by the compounding flux of acquisition Shock bracket is prepared with the non-linear high pressure die casting technique of optimization, mid-early stage is that 3m/s slowly fills type, to realize that advection fills type And be conducive to gas in mold cavity and be smoothly discharged, it is full of the moment of (riser underfill) to type chamber, improves injection speed extremely 40m/s, and pressure is being kept to obtain die casting shock bracket to 100MPa, dwell time 15s.

The die-casting blank of dead head and overlap will be cut off, is put into heat-treatment furnace and carries out artificial aging, the 300 of aging temp DEG C, aging time is 8 hours.

Sampling analysis shows that the hardness of shock bracket is greater than 97HBS, and tensile strength has reached 352MPa, and yield strength reaches 285MPa is arrived, elongation percentage 10.6%, the repeated tension and compression test service life is greater than 2 × 10 under 7.6kN load⁶It is secondary, final products Durability test is carried out through Special-purpose bench, minimum cycle-index has reached 1,000,000 times, is much higher than customer requirement 500,000 times.Product Reach germany volkswagen (shock bracket) DIN EN1706-1998 standard and Japan Mazda (shock-absorbing casing) MES MM 621- ADC12 standard.It, can be with from figure as shown in Figure 1 b for using the metallographic structure figure of shock bracket prepared by the present embodiment technique Find out and compare routine AlSi9Cu3 die casting, the needle-shaped precipitated phase in die casting prepared by this patent disappears, and is converted into particle The circle of shape or short-movie shape precipitated phase, improves the disperse degree of precipitated phase, conducive to the raising of workpiece strong plasticity and fatigue behaviour. Fig. 2 is shock bracket die casting TEM organization chart prepared by the present embodiment technique, it can be seen from the figure that made using this patent There are a large amount of in-situ nano ZrB for the transgranular and crystal boundary of standby die casting₂Ceramic enhancement phase and more fine uniform nanometer Al₃Er Nanometer precipitated phase, comprehensive conducive to the strong plasticity of workpiece, anti-fatigue performance and damping capacity are improved.

Embodiment 2

With Al-10Zr, Al-5B, Al-10Er, Al-10Fe, Al-10Mn intermediate alloy and pure Ni, pure Mg, pure Zn, and AlSi9Cu3 is raw material, prepares automobile engine shock-absorbing casing (shell structure using the non-linear high pressure die casting technology of optimization Complexity fills type and discharge gas difficulty is high, usually reduces Mg content, improves die casting pressure, improves die casting performance and yield rate).

The 500Kg commercialization AlSi9Cu3 alloy (750 DEG C) of melting is transferred in moderate soak furnace, then by Al-10Zr and Al-5B intermediate alloy is added in holding furnace and is warming up to 840 DEG C, while using graphite stirring rotator agitation melt to promote alloy Be sufficiently mixed, then alloy is cooled to 740 DEG C and kept the temperature by soaking time 10min；By Al-10Er, Al-10Fe and Al- 10Mn and pure Ni is added in melt, the powdered composite refiner inertia after stirring heat preservation 10min by partial size less than 500 μm Gas is blown into melt by the hollow channel of graphite rotator, carries out refining degasification to melt, with remove alloy high-temp melting and The hydrogen dissolved in the slag inclusion and melt generated in reaction process, refining time 25min, temperature are maintained at 740 DEG C, refine degasification After be cooled to 660 DEG C and by pure Mg and pure Zn with bell jar be pressed into refining degasification after melt in, start graphite stirring rotator, And mix slowly, insulated and stirred time 20min makes the alloy ultimate constituent reach Si 11, Cu 3.5, Zr 5.0, B 1.0, Zn 2.0, Mg 0.5, Fe 1.5, Mn 1.0, Ni 0.5, Er 0.15, surplus Al, finally by the compounding flux of acquisition to optimize Non-linear high pressure die casting technique prepares shock-absorbing casing, and mid-early stage is that 5m/s slowly fills type, to realize that advection fills type and conducive to mould Gas is smoothly discharged in tool type chamber, and the moment of (riser underfill) is full of to type chamber, improves injection speed to 50m/s, and It keeps pressure to 150MPa, time 15s, obtains die casting shock-absorbing casing.

The die-casting blank of dead head and overlap will be cut off, is put into heat-treatment furnace and carries out artificial aging, the 250 of aging temp DEG C, aging time is 10 hours.

Sampling analysis shows that the hardness of shock bracket is greater than 92HBS, and tensile strength has reached 315MPa, and yield strength reaches 243MPa is arrived, elongation percentage 8.9%, the repeated tension and compression test service life is greater than 1.5 × 10 under 7.6kN load⁶It is secondary, final products Durability test is carried out through Special-purpose bench, minimum cycle-index has reached 1,000,000 times, is much higher than customer requirement 500,000 times.

Embodiment 3

With Al-10Zr, Al-5B, Al-20Er, Al-20Fe, Al-5Mn intermediate alloy and pure NIi, pure Mg, pure Zn, and AlSi9Cu3 is raw material, prepares automobile engine oil pump case using the non-linear high pressure die casting technology of optimization.

The 500Kg commercialization AlSi9Cu3 alloy (780 DEG C) of melting is transferred in moderate soak furnace, then by Al-10Zr and Al-5B intermediate alloy is added in holding furnace and is warming up to 860 DEG C, while using graphite stirring rotator agitation melt to promote alloy Be sufficiently mixed, then alloy is cooled to 750 DEG C and kept the temperature by soaking time 15min；By Al-20Er, Al-20Fe and Al- 50Mn and pure Ni is added in melt, and ultra-fine powdered refining agent inert gas is passed through graphite after stirring heat preservation 10min The hollow channel of rotor is blown into melt, is carried out refining degasification to melt, is produced with removing in alloy high-temp melting and reaction process The hydrogen dissolved in raw slag inclusion and melt, refining time 30min, temperature are maintained at 750 DEG C, are cooled to after refining degasification 680 DEG C and pure Mg and pure Zn bell jar is pressed into the melt after refining degasification, starts graphite stirring rotator, and mix slowly, Insulated and stirred time 20min makes the alloy ultimate constituent reach Si 11, Cu 2.5, Zr 5.0, B 1.0, Zn 2.5, Mg 1.0, Fe 1.5, Mn 1.0, Ni 1.0, Er 0.1, surplus Al, the finally non-linear high pressure pressure by the compounding flux of acquisition to optimize Casting process prepares oil pump case, and mid-early stage is that 4m/s slowly fills type, to realize that advection fills type and conducive to gas in mold cavity Be smoothly discharged, the moment of (riser underfill) is full of to type chamber, improves injection speed to 50m/s, and is keeping pressure extremely 130MPa, time 15s obtain die casting oil pump case.

The die-casting blank of dead head and overlap will be cut off, is put into heat-treatment furnace and carries out artificial aging, the 220 of aging temp DEG C, aging time is 15 hours.

Sampling analysis shows that the hardness of shock bracket is greater than 93HBS, and tensile strength has reached 330MPa, and yield strength reaches 250MPa is arrived, elongation percentage 7.8%, the repeated tension and compression test service life is greater than 1.2 × 10 under 7.6kN load⁶It is secondary, final products Durability test is carried out through Special-purpose bench, minimum cycle-index has reached 1,000,000 times, is much higher than customer requirement 500,000 times.

Compare embodiment

Comparative example 1

Using AlSi9Cu3 alloy as raw material, automobile engine damping is prepared using the non-linear high pressure die casting technology of optimization Bracket.

By (700 DEG C) of 500Kg commercialization AlSi9Cu3 alloy of the melting non-linear high pressure die casting technology preparations using optimization Automobile engine shock bracket, and to excision dead head and overlap die-casting blank carry out artificial aging, the 300 of aging temp DEG C, aging time is 8 hours.

Sampling analysis shows that the hardness of shock bracket is greater than 82HBS, and tensile strength has reached 285MPa, and yield strength reaches 193MPa is arrived, elongation percentage 6.4%, the repeated tension and compression test service life is greater than 1 × 10 under 7.6kN load⁶It is secondary.

Comparative example 2

With Al-10Zr, Al-10B, Al-20Er, Al-20Fe, Al-10Mn intermediate alloy and pure Ni, pure Mg, pure Zn, and AlSi9Cu3 is raw material, prepares automobile engine shock bracket using conventional die-casting technique.

Fabricated in situ nanometer ZrB₂Reinforcement and alloy elements regulation are same as Example 1, and will obtain temperature is 680 DEG C, Ingredient be Si 9.5, Cu 3, Zr 3.5, B 0.75, Zn 1.5, Mg 0.8, Fe 1.3, Mn 1.0, Ni 0.7, Er 0.12, it is remaining Amount is the alloy melt of Al, obtains die casting shock bracket using conventional die-casting process.

Ageing treatment is carried out to die casting using the identical aging technique of embodiment 1.

Sampling analysis shows that the hardness of shock bracket is greater than 93HBS, and tensile strength has reached 335MPa, and yield strength reaches 263MPa is arrived, elongation percentage 9.2%, the repeated tension and compression test service life is greater than 1.8 × 10 under 7.6kN load⁶It is secondary.

Claims

1. A high-strength anti-fatigue in-situ nano-strengthened aluminum alloy is characterized in that: through alloy composition regulation and in-situ nano-strengthening, and in combination with optimized nonlinear high-pressure die-casting to obtain intragranular and grain boundaries containing a large amount of and uniformly dispersed nano ZrB _2. Ceramic reinforcement, containing nano-Al ₃ Er precipitation phase in the crystal, and die-casting parts with small and round precipitation phases including eutectic Si phase, Mg2Si phase, Al2Cu phase and Fe-containing phase; its specific chemical composition is The element mass percentages are: Si 8.0-11.0, Cu2.0-3.5, Zr 3.0-5.0, B 0.5-1.0, Zn 1.5-2.5, Mg 0.5-1.0, Fe 1.0-1.5, Mn 0.5-1.0, Ni 0.5-1.0 , Er 0.1-0.15, the remainder is Al; with the aid of the dispersion strengthening of nano-reinforcement and nano-precipitate phase, the interface damping effect and the grain refinement of Al ₃ Er phase produced by Er element with low solid solubility in the alloy melt, Significantly improve the strong plasticity, fatigue resistance and damping properties of alloy components; at the same time, the increase in the content of Mg, Zn and Fe elements, as well as the introduction of Mn and Ni elements, while ensuring good die casting properties and increasing the content of alloy strengthening phase, make Al-Fe and other alloy strengthening phases are effectively refined and rounded; thus, the strong plasticity, fatigue resistance and damping performance are synergistically improved.

2. The die-casting method of high-strength anti-fatigue in-situ nano-strengthened aluminum alloy as claimed in claim 1, characterized in that the specific steps are as follows:

(1) Alloy smelting: Melt the AlSi9Cu3 alloy to 750-780°C and keep it warm; the AlSi9Cu3 alloy is a commercial alloy, and the element mass percentage of its specific chemical composition is: Si 8.0～11.0, Cu 2.0～3.5, Zn 1.0～ 1.5, Mg0.3～0.5, Fe≤0.8, Mn 0.1～0.5, the balance is Al;

(2) In-situ synthesis of nano-ZrB ₂ nano-ceramic reinforcements: Al-Zr and Al-B master alloys are added to the melt smelted and held in step (1) and rapidly heated to 840-860 °C, while a graphite stirring rotor is used Stir the melt to promote the full mixing of the alloy, the holding time is 10-15min, so that the Zr and B elements in the alloy react in situ to synthesize the nano- _ZrB ceramic reinforcement under the driving force of reduced free energy, and then cool down to 730-750 ℃ and heat preservation, so that the mass percentage of zirconium and boron elements in the alloy in step (2) reaches Zr: 3.0-5.0, B: 0.5-1.0;

(3) Introducing Er and Ni elements, adjusting the content of Fe and Mn elements in the alloy and refining and degassing: Al-Er, Al-Fe and Al-Mn master alloys and pure Ni are added to the composite melt obtained in step (2). Then, the powder composite refining agent with a particle size of less than 500 μm is blown into the melt through the hollow channel of the graphite rotor with an inert gas, The melt is refined and degassed to remove slag inclusions and hydrogen dissolved in the melt produced during high-temperature smelting and reaction of the alloy. 3) The content of erbium, nickel and iron in the alloy reaches Er: 0.1-0.15, Fe: 1.0-1.5, Mn: 0.5-1.0, Ni 0.5-1.0;

(4) adjust Mg, the content of Zn elements: the melt obtained in step (3) is cooled to 660-700 ℃ and kept warm, then pure Mg and pure Zn are pressed into the melt after refining and degassing by using a bell jar, Start the graphite stirring rotor, stir at a slow speed, and keep stirring for more than 15 minutes, so that Mg and Zn are dissolved into the alloy and avoid melt inhalation, and the content of magnesium and zinc elements in the alloy in step (4) reaches Mg: 0.5-1.0, Zn: 1.5～2.5;

(5) Nonlinear high pressure die casting: Put the composite melt obtained in step (4) into the heat preservation bag of the die casting machine, and use the optimized nonlinear die casting process for die casting to obtain nanocomposite reinforced die castings, where the injection speed is from small to Large parabolic injection; the nonlinear high-pressure die-casting process refers to the use of a die-casting machine with programmable control of the speed of the die-casting cylinder, and the nonlinear high-pressure die-casting process obtained by optimizing it to avoid the melt filling process. The turbulent flow and air entrainment are favorable for the discharge of the gas in the cavity, and the infiltration and dispersion of the nano-reinforcement are promoted under the instantaneous high speed and high pressure filling the cavity, so as to obtain a die-casting product with few structural defects and excellent performance; the injection speed For parabolic injection from small to large, to achieve slow filling 2.5-3m/s in the early stage, and non-linear filling of instant high-speed filling at the end, the maximum injection speed reaches 40-50m/s, and the die-casting pressure reaches 100-150MPa ;

(6) Aging treatment: the die-casting obtained in step (5) is subjected to aging treatment to obtain an in-situ nano-strengthened aluminum alloy die-casting with high strength, fatigue resistance and good damping performance.

3. The die-casting method of high-strength anti-fatigue in-situ nano-strengthened aluminum alloy as claimed in claim 2, wherein the Al-Zr, Al-B, Al-Er, Al-Fe and Al-Mn For the master alloy, select the master alloy with high content of alloying elements, specifically Al-10Zr, Al-10B, Al-20Er, Al-20Fe and Al-10Mn.

4. The die-casting method for high-strength and fatigue-resistant in-situ nano-strengthened aluminum alloys as claimed in claim 2, wherein the in-situ synthesis of nano- _ZrB nano-ceramic reinforcements refers to using the multi-component alloy system in The Gibbs free energy of ZrB ₂ is low, and Zr has the thermodynamic-kinetic properties of low solubility and low thermal diffusivity in Al. After introducing Zr and B elements into the alloy, nano-scale ZrB ₂ was synthesized in situ in the melt. Ceramic particles, the size of which is 20-80 nm, the content is 2-6 wt.% of the alloy mass, and the synthesis temperature is 840-860 °C; thus during the solidification process of the alloy melt: on the one hand, the in-situ nano- _ZrB ceramic particles can be used as The heterogeneous nucleation core improves the nucleation rate of the alloy, refines the grains, and finally contains and disperses inside the alloy grains, which significantly improves the strength and fatigue resistance of the alloy; on the other hand, the nano-ZrB ₂ that does not become the nucleation core The ceramic particles will be dispersed in the grain boundary during the grain growth process, which can effectively pin the grain boundary and hinder the migration of the grain boundary, improve the strength of the alloy, maximize the interface damping effect, and improve the damping performance of the alloy.

5. The die-casting method of high-strength anti-fatigue in-situ nano-strengthened aluminum alloy as claimed in claim 2, characterized in that, by introducing Er and Ni elements, adjusting the content of Fe and Mn elements in the alloy and refining and degassing , refers to the introduction of 0.1-0.15wt.% Er into the alloy. On the one hand, with the help of the low solubility of Er in the aluminum solution, Al ₃ Er heterogeneous nucleation core is precipitated in the alloy melt to improve the nucleation rate of aluminum, Refining the alloy, on the other hand, the Er element dissolved in the alloy will precipitate a fine L1 ₂ type nano-Al ₃ Er precipitation phase that is well matched with the aluminum matrix lattice during the aging of the alloy, which significantly improves the alloy die casting. Ageing strength and fatigue resistance.

6. The die-casting method of high-strength fatigue-resistant in-situ nano-strengthened aluminum alloy as claimed in claim 2, characterized in that, increasing the content of Fe element in the alloy is used to increase the content of Fe precipitation in the alloy and improve the strength of the alloy At the same time, it further improves the anti-sticking properties of the alloy, and avoids the difficulty of demolding and the problem of sticking caused by the increase of the alloy precipitation phase and the reduction of the expansion system; the purpose of introducing Ni element and increasing the content of Mn element is to pass Ni, Mn and alloy. The needle-shaped β-Fe phase is transformed into the block or Chinese character-shaped α-Al(Mn,Fe)Si and α-Al(Ni,Fe)Si phases, avoiding the increase of Fe content to produce a large amount of needle-shaped β-Fe Phase reduces the plastic toughness of the alloy; the adjustment of the content of Mg and Zn elements is to further increase the content of the precipitation phase in the alloy to improve the strength and fatigue resistance of the alloy, and improve the damping performance of the alloy by means of the increased phase boundary.