High-silicon high-magnesium aluminum alloy and preparation method thereof

Abstract

The invention discloses a high-silicon high-magnesium aluminum alloy and a preparation method thereof, relates to the field of nonferrous metal materials and processing thereof, and effectively improves the microstructure of the alloy by utilizing the interaction among alloy elements and adding a composite alterant. The heat-treatment-free high-silicon and high-magnesium aluminum alloy which is more excellent in performance, different from existing traditional Al-Mg series (high-magnesium and low-silicon) and Al-Si series (high-silicon and low-magnesium) aluminum alloys and suitable for die casting is prepared. Compared with the prior art, the alloy has good casting performance and good obdurability at the same time, the requirement for aluminum alloy performance in the automobile lightweight field can be met, and production of large complex thin-wall integrated die-casting aluminum alloy castings can be achieved.

Description

Technical Field

[0001] The present invention relates to the field of non-ferrous metal materials and their processing, and specifically relates to a high-silicon and high-magnesium aluminum alloy and a preparation method thereof. Background Art

[0002] Aluminum alloy is one of the most widely used structural materials in the field of automotive lightweighting. With the rapid development of new energy vehicles, the requirements for automotive lightweighting are also getting higher and higher. Integral die-casting of large automotive body components can significantly reduce the weight of the vehicle. However, during the subsequent heat treatment strengthening process, large castings are prone to deformation, bulging and other phenomena, which directly affect the mechanical properties of the castings and reduce the yield rate.

[0003] Currently, the castings for large integral die-casting in the automotive field often have a small wall thickness, and have high requirements for the casting performance of the alloy. Al-Si series alloys have incomparable advantages in this field. Although this series of aluminum alloys have excellent casting performance, their strength is relatively poor. For example, the heat-treatable Silafont 36 alloy reported abroad, namely AlSi10MnMg aluminum alloy (patent publication number: US6364970B1), is widely used in the field of automotive lightweighting. It can obtain excellent mechanical properties through heat treatment processes such as solution aging. However, its plasticity is relatively poor, and it is prone to deformation and bulging during the heat treatment process, directly affecting subsequent applications. A large amount of research work has also been carried out in the domestic field of heat-treatment-free die-casting aluminum alloys. CN 115198149B discloses a heat-treatment-free die-casting aluminum alloy and a preparation method thereof. The die-casting aluminum alloy includes the following elemental components by mass percentage: Si 6.0%-7.5%, Mg 0.13%-0.38%, Fe <0.20%, Ti 0.01%-0.15%, Sc 0.005%-0.01%, Mn 0.08%-0.5%, Cr 0.05%-0.15%, V 0.05%-0.15%, Zr 0.05%-0.15%, Cu <0.01%; the balance is Al and inevitable impurity elements, where the content of a single impurity is not more than 0.05%, and the total impurity content is not more than 0.2%. This heat-treatment-free die-casting aluminum alloy can achieve yield strength, tensile strength, and elongation at break of 142.5-168.3 MPa, 266.7-280.2 MPa, and 15.7-18.4% respectively without heat treatment by controlling the content of Cu in the components, adding a small amount of Sc and Zr, and optimizing other components on this basis. However, its yield strength and tensile strength are still relatively low and need to be further improved.

[0004] Al-Mg alloys can significantly reduce the alloy density and are highly favored in fields such as aerospace where weight requirements are extremely strict. Moreover, high-magnesium aluminum alloys also have good corrosion resistance, etc. However, they also have relatively poor casting properties and are prone to defects such as shrinkage cavities and porosity.

[0005] Although high-silicon aluminum alloys and high-magnesium aluminum alloys have their respective advantages, there are few studies in the existing technology that can perfectly combine the two. This is because silicon and magnesium interact with each other in aluminum alloys. Increasing the magnesium content in high-silicon aluminum alloys easily forms excessive intermetallic compounds such as Mg2Si phases. The large formation of these phases will cause the alloy structure to be coarse and unevenly distributed, not only unable to effectively improve the alloy properties, but on the contrary, will reduce the strength, toughness, etc. of the alloy, deteriorating the processing performance and service performance of the alloy. Therefore, the present invention provides a high-silicon high-magnesium aluminum alloy and its preparation method, effectively solving the above technical problems and strongly promoting the rapid development of the automotive lightweight field. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a high-silicon high-magnesium aluminum alloy and its preparation method.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] <First aspect>

[0009] The present invention provides a high-silicon high-magnesium aluminum alloy. By mass percentage, the components are: 9.5 - 12.0% of Si, 4.0 - 6.0% of Mg, 0.4 - 0.8% of Mn, 0.1 - 0.2% of Ti, 0.1 - 0.2% of RE, 0.02 - 0.04% of B, 0.01 - 0.03% of Sr. The RE element is selected from one or more of La, Ce, Pr, Nd, Sm, Gd, Yb, and Y. The impurities do not exceed 0.5%, and the balance is Al.

[0010] As an embodiment, the RE element is one or a combination of two of La, Ce, Pr, and Nd.

[0011] As an embodiment, the RE element is a combination of elements composed of one or more of the light rare earths La, Ce, Pr, Nd and one or more of the medium-heavy rare earths Sm, Gd, Yb, and Y.

[0012] As an embodiment, the RE element is a combination of elements composed of one or more of the light rare earths La, Ce, Pr, Nd and one or more of the medium-heavy rare earths Gd, Yb, and Y.

[0013] As an embodiment, the mass ratio of the light rare earth and the medium-heavy rare earth in the RE element is (1 - 2):1.

[0014] As an embodiment, the mass percentage of Mg is 4-6%.

[0015] As an embodiment, the mass percentage of Si is 11-12%.

[0016] As an embodiment, the mass percentage of Mn is 0.5-0.8%.

[0017] As an embodiment, the high-silicon high-magnesium aluminum alloy, by mass percentage, has the following composition: 11-12% Si, 4-6% Mg, 0.5-0.8% Mn, 0.1-0.2% Ti, 0.02-0.04% B, 0.01-0.03% Sr, 0.05-0.1% light rare earths, 0.05-0.1% medium and heavy rare earths, impurities not exceeding 0.5%, and the balance being Al.

[0018] As an embodiment, the mass ratio of B and RE elements is 1:5.

[0019] As an embodiment, the mass ratio of Ti, B and RE elements is 5:1:5.

[0020] As an embodiment, the content of impurity Fe in the high-silicon high-magnesium aluminum alloy does not exceed 0.2 wt.%.

[0021] <Second aspect>

[0022] The present invention provides a method for preparing the above-mentioned high-silicon high-magnesium aluminum alloy, comprising the following steps:

[0023] S1. Raw material preheating: The involved raw materials are preheated respectively to obtain various corresponding preheated materials. The raw materials include four groups. The first group of raw materials is pure aluminum, the second group of raw materials is aluminum-silicon master alloy and aluminum-manganese master alloy, the third group of raw materials is pure Mg, and the fourth group of raw materials is aluminum-titanium-boron-rare earth master alloy and aluminum-strontium master alloy;

[0024] S2. Melting: The preheated first three groups of raw materials are fed in sequence and melted. The feeding time is after all the previous group of raw materials is melted. After all the preheated materials of the first three groups are melted, an aluminum-silicon alloy melting covering agent is sprinkled on the surface of the melt to protect the melt, and a melting melt is obtained;

[0025] S3. Refining: The melting melt is refined and statically settled to obtain a refined melt;

[0026] S4. Refinement and modification: The preheated fourth group of raw materials is added to the refined melt for refinement and modification to obtain a modified melt;

[0027] S5. Die casting: The modified melt is die-cast to obtain an aluminum alloy casting.

[0028] As an implementation scheme, in step S1, the preheating parameters are 200-250°C and the time is 1-2 h.

[0029] In some embodiments, in step S1, the preheating temperature is 250°C and the time is 1 h.

[0030] As an implementation scheme, the specific steps of step S2 are as follows:

[0031] The preheated first group of raw materials are melted at 690-700°C. After melting is completed, the temperature is raised to 720-750°C, the preheated second group of raw materials are added for melting. After melting is completed, the temperature is lowered to 680-700°C, and the preheated third group of raw materials are added for melting; then a covering agent is sprinkled to protect the melt, and a smelted melt is obtained, wherein the addition amount of the covering agent is 1-3% of the total mass of all raw materials.

[0032] In some embodiments, the preheated first group of raw materials are melted at 700°C. After melting is completed, the temperature is raised to 710°C, the preheated second group of raw materials are added for melting. After melting is completed, the temperature is lowered to 700°C, and the preheated third group of raw materials are added for melting; then a covering agent is sprinkled to protect the melt, and a smelted melt is obtained, wherein the addition amount of the covering agent is 2% of the total mass of all raw materials.

[0033] As an implementation scheme, the Fe impurity content is controlled to be <0.2 wt.% during the smelting process.

[0034] As an implementation scheme, the specific steps of step S3 are as follows:

[0035] The smelted melt is heated to 700-730°C, and then a refining agent is added for refining for 10-15 min. After refining is completed, it is left standing for 10-15 min to obtain a refined melt, wherein the addition amount of the refining agent is 1-5% of the total mass of all raw materials.

[0036] In some embodiments, the specific steps of step S3 are as follows:

[0037] The smelted melt is heated to 710°C, and then a refining agent is added for refining for 15 min. After refining is completed, it is left standing for 10 min to obtain a refined melt, wherein the refining agent is a refining agent for aluminum-silicon alloy, and the addition amount is 3% of the total mass of all raw materials.

[0038] As an implementation scheme, the specific steps of step S4 are as follows:

[0039] The preheated fourth group of raw materials are added to the refined melt for refinement and modification treatment. After melting, it is fully stirred; after the temperature is cooled to 680-700°C, the floating slag is skimmed off to obtain a modified melt.

[0040] In some embodiments, the specific steps of step S4 are as follows:

[0041] Add the preheated fourth group of raw materials into the refined melt, carry out refinement and modification treatment, and fully stir after melting; skim the dross after the temperature cools to 690 °C to obtain a modified melt.

[0042] As an implementation scheme, the specific steps of step S5 are as follows:

[0043] Die-cast the modified melt, and the cooling rate is 60 - 100 °C / s.

[0044] In some embodiments, in step S5, the die-casting process parameters are: the first fast speed is 0.2 m / s, the second fast speed is 3 m / s, the boosting pressure is 80 MPa, the die-casting temperature is 690 °C, and the mold temperature is 200 °C.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] 1) The present invention provides a high-silicon and high-magnesium aluminum alloy and its preparation method, which is different from the current traditional Al-Mg series (high magnesium and low silicon) and Al-Si series (high silicon and low magnesium) aluminum alloys. It is a heat-treatment-free high-silicon and high-magnesium aluminum alloy suitable for die-casting. For alloys with relatively high Si and Mg contents in aluminum alloys, while fully ensuring their excellent casting performance, the mechanical properties of the alloy have been greatly improved compared with traditional Al-Si series and Al-Mg series alloys.

[0047] 2) Through the change of the composite modifier parameters, the present invention realizes the precise and effective regulation of high-silicon and high-magnesium aluminum alloys with 9.5 - 12 wt.% Si and 3 - 6 wt.% Mg. On the one hand, by reasonably controlling the contents of B and rare earth elements in the high-silicon and high-magnesium alloy, in the aluminum-titanium-boron-rare earth master alloy, the TiB2 compound formed by the B element and elements such as Ti can act as heterogeneous nucleation sites for the alloy, refining the alloy grains, and the aluminum-titanium-boron-rare earth alloy can optimize the morphology, distribution size, etc. of heterogeneous nucleation sites such as Al3Ti and TiB2, having a better refining effect; on the second hand, through the selection of the combination of light, medium, and heavy rare earths, the strength and plasticity of the alloy are effectively balanced. Through the comparative analysis of each embodiment, it can be seen that although the addition without medium and heavy rare earths or without light rare earths can improve the mechanical properties of the high-silicon and high-magnesium aluminum alloy to some extent, there is a problem that the increase in strength is limited. After adopting the composite addition strategy of light, medium, and heavy rare earths, the yield strength and tensile strength of the alloy can also be greatly improved. This performance breakthrough stems from the synergistic effect of light, medium, and heavy rare earths, achieving the best match of strength and plasticity; on the third hand, rare earth elements such as Eu, Dy, and Er are not selected in the present invention because these elements are expensive and their use will significantly increase the preparation cost of the alloy.

[0048] 3) Compared with the prior art, through the optimized adjustment of alloying elements, while fully ensuring the excellent casting performance of the alloy, the alloy can have excellent mechanical properties without going through the heat treatment strengthening process. This alloy is very suitable for the integrated die-casting of large thin-walled complex structural parts, such as body structures, frames, skeletons, etc. in the automotive field, shortening the production cycle and improving the yield rate of castings. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] By reading the following detailed description of the non-limiting embodiments with reference to the accompanying drawings, other features, objects, and advantages of the present invention will become more apparent:

[0050] Figure 1 It is the metallographic structure diagram of the aluminum alloy sample prepared in Example 6 of the present invention;

[0051] Figure 2 It is the XRD diagram of the aluminum alloy sample prepared in Example 6 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0052] The present invention will be described in detail below with reference to the embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several adjustments and improvements can still be made. These all fall within the protection scope of the present invention.

[0053] It should be noted that according to certain differences in the physical, chemical, and geochemical properties of rare earth elements and the requirements of production processes, rare earth elements are often divided into three groups: light, medium, and heavy rare earths. Among the rare earth elements involved in the present invention, La, Ce, Pr, and Nd belong to light rare earths, Sm and Gd belong to medium rare earths, and Yb and Y belong to heavy rare earths. In the present invention, in view of the similarity of samarium (Sm), gadolinium (Gd), ytterbium (Yb), and yttrium (Y) in subsequent research and application scenarios, as well as the related property correlations, they are collectively referred to as medium and heavy rare earths for the convenience of unified discussion and analysis.

[0054] This specific embodiment provides a preparation method of the above high-silicon and high-magnesium aluminum alloy, wherein the raw materials involved are:

[0055] The first group of raw materials: pure Al;

[0056] The second group of raw materials: Al-10Si master alloy, Al-10Mn master alloy;

[0057] The third group of raw materials: pure Mg;

[0058] The fourth group of raw materials (modifier): aluminum-titanium-boron-rare earth master alloy, Al-10Sr master alloy.

[0059] A preparation method of a high-silicon and high-magnesium aluminum alloy, comprising the following steps:

[0060] S1. Raw material preheating

[0061] Preheat the involved raw materials respectively to obtain various corresponding preheated materials, specifically:

[0062] The first group of preheated materials: preheated pure Al;

[0063] The second group of preheated materials: preheated aluminum-silicon master alloy, preheated aluminum-manganese master alloy;

[0064] The third group of preheated materials: preheated pure Mg;

[0065] The fourth group of preheated materials: preheated aluminum-titanium-boron-rare earth master alloy, preheated aluminum-strontium master alloy.

[0066] S2. Melting

[0067] Feed the first three groups of preheated materials in sequence and melt them. The feeding time is after all the materials in the previous group are melted;

[0068] After all the first three groups of preheated materials are melted, sprinkle a covering agent for melting aluminum-silicon-based alloys on the surface of the melt to protect the melt, and obtain a molten melt.

[0069] S3. Refining

[0070] Refine and let stand the molten melt obtained in step S2 to obtain a refined melt.

[0071] S4. Grain refinement and modification

[0072] Add the fourth group of preheated materials to the refined melt obtained in step S3 for grain refinement and modification to obtain a modified melt.

[0073] S5. Die casting

[0074] Perform die casting on the modified melt obtained in step S4 to obtain an aluminum alloy casting.

[0075] Furthermore, in step S1, the preheating temperature is 250 °C and the time is 1 h.

[0076] Furthermore, the specific steps of step S2 are:

[0077] First, place the first group of preheated materials in a smelting device, heat it to 690°C at a rate of 10°C / min, and keep the temperature to melt. After melting, heat it to 710°C (heating rate 10°C / min), then add the second group of preheated materials to melt, keep the temperature at 710°C until melting, cool it to 700°C (cooling rate 5°C / min), then add the third group of preheated materials to melt, keep 700°C until melting. Sprinkle a sodium-free covering agent on the melt to protect it, and obtain a smelting melt. The amount of covering agent added is 2% of the total mass of all raw materials.

[0078] Furthermore, after the three groups of preheated materials were melted, a covering agent was sprinkled on the melt to protect the melt and allowed to stand for 10 minutes to allow the covering agent to fully react with impurities such as the oxide film on the surface of the melt to form a stable covering layer, which can better isolate the air and prevent the melt from oxidation.

[0079] It should be noted that Fe impurities will be introduced during the smelting process, and the Fe impurity content needs to be controlled to be <0.2wt.%.

[0080] Furthermore, the specific steps of step S3 are:

[0081] The molten melt obtained in step S2 is heated to 710°C (heating rate 10°C / min), and then a chloride salt refining agent is added to perform refining for 15 minutes. After the refining is completed, the melt is allowed to stand for 10 minutes, and the temperature is maintained at not less than 700°C to obtain a refined melt. The refining agent is a refining agent for aluminum-silicon alloy (a chloride salt refining agent is used in this embodiment, and is added to the melt by wrapping with aluminum foil), and the amount added is 3% of the total mass of all raw materials.

[0082] Furthermore, the specific steps of step S4 are:

[0083] The fourth group of preheated materials is added to the refined melt obtained in step S3, and the temperature is maintained between 700 and 720°C for refinement and modification. After melting, it is fully stirred at a speed of 60-70r / min for 3 minutes; when the temperature is cooled to 690°C, the scum is skimmed off to obtain a modified melt.

[0084] It should be noted that in order to reduce the attenuation of the refining and modification effects during the smelting process as the smelting time increases, refining is performed first and then the refining and modification treatment is performed.

[0085] Furthermore, the specific steps of step S5 are:

[0086] The modified melt obtained in step S4 is die-casted at a cooling rate of 60 to 100° C. / s.

[0087] Specifically, in step S5, the die-casting process parameters are as follows: the first fast speed is 0.2 m / s, the second fast speed is 3 m / s, the boosting pressure is 80 MPa, the die-casting temperature is 690 °C, and the mold temperature is 200 °C.

[0088] The temperature range during casting can ensure that the melt has good fluidity in the mold, can fill the cavity completely, and can obtain die-castings with dense and complete structures. Through the reasonable combination of the first fast speed and the second fast speed, the phenomenon of gas entrapment in the die-casting can be effectively avoided, and the defects in the die-casting can be reduced.

[0089] It should be noted that in order to reduce the hydrogen content and the contents of metallic and non-metallic inclusions in the aluminum alloy ingot, a bell jar can be used to press the added materials to the bottom of the crucible for melting, and after melting is completed, it is stirred thoroughly.

[0090] The following specifically introduces the preparation method of the high-silicon and high-magnesium aluminum alloy with 11 examples.

[0091] Example 1

[0092] This example provides a preparation method of a high-silicon and high-magnesium aluminum alloy. The components of the prepared aluminum alloy are as follows: 9.5 wt.% of Si, 6 wt.% of Mg, 0.4 wt.% of Mn, 0.1 wt.% of Ti, 0.02 wt.% of B, 0.01 wt.% of Sr, 0.05 wt.% of La, 0.05 wt.% of Gd, and the balance is Al.

[0093] In the preparation method, the aluminum-titanium-boron rare-earth master alloy in the raw materials is selected as the aluminum-titanium-boron-lanthanum-gadolinium master alloy (abbreviated as Al-5Ti-1B-2.5La-2.5Gd). The mass ratios of the respective raw materials can be calculated according to the components of the aluminum alloy prepared in this example, and will not be elaborated here.

[0094] After testing, the total amount of impurities in the prepared aluminum alloy is ≤ 0.4 wt.%, and the content of Fe impurities is ≤ 0.1 wt.%.

[0095] Example 2

[0096] This example provides a preparation method of a high-silicon and high-magnesium aluminum alloy. The components of the prepared aluminum alloy are as follows: 11 wt.% of Si, 4 wt.% of Mg, 0.6 wt.% of Mn, 0.15 wt.% of Ti, 0.03 wt.% of B, 0.02 wt.% of Sr, 0.1 wt.% of La, 0.05 wt.% of Y, and the balance is Al.

[0097] The aluminum-titanium-boron rare-earth master alloy in the raw materials is selected as: the aluminum-titanium-boron-lanthanum-yttrium master alloy (Al-5Ti-1B-5(La+Y) with 66.7 wt% La (33.3 wt% Y)).

[0098] The preparation method is the same as that of Example 1.

[0099] After testing, the total amount of impurities in the prepared aluminum alloy is ≤ 0.5 wt.%, and the Fe impurity content is ≤ 0.2 wt.%.

[0100] Example 3

[0101] This example provides a preparation method of a high-silicon and high-magnesium aluminum alloy. The composition of the prepared aluminum alloy is: 11 wt.% Si, 5 wt.% Mg, 0.6 wt.% Mn, 0.15 wt.% Ti, 0.03 wt.% B, 0.02 wt.% Sr, 0.1 wt.% Pr, 0.05 wt.% Gd, and the balance is Al.

[0102] The aluminum-titanium-boron rare earth master alloy in the raw materials is selected as: aluminum-titanium-boron-praseodymium-gadolinium master alloy (Al-5Ti-1B-5(Pr+Gd) with 66.7 wt.% Pr (33.3 wt.% Gd)).

[0103] The preparation method is the same as that of Example 1.

[0104] After testing, the total amount of impurities in the prepared aluminum alloy is ≤ 0.45 wt.%, and the Fe impurity content is ≤ 0.15 wt.%.

[0105] Example 4

[0106] This example provides a preparation method of a high-silicon and high-magnesium aluminum alloy. The composition of the prepared aluminum alloy is: 11 wt.% Si, 5 wt.% Mg, 0.5 wt.% Mn, 0.15 wt.% Ti, 0.03 wt.% B, 0.03 wt.% Sr, 0.1 wt.% Ce, 0.05 wt.% Y, and the balance is Al.

[0107] The aluminum-titanium-boron rare earth master alloy in the raw materials is selected as: aluminum-titanium-boron-cerium-yttrium master alloy (Al-5Ti-1B-5(Ce+Y) with 66.7 wt.% Ce (33.3 wt.% Y)).

[0108] The preparation method is the same as that of Example 1.

[0109] After testing, the total amount of impurities in the prepared aluminum alloy is ≤ 0.45 wt.%, and the Fe impurity content is ≤ 0.15 wt.%.

[0110] Example 5

[0111] This embodiment provides a method for preparing a high-silicon and high-magnesium aluminum alloy. The composition of the prepared aluminum alloy is as follows: 11 wt.% Si, 6 wt.% Mg, 0.6 wt.% Mn, 0.2 wt.% Ti, 0.04 wt.% B, 0.02 wt.% Sr, 0.1 wt.% Nd, 0.1 wt.% Gd, and the balance is Al.

[0112] The aluminum-titanium-boron rare-earth master alloy in the raw materials is selected as: aluminum-titanium-boron-neodymium-gadolinium master alloy (Al-5Ti-1B-2.5Nb-2.5Gd).

[0113] The preparation method is the same as that of Example 1.

[0114] After testing, the total amount of impurities in the prepared aluminum alloy is ≤ 0.45 wt.%, and the Fe impurity content is ≤ 0.15 wt.%.

[0115] Example 6

[0116] This embodiment provides a method for preparing a high-silicon and high-magnesium aluminum alloy. The composition of the prepared aluminum alloy is as follows: 12 wt.% Si, 4 wt.% Mg, 0.8 wt.% Mn, 0.1 wt.% Ti, 0.02 wt.% B, 0.01 wt.% Sr, 0.05 wt.% Pr, 0.05 wt.% Yb, and the balance is Al.

[0117] The aluminum-titanium-boron rare-earth master alloy in the raw materials is selected as: aluminum-titanium-boron-praseodymium-ytterbium master alloy (abbreviated as Al-5Ti-1B-2.5Pr-2.5Y).

[0118] The preparation method is the same as that of Example 1.

[0119] After testing, the total amount of impurities in the prepared aluminum alloy is ≤ 0.45 wt.%, and the Fe impurity content is ≤ 0.15 wt.%.

[0120] Example 7

[0121] This embodiment provides a method for preparing a high-silicon and high-magnesium aluminum alloy. The composition of the prepared aluminum alloy is as follows: 12 wt.% Si, 4 wt.% Mg, 0.8 wt.% Mn, 0.15 wt.% Ti, 0.03 wt.% B, 0.01 wt.% Sr, 0.1 wt.% Ce, 0.05 wt.% Sm, and the balance is Al.

[0122] The aluminum-titanium-boron rare-earth master alloy in the raw materials is selected as: aluminum-titanium-boron-cerium-samarium master alloy (Al-5Ti-1B-5(Ce+Sm) with 66.7 wt% Ce (33.3 wt% Sm)).

[0123] The preparation method is the same as that of Example 1.

[0124] After detection, the total amount of impurities in the prepared aluminum alloy is ≤ 0.45 wt.%, and the Fe impurity content is ≤ 0.15 wt.%.

[0125] Example 8

[0126] This example provides a method for preparing a high-silicon and high-magnesium aluminum alloy. The composition of the prepared aluminum alloy is: 12 wt.% Si, 5 wt.% Mg, 0.8 wt.% Mn, 0.2 wt.% Ti, 0.04 wt.% B, 0.02 wt.% Sr, 0.1 wt.% La, 0.1 wt.% Yb, and the balance is Al.

[0127] The aluminum-titanium-boron rare earth master alloy in the raw materials is selected as: aluminum-titanium-boron-lanthanum-ytterbium master alloy (abbreviated as Al-5Ti-1B-2.5La-2.5Y).

[0128] The preparation method is the same as that in Example 7.

[0129] After detection, the total amount of impurities in the prepared aluminum alloy is ≤ 0.45 wt.%, and the Fe impurity content is ≤ 0.15 wt.%.

[0130] Example 9

[0131] This example provides a method for preparing a high-silicon and high-magnesium aluminum alloy. The composition of the prepared aluminum alloy is: 12 wt.% Si, 6 wt.% Mg, 0.8 wt.% Mn, 0.2 wt.% Ti, 0.04 wt.% B, 0.03 wt.% Sr, 0.1 wt.% Nd, 0.1 wt.% Sm, and the balance is Al.

[0132] The aluminum-titanium-boron rare earth master alloy in the raw materials is selected as: aluminum-titanium-boron-neodymium-samarium master alloy (abbreviated as Al-5Ti-1B-2.5Nb-2.5Sm).

[0133] The preparation method is the same as that in Example 1.

[0134] After detection, the total amount of impurities in the prepared aluminum alloy is ≤ 0.45 wt.%, and the Fe impurity content is ≤ 0.15 wt.%.

[0135] Example 10

[0136] This comparative example provides a method for preparing a high-silicon and high-magnesium aluminum alloy. The composition of the prepared aluminum alloy is: 9.5 wt.% Si, 6 wt.% Mg, 0.4 wt.% Mn, 0.1 wt.% Ti, 0.02 wt.% B, 0.01 wt.% Sr, 0.1 wt.% La, 0.1 wt.% Gd, and the balance is Al.

[0137] Compared with Example 1, the Al-Ti-B-rare earth master alloy in the raw materials is selected as an Al-Ti-B-La-Gd master alloy (Al-5Ti-1B-5La-5Gd), and the preparation method is the same as that of Example 1.

[0138] After testing, the total amount of impurities in the prepared aluminum alloy is ≤0.4 wt.%, and the Fe impurity content is ≤0.1 wt.%.

[0139] Example 11

[0140] This comparative example provides a method for preparing a high-silicon and high-magnesium aluminum alloy. The components of the prepared aluminum alloy are: 9.5 wt.% Si, 6 wt.% Mg, 0.4 wt.% Mn, 0.15 wt.% Ti, 0.03 wt.% B, 0.075 wt.% La, 0.075 wt.% Gd, and the balance is Al.

[0141] Compared with Example 1, the content of the Al-Ti-B-rare earth master alloy increases, and the Al-Sr master alloy is not included, and other process parameters remain unchanged.

[0142] The preparation method is basically the same as that of Example 1, and the difference lies in:

[0143] Then, during the refinement and modification process, the added one is the Al-Ti-B-La-Gd master alloy, and other process parameters remain unchanged.

[0144] After testing, the total amount of impurities in the prepared aluminum alloy is ≤0.45 wt.%, and the Fe impurity content is ≤0.1 wt.%.

[0145] Example 12

[0146] This example provides a method for preparing a high-silicon and high-magnesium aluminum alloy. The components of the prepared aluminum alloy are: 9.5 wt.% Si, 6 wt.% Mg, 0.4 wt.% Mn, 0.1 wt.% Ti, 0.02 wt.% B, 0.01 wt.% Sr, 0.1 wt.% La, and the balance is Al.

[0147] Compared with Example 1, the raw materials do not contain medium and heavy rare earths, and the Al-Ti-B-rare earth master alloy is selected as an Al-Ti-B-La master alloy (Al-5Ti-1B-5La), and the preparation method is the same as that of Example 1.

[0148] After testing, the total amount of impurities in the prepared aluminum alloy is ≤0.4 wt.%, and the Fe impurity content is ≤0.1 wt.%.

[0149] Example 13

[0150] This embodiment provides a method for preparing a high-silicon and high-magnesium aluminum alloy. The composition of the prepared aluminum alloy is as follows: 9.5 wt.% Si, 6 wt.% Mg, 0.4 wt.% Mn, 0.1 wt.% Ti, 0.02 wt.% B, 0.01 wt.% Sr, 0.05 wt.% La, 0.05 wt.% Ce, and the balance is Al.

[0151] Compared with Example 1, the raw materials do not contain medium and heavy rare earths, and the aluminum-titanium-boron-rare earth master alloy is selected as the aluminum-titanium-boron-lanthanum-cerium master alloy (Al-5Ti-1B-2.5La-2.5Ce).

[0152] The preparation method is the same as that of Example 1.

[0153] After testing, the total amount of impurities in the prepared aluminum alloy is ≤ 0.4 wt.%, and the Fe impurity content is ≤ 0.1 wt.%.

[0154] Example 14

[0155] This embodiment provides a method for preparing a high-silicon and high-magnesium aluminum alloy. The composition of the prepared aluminum alloy is as follows: 9.5 wt.% Si, 6 wt.% Mg, 0.4 wt.% Mn, 0.1 wt.% Ti, 0.02 wt.% B, 0.01 wt.% Sr, 0.1 wt.% Y, and the balance is Al.

[0156] Compared with Example 1, the raw materials do not contain light rare earths, and the aluminum-titanium-boron-rare earth master alloy is selected as: the aluminum-titanium-boron-lanthanum-cerium master alloy (Al-5Ti-1B-5Y).

[0157] The preparation method is the same as that of Example 1.

[0158] After testing, the total amount of impurities in the prepared aluminum alloy is ≤ 0.4 wt.%, and the Fe impurity content is ≤ 0.1 wt.%.

[0159] Example 15

[0160] This comparative example provides a method for preparing a heat-treatable-free high-strength and high-toughness high-silicon and high-magnesium aluminum alloy. The composition of the prepared aluminum alloy is as follows: 6 wt.% Si, 5 wt.% Mg, 0.5 wt.% Mn, 0.15 wt.% Ti, 0.03 wt.% B, 0.03 wt.% Sr, 0.1 wt.% Ce, 0.05 wt.% Y, and the balance is Al.

[0161] Compared with Example 4, the raw materials are basically the same as those in Example 4, but the amount of Si used is relatively reduced, that is, the amount of the aluminum-silicon master alloy used is reduced.

[0162] The preparation method is the same as that of Example 4.

[0163] After detection, the total amount of impurities in the prepared aluminum alloy is ≤ 0.45 wt.%, and the Fe impurity content is ≤ 0.15 wt.%.

[0164] Example 16

[0165] This comparative example provides a preparation method of a heat-treatable high-strength and high-toughness high-silicon and high-magnesium aluminum alloy. The components of the prepared aluminum alloy are: 15 wt.% of Si, 5 wt.% of Mg, 0.5 wt.% of Mn, 0.15 wt.% of Ti, 0.03 wt.% of B, 0.03 wt.% of Sr, 0.1 wt.% of Ce, 0.05 wt.% of Y, and the balance is Al.

[0166] Compared with Example 4, the raw materials are basically the same as those in Example 4, but the amount of Si used is relatively increased, that is, the amount of aluminum-silicon master alloy used is increased.

[0167] The preparation method is the same as that of Example 4.

[0168] After detection, the total amount of impurities in the prepared aluminum alloy is ≤ 0.45 wt.%, and the Fe impurity content is ≤ 0.15 wt.%.

[0169] Comparative Example 1

[0170] This comparative example provides a preparation method of a high-silicon and high-magnesium aluminum alloy. The components of the prepared aluminum alloy are: 9.5 wt.% of Si, 6 wt.% of Mg, 0.4 wt.% of Mn, and the balance is Al.

[0171] Compared with Example 1, the raw materials do not contain aluminum-titanium-boron rare earth master alloy and aluminum-strontium master alloy.

[0172] The preparation method is basically the same as that of Example 1, and the difference is that:

[0173] That is to say, in step S4, the step of adding these two substances to the melt is missing, and other process parameters remain unchanged.

[0174] After detection, the total amount of impurities in the prepared aluminum alloy is ≤ 0.45 wt.%, and the Fe impurity content is ≤ 0.1 wt.%.

[0175] Comparative Example 2

[0176] This comparative example provides a preparation method of a high-silicon and high-magnesium aluminum alloy. The components of the prepared aluminum alloy are: 9.5 wt.% of Si, 6 wt.% of Mg, 0.4 wt.% of Mn, 0.1 wt.% of Ti, 0.02 wt.% of B, and the balance is Al.

[0177] Compared with Example 1, the Al-Ti-B-rare earth master alloy in the raw materials is replaced with an Al-Ti-B master alloy, and no Al-Sr master alloy is contained.

[0178] The preparation method is basically the same as that of Example 1, and the difference lies in:

[0179] Then, during the refinement and modification process, the added one is the Al-Ti-B master alloy, and other process parameters remain unchanged.

[0180] After testing, the total amount of impurities in the prepared aluminum alloy is ≤ 0.45 wt.%, and the content of Fe impurities is ≤ 0.1 wt.%.

[0181] Comparative Example 3

[0182] This comparative example provides a preparation method of a high-silicon and high-magnesium aluminum alloy. The components of the prepared aluminum alloy are: 9.5 wt.% of Si, 6 wt.% of Mg, 0.4 wt.% of Mn, 0.01 wt.% of Sr, and the balance is Al.

[0183] Compared with Example 1, the raw materials do not contain Al-Ti-B-rare earth master alloy.

[0184] The preparation method is basically the same as that of Example 1, and the difference lies in:

[0185] Then, during the refinement and modification process, the added one is the Al-Sr master alloy, and other process parameters remain unchanged.

[0186] After testing, the total amount of impurities in the prepared aluminum alloy is ≤ 0.45 wt.%, and the content of Fe impurities is ≤ 0.1 wt.%.

[0187] Comparative Example 4

[0188] This comparative example provides a preparation method of a high-silicon and high-magnesium aluminum alloy. The components of the prepared aluminum alloy are: 9.5 wt.% of Si, 6 wt.% of Mg, 0.4 wt.% of Mn, 0.15 wt.% of Ti, 0.03 wt.% of Sr, 0.03 wt.% of B, and the balance is Al.

[0189] Compared with Example 1, the raw materials do not contain Al-Ti-B-rare earth master alloy, which is replaced with an Al-Ti-B master alloy, and the contents of the Al-Ti-B master alloy and the Al-Sr master alloy increase, and other process parameters remain unchanged.

[0190] The preparation method is the same as that of Example 1.

[0191] After testing, the total amount of impurities in the prepared aluminum alloy is ≤ 0.45 wt.%, and the content of Fe impurities is ≤ 0.1 wt.%.

[0192] Performance testing:

[0193] The components of the aluminum alloys prepared in the above-mentioned examples and comparative examples are listed in Table 1.

[0194] The room temperature mechanical properties of the above aluminum alloy samples were tested by the room temperature tensile method of metal materials at a tensile rate of 2 mm / min, and the results are shown in Table 2.

[0195] As can be seen from Table 1 and Table 2, compared with the prior art, the aluminum alloy material prepared by the present invention has good strength and toughness while having good casting properties.

[0196] Table 1 Composition table of aluminum alloys prepared in each example and comparative example

[0197]

[0198] Table 2 Test results of room temperature mechanical properties and fluidity

[0199]

[0200]

[0201] For alloys with relatively high Si and Mg contents in aluminum alloys (especially 9.5 - 12.0 wt.% Si, 4.0 - 6.0 wt.% Mg), while fully ensuring their excellent casting properties, the mechanical properties of the alloys have been greatly improved compared with traditional Al - Si series alloys (as Figure 1 shown, the metallographic structure of Example 6).

[0202] Combined with the analysis of Comparative Examples 1 to 5 and Example 2, it can be seen that when adding aluminum - titanium - boron - rare - earth alone or only adding aluminum - strontium, there are deficiencies in the modification treatment of eutectic silicon in the prepared aluminum alloy, resulting in an unbalanced improvement in mechanical properties; while adding two master alloys of aluminum - titanium - boron - rare - earth and aluminum - strontium together realizes complementary advantages, and their synergistic effect enables the comprehensive improvement of the casting properties and mechanical properties of high - silicon - high - magnesium aluminum alloys, showing more excellent overall performance than adding them alone; comparing Example 6 and Comparative Example 6, it can be seen that the relative contents of aluminum - titanium - boron - rare - earth, aluminum - strontium master alloy and silicon have a greater impact on the comprehensive mechanical properties of aluminum alloys. Therefore, it can be seen that although high silicon and high magnesium will increase the sizes of primary silicon, eutectic silicon and Mg2Si, exacerbating their splitting effect on the alloy, through the introduction of aluminum - titanium - boron - rare - earth and aluminum - strontium composite refining and modifying agents, and at the same time, through the reasonable selection and content control of light and medium - heavy rare - earths, the microstructure of the alloy can be effectively improved, and the sizes, morphologies and distributions of primary silicon, eutectic silicon and Mg2Si can be optimized, thereby realizing the improvement of the mechanical properties of the alloy.

[0203] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various deformations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A high-silicon and high-magnesium aluminum alloy, characterized in that, By mass percentage, the components are: 9.5 - 12.0% of Si, 4.0 - 6.0% of Mg, 0.4 - 0.8% of Mn, 0.1 - 0.2% of Ti, 0.1 - 0.2% of RE, 0.02 - 0.04% of B, 0.01 - 0.03% of Sr. The RE element is selected from one or more of La, Ce, Pr, Nd, Sm, Gd, Yb and Y. The impurities do not exceed 0.5%, and the balance is Al.

2. The high-silicon and high-magnesium aluminum alloy according to claim 1, wherein It also includes one or more of the following technical features: A. The RE element is one or a combination of two of La, Ce, Pr, and Nd; B. The RE element is a combination of elements composed of one or more of the light rare earths La, Ce, Pr, Nd and one or more of the medium and heavy rare earths Sm, Gd, Yb, Y; C. The mass ratio of the light rare earth to the medium and heavy rare earth in the RE element is (1 - 2):

1.

3. The high-silicon and high-magnesium aluminum alloy according to claim 1, wherein, By mass percentage, the components are: 11 - 12% of Si, 4 - 6% of Mg, 0.5 - 0.8% of Mn, 0.1 - 0.2% of Ti, 0.02 - 0.04% of B, 0.01 - 0.03% of Sr, 0.05 - 0.1% of light rare earth, 0.05 - 0.1% of medium and heavy rare earth. The impurities do not exceed 0.5%, and the balance is Al. The light rare earth is one or more of La, Ce, Pr, Nd, and the medium and heavy rare earth is a combination of elements composed of one or more of Gd, Yb, Y.

4. The high-silicon and high-magnesium aluminum alloy according to claim 3, wherein The mass ratio of the light rare earth to the medium and heavy rare earth is (1 - 2):1, and the mass ratio of B to the RE element is 1:

5.

5. The preparation method of the high-silicon and high-magnesium aluminum alloy according to any one of claims 1 to 4, characterized in that, It includes the following steps: S1. Raw material preheating: Preheat the involved raw materials respectively to obtain various corresponding preheated materials. The raw materials include four groups. The first group of raw materials is pure aluminum, the second group of raw materials is aluminum - silicon master alloy and aluminum - manganese master alloy, the third group of raw materials is pure Mg, and the fourth group of raw materials is aluminum - titanium - boron - rare - earth master alloy and aluminum - strontium master alloy; S2. Melting: Feed and melt the preheated first three groups of raw materials in sequence. The feeding time is after all the previous group of raw materials are completely melted. After all the preheated materials of the first three groups are melted, sprinkle a covering agent for aluminum - silicon alloy melting on the melt surface to protect the melt and obtain a melted melt; S3. Refining: Refine and let stand the melted melt to obtain a refined melt; S4. Grain refinement and modification: Add the preheated fourth group of raw materials to the refined melt for grain refinement and modification to obtain a modified melt; S5. Die - casting: Perform die - casting on the modified melt to obtain an aluminum alloy casting.

6. The preparation method of the high-silicon and high-magnesium aluminum alloy according to claim 5, wherein In step S1, the preheating parameters are 200 - 250°C and the time is 1 - 2 h.

7. The preparation method of the high-silicon and high-magnesium aluminum alloy according to claim 5, characterized in that, In step S2, melt the preheated first group of raw materials at 690 - 700°C. After melting is completed, raise the temperature to 720 - 750°C, add the preheated second group of raw materials for melting. After melting is completed, lower the temperature to 680 - 700°C, add the preheated third group of raw materials for melting; then sprinkle the covering agent to protect the melt and obtain a melted melt, where the addition amount of the covering agent is 1 - 3% of the total mass of all raw materials.

8. The preparation method of the high-silicon and high-magnesium aluminum alloy according to claim 5, characterized in that, In step S3, after heating the smelting melt to 700 - 730 °C, a refining agent is added for refining for 10 - 15 minutes. After the refining is completed, it is left standing for 10 - 15 minutes to obtain a refined melt. Among them, the refining agent is a refining agent for aluminum-silicon alloy, and the addition amount is 1 - 5% of the total mass of all raw materials.

9. The preparation method of the high-silicon and high-magnesium aluminum alloy according to claim 5, characterized in that, In step S4, preheated fourth-group raw materials are added to the refined melt for refinement and modification treatment. After melting, it is fully stirred; after the temperature is cooled to 680 - 700 °C, the dross is skimmed off to obtain a modified melt.

10. The preparation method of the high-silicon and high-magnesium aluminum alloy according to claim 5, characterized in that, In step S5, the modified melt is die-cast with a cooling rate of 60 - 100 °C / s.

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