CN114457266A - Ultrahigh-strength and toughness cast aluminum alloy and forming method thereof - Google Patents
Ultrahigh-strength and toughness cast aluminum alloy and forming method thereof Download PDFInfo
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Abstract
The invention provides an ultrahigh-strength and high-toughness cast aluminum alloy and a forming method thereof, wherein the ultrahigh-strength and high-toughness cast aluminum alloy comprises the following components in percentage by mass: 7.6-8.6% of Zn, 1.8-2.4% of Mg, 1.1-1.7% of Cu, 0.1-0.2% of Zr, 0.1-0.2% of Sc and the balance of Al and inevitable impurities; wherein, the content of Fe in the inevitable impurities is less than or equal to 0.06 percent, the content of Si is less than or equal to 0.06 percent, and the total amount of the rest impurities is less than or equal to 0.15 percent. The high-strength and high-toughness cast aluminum alloy has the tensile strength of more than or equal to 600MPa, the yield strength of more than or equal to 520MPa and the elongation of more than or equal to 10 percent, is cast instead of forged, and can replace wrought aluminum alloy in the prior art.
Description
Technical Field
The invention relates to the technical field of high-performance cast aluminum alloy materials and processing thereof, in particular to an ultrahigh-strength and high-toughness cast aluminum alloy and a forming method thereof.
Background
At present, the high-strength and high-toughness aluminum alloy mainly comprises 2XXX and 7XXX series traditional wrought aluminum alloys, and powder metallurgy aluminum alloys, spray forming aluminum alloys, aluminum-based composite materials, superplastic aluminum alloys and the like developed on the basis of the traditional wrought aluminum alloys. Because the casting forming performance is poor, and the defects of shrinkage porosity, air holes and the like under the conventional casting condition are difficult to avoid, the existing 7XXX series Al-Zn-Mg-Cu high-strength-toughness wrought aluminum alloys are all forged, rolled, extruded and other parts, and high-performance complex castings can not be directly obtained through a casting method under the general condition.
With the continuous expansion of the application field of ultra-high strength aluminum alloy, some important aluminum alloy castings also need to realize the dual purposes of improving the bearing capacity and reducing the weight, and the development of ultra-high strength and toughness aluminum alloy castings with the performance close to that of wrought aluminum alloy is also needed urgently. In recent years, research on preparing aluminum alloy castings by wrought aluminum alloys is frequently reported in China, but still in the laboratory research stage, so that ultrahigh-strength and high-toughness cast aluminum alloy materials capable of replacing wrought aluminum alloys and a casting forming method thereof are developed, the purpose of replacing forging with casting is achieved, and the method has important practical significance for expanding the application range of ultrahigh-strength and high-toughness aluminum alloys.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention mainly aims to provide the ultrahigh-strength and high-toughness cast aluminum alloy and the forming method thereof, the ultrahigh-strength and high-toughness cast aluminum alloy has the tensile strength of more than or equal to 600MPa, the yield strength of more than or equal to 520MPa and the elongation of more than or equal to 10 percent, is cast instead of forged and can replace the wrought aluminum alloy in the prior art.
In order to achieve the above object, according to a first aspect of the present invention, there is provided an ultra high toughness cast aluminum alloy.
The ultrahigh-strength and high-toughness cast aluminum alloy comprises the following components in percentage by mass: 7.6-8.6% of Zn, 1.8-2.4% of Mg, 1.1-1.7% of Cu, 0.1-0.2% of Zr, 0.1-0.2% of Sc, and the balance of Al and inevitable impurities;
wherein, the content of Fe in the inevitable impurities is less than or equal to 0.06 percent, the content of Si is less than or equal to 0.06 percent, and the total amount of the other impurities is less than or equal to 0.15 percent.
Furthermore, the metallographic structure of the cast aluminum alloy comprises alpha-Al primary phases and eutectic phases distributed among the primary phases, wherein the alpha-Al primary phases are spherical, and the average grain size is less than or equal to 50 mu m.
Furthermore, the tensile strength of the ultrahigh strength and toughness cast aluminum alloy is more than or equal to 600MPa, the yield strength is more than or equal to 520MPa, and the elongation is more than or equal to 10%.
In order to achieve the above object, according to a second aspect of the present invention, there is provided a molding method of an ultra-high strength and toughness cast aluminum alloy.
The forming method of the ultrahigh-strength and high-toughness cast aluminum alloy comprises the following steps of:
according to a certain alloy proportion, carrying out mixed smelting on metal simple substances or alloys of all components to obtain a melt;
homogenizing the melt under the action of a physical external field to obtain alloy slurry with uniform temperature and components;
and (3) casting and molding the alloy slurry, and sequentially carrying out solid solution treatment and time effect treatment on the obtained alloy casting to obtain the ultrahigh-strength and high-toughness cast aluminum alloy part.
Further, the Al, Zn and Mg components are introduced in the form of metal simple substances, and the Cu, Zr and Sc components are introduced in the form of Al-Cu, Al-Zr and Al-Sc alloys.
Further, the content of Cu in the Al-Cu alloy is 30-50% by mass, and the balance is Al.
Further, the Al-Zr alloy contains 3-5% of Zr by mass percent, and the balance is Al.
Further, the content of Sc in the Al-Sc alloy is 1-2% by mass, and the balance is Al.
Further, the homogenization treatment specifically comprises: and injecting the melt into a crucible, and placing the crucible in a physical external field for stirring treatment, so that the melt is rapidly cooled to 610-660 ℃, and the time t is less than or equal to 120 s.
Furthermore, the casting temperature of the melt is 680-720 ℃, the temperature of the crucible is 20-200 ℃, and the specific melting ratio of the crucible is more than or equal to 500J/(Kg.C.).
Further, the physical external field includes an electromagnetic field, an ultrasonic field, and a mechanical field.
Further, the alloy slurry casting molding specifically comprises: the alloy slurry is directly formed by high-pressure die casting, extrusion casting or liquid die forging, and the forming pressure is more than or equal to 50 MPa.
Further, the solution treatment is divided into three stages, which are respectively: the temperature of the primary solution treatment is 450-460 ℃, and the time is 3-9 h; the temperature of the secondary solution treatment is 460-470 ℃, and the time is 3-6 h; the temperature of the third-stage solution treatment is 470-475 ℃, and the time is 1-3 h.
Further, the temperature of the aging treatment is 110-130 ℃, and the time is 12-36 h.
Further, the smelting comprises alloy smelting and alloy refining,
the alloy smelting temperature is 780-800 ℃, the temperature is kept for 10-20 min after the alloy is smelted, then the temperature is reduced to 750 ℃, alloy refining is carried out, the refining time is 20-30 min, and the alloy is kept for standing for 10-20 min after the refining is finished;
wherein the alloy refining is to perform degassing, deslagging and refining treatment by adopting a bottom blowing gas mode.
The common problems of the existing Al-Zn-Mg-Cu series wrought aluminum alloy are wide crystallization temperature range, strong dendritic crystal growth trend and low plasticity of the conventional cast structure. Wherein, the excessive paste solidification area and the low content of eutectic structures lead to insufficient feeding at the final stage of solidification and difficult floating removal of precipitated gas, thus causing the problems of larger hot and cold cracking tendency of the alloy, and the like. The above problems are fundamental points of the Al-Zn-Mg-Cu wrought aluminum alloys that are not suitable for use as casting alloys. In order to improve the casting performance of the alloy and simultaneously not weaken the toughness of the alloy, the invention improves the casting performance of the alloy by measures such as alloy component design, melt physical external field treatment, subsequent heat treatment and the like, and simultaneously exerts the toughness performance advantage of the alloy.
Al-Zn-Mg-Cu alloy as aging-strengthening alloy, eta (MgZn)2) The alloy is a main strengthening phase in the alloy, and the eta phase has high solubility in Al and is changed violently along with the temperature rise and fall, so the obdurability of the alloy is greatly influenced by a heat treatment process. The mechanical properties of the alloy are finally determined by the size, distribution and uniformity of matrix precipitated phases, intercrystalline precipitated phases and grain boundary non-precipitated zones and recrystallization-inhibiting compounds, so that the componentsOnce determined, the primary way to achieve optimal control of the alloy structure is to use a suitable heat treatment process.
For Al-Zn-Mg-Cu alloy, the content of Zn and Mg and the Zn/Mg ratio are improved, the eutectic phase generation amount and the eta strengthening phase content in an alloy structure can be increased, and the feeding capacity at the later solidification stage of the alloy can be improved to a certain extent. Therefore, the alloy of the invention adopts a relatively high Zn/Mg ratio, on one hand, the strength index of the alloy is ensured, and on the other hand, the contents of the strengthening phase and the eutectic phase are properly increased; simultaneously, Cu/Mg is reduced, and coarse Al can be effectively reduced2CuMg and Al2The Cu insoluble phase further improves the mechanical property of the alloy and reduces the hot cracking tendency of the alloy.
The grain refinement of the solidification structure is an important means for improving the flow property of the alloy melt, improving the feeding capacity of the alloy and reducing the hot cracking tendency of the alloy. Sc is the most effective refining element in various aluminum alloy refiners, and particularly, the strong refining effect of Sc on Al-Mg series and Al-Zn-Mg-Cu series alloys is fully embodied. In recent years, the composite microalloying treatment can further refine the alloy solidification structure, and simultaneously can reduce the addition amount of each element, especially for expensive Sc, and the composite addition can obviously reduce the cost of alloy materials. According to the invention, Sc and Zr are added in a compounding way to obtain an as-cast structure with a certain refining degree, so that composite particles which are more matched with an aluminum matrix are formed, the density and precipitation strength of heterogeneous nucleation are increased, and the critical components of micro-alloying elements under the same alloying effect can be further reduced.
In order to ensure the comprehensive mechanical property of the alloy, high-purity raw materials can be adopted, and the crucible and tools for smelting are prevented from adopting iron materials so as to prevent Fe and Si elements from being dissolved. Before the alloy is cast, inert gas is recommended to be used for degassing and deslagging the melt.
In order to ensure the comprehensive mechanical property of the alloy, the melt of the alloy needs to be subjected to rapid forced homogenization treatment under the action of a physical external field before pressure forming, so that the temperature of the melt is rapidly reduced to a specific temperature, the component field and the temperature field of the alloy melt are uniformly distributed, the refining and homogenization of an alloy solidification structure are realized, and the formation of dendritic crystals is reduced.
In order to ensure the comprehensive mechanical property of the alloy, the alloy melt needs to be formed under pressure, the forming pressure is more than or equal to 50MPa, and the forming mode comprises high-pressure die casting, extrusion casting or liquid die forging and the like.
The alloy of the invention is heat-treatable strengthened aluminum alloy, and has very strict requirements on the heat treatment process of as-cast alloy compared with similar wrought alloy. Aiming at the alloy, the alloy casting of the invention can be used for producing the aluminum alloy casting with the tensile strength of more than or equal to 600MPa, the yield strength of more than or equal to 520MPa and the elongation of more than or equal to 10 percent through multi-stage strengthening solution treatment and aging treatment.
The invention has the advantages that:
by adopting high Zn and Mg contents and Zn/Mg ratio, Sc and Zr composite micro-alloying and simultaneously applying physical external field to the alloy melt to rapidly and forcibly homogenize, the aims of increasing the proportion of eta strengthening phase and eutectic phase, refining grain structure, inhibiting dendritic crystal growth and changing the solidification mode of the alloy are further fulfilled, so that the hot cracking tendency of the alloy is reduced and the casting performance of the alloy is remarkably improved. The alloy can obtain excellent strength and toughness performance through multi-stage strengthening solution treatment and aging treatment, can produce aluminum alloy castings with tensile strength of more than 600MPa, yield strength of more than 520MPa and elongation of more than 10%, and is used as a substitute material of high-strength and toughness wrought aluminum alloy.
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Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
FIG. 1a is a prior art squeeze cast microstructure of a 7xxx series alloy (Al-7.92Zn-1.90Mg-1.59Cu-0.12 Zr);
FIG. 1b is a schematic view showing the squeeze-cast structure of Al-8.14Zn-1.93Mg-1.56Cu-0.11Zr-0.13Sc alloy in example 1 of the present invention;
FIG. 2a is a prior art hot crack sensitive test bar for a 7xxx series alloy (Al-7.92Zn-1.90Mg-1.59Cu-0.12 Zr);
FIG. 2b is a heat cracking susceptibility test bar of the Al-8.14Zn-1.93Mg-1.56Cu-0.11Zr-0.13Sc alloy of example 1 of the present invention;
FIG. 3a is a photograph of a prior art extrusion cast brake hub of a 7 xxx-series alloy (Al-7.92Zn-1.90Mg-1.59Cu-0.12 Zr);
FIG. 3b is a photograph of an extrusion cast brake hub made of Al-8.14Zn-1.93Mg-1.56Cu-0.11Zr-0.13Sc alloy in example 1 of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The invention provides an ultrahigh strength and toughness cast aluminum alloy, in particular to an ultrahigh strength and toughness cast Al-Zn-Mg-Cu-Zr-Sc alloy which is an ultrahigh strength and toughness aluminum alloy material capable of being used as a cast alloy.
The ultrahigh-strength and high-toughness cast aluminum alloy comprises the following components in percentage by mass: 7.6-8.6% of Zn, 1.8-2.4% of Mg, 1.1-1.7% of Cu, 0.1-0.2% of Zr, 0.1-0.2% of Sc, and the balance of Al and inevitable impurities; wherein, the content of Fe in the inevitable impurities is less than or equal to 0.06 percent, the content of Si is less than or equal to 0.06 percent, and the total amount of the other impurities is less than or equal to 0.15 percent.
The ultra-high strength and toughness cast aluminum alloy has the advantages of fine and round solidified grain structure, uniform chemical components, no segregation, no shrinkage porosity, no hot cracking and other defects, the tensile strength is more than or equal to 600MPa, the yield strength is more than or equal to 520MPa, the elongation is more than or equal to 10 percent, and the replacement casting and forging of the ultra-high strength and toughness aluminum alloy are realized.
The invention also provides a molding method of the ultrahigh-strength and high-toughness cast aluminum alloy, and the molding process comprises alloy smelting, melt refining, rapid forced homogenization treatment of the melt under the action of a physical external field, pressure casting molding and heat treatment.
The preparation method specifically comprises the following steps:
(1) preparing raw materials: taking high-purity metal Al, high-purity metal Zn, high-purity metal Mg, high-purity Al-Cu intermediate alloy, high-purity Al-Zr intermediate alloy and high-purity Al-Sc intermediate alloy as raw materials, and according to the weight percentage of the Al-Zn-Mg-Cu-Zr-Sc alloy components: 7.6 to 8.6 percent of Zn, 1.8 to 2.4 percent of Mg, 1.1 to 1.7 percent of Cu, 0.1 to 0.2 percent of Zr, 0.1 to 0.2 percent of Sc, the balance of Al, and inevitable impurities of less than or equal to 0.06 percent of Fe, less than or equal to 0.06 percent of Si and less than or equal to 0.15 percent of the total amount of the other impurities.
Wherein the Cu content in the Al-Cu intermediate alloy is 30-50% by mass, and the balance is Al;
the Zr content in the Al-Zr intermediate alloy is 3-5% in percentage by mass, and the balance is Al;
the content of Sc in the Al-Sc intermediate alloy is 1-2% by mass, and the balance is Al.
(2) Alloy smelting: and mixing the metal and the intermediate alloy, smelting at 780-800 ℃, and preserving heat for 10-20 min after all the metal and the intermediate alloy are molten.
(3) Alloy refining: and (3) cooling the melt to 750 ℃, then performing degassing, deslagging and refining treatment in a bottom argon blowing mode for 20-30 min, and standing for 10-20 min after finishing heat preservation.
(4) Homogenizing: pouring the refined melt into a crucible, wherein the pouring temperature of the melt is 680-720 ℃, the temperature of the crucible is 20-200 ℃, then placing the crucible into melt processing equipment of a physical external field (an electromagnetic field, an ultrasonic field or a mechanical field and the like), and carrying out vigorous stirring processing under the action of the physical external field, so that the melt is rapidly cooled to 610-660 ℃, and the time is less than or equal to 120s, thereby obtaining the alloy slurry with uniform temperature and components. Wherein the crucible ratio is more than or equal to 500J/(Kg.C).
(5) Pressure forming alloy casting or sample: and pouring the alloy slurry into a mold or a pressing chamber and pressure-forming a casting or a sample, wherein the forming mold is a metal mold, the preheating temperature of the mold is 200-250 ℃, and the forming pressure is not less than 50 Mpa.
(6) Carrying out heat treatment on the alloy casting or sample: the heat treatment comprises the steps of carrying out three-stage solution treatment and aging treatment on the alloy casting, wherein:
the primary solid solution temperature is 450-460 ℃, and the time is 3-9 h; the secondary solid solution temperature is 460-470 ℃, and the time is 3-6 h; the third-stage solid solution temperature is 470-475 ℃, the time is 1-3 h, and water quenching is carried out after solid solution treatment;
the aging temperature is 110-130 ℃, the time is 12-36 h, and high-strength and high-toughness cast aluminum alloy castings or samples are obtained.
The method for producing the high-toughness cast aluminum alloy according to the present invention will be described in detail below with reference to specific examples.
Example 1:
a high-toughness cast Al-8.14Zn-1.93Mg-1.56Cu-0.11Zr-0.13Sc alloy comprises the following chemical components in percentage by weight: zn 8.14, Mg 1.93, Cu 1.56, Zr 0.11, Sc 0.13, and the balance of Al.
The preparation method comprises the following steps:
(1) preparing raw materials: al, Mg and Zn are added in a high-purity metal form, and alloy elements Cu, Zr and Sc are added in a high-purity aluminum-based intermediate alloy form;
(2) alloy smelting: a resistance furnace and a graphite crucible are adopted, when in smelting, after metal materials (pure Al and intermediate alloys Al-50Cu, Al-5Zr and Al-2Sc) are completely melted, metal Zn and metal Mg are coated by aluminum foil, pressed into the bottom by a bell jar and completely melted without stirring. In order to fully melt the existing coarse intermetallic compound particles in the intermediate alloy, the melting temperature is set to 780 ℃, and the heat preservation time is 20 min.
(3) Alloy refining: and (3) reducing the temperature of the melt to 750 ℃, and then refining, degassing and deslagging by adopting bottom blowing argon, wherein the refining time is 30min, and the standing and heat preservation time is 10 min.
(4) Pouring 720 ℃ alloy liquid into a special stainless steel crucible, carrying out hot melting at the crucible ratio of more than or equal to 500J/(Kg. DEG C), and putting the crucible into a magnetic stirrer for stirring, wherein the treatment time is less than 120s, so that the temperature of the alloy melt is quickly reduced to 660 ℃.
(5) Pouring into a forming die, and performing extrusion casting forming, wherein the preheating temperature of the die is 240 ℃, and the pressure is 80 MPa.
(6) And (3) heat treatment: comprises three-stage solution treatment and aging treatment;
primary solid solution: the temperature is 450 ℃, and the heat preservation time is 3 h;
secondary solid solution: the temperature is 460 ℃, and the heat preservation time is 3 h;
third-stage solid solution: keeping the temperature at 470 ℃ for 3h, and quenching with cold water;
and (3) immediately performing aging treatment on the alloy sample after water quenching, wherein the aging temperature is 120 ℃, and the heat preservation time is 24 h.
In the embodiments 2-3, the same preparation process as that of the embodiment 1 is adopted for the ultrahigh-strength and high-toughness cast Al-Zn-Mg-Cu-Zr-Sc alloy, and the difference is only in the arrangement of the mixture ratio of the raw material alloy.
In the invention, the mechanical properties of the cast aluminum alloys prepared in the examples 1 to 3 are tested by a conventional testing method, and the alloy compositions and the mechanical property results of the cast aluminum alloys in the examples 1 to 3 are shown in table 1 in detail.
Also, the mechanical properties of the conventional 7xxx series alloys of the prior art, as well as the cast aluminum alloys disclosed by the researchers, are also summarized by the present invention to provide an effective comparison with the cast aluminum alloys of the present invention. Wherein:
comparative example 1 used a conventional 7 xxx-series alloy, specifically Al-7.92Zn-1.90Mg-1.59Cu-0.12 Zr;
comparative example 2A cast Al-Zn-Mg-Cu-Ta alloy (specified in CN105154729A) disclosed in the prior art was used, the alloy composition in mass percent being Mg: 1.5-3%, Zn: 6-10%, Cu: 1.5-2.5%, Ta: 0.02-0.51%, cerium-rich mischmetal: 0.0004-0.102% and the balance of Al, wherein the room-temperature tensile strength of the alloy is 287-479 MPa, the fluctuation is large, the reliability of the strength is to be improved, and the strength cannot meet the requirement of the national defense and military industry fields on high-performance castings;
comparative example 3a cast Al-Zn-Mg-Cu-RE alloy (see CN108642336A for details) disclosed in the prior art was used, the alloy composition in mass percent being Mg: 2.5-6.0%, Zn: 3.0-6.0%, Cu: 0.5-2.0%, RE: 0.01 to 1.5%, Ti: 0.00005-0.2%, B: 0.00001% -0.1%, Sr: 0-0.2%, Zr: 0-0.2%, less than or equal to 0.45% of impurities, and the balance of Al, wherein the rare earth elements are one or a combination of more of Ce, Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu, the room-temperature tensile strength of the alloy is about 500MPa, the elongation is about 10%, but the strength of the alloy still cannot meet the requirements of the national defense and military industry field on high-performance castings.
TABLE 1 summary of mechanical properties of the cast aluminum alloys of examples 1-3 and comparative examples 1-3
As can be seen from table 1 and fig. 1a to 3 b: compared with the conventional 7xxx aluminum alloy (Al-7.92Zn-1.90Mg-1.59Cu-0.12Zr), the alloy in the embodiment of the invention has the advantages of finer and more uniform as-cast structure, obviously reduced hot cracking sensitivity, good alloy formability and less surface defects under the same solidification condition.
Comparing FIG. 1a with FIG. 1b, it can be seen that primary alpha-Al crystal grains in the aluminum alloy Al-7.92Zn-1.90Mg-1.59Cu-0.12Zr squeeze casting structure are coarse irregular dendritic crystal structures, secondary dendritic arms are coarse, the size of the crystal grains is larger than 150 μm, and intergranular distribution is coarse eutectic phase; the primary alpha-Al crystal grains in the alloy extrusion casting structure obtained in the embodiment 1 are typical spherical grains, and are finer and more uniform, the size of the crystal grains is less than 50 μm, and the distribution of intergranular eutectic phases is more uniform and finer.
Moreover, the tensile strength of the cast aluminum alloy prepared by the method is more than or equal to 600MPa, the yield strength is more than or equal to 520MPa, the elongation is more than or equal to 10 percent, the requirement of ultrahigh strength and toughness is met, and the replacement forging of the high strength and toughness aluminum alloy by casting is realized.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (12)
1. The ultrahigh-strength and high-toughness cast aluminum alloy is characterized by comprising the following components in percentage by mass: 7.6-8.6% of Zn, 1.8-2.4% of Mg, 1.1-1.7% of Cu1, 0.1-0.2% of Zr, 0.1-0.2% of Sc, and the balance of Al and inevitable impurities;
wherein, the content of Fe in the inevitable impurities is less than or equal to 0.06 percent, the content of Si is less than or equal to 0.06 percent, and the total amount of the other impurities is less than or equal to 0.15 percent.
2. The ultra-high strength and toughness cast aluminum alloy according to claim 1, wherein the metallographic structure of said cast aluminum alloy comprises α -Al primary phases and eutectic phases distributed between said primary phases, said α -Al primary phases being spherical and having an average grain size of 50 μm or less.
3. The ultra-high strength and toughness cast aluminum alloy according to claim 1, wherein the ultra-high strength and toughness cast aluminum alloy has a tensile strength of not less than 600MPa, a yield strength of not less than 520MPa, and an elongation of not less than 10%.
4. The method of forming an ultra high strength and toughness cast aluminum alloy as recited in any one of claims 1-3, comprising the steps of:
according to a certain alloy proportion, carrying out mixed smelting on metal simple substances or alloys of all components to obtain a melt;
homogenizing the melt under the action of a physical external field to obtain alloy slurry with uniform temperature and components;
and (3) casting and molding the alloy slurry, and sequentially carrying out solid solution treatment and time effect treatment on the obtained alloy casting to obtain the ultrahigh-strength and high-toughness cast aluminum alloy part.
5. The molding method according to claim 4, wherein the Al, Zn, Mg components are introduced in the form of a metal element, and the Cu, Zr, Sc components are introduced in the form of Al-Cu, Al-Zr, Al-Sc alloy.
6. The molding method according to claim 4, wherein the homogenization treatment is specifically: and injecting the melt into a crucible, and placing the crucible in a physical external field for stirring treatment, so that the melt is rapidly cooled to 610-660 ℃, and the time t is less than or equal to 120 s.
7. The molding method according to claim 6, wherein the physical external field comprises an electromagnetic field, an ultrasonic field, or a mechanical field.
8. The molding method according to claim 6, wherein the casting temperature of the melt is 680-720 ℃, the crucible temperature is 20-200 ℃, and the crucible specific heat melting is not less than 500J/(Kg-C).
9. The forming method according to claim 4, wherein the alloy slurry is cast and formed by: the alloy slurry is directly formed by high-pressure die casting, extrusion casting or liquid die forging, and the forming pressure is more than or equal to 50 MPa.
10. The molding method as claimed in claim 4, wherein said solution treatment is divided into three stages, respectively: the temperature of the primary solution treatment is 450-460 ℃, and the time is 3-9 h; the temperature of the secondary solution treatment is 460-470 ℃, and the time is 3-6 h; the temperature of the third-stage solution treatment is 470-475 ℃, and the time is 1-3 h.
11. The molding method according to claim 4, wherein the aging treatment is carried out at a temperature of 110 to 130 ℃ for 12 to 36 hours.
12. The molding method according to claim 4, wherein the melting includes alloy melting and alloy refining,
the alloy smelting temperature is 780-800 ℃, the temperature is kept for 10-20 min after the alloy is smelted, then the temperature is reduced to 750 ℃, alloy refining is carried out, the refining time is 20-30 min, and the alloy is kept for standing for 10-20 min after the refining is finished;
wherein the alloy refining is to perform degassing, deslagging and refining treatment by adopting a bottom blowing gas mode.
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