Al-Cu series aluminum alloy, preparation method thereof and aluminum alloy structural part

Abstract

The invention provides an Al-Cu series aluminum alloy, a preparation method thereof and an aluminum alloy structural part. The Al-Cu series aluminum alloy is prepared from the following components in percentage by mass: 2.5 to 4 weight percent of Cu, 0.001 to 0.6 weight percent of Si, 0.001 to 0.5 weight percent of Fe, 0.001 to 1.2 weight percent of Mg, 0 to 0.8 weight percent of Mn, 0 to 0.3 weight percent of Ti, 0 to 0.3 weight percent of Cd, 0 to 0.3 weight percent of Cr, 0 to 0.3 weight percent of Zr, 0 to 0.3 weight percent of V, 0 to 0.5 weight percent of Ag, 0 to 0.1 weight percent of B, 0.001 to 0.3 weight percent of Zn, 0 to 0.1 weight percent of Be and 0 to 0.8 weight percent of RE.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy technology, and more particularly to an Al-Cu aluminum alloy, a method for preparing the Al-Cu aluminum alloy, and aluminum alloy structural components. Background Technology

[0002] Al-Cu aluminum alloys are among the earliest developed and most widely used high-strength aluminum alloys. Due to their high strength, good thermal stability, excellent fatigue performance, and good machinability, they are widely used in aerospace, automotive and transportation, military and weaponry, mold and machinery manufacturing, and special high-temperature aluminum alloy structural components. However, the low plasticity of Al-Cu aluminum alloys makes them unsuitable for deep drawing and spinning processes. Therefore, there is an urgent need to develop an Al-Cu aluminum alloy with superior mechanical properties. Summary of the Invention

[0003] In view of the above-mentioned deficiencies of the prior art, the present invention provides a method for preparing Al-Cu aluminum alloys, aiming to obtain Al-Cu aluminum alloys with excellent mechanical properties.

[0004] This invention provides an Al-Cu aluminum alloy containing 2.5-4% Cu by mass, 0.001-0.6% Si by mass, 0.001-0.5% Fe by mass, 0.001-1.2% Mg by mass, 0-0.8% Mn by mass, 0-0.3% Ti by mass, 0-0.3% Cd by mass, 0-0.3% Cr by mass, 0-0.3% Zr by mass, 0-0.3% V by mass, 0-0.5% Ag by mass, 0-0.1% B by mass, 0.001-0.3% Zn by mass, 0-0.1% Be by mass, 0-0.8% RE by mass, and Al and unavoidable impurities.

[0005] Further, the Al-Cu aluminum alloy contains 2.5-4% Cu by mass, 0.01-0.3% Si by mass, 0.05-0.3% Fe by mass, 0.05-1.2% Mg by mass, 0.001-0.5% Mn by mass, 0.001-0.2% Ti by mass, 0.001-0.25% Cd by mass, and other components by mass. The content of Cr is 0.001-0.25%, Zr is 0.001-0.25%, V is 0.001-0.3%, Ag is 0.001-0.5%, B is 0.001-0.1%, Zn is 0.001-0.3%, Be is 0.001-0.1%, and RE is 0.001-0.5%.

[0006] Furthermore, at least one of the following conditions must be met: The sum of the mass percentages of Si and Fe is less than 0.6%; The sum of the mass percentages of V and Ti is less than 0.4%; The mass ratio of Mn to Fe is greater than 0.4.

[0007] Furthermore, the Al-Cu aluminum alloy also contains at least one of In, Nb, Bi, Ge, Mo, Ag, Sn, Sr, Te, Co, and Ca, wherein the mass percentage content of In is 0-0.2%, the mass percentage content of Nb is 0-0.5%, the mass percentage content of Ni is 0-0.3%, the mass percentage content of Bi is 0-0.2%, the mass percentage content of Ge is 0-0.5%, the mass percentage content of Mo is 0-0.5%, the mass percentage content of Sn is 0-0.5%, the mass percentage content of Sr is 0-0.1%, the mass percentage content of Te is 0-0.5%, the mass percentage content of Co is 0-0.5%, and the mass percentage content of Ca is 0-0.5%.

[0008] This invention also provides a method for preparing Al-Cu aluminum alloys, comprising the following steps: The Al source is subjected to a first heating treatment to obtain molten aluminum. Add Cu source, Si source, Fe source, Mg source, Mn source, Ti source, Cd source, Cr source, Zr source, V source, Ag source, B source, Zn source, Be source, and RE source to the aluminum liquid, and perform a second heat treatment to obtain an alloy liquid; The alloy liquid is refined, slag removed, and formed to obtain an Al-Cu aluminum alloy. The Al-Cu aluminum alloy contains 2.5-4% Cu by mass, 0.001-0.6% Si by mass, 0.001-0.5% Fe by mass, 0.001-1.2% Mg by mass, 0-0.8% Mn by mass, 0-0.3% Ti by mass, and [other components not specified in the original text]. The composition includes 0-0.3% Cd, 0-0.3% Cr, 0-0.3% Zr, 0-0.3% V, 0-0.5% Ag, 0-0.1% B, 0.001-0.3% Zn, 0-0.1% Be, 0-0.8% RE, and Al and unavoidable impurities.

[0009] Furthermore, the preparation method of the Al-Cu aluminum alloy further includes the step of adding at least one of the following sources to the molten aluminum: In, Ni, Nb, Bi, Ge, Mo, Sn, Sr, Te, Co, and Ca. The mass percentage content of In is 0-0.2%, Ni is 0-0.3%, Nb is 0-0.5%, Bi is 0-0.2%, Ge is 0-0.5%, Mo is 0-0.5%, Sn is 0-0.5%, Sr is 0-0.1%, Te is 0-0.5%, Co is 0-0.5%, and Ca is 0-0.5%.

[0010] Furthermore, the molding process includes the following steps: The molten alloy is pushed into a mold and subjected to low-pressure filling casting. Once the molten alloy enters the semi-solid solidification zone, semi-solid aluminum alloy parts are formed. These parts are then subjected to in-situ primary forging and in-situ secondary forging pre-deformation processes within the mold to obtain the aluminum alloy parts. The deformation of the semi-solid aluminum alloy parts during the in-situ primary forging process is 5-70%. The aluminum alloy parts are heat-treated to obtain an Al-Cu aluminum alloy.

[0011] Furthermore, in the low-pressure filling casting process, the filling speed is 0.1-1.2 m / s, the filling time is 2-20 s, the casting pressure is 0.1-40 MPa, the holding time is 2-10 s, the mold temperature is 180-350 ℃, and the alloy casting temperature is 660-720 ℃. In the in-situ primary forging process, the forging temperature is 600-650℃, the forging specific pressure is 50-300MPa, the forging start time is 2-20s, and the holding time is 2-20s. In the in-situ secondary forging pre-deformation treatment, the forging temperature is 250-480℃, the forging specific pressure is 50-500MPa, the holding time is 0-10s, and the deformation amount is 10-70%. The heat treatment includes solution treatment and aging treatment. In the solution treatment, the temperature is 490-530°C and the time is 0.2-20h. In the aging treatment, the temperature is 160-190°C and the time is 2-30h.

[0012] Furthermore, the molding process includes the following steps: The forming process includes die casting and aging treatment. The die casting temperature is 660-720ºC, and the die casting speed is 0.23-2.5 m / s. The aging treatment temperature is 160-190°C, and the time is 2-30 h; or The forming process includes vacuum die casting and heat treatment. The vacuum die casting process has a temperature of 660-700°C, a vacuum degree of 20-80 mbar, an injection speed of 2-5 m / s, and a casting pressure of 80-120 MPa. The heat treatment includes solution treatment and aging treatment. In the solution treatment, the temperature is 480-520°C and the time is 0.2-6 h. In the aging treatment, the temperature is 160-190°C and the time is 2-30 h.

[0013] The present invention also provides an aluminum alloy structural component, wherein at least a portion of the aluminum alloy structural component is made of the above-mentioned Al-Cu aluminum alloy or an Al-Cu aluminum alloy prepared by the preparation method described above.

[0014] In the technical solution of this invention, the Al-Cu aluminum alloy contains 2.5-4% Cu by mass, 0.001-0.6% Si by mass, 0.001-0.5% Fe by mass, 0.001-1.2% Mg by mass, 0-0.8% Mn by mass, 0-0.3% Ti by mass, 0-0.3% Cd by mass, 0-0.3% Cr by mass, 0-0.3% Zr by mass, 0-0.3% V by mass, 0-0.5% Ag by mass, 0-0.1% B by mass, 0.001-0.3% Zn by mass, 0-0.1% Be by mass, 0-0.8% RE by mass, and Al and unavoidable impurities. The addition of Cu, Si, Fe, Mg, Mn, Ti, Cd, Cr, Zr, V, Ag, B, Zn, Be, and RE within the above content range interacts and influences each other, ensuring that Al-Cu aluminum alloys have good formability and excellent mechanical properties. Detailed Implementation

[0015] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0016] One embodiment of the present invention provides an Al-Cu aluminum alloy containing 2.5-4% Cu by mass, 0.001-0.6% Si by mass, 0.001-0.5% Fe by mass, 0.001-1.2% Mg by mass, 0-0.8% Mn by mass, 0-0.3% Ti by mass, 0-0.3% Cd by mass, 0-0.3% Cr by mass, 0-0.3% Zr by mass, 0-0.3% V by mass, 0-0.5% Ag by mass, 0-0.1% B by mass, 0.001-0.3% Zn by mass, 0-0.1% Be by mass, 0-0.8% RE by mass, and Al and unavoidable impurities.

[0017] The specific percentage of Cu by mass can be 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, or 4%.

[0018] The specific percentage content of Si by mass can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, or 0.6%.

[0019] The specific percentage content of Fe by mass can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%.

[0020] The specific percentage content of Mg by mass can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%, 1.1%, or 1.2%.

[0021] The specific percentage content of Mn by mass can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, or 0.8%.

[0022] The specific mass percentage content of Ag can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. The mass percentage content of Ag can be proportional to the mass percentage content of Cu, which allows the mass percentage content of Ag in this invention to reach 0.5%, and it can combine with Cu (specifically, it can react to form an Al2CuAg reinforcing phase) to improve the tensile strength of the aluminum alloy.

[0023] The specific mass percentage contents of Cd, Cr, Zr, V, Ti, and Zn can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, or 0.3%.

[0024] The specific percentage content of B and Be by mass can be 0.0001%, 0.0005%, 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%.

[0025] The specific percentage content of RE by mass can be 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, or 0.8%. RE is at least one of La, Ce, Pr, Nd, Er, Sm, Y, and Gd.

[0026] In one embodiment, the Al-Cu aluminum alloy contains 2.5-4% Cu by mass, 0.01-0.3% Si by mass, 0.05-0.3% Fe by mass, 0.05-1.2% Mg by mass, 0.001-0.5% Mn by mass, 0.001-0.2% Ti by mass, 0.001-0.25% Cd by mass, and [other components not specified in the original text]. The content of Cr is 0.001-0.25%, Zr is 0.001-0.25%, V is 0.001-0.3%, Ag is 0.001-0.5%, B is 0.001-0.1%, Zn is 0.001-0.3%, Be is 0.001-0.1%, and RE is 0.001-0.5%.

[0027] The sum of the mass percentages of Si and Fe is less than 0.6%, specifically 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.22%, 0.24%, 0.26%, 0.28%, 0.3%, 0.32%, 0.34%, 0.36%, 0.38%, 0.4%, 0.42%, 0.44%, 0.46%, 0.48%, 0.5%, 0.52%, 0.54%, 0.56%, and 0.58%. In the mold filling process of integrated casting and forging, a slow, high-pressure push is required to propel the alloy solution into the mold cavity; fluidity of the alloy solution is not required. Therefore, the sum of the mass percentages of Si and Fe can be set to less than 0.7%.

[0028] The sum of the mass percentages of V and Ti is less than 0.4%, and can be between 0.002% and 0.4%, specifically 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, or 0.39%. When V and Ti are combined, their individual contents can be reduced; however, if the combined content exceeds 0.4%, a coarse second phase will form, leading to a decrease in the alloy's mechanical properties.

[0029] The mass ratio of Mn to Fe is greater than 0.4, preferably 0.45-10, and can specifically be 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. Setting the mass ratio of Mn to Fe to be greater than 0.4, preferably 0.45-10, reduces the harmful effects of Fe and improves the release properties and mechanical properties of aluminum alloys through Mn.

[0030] In the technical solution of this invention, the Al-Cu aluminum alloy contains 2.5-4% Cu by mass, 0.001-0.6% Si by mass, 0.001-0.5% Fe by mass, 0.001-1.2% Mg by mass, 0-0.8% Mn by mass, 0-0.3% Ti by mass, 0-0.3% Cd by mass, 0-0.3% Cr by mass, 0-0.3% Zr by mass, 0-0.3% V by mass, 0-0.5% Ag by mass, 0-0.1% B by mass, 0.001-0.3% Zn by mass, 0-0.1% Be by mass, 0-0.8% RE by mass, and Al and unavoidable impurities. The addition of Cu, Si, Fe, Mg, Mn, Ti, Cd, Cr, Zr, V, Ag, B, Zn, Be, and RE within the above-mentioned content ranges interacts and influences each other, ensuring that Al-Cu aluminum alloys possess excellent mechanical properties while maintaining good formability. Specifically: Adding a Cu content of 2.5-4% by mass can significantly improve the tensile strength of aluminum alloys, but it will reduce the elongation. Cu can react with Al, Fe, Si, Mg, Zn, Mn, Ag, etc., to form Al₂Cu, Al₂CuAg, (CuMg)Al₂, AlFeSiCu, Al₂CuZn, and Al₂O₃. 12 CuMn2、τ(Cu2Mn3Al 20 Secondary phases such as Al, Cu, Mg, and Si are added to improve the tensile strength of aluminum alloys. Setting the Si mass percentage content to 0.001-0.6% can improve the process fluidity and die-casting performance of aluminum alloys. Setting the Fe mass percentage content to 0.001-0.5% can improve demolding performance. Fe can also react with Al, Si, Cu, Ni, Mg, and Mn to form Al3Fe, AlFeSi, AlFeSiCu, AlFeMgSiNi, AlFeSiNi, FeNiAl9, AlFeMgSi, α-(Fe,Mn)Al6, α- Secondary phases such as Al(FeMn)Si are used to improve the tensile strength of aluminum alloys. Setting the mass percentage content of Mg to 0.001-1.2% allows Mg to react with Al, Fe, Si, Cu, Zn, etc., to form secondary phases such as AlFeMgSi, (CuMg)Al2, AlCuMgSi, Mg2Si, Mg2Zn, and Mg2SiZn, thereby improving the tensile strength of aluminum alloys. Setting the mass percentage content of Mn to 0-0.8% allows Mn to react with Al, Fe, Si, Cu, etc., to form MnAl2, MnAl6, α-(Fe,Mn)Al6, Al... 12 CuMn2, α-Al(FeMn)Si, τ(Cu2Mn3Al 20The addition of second phases such as Mn and Al can improve the tensile strength of aluminum alloys. Mn can significantly refine the grain size by causing lattice distortion in the matrix and producing MnAl6 dispersed particles through reaction with Al, thereby improving elongation. MnAl6 can also dissolve Fe to form α-(Fe,Mn)Al6 phase, thereby reducing Fe content and mitigating Fe toxicity. Mn can also prevent the formation of long needle-like Fe phases, thus reducing Fe toxicity. Setting the mass percentage content of Ti to 0-0.3% allows Ti to react with Al to form TiAl2 phase, which acts as a non-spontaneous nucleus during crystallization, refining grains, second phases, and precipitates, thereby improving the tensile strength of aluminum alloys. Tensile strength and elongation; Setting the Cr mass percentage content to 0-0.3%, Cr can transform the acicular β-Fe phase into the α-Fe phase to improve the Fe morphology and eliminate the harmful effects of Fe. It can also easily form a dispersed phase with Fe to reduce the Fe content and mitigate its harmful effects. Cr can also hinder the nucleation and growth process of recrystallization, thus improving the tensile strength and elongation of aluminum alloys. Various chromium-containing fine compounds formed by Cr in aluminum alloys can redissolve in the α phase during the solid solution stage, and disperse into various Cr-containing phases, such as the α-AlCrSi dispersed phase, during the natural aging stage. These Cr-containing phases can be used as… The nuclei of heterogeneous nucleation of the θ", β", and S" phases accelerate 、 The formation of θ", β", and S" phases improves the tensile strength of aluminum alloys. Setting the Cd mass percentage content to 0-0.3% refines α-Al; during aging, Cd forms numerous Cd-vacancy clusters, promoting and accelerating the precipitation of Al2CuAg, (CuMg)Al2, Al2Cu, and Mg2Si phases, thus reducing the impact of high Cu content on the elongation of aluminum alloys. Setting the Zr mass percentage content to 0-0.3% increases the tensile strength of aluminum alloys and promotes the precipitation of second phases such as Al2CuAg, (CuMg)Al2, Mg2Zn, Mg2Si, and Al2Cu, reducing the solid solubility of these elements in the aluminum matrix. Zr also refines grains, second phases, and precipitated phases, further improving the elongation of aluminum alloys. Setting the V mass percentage content to 0-0.3% allows V to react with Al to form VAl. 11Refractory compounds such as potassium (V) play a role in refining grains during the casting process. V can also refine the recrystallization structure and increase the recrystallization temperature, thereby improving the tensile strength and elongation of aluminum alloys. Setting the mass percentage content of Ag to 0-0.5% allows Ag to promote the precipitation of second phases such as (CuMg)Al2, Al2Cu, Mg2Si, Mg2Sb, Mg3Sn2, and Mg3Bi2, refining the precipitated phases and increasing their density, thus enhancing the precipitation strengthening effect of the aluminum alloy and improving its mechanical properties. Setting the mass percentage content of boron (B) to 0-0.1% allows B to react with transition metals... Metallic elements (including transition metals such as Fe) undergo borylation reactions to generate compounds that can be separated from molten aluminum alloys, such as ferroboron compounds, thus purifying the molten aluminum alloy. Boron (B) readily adsorbs onto the surface of the iron-rich phase, inhibiting its growth and controlling its size. It also prevents the formation of the iron-rich phase in the molten aluminum alloy. Boron can inhibit the segregation of Ti3Al; therefore, the combined use of Ti and Bo yields better results. Boron can also refine grains, the second phase, and precipitated phases, thereby improving the elongation of the aluminum alloy. Setting the mass percentage content of Be to 0-0.1% can improve the tensile strength of the aluminum alloy and also... The plate-like β-mezzanine phase transforms into the relatively harmless Chinese character-shaped Be-Fe (Al8Fe2SiBe) phase and inhibits the formation of the acicular β-Fe phase, thereby reducing or eliminating the adverse effects of Fe on the properties of aluminum alloys. Be can also promote the formation and precipitation of phases such as Al2CuAg, (CuMg)Al2, Mg2Si, Mg2Zn, Mg2SiZn, and Al2Cu, thereby reducing the solid solubility of these elements in the aluminum matrix. Be can also form an active film on the surface of impurity element phases such as Fe, preventing the growth of impurity elements, and can segregate on grain boundaries or adsorb on solid-liquid interfaces, forming a supercooled phase. This increases the chance of dendrite melting, thereby refining the grains; setting the Zn mass percentage content to 0.001-0.3% allows Zn to improve the mechanical properties of aluminum alloys. Zn can promote the precipitation of second phases such as Al2CuAg, (CuMg)Al2, Al3Fe, AlFeSi, AlFeSiCu, Al2Cu, and Mg2Si, thereby increasing the tensile strength of aluminum alloys. Zn can also eliminate elemental Si to reduce the influence of Si on the properties of aluminum alloys, such as reducing the effect of high Si content on the elongation of aluminum alloys; setting the RE mass percentage content to 0-0.8% of the rare earth element (RE) can refine the alloy microstructure to improve the mechanical properties of aluminum alloys. It can also form a rare earth active film on the surface of Fe-containing phases or combine with Al, Fe, Ti, and other atoms to form rare earth compounds, effectively reducing the solid solution of harmful elements in the aluminum matrix. RE can also transform elongated β-Fe phases into spherical α-Fe phases and modify elemental Si. RE can also promote the precipitation of dispersed phases such as Al2CuAg, (CuMg)Al2, Al2Cu, Al3Fe, and Mg2Si, improving the tensile strength and elongation of aluminum alloys. Furthermore, RE can refine grains, second phases, and precipitated phases (e.g., refining Al2CuAg, (CuMg)Al2, Al2Cu, Mg2Si, and Al3Fe phases), further improving the tensile strength and elongation of aluminum alloys.

[0031] In summary, the tensile strength of aluminum alloys can be significantly improved by increasing the content of Cu and Mg as described above; the fluidity and die-casting performance of aluminum alloys can be ensured by increasing the content of Si as described above; the tensile strength and demolding performance of aluminum alloys can be improved by increasing the content of Fe as described above; the tensile strength and elongation of aluminum alloys can be improved by increasing the content of Ti and V as described above; the tensile strength and elongation of aluminum alloys can be improved by increasing the content of Mn, Cr, B, Be, and RE as described above; the tensile strength of aluminum alloys can be improved by increasing the content of Zr, Cd, Zn, Ni, and Ag as described above, and the precipitation of second phases (such as Al2CuMg, Al2CuAg, Al2Cu, and Mg2Si phases) can be further improved by increasing the content of Zr, Cd, Zn, Ni, and Ag as described above. This results in Al-Cu aluminum alloys with excellent mechanical and formability properties.

[0032] The Al-Cu aluminum alloy also contains 0-0.2% In by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, or 0.2%. In can improve the mechanical properties of aluminum alloys. In can react with other elements to form second phases, thereby improving the mechanical properties of aluminum alloys. Specifically, In can react with Al and Cu to form second phases such as AlIn and CuIn. In addition, In can refine the grains, thereby improving the elongation of aluminum alloys.

[0033] The Al-Cu aluminum alloy also contains 0-0.5% Nb by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. Nb can improve the mechanical properties of aluminum alloys. Nb can react with other elements to form a second phase, thereby improving the mechanical properties of aluminum alloys. Specifically, Nb can react with Ti and Al to form the TiAl-Nb phase. In addition, Nb can refine the grain size, thereby increasing the elongation of the aluminum alloy.

[0034] The Al-Cu aluminum alloy also contains 0-0.3% Ni by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, or 0.3%. Ni can refine the grains, improve the tensile strength of the aluminum alloy, and promote the precipitation of the second phase, increasing the volume fraction and dispersion of the precipitated phase.

[0035] The Al-Cu aluminum alloy also contains 0-0.2% Bi by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, or 0.2%. Bi can improve the mechanical properties of aluminum alloys. Bi can react with other elements to form second phases, thereby improving the mechanical properties of aluminum alloys. Specifically, Bi can react with Mg and Cd to form second phases such as Mg3Bi2 and Mg3(BiCd)2.

[0036] The Al-Cu aluminum alloy also contains 0-0.5% Ge by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. Ge can improve the mechanical properties of aluminum alloys. Ge can react with other elements to improve the mechanical properties of aluminum alloys. Specifically, Ge can react with Al and Si to form second phases such as Al9Ge7, Al6Ge5, Al5Ge2, Al3Ge4, and SiGe. Ge can also promote the precipitation of second phases such as CuAl2, refine the precipitated phases, and reduce the solid solubility of the above elements in the aluminum matrix. Ge can also replace some Si atoms in metastable precipitated phases. The Si-Ge phase precipitated in the early stage of aging provides a nucleation site for the θ phase, increases the density of the θ phase, and further improves the mechanical properties of aluminum alloys.

[0037] The Al-Cu aluminum alloy also contains 0-0.5% Mo by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. Mo can improve the mechanical properties of aluminum alloys. Mo can react with other elements to improve the mechanical properties of aluminum alloys. Specifically, Mo can react with Al, Si, Fe, etc., to form second phases such as AlMo, AlSiMo, and AlSiFeMo, which are dispersed phases distributed at the grain boundaries of the aluminum matrix. In addition, Mo can refine the grains and improve the morphology of Fe-containing intermetallic compounds, further improving the mechanical properties of aluminum alloys.

[0038] The Al-Cu aluminum alloy also contains Sn in a mass percentage of 0-0.5%, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. The Al-Cu aluminum alloy also contains 0-0.5% Te by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. Te can improve the mechanical properties of aluminum alloys. Te can narrow the solidification temperature range of aluminum alloys, form fine petal-like rather than dendritic primary crystals, and reduce or eliminate micro-shrinkage porosity, thereby improving the mechanical properties of aluminum alloys. Sn can also improve the mechanical properties of aluminum alloys. Specifically, Sn can form various high-temperature strengthening phases such as Al9Sn7, Al6Sn5, Al5Sn2, and Al3Sn4 with Al.

[0039] The Al-Cu aluminum alloy also contains 0-0.1% Sr by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%. Sr can alter the morphology of the eutectic Si phase through modification to avoid reducing the elongation of the aluminum alloy when the Si content is high. Sr can also transform the coarse needle-like AlFeSi phase in the ingot into small granular Chinese character-shaped particles, preventing the AlFeSi phase from cutting the aluminum matrix, thereby improving the tensile strength and elongation of the aluminum alloy.

[0040] The Al-Cu aluminum alloy also contains 0-0.5% Co by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. Co can refine the grains to improve the mechanical properties of the aluminum alloy, and can also react with other elements to form a second phase, further improving the mechanical properties of the aluminum alloy. Specifically, Co can react with Al, Fe, Si, etc., to form Al 15Secondary phases include (Fe,Co)3Si2 and Al3(Fe,Co). Furthermore, Co has a refining effect on the Al3Fe phase, transforming coarse needle-like and plate-like β-Al3Fe phases into small flower-like and fine strip-like α-Al3Fe phases. 15 The (Fe,Co)3Si2 phase can also promote α-Al 15 The precipitation of the (Fe,Co)3Si2 phase further improves the mechanical properties of aluminum alloys. The combined addition of Ni and Co can effectively modify Fe and transform free Fe into the second phase. The combined addition of Co, Ni and Be can rapidly reduce their solid solubility in the alloy and increase the volume fraction of the second phase, thereby improving the mechanical properties of aluminum alloys.

[0041] The Al-Cu aluminum alloy also contains 0-0.5% Ca by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. Ca can improve the β-Fe phase to reduce the harmful effects of Fe. It can also react with Al, Cu, Zn, and Si to form second phases such as Al4Ca, Al2Ca3, AlCa2, AlCaCu, CaZn, CaAlZn, and Al2CaSi2, thereby improving the tensile strength of aluminum alloys. Ca can also refine the eutectic structure and improve the β-Fe phase. It also has a modifying effect on Al-Cu alloys, refining the Si phase. Sn can react with Al, Mg, and Sc to form second phases such as Al9Sn7, Al6Sn5, Al5Sn2, Al3Sn4, Mg2Sn, and Mg2ScSn, thereby improving the tensile strength of aluminum alloys. Sn can promote the precipitation of second phases such as Mg2Si, Mg2Zn, Mg2SiZn, and Al2Cu, thereby reducing the solid solubility of these elements in the aluminum matrix. Ca and Sn can also significantly reduce the surface tension of molten aluminum alloys, reducing or even eliminating the influence of the surface tension of the oxide film on the aluminum alloy surface, thereby improving the fluidity of aluminum alloys. The combination of Ca and RE can significantly refine the grains and the second phase, thereby improving tensile strength, fluidity, and elongation.

[0042] This invention also provides a method for preparing Al-Cu aluminum alloys, comprising the following steps: Aluminum liquid is obtained by heating an Al source at a temperature of 750-830°C; At a temperature of 720-780°C, Cu source, Si source, Fe source, Mg source, Mn source, Ti source, Cd source, Cr source, Zr source, V source, Ag source, B source, Zn source, Be source, and RE source are added to the aluminum liquid to obtain an alloy liquid; The alloy liquid is refined, slag removed, and formed to obtain an Al-Cu aluminum alloy. The Al-Cu aluminum alloy contains 2.5-4% Cu by mass, 0.001-0.6% Si by mass, 0.001-0.5% Fe by mass, 0.001-1.2% Mg by mass, 0-0.8% Mn by mass, 0-0.3% Ti by mass, and [other components not specified in the original text]. The composition includes 0-0.3% Cd, 0-0.3% Cr, 0-0.3% Zr, 0-0.3% V, 0-0.5% Ag, 0-0.1% B, 0.001-0.3% Zn, 0-0.1% Be, 0-0.8% RE, and Al and unavoidable impurities.

[0043] Sources such as Cu, Si, Fe, Mg, Mn, Ti, Cd, Cr, Zr, V, Ag, B, Zn, Be, and RE can be added in the form of elements or alloys.

[0044] At least one of the following sources can be added to the molten aluminum: In, Ni, Nb, Bi, Ge, Mo, Sn, Sr, Te, Co, and Ca. These raw materials can also be added in elemental form or as intermediate alloys.

[0045] The degassing process involves adjusting the temperature of the molten alloy to 650-780℃ and introducing an inert gas such as argon into the molten alloy using a degassing machine. Specific degassing temperatures can be 650℃, 660℃, 670℃, 680℃, 690℃, 700℃, 710℃, 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, or 780℃. The degassing time is 10-30 minutes, specifically 10 minutes, 15 minutes, 20 minutes, 25 minutes, or 30 minutes.

[0046] The refining process involves introducing inert gases such as argon into the molten alloy using a degasser. A refining agent can be added simultaneously. The vortex formed by the degasser's rotating disc in the molten alloy allows the refining agent to be evenly mixed into the alloy. The refining agent refines the alloy microstructure, thereby improving the tensile strength and elongation of the aluminum alloy. It has the advantages of good dispersibility and low cost. The refining time is 10-30 minutes, specifically 10, 15, 20, 25, or 30 minutes. The refining temperature is 650-780℃, specifically 650℃, 660℃, 670℃, 680℃, 690℃, 700℃, 710℃, 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, or 780℃. The refining agent contains: 5-10 parts potassium fluoroaluminate, 6-20 parts AlTi5B1 metal powder, 8-25 parts potassium titanate whisker powder, 20-40 parts sodium chloride + potassium chloride, 5-10 parts potassium nitrate, 5-10 parts potassium carbonate, and 0.5-3 parts potassium silicate.

[0047] The parting surface of the mold can undergo surface treatment to form a boron carbide layer. This layer not only improves demolding performance but also enhances the mold's wear resistance and protects against corrosion from acids, alkalis, salts, and other chemicals, as well as thermal erosion of aluminum alloys, thus extending the mold's service life. The thickness of the boron carbide layer can range from 1 to 10 mm, specifically 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm. The surface treatment can involve mixing a boron-containing gas (such as BCl3) with a carbon-containing gas (such as CH4) to obtain a mixed gas. This mixed gas is then introduced into the cavity, and through chemical vapor deposition (CVD), the boron-containing and carbon-containing gases react chemically and deposit onto the parting surface to form the boron carbide layer. The CVD temperature is 900-1200°C, the deposition pressure is 200-500 Pa, and the carrier gas flow rate is 100-200 sccm. The boron carbide layer can increase the hardness of mold steel to 3000-4000 Hv; the boron carbide layer can reduce the affinity of the mixed melt to the mold surface, improve the demolding performance of aluminum alloy, and greatly increase the elongation of aluminum alloy; the boron carbide layer can resist the corrosion of chemicals such as acids, alkalis, and salts, and can improve the corrosion resistance of aluminum alloy; the boron carbide layer can maintain good physical and chemical properties at high temperature, and can improve the thermal stability of aluminum alloy; the boron carbide layer has an extremely low coefficient of friction, which can improve the surface smoothness of aluminum alloy and significantly reduce the wear and energy consumption of aluminum alloy products caused by mechanical friction; the boron carbide layer also has high heat transfer properties. During the instant of aluminum alloy forming, the boron carbide layer can quickly conduct away heat, increasing the heat transfer rate of the mold by 2-4 times that of ordinary molds, allowing the aluminum alloy to cool down faster.

[0048] In one embodiment, the forming process includes: die casting the alloy liquid at a temperature of 660-720ºC (i.e., ordinary die casting), followed by aging treatment. During the die casting process, the die casting speed of the die casting machine is 0.23-2.5 m / s. During the die casting process, the temperature cooling rate is 50-150 K / s, specifically 50 K / s, 60 K / s, 70 K / s, 80 K / s, 90 K / s, 100 K / s, 110 K / s, 120 K / s, 130 K / s, 140 K / s, or 150 K / s. During the die casting process, a temperature cooling rate of 50-150 K / s can suppress the formation of the β-AlFeSi phase, generating only a small amount of dispersed AlFe phase. The AlFe phase can improve the tensile strength of the aluminum alloy without affecting its elongation. Solution treatment promotes uniform diffusion of solute atoms, dissolves coarse second phases (such as MgZn2 phase, Mg2Si phase, Al2Cu phase, and AlFeSi phase, if present), and increases the solid solubility of alloying elements in the aluminum matrix, creating conditions for subsequent aging treatment. During aging heat treatment, the precipitated phases gradually grow, resulting in aluminum alloy products with excellent comprehensive properties (including tensile strength and elongation). The aging treatment temperature is 160-190℃, specifically 160℃, 165℃, 170℃, 175℃, 180℃, 185℃, or 190℃, for 2-30 hours, specifically 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 15 hours, 20 hours, 25 hours, or 30 hours. During aging treatment, the precipitated phases gradually grow, resulting in aluminum alloy products with excellent comprehensive properties (including tensile strength and elongation).

[0049] In another embodiment, the forming process includes: vacuum die casting of the alloy liquid at a temperature of 660-700°C, followed by heat treatment. In the vacuum die casting process, the vacuum degree is 30-50 mbar, the injection speed is 2-5 m / s, and the casting pressure is 80-120 MPa. It is understood that vacuum die casting can significantly reduce the porosity of aluminum alloy castings and increase their density, resulting in higher tensile strength and elongation of the aluminum alloy after vacuum die casting compared to that after ordinary die casting. During vacuum die casting, the cooling rate is 100-200 K / s, specifically 100 K / s, 110 K / s, 120 K / s, 130 K / s, 140 K / s, 150 K / s, 160 K / s, 170 K / s, 180 K / s, 190 K / s, or 200 K / s. At a cooling rate of 100-200 K / s, the formation of the β-AlFeSi phase is suppressed, resulting in only a small amount of dispersed AlFe phase. This AlFe phase improves the tensile strength of the aluminum alloy without affecting its elongation. Heat treatment includes solution treatment and aging treatment. In solution treatment, the temperature is 480-520℃, specifically 480℃, 485℃, 490℃, 495℃, 500℃, 505℃, 510℃, 515℃, or 520℃, and the time is 0.2-6h, specifically 0.2h, 0.5h, 1h, 2h, 3h, 4h, 5h, or 6h. In aging treatment, the temperature is 160-190℃, specifically 160℃, 165℃, 170℃, 175℃, 180℃, 185℃, or 190℃, and the time is 2-30h, specifically 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 15h, 20h, 25h, or 30h. During solution treatment, the solute atoms diffuse more uniformly, dissolving coarse second phases (such as Al2CuAg, (CuMg)Al2, MgZn2, Mg2Si, Al2Cu, and AlFeSi phases, if present), and increasing the solid solubility of alloying elements in the aluminum matrix, thus creating conditions for subsequent aging treatment. During aging treatment, the precipitated phases gradually grow, resulting in aluminum alloy products with excellent comprehensive properties (including tensile strength and elongation).

[0050] It is understandable that, despite the use of cooling treatment, die casting and vacuum die casting processes, a small amount of β-AlFeSi phase will still exist.

[0051] In another embodiment, the forming process includes the following steps: molten alloy is pushed into a mold and subjected to low-pressure filling casting. Once the molten alloy enters the semi-solid solidification zone, a semi-solid aluminum alloy part is formed. The semi-solid aluminum alloy part is then subjected to in-situ primary forging and in-situ secondary forging pre-deformation processes within the mold to obtain the aluminum alloy part. The deformation amount of the semi-solid aluminum alloy part in the in-situ primary forging process is 5-70%, and the deformation amount in the in-situ secondary forging process is 10-70%. The aluminum alloy part is then heat-treated to obtain an Al-Cu aluminum alloy. Preferably, the deformation amount of the semi-solid aluminum alloy part in the in-situ primary forging process is greater than the deformation amount in the in-situ secondary forging process.

[0052] In low-pressure filling casting, the filling speed (i.e., the moving speed of the punch) is 0.1-1.2 m / s, the filling time (i.e., the time required for the molten alloy to completely fill the mold) is 2-20 s, the casting pressure is 0.1-40 MPa, the holding time is 2-10 s (i.e., the time to hold the molten alloy under a certain pressure after it has completely filled the mold), the mold temperature is 180-350℃, and the alloy casting temperature (i.e., the temperature when the molten alloy is filled into the mold) is 660-720℃.

[0053] A filling speed of 0.1-1.2 m / s increases the fluidity of the molten alloy, facilitating its full filling of the cavity. At this speed, the pressure applied by the punch to the molten alloy is also relatively low (specific pressure approximately 50-200 MPa), preventing casting defects such as porosity, shrinkage cavities, and looseness in the aluminum alloy product. It also avoids splashing and turbulence caused by excessively fast filling speeds, which can lead to casting defects such as oxide inclusions and air entrapment. Specific filling speeds can be 0.1 m / s, 0.2 m / s, 0.3 m / s, 0.4 m / s, 0.5 m / s, 0.6 m / s, 0.7 m / s, 0.8 m / s, 0.9 m / s, 1 m / s, 1.05 m / s, 1.1 m / s, 1.15 m / s, or 1.2 m / s. Specific filling times can be 2 s, 5 s, 10 s, 15 s, or 20 s.

[0054] Under casting pressures ranging from 0.1 to 40 MPa, the molten alloy is relatively stable and can solidify in a directional sequence. The precipitated phases within the semi-solid aluminum alloy parts are perpendicular to the basal surface of the aluminum alloy matrix. When the molten alloy solidifies stably, there are fewer pores, looseness, and cracks in the semi-solid aluminum alloy parts. Specific casting pressures can be 0.1 MPa, 0.5 MPa, 1 MPa, 5 MPa, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, or 40 MPa.

[0055] Semi-solid aluminum alloy parts can be formed within a holding time of 2-10 seconds and a casting pressure of 0.1-40 MPa. As the holding time and casting pressure increase, the casting microstructure within the semi-solid aluminum alloy parts gradually becomes more uniform and dense. After 10 seconds or if the casting pressure is too high, the liquid phase within the mold completely solidifies, preventing the formation of semi-solid aluminum alloy parts. Specific holding times can be 2s, 3s, 4s, 5s, 6s, 7s, 8s, 9s, or 10s.

[0056] The low-pressure filling casting process of this invention requires lower casting and mold preheating temperatures, which not only reduces thermal shock corrosion to the mold but also saves energy. The mold temperature can specifically be 180°C, 200°C, 250°C, 300°C, or 350°C. The alloy casting temperature can specifically be 660°C, 670°C, 680°C, 690°C, 700°C, 710°C, or 720°C.

[0057] In semi-solid aluminum alloy parts, the solid-liquid ratio, or solid phase fraction, is 20-90%, specifically 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%. At this solid-liquid ratio, there are fewer casting defects in semi-solid aluminum alloy parts, and the precipitated phases within them solidify almost entirely vertically.

[0058] In the in-situ primary forging process, the forging temperature (i.e., the temperature of the semi-solid aluminum alloy parts in the mold) is 600-650℃, the forging specific pressure is 50-300MPa, the forging start time (i.e., the time interval between the formation of the semi-solid aluminum alloy parts and the in-situ primary forging process) is 2-20s, the holding time is 2-20s, and the deformation is 5-70%. After this in-situ primary forging process, the semi-solid aluminum alloy parts are transformed into solid parts.

[0059] Setting the forging temperature to 600-650℃ ensures the alloy remains in a semi-solid state. Specific forging temperatures can be 600℃, 610℃, 620℃, 630℃, 640℃, or 650℃. Specific forging pressures can be 50MPa, 60MPa, 70MPa, 80MPa, 90MPa, 100MPa, 120MPa, 140MPa, 160MPa, 180MPa, 200MPa, 220MPa, 240MPa, 260MPa, 280MPa, or 300MPa. Specific forging start times can be 2s, 3s, 4s, 5s, 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s, 14s, 15s, 16s, 17s, 18s, 19s, or 20s. The pressure holding time can be 2s, 3s, 4s, 5s, 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s, 14s, 15s, 16s, 17s, 18s, 19s, or 20s.

[0060] With a deformation amount of 5-70%, semi-solid aluminum alloy parts can be transformed into solid aluminum alloy parts after in-situ primary forging. As the deformation amount increases, the volume fraction of Al2CuMg precipitates in the solid aluminum alloy parts gradually increases, while the volume fraction of Al2Cu phase gradually decreases, thereby improving the mechanical properties of the aluminum alloy (including tensile strength and elongation). The preferred deformation amount is 20-60%, with the precipitates being essentially perpendicular to the basal plane, significantly improving the alloy's mechanical properties (including tensile strength and elongation). Specific deformation amounts can be 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, or 70%.

[0061] In this in-situ primary forging process, the semi-solid aluminum alloy parts are not cooled, removed from the mold, and then placed in the forging device for reheating to the forging temperature. Instead, the semi-solid aluminum alloy parts are directly subjected to in-situ primary forging in the original mold without the need for cooling and reheating. This allows the solid-liquid mixed phases present in the semi-solid aluminum alloy parts to deform and solidify uniformly in the in-situ primary forging process on the basis of low-pressure filling casting (without cooling to room temperature before reheating and forging, the deformation during cooling and heating is uncontrollable and it is difficult to maintain the semi-solid state). This further eliminates casting defects in the semi-solid aluminum alloy parts, significantly refines the coarse grains and the second-phase as-cast structure, refines the size of the precipitates, and introduces a large number of nano-sized precipitates inside the grains. The volume fraction of the precipitates gradually increases, thereby improving the mechanical properties of the alloy.

[0062] To improve the smooth transition between low-pressure filling casting and in-situ primary forging, a first cooling process is performed during low-pressure filling casting. This ensures that semi-solid aluminum alloy parts with a temperature of 600-650℃ are obtained immediately after pressure holding, allowing for faster entry into the in-situ primary forging process. Alternatively, if the first cooling process during low-pressure filling casting does not result in a semi-solid aluminum alloy part with a solid content of 20-90% after pressure holding (e.g., the solid content is below 20%), a semi-solid aluminum alloy part with a temperature of 600-650℃ (solid content of 20-90%) can be obtained by undergoing a forging start-up time. Or, a second cooling process during the forging start-up time and in-situ primary forging can achieve a semi-solid aluminum alloy part with a temperature of 600-650℃ (solid content of 20-90%). A circulating oil circuit, such as a 3D contour cooling circuit, can be configured for cooling and temperature control.

[0063] In low-pressure filling casting, the cooling rate for the first cooling process is 1-50℃ / s, specifically 1℃ / s, 5℃ / s, 10℃ / s, 15℃ / s, 20℃ / s, 25℃ / s, 30℃ / s, 35℃ / s, 40℃ / s, 45℃ / s, or 50℃ / s. In in-situ primary forging, the cooling rate for the second cooling process is 5-60℃ / s, specifically 5℃ / s, 10℃ / s, 15℃ / s, 20℃ / s, 25℃ / s, 30℃ / s, 35℃ / s, 40℃ / s, 45℃ / s, 50℃ / s, 55℃ / s, or 60℃ / s.

[0064] In in-situ two-stage forging pre-deformation treatment, the forging temperature is 250-480℃, the forging specific pressure is 50-500MPa, the holding time is 0-10s, and the deformation is 10-70%. The deformation of semi-solid aluminum alloy parts in in-situ one-stage forging treatment is greater than that of solid aluminum alloy parts in in-situ two-stage forging pre-deformation treatment. The deformation of semi-solid aluminum alloy parts in in-situ one-stage forging treatment is 2.5-25 times that of solid aluminum alloy parts in in-situ two-stage forging pre-deformation treatment.

[0065] The specific forging temperature can be 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, or 480℃. Temperatures below 250℃ can lead to breakage of aluminum alloy parts, while temperatures above 480℃ can easily cause complete recrystallization, resulting in excessively large grain and precipitated phase sizes, which is also unfavorable for twin formation, leading to a decrease in mechanical properties.

[0066] The forging specific pressure can be 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa, 120 MPa, 140 MPa, 160 MPa, 180 MPa, 200 MPa, 220 MPa, 240 MPa, 260 MPa, 280 MPa, 300 MPa, 320 MPa, 340 MPa, 360 MPa, 380 MPa, 400 MPa, 420 MPa, 440 MPa, 460 MPa, 480 MPa, or 500 MPa. The forging specific pressure in the in-situ secondary forging pre-deformation treatment is preferably greater than the forging specific pressure in the in-situ primary forging treatment to further promote the refinement of the precipitated phase size. In one embodiment, the forging specific pressure of the in-situ secondary forging pre-deformation treatment is 1.5-5 times that of the forging specific pressure in the in-situ primary forging treatment, specifically 1.5 times, 2 times, 2.5 times, 3 times, 3.5 times, 4 times, 4.5 times, or 5 times.

[0067] The holding time can be 0s, 1s, 2s, 3s, 4s, 5s, 6s, 7s, 8s, 9s, or 10s. For example, after in-situ primary forging, when the parameter requirements of in-situ secondary forging pre-deformation are met, the pressure can be held for a certain period of time (e.g., 2s). For example, when the parameters reach the in-situ secondary forging pre-deformation, the in-situ secondary forging pre-deformation can be stopped immediately, and subsequent heat treatment can be carried out. This holding time can be 0s. For example, when the parameters reach the in-situ secondary forging pre-deformation, the pressure can be held for 5s before subsequent heat treatment.

[0068] The deformation amount can be 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, or 70%.

[0069] The deformation amount in the in-situ primary forging process is 0.5-7 times that in the in-situ secondary forging pre-deformation process, specifically 0.5, 3, 4, 5, 6, or 7 times. This process effectively eliminates casting defects in semi-solid aluminum alloy parts and initially refines the grains and second-phase as-cast structure, resulting in a large number of nanoscale precipitates within the grains. The in-situ secondary forging pre-deformation process further refines these precipitates, leading to an aluminum alloy with excellent mechanical properties.

[0070] Understandably, the mold is an integrated casting and forging mold, where the punch, driven by a feed rod, pushes the mixture into the mold cavity for casting and forging. During low-pressure filling casting, the filling speed and time can be adjusted by regulating the punch speed. The downward pressure of the punch during filling generates injection force, and the stroke of the punch after filling generates additional pressure. This injection force and additional pressure can be used to regulate the casting pressure during the casting process. Similarly, in subsequent in-situ primary forging and secondary forging pre-deformation processes, the forging pressure can also be adjusted by regulating the punch stroke.

[0071] To improve the smoothness of the connection between the in-situ primary forging process and the in-situ secondary forging pre-deformation process, a second cooling process was carried out during the in-situ primary forging process. This allows solid aluminum alloy parts with a temperature of 250-420℃ to be obtained as soon as possible after the pressure holding is completed, so that they can enter the in-situ secondary forging pre-deformation process as soon as possible.

[0072] The high dislocation density generated by the pre-formed twins through in-situ secondary forging pre-deformation treatment provides more diffusion pathways for the dissolution of Cu, Mg, Si, Fe, Ag, and Mn solute atoms in the aluminum matrix, accelerates aging kinetics and promotes the nucleation of precipitates, thus accelerating the formation of precipitates during aging, enhancing the age hardening response of the alloy, and further refining the grain size.

[0073] A third cooling process was performed during the in-situ secondary forging pre-deformation treatment to facilitate the formation of twins. The cooling rate for this third cooling process in the in-situ secondary forging pre-deformation treatment was 20-60℃ / s, specifically 20℃ / s, 25℃ / s, 30℃ / s, 35℃ / s, 40℃ / s, 45℃ / s, 50℃ / s, 55℃ / s, or 60℃ / s. Cooling treatment was performed during the low-pressure filling casting process, in-situ primary forging process, and in-situ secondary forging pre-deformation process. After the low-pressure filling casting process, in-situ primary forging process, and in-situ secondary forging pre-deformation process with cooling treatment, not only was the precipitation of Al2CuAg, Al2CuMg, and Al2Cu phases promoted, but the proportion of Al2CuAg and Al2CuMg precipitates also gradually increased, inhibiting the formation of coarse Al2Cu phase, improving the tensile strength of aluminum alloy, and avoiding excessive Al2Cu phase to reduce the elongation of aluminum alloy.

[0074] In one embodiment, the heat treatment includes solution treatment and aging treatment. In the solution treatment, the temperature is 490-530℃, specifically 490℃, 495℃, 500℃, 505℃, 510℃, 515℃, 520℃, 525℃, or 530℃, and the time is 0.2-20 hours, specifically 0.2 hours, 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 1 hour. The aging treatment can be carried out at temperatures ranging from 160 to 190°C (specifically 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, or 190°C) for 2 to 30 hours (specifically 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 15 hours, 20 hours, 25 hours, or 30 hours). During solution treatment, the solute atoms diffuse evenly, dissolving coarse second phases (such as Al2CuAg, (CuMg)Al2, MgZn2, Mg2Si, Al2Cu, and AlFeSi phases, if present) and increasing the solid solubility of alloying elements in the aluminum matrix, thus creating conditions for subsequent aging treatment. During the aging heat treatment process, the precipitated phase gradually grows, resulting in aluminum alloy products with excellent comprehensive properties (including tensile strength and elongation).

[0075] During solution treatment, the solute atoms diffuse uniformly, dissolving coarse second phases (such as Al2CuAg, (CuMg)Al2, MgZn2, Mg2Si, Al2Cu, AlFeSi, and Al2CuMg, if present), and increasing the solid solubility of alloying elements in the aluminum matrix, creating conditions for subsequent aging treatment. During aging heat treatment, new precipitates formed along the prismatic or pyramidal surfaces grow uniformly and diffusely along their original orientation. These precipitates, perpendicular to the basal plane of the alloy matrix, significantly improve the tensile strength and elongation of the alloy. Thus, in-situ primary forging can eliminate casting defects in the semi-solid alloy formed during low-pressure filled casting and refine the alloy. In in-situ secondary forging pre-deformation, pre-formed twins intensify the vertical precipitation of more precipitates. In solution treatment, the solid solubility further increases, and in subsequent aging treatment, the precipitates gradually grow. The combination of low-pressure filling casting, in-situ first-stage forging, in-situ second-stage forging pre-deformation, and heat treatment yields aluminum alloy products with excellent comprehensive performance (including tensile strength and elongation).

[0076] In this invention, an alloy liquid containing Cu, Si, Fe, Mg, Mn, Ti, Cd, Cr, Zr, V, Ag, B, Zn, Be, and RE elements is refined, degassed, and formed to obtain an Al-Cu aluminum alloy. The combined addition of Cu, Si, Fe, Mg, Mn, Ti, Cd, Cr, Zr, V, Ag, B, Zn, Be, and RE elements within the aforementioned content range interacts and influences each other, resulting in superior mechanical properties for the Al-Cu aluminum alloy. The alloy liquid may further contain at least one source selected from In, Ni, Nb, Bi, Ge, Mo, Sn, Sr, Te, Co, and Ca.

[0077] During the forming process, the molten alloy is pushed into the mold by a punch for low-pressure filling casting. Once the molten alloy enters the semi-solid solidification zone, the semi-solid aluminum alloy part undergoes in-situ first-stage forging with large deformation and in-situ second-stage forging pre-deformation treatment within the mold to obtain the aluminum alloy part. The aluminum alloy part is then heat-treated to obtain the aluminum alloy product. This aluminum alloy product not only possesses the structural complexity of cast products but also the high strength and toughness of deformed products. The method eliminates the need to remove the semi-solid aluminum alloy part from the low-pressure filling casting mold and place it into the mold for subsequent multi-stage forging, giving the aluminum alloy preparation method of this invention advantages such as fewer process steps, shorter production cycle, higher production efficiency, and lower cost. During the low-pressure filling casting process, casting defects inside the aluminum alloy part are minimal. During the in-situ primary forging process with large deformation, casting defects inside the semi-solid aluminum alloy parts are further eliminated, and the coarse grains and second-phase as-cast structure are significantly refined. A large number of nanoscale precipitates appear inside the grains, and the size of the precipitates is refined, increasing the volume fraction of the precipitates and improving the mechanical properties of the alloy (including tensile strength and elongation). During the in-situ secondary forging pre-deformation process, the grain size can be further refined. The high-density dislocation density generated by the pre-formed twins provides more diffusion pathways for the dissolution of Cu, Mg, Si, Fe, Ag, and Mn solute atoms in the aluminum matrix during subsequent heat treatment. This accelerates the aging kinetics and promotes the nucleation of precipitates, enhancing the age hardening response of the alloy and accelerating the formation of precipitates during aging, further increasing the volume fraction of precipitates and thus improving the mechanical properties of the alloy.

[0078] This invention also provides an aluminum alloy structural component, at least a portion of which is made of the aforementioned Al-Cu aluminum alloy or an Al-Cu aluminum alloy prepared by the same method. The aluminum alloy structural component possesses excellent mechanical properties and elongation, and can be applied in aerospace, automotive and transportation, military and weaponry, mold and machinery manufacturing, and special high-temperature aluminum alloy structural components. Since this aluminum alloy structural component employs all the technical solutions of all the embodiments of the aforementioned Al-Cu aluminum alloy, it possesses at least all the beneficial effects brought about by the technical solutions of the aforementioned embodiments, which will not be elaborated upon here.

[0079] For aluminum alloy structural components, the mechanical properties decrease sharply with increasing thickness. However, the aluminum alloy of this invention, when using an integrated casting and forging process, maintains good mechanical properties even when its thickness is greater than 3mm, and further greater than 5mm. Furthermore, when using die casting and vacuum die casting processes, the aluminum alloy of this invention maintains good mechanical properties even when its thickness is greater than 2mm.

[0080] Example Please refer to Table 1 for the composition and content of the aluminum alloys in Examples 1 to 13, and Table 2 for the performance test results.

[0081] Table 1. Composition and content of aluminum alloys in Examples 1 to 13 For the sake of simplicity, the content of trace elements such as impurities in the examples is not shown.

[0082] When preparing the aluminum alloys of Examples 1 to 14, the preparation methods of these aluminum alloys differ in the types and contents of elements, as well as in the forming process. Other steps, such as Al source heating temperature, refining process, and degassing process, can be the same.

[0083] In preparing the Al-Cu integrated cast-forged aluminum alloy of Example 1, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging pre-deformation, solution treatment, and aging treatment. In the low-pressure filling casting, the filling speed was 0.1 m / s, the filling time was 20 s, the casting pressure was 0.2 MPa, the holding time was 2 s, the mold temperature was 200℃, the alloy casting temperature was 660℃, and the cooling rate was 5℃ / s. In the in-situ primary forging, the forging temperature was 600℃, the forging specific pressure was 60 MPa, the forging start time was 7 s, the holding time was 17 s, the cooling rate was 10℃ / s, and the deformation was 10%. In the in-situ secondary forging pre-deformation, the forging temperature was 430℃, the forging specific pressure was 110 MPa, the holding time was 2 s, the cooling rate was 50℃ / s, and the deformation was 10%. The solution treatment was carried out at a temperature of 530℃ for 6 hours. The aging treatment was carried out at a temperature of 170℃ for 3 hours.

[0084] In preparing the Al-Cu integrated cast-forged aluminum alloy of Example 2, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging pre-deformation, solution treatment, and aging treatment. In the low-pressure filling casting, the filling speed was 0.2 m / s, the filling time was 15 s, the casting pressure was 0.5 MPa, the holding time was 2 s, the mold temperature was 200℃, the alloy casting temperature was 660℃, and the cooling rate was 5℃ / s. In the in-situ primary forging, the forging temperature was 610℃, the forging specific pressure was 300 MPa, the forging start time was 4 s, the holding time was 20 s, the cooling rate was 10℃ / s, and the deformation was 70%. In the in-situ secondary forging pre-deformation, the forging temperature was 410℃, the forging specific pressure was 120 MPa, the holding time was 5 s, the cooling rate was 30℃ / s, and the deformation was 15%. The solution treatment was carried out at a temperature of 525℃ for 6 hours. The aging treatment was carried out at a temperature of 175℃ for 2 hours.

[0085] In preparing the Al-Cu integrated cast-forged aluminum alloy of Example 3, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging pre-deformation, solution treatment, and aging treatment. In the low-pressure filling casting, the filling speed was 0.6 m / s, the filling time was 10 s, the casting pressure was 40 MPa, the holding time was 6 s, the mold temperature was 260℃, the alloy casting temperature was 720℃, and the cooling rate was 10℃ / s. In the in-situ primary forging, the forging temperature was 600℃, the forging specific pressure was 300 MPa, the forging start time was 2 s, the holding time was 7 s, the cooling rate was 30℃ / s, and the deformation was 49%. In the in-situ secondary forging pre-deformation, the forging temperature was 390℃, the forging specific pressure was 80 MPa, the holding time was 1 s, the cooling rate was 20℃ / s, and the deformation was 15%. In the solution treatment, the temperature was 510℃ and the time was 10h; in the aging treatment, the temperature was 170℃ and the time was 6h.

[0086] In preparing the Al-Cu integrated cast-forged aluminum alloy of Example 4, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging pre-deformation, solution treatment, and aging treatment. In the low-pressure filling casting, the filling speed was 0.5 m / s, the filling time was 12 s, the casting pressure was 35 MPa, the holding time was 3 s, the mold temperature was 260℃, the alloy casting temperature was 660℃, and the cooling rate was 10℃ / s. In the in-situ primary forging, the forging temperature was 600℃, the forging specific pressure was 280 MPa, the forging start time was 2 s, the holding time was 10 s, the cooling rate was 15℃ / s, and the deformation was 49%. In the in-situ secondary forging pre-deformation, the forging temperature was 450℃, the forging specific pressure was 120 MPa, the holding time was 1 s, the cooling rate was 30℃ / s, and the deformation was 15%. In the solution treatment, the temperature was 520℃ and the time was 10h; in the aging treatment, the temperature was 170℃ and the time was 25h.

[0087] In preparing the Al-Cu integrated cast-forged aluminum alloy of Example 5, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging pre-deformation, solution treatment, and aging treatment. In the low-pressure filling casting, the filling speed was 1.1 m / s, the filling time was 3 s, the casting pressure was 3 MPa, the holding time was 2 s, the mold temperature was 350℃, the alloy casting temperature was 720℃, and the temperature cooling rate was 40℃ / s. In the in-situ primary forging, the forging temperature was 600℃, the forging specific pressure was 120 MPa, the forging start time was 2 s, the holding time was 10 s, the temperature cooling rate was 20℃ / s, and the deformation was 20%. In the in-situ secondary forging pre-deformation, the forging temperature was 400℃, the forging specific pressure was 150 MPa, the holding time was 1 s, the temperature cooling rate was 20℃ / s, and the deformation was 25%. In the solution treatment, the temperature was 490℃ and the time was 0.2h; in the aging treatment, the temperature was 160℃ and the time was 2h.

[0088] In preparing the Al-Cu integrated cast-forged aluminum alloy of Example 6, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging pre-deformation, solution treatment, and aging treatment. In the low-pressure filling casting, the filling speed was 1.1 m / s, the filling time was 3 s, the casting pressure was 5 MPa, the holding time was 2 s, the mold temperature was 350℃, the alloy casting temperature was 710℃, and the cooling rate was 30℃ / s. In the in-situ primary forging, the forging temperature was 610℃, the forging specific pressure was 140 MPa, the forging start time was 2 s, the holding time was 12 s, the cooling rate was 20℃ / s, and the deformation was 25%. In the in-situ secondary forging pre-deformation, the forging temperature was 370℃, the forging specific pressure was 160 MPa, the holding time was 1 s, the cooling rate was 20℃ / s, and the deformation was 30%. In the solution treatment, the temperature was 490℃ and the time was 15h; in the aging treatment, the temperature was 185℃ and the time was 8h.

[0089] In preparing the Al-Cu integrated cast-forged aluminum alloy of Example 7, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging pre-deformation, solution treatment, and aging treatment. In the low-pressure filling casting, the filling speed was 1 m / s, the filling time was 5 s, the casting pressure was 15 MPa, the holding time was 10 s, the mold temperature was 300 °C, the alloy casting temperature was 700 °C, and the cooling rate was 10 °C / s. In the in-situ primary forging, the forging temperature was 610 °C, the forging specific pressure was 80 MPa, the forging start time was 3 s, the holding time was 13 s, the cooling rate was 15 °C / s, and the deformation was 10%. In the in-situ secondary forging pre-deformation, the forging temperature was 415 °C, the forging specific pressure was 500 MPa, the holding time was 1 s, the cooling rate was 60 °C / s, and the deformation was 60%. The solution treatment was carried out at a temperature of 515℃ for 8 hours. The aging treatment was carried out at a temperature of 180℃ for 5 hours.

[0090] In preparing the Al-Cu cast-forged aluminum alloy of Example 8, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging pre-deformation, solution treatment, and aging treatment. In the low-pressure filling casting, the filling speed was 0.8 m / s, the filling time was 10 s, the casting pressure was 20 MPa, the holding time was 10 s, the mold temperature was 300 °C, the alloy casting temperature was 700 °C, and the cooling rate was 10 °C / s. In the in-situ primary forging, the forging temperature was 600 °C, the forging specific pressure was 60 MPa, the forging start time was 3 s, the holding time was 18 s, the cooling rate was 10 °C / s, and the deformation was 10%. In the in-situ secondary forging pre-deformation, the forging temperature was 420 °C, the forging specific pressure was 120 MPa, the holding time was 10 s, the cooling rate was 30 °C / s, and the deformation was 10%. The solution treatment was carried out at a temperature of 530℃ for 7 hours. The aging treatment was carried out at a temperature of 170℃ for 7 hours.

[0091] In preparing the Al-Cu cast-forged aluminum alloy of Example 9, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging pre-deformation, solution treatment, and aging treatment. In the low-pressure filling casting, the filling speed was 1 m / s, the filling time was 5 s, the casting pressure was 10 MPa, the holding time was 10 s, the mold temperature was 300℃, the alloy casting temperature was 700℃, and the cooling rate was 10℃ / s. In the in-situ primary forging, the forging temperature was 600℃, the forging specific pressure was 60 MPa, the forging start time was 3 s, the holding time was 18 s, the cooling rate was 10℃ / s, and the deformation was 10%. In the in-situ secondary forging pre-deformation, the forging temperature was 420℃, the forging specific pressure was 450 MPa, the holding time was 10 s, the cooling rate was 30℃ / s, and the deformation was 50%. The solution treatment was carried out at a temperature of 530℃ for 7 hours. The aging treatment was carried out at a temperature of 170℃ for 7 hours.

[0092] In preparing the Al-Cu cast-forged aluminum alloy of Example 10, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging pre-deformation, solution treatment, and aging treatment. In the low-pressure filling casting, the filling speed was 0.1 m / s, the filling time was 20 s, the casting pressure was 0.2 MPa, the holding time was 2 s, the mold temperature was 200℃, the alloy casting temperature was 660℃, and the cooling rate was 5℃ / s. In the in-situ primary forging, the forging temperature was 600℃, the forging specific pressure was 60 MPa, the forging start time was 7 s, the holding time was 12 s, the cooling rate was 10℃ / s, and the deformation was 10%. In the in-situ secondary forging pre-deformation, the forging temperature was 480℃, the forging specific pressure was 110 MPa, the holding time was 2 s, the cooling rate was 50℃ / s, and the deformation was 13%. The solution treatment was carried out at a temperature of 530℃ for 6 hours. The aging treatment was carried out at a temperature of 175℃ for 3 hours.

[0093] In preparing the Al-Cu aluminum alloy of Example 11, the forming process included: die casting the alloy liquid at 680ºC, followed by aging treatment. During die casting, the die casting speed was 0.8 m / s and the cooling rate was 60 K / s. During aging treatment, the temperature was 170°C and the time was 5 hours.

[0094] In preparing the Al-Cu vacuum die-cast aluminum alloy of Example Twelve, the forming process included: vacuum die casting of the alloy liquid at 660ºC, followed by solution treatment and aging treatment. In the vacuum die casting process, the vacuum degree was 80 mbar, the injection speed was 4 m / s, the casting pressure was 120 MPa, and the temperature cooling rate was 160 K / s. In the solution treatment, the temperature was 520 °C and the time was 6 h. In the aging treatment, the temperature was 175 °C and the time was 2 h.

[0095] In preparing the Al-Cu aluminum alloy of Example Thirteen, the forming process included: die casting the alloy liquid at 710ºC, followed by aging treatment. During die casting, the die casting speed was 1.2 m / s, and the cooling rate was 90 K / s. During aging treatment, the temperature was 160 °C, and the time was 30 h.

[0096] In preparing the Al-Cu vacuum die-cast aluminum alloy of Example Fourteen, the forming process included: vacuum die casting of the alloy liquid at 680ºC, followed by solution treatment and aging treatment. In the vacuum die casting process, the vacuum degree was 50 mbar, the injection speed was 5 m / s, the casting pressure was 100 MPa, and the temperature cooling rate was 180 K / s. In the solution treatment, the temperature was 510 °C and the time was 5 h. In the aging treatment, the temperature was 180 °C and the time was 3 h.

[0097] Table 2 Performance test results of aluminum alloys in Examples 1 to 14 Referring to Table 2, the Al-Cu aluminum alloys of Examples 1 to 14 exhibit excellent tensile strength and elongation. Specifically, the Al-Cu cast-forged aluminum alloys of Examples 1 to 10 have a tensile strength of not less than 360 MPa and an elongation of not less than 9%; the Al-Cu die-cast aluminum alloys of Examples 11 and 12 have a tensile strength of not less than 210 MPa and an elongation of not less than 9%; and the Al-Cu vacuum die-cast aluminum alloys of Examples 13 and 14 have a tensile strength of not less than 230 MPa and an elongation of not less than 11%. This indicates that the Al-Cu aluminum alloys of the present invention possess superior mechanical properties. Furthermore, the Al-Cu cast-forged aluminum alloys of Examples 1 to 10 maintain superior mechanical properties even when their thickness is greater than 5 mm. The Al-Cu aluminum alloys of Examples 11 to 14 also exhibit superior mechanical properties when their thickness is greater than 2 mm.

[0098] In summary, the tensile strength of the Al-Cu series cast-forged aluminum alloy of the present invention is not less than 360 MPa and the elongation is not less than 9%; the tensile strength of the Al-Cu series die-cast aluminum alloy of the present invention is not less than 210 MPa and the elongation is not less than 9%; the tensile strength of the Al-Cu series vacuum die-cast aluminum alloy of the present invention is not less than 230 MPa and the elongation is not less than 11%.

[0099] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the content of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

[0100] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the content of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An Al-Cu-based aluminum alloy, characterized by, The Al-Cu aluminum alloy contains Cu at a mass percentage of 2.5-4%, Si at a mass percentage of 0.001-0.6%, Fe at a mass percentage of 0.001-0.5%, Mg at a mass percentage of 0.001-1.2%, Mn at a mass percentage of 0-0.8%, Ti at a mass percentage of 0-0.3%, Cd at a mass percentage of 0-0.3%, Cr at a mass percentage of 0-0.3%, Zr at a mass percentage of 0-0.3%, V at a mass percentage of 0-0.3%, Ag at a mass percentage of 0-0.5%, B at a mass percentage of 0-0.1%, Zn at a mass percentage of 0.001-0.3%, Be at a mass percentage of 0-0.1%, RE at a mass percentage of 0-0.8%, and Al and inevitable impurities.

2. The Al-Cu based aluminum alloy according to claim 1, wherein The Al-Cu aluminum alloy contains Cu at a mass percentage of 2.5-4%, Si at a mass percentage of 0.01-0.3%, Fe at a mass percentage of 0.05-0.3%, Mg at a mass percentage of 0.05-1.2%, Mn at a mass percentage of 0.001-0.5%, Ti at a mass percentage of 0.001-0.2%, Cd at a mass percentage of 0.001-0.25%, Cr at a mass percentage of 0.001-0.25%, Zr at a mass percentage of 0.001-0.25%, V at a mass percentage of 0.001-0.3%, Ag at a mass percentage of 0.001-0.5%, B at a mass percentage of 0.001-0.1%, Zn at a mass percentage of 0.001-0.3%, Be at a mass percentage of 0.001-0.1%, and RE at a mass percentage of 0.001-0.5%.

3. The Al-Cu based aluminum alloy according to claim 1, wherein At least one of the following conditions is satisfied: The sum of the mass percentages of Si and Fe is less than 0.6%; The sum of the mass percentages of V and Ti is less than 0.4%; The mass ratio of Mn to Fe is greater than 0.

4.

4. The Al-Cu based aluminum alloy according to claim 1, wherein The Al-Cu aluminum alloy further contains at least one of In at a mass percentage of 0-0.2%, Nb at a mass percentage of 0-0.5%, Ni at a mass percentage of 0-0.3%, Bi at a mass percentage of 0-0.2%, Ge at a mass percentage of 0-0.5%, Mo at a mass percentage of 0-0.5%, Sn at a mass percentage of 0-0.5%, Sr at a mass percentage of 0-0.1%, Te at a mass percentage of 0-0.5%, Co at a mass percentage of 0-0.5%, and Ca at a mass percentage of 0-0.5%.

5. A method for preparing an Al-Cu aluminum alloy, comprising the following steps: heating the Al source to obtain an aluminum liquid; adding a Cu source, a Si source, an Fe source, a Mg source, a Mn source, a Ti source, a Cd source, a Cr source, a Zr source, a V source, an Ag source, a B source, a Zn source, a Be source, and an RE source into the aluminum liquid, and performing a second heating treatment to obtain an alloy liquid; performing a refining treatment, a slagging treatment, and a forming treatment on the alloy liquid to obtain an Al-Cu aluminum alloy, the Al-Cu aluminum alloy containing Cu at a mass percentage of 2.5-4%, Si at a mass percentage of 0.001-0.6%, Fe at a mass percentage of 0.001-0.5%, Mg at a mass percentage of 0.001-1.2%, Mn at a mass percentage of 0-0.8%, Ti at a mass percentage of 0-0.3%, Cd at a mass percentage of 0-0.3%, Cr at a mass percentage of 0-0.3%, Zr at a mass percentage of 0-0.3%, V at a mass percentage of 0-0.3%, Ag at a mass percentage of 0-0.5%, B at a mass percentage of 0-0.1%, Zn at a mass percentage of 0.001-0.3%, Be at a mass percentage of 0-0.1%, RE at a mass percentage of 0-0.8%, and Al and inevitable impurities.

6. The method of producing an Al-Cu based aluminum alloy according to claim 5, wherein The preparation method of the Al-Cu aluminum alloy further comprises the step of adding at least one of an In source, a Ni source, a Nb source, a Bi source, a Ge source, a Mo source, a Sn source, a Sr source, a Te source, a Co source, and a Ca source into the aluminum liquid, wherein the mass percentage of In is 0-0.2%, the mass percentage of Ni is 0-0.3%, the mass percentage of Nb is 0-0.5%, the mass percentage of Bi is 0-0.2%, the mass percentage of Ge is 0-0.5%, the mass percentage of Mo is 0-0.5%, the mass percentage of Sn is 0-0.5%, the mass percentage of Sr is 0-0.1%, the mass percentage of Te is 0-0.5%, the mass percentage of Co is 0-0.5%, and the mass percentage of Ca is 0-0.5%.

7. The method of producing an Al-Cu based aluminum alloy according to claim 5, wherein The forming treatment comprises the following steps: pushing the alloy liquid into a mold to perform a low-pressure filling casting forming treatment, and waiting for the alloy liquid to enter a semi-solid solidification interval to form a semi-solid aluminum alloy part, and sequentially performing in-situ primary forging treatment and in-situ secondary forging pre-deformation treatment on the semi-solid aluminum alloy part in the mold to obtain an aluminum alloy part, wherein the deformation amount of the semi-solid aluminum alloy part in the in-situ primary forging treatment is 5-70%; and performing heat treatment on the aluminum alloy part to obtain the Al-Cu aluminum alloy.

8. The preparation method of the Al-Cu aluminum alloy according to claim 7, wherein The low-pressure filling casting forming process has a filling speed of 0.1-1.2 m / s, a filling time of 2-20 s, a casting pressure of 0.1-40 MPa, a pressure maintaining time of 2-10 s, a mold temperature of 180-350 °C, and an alloy pouring temperature of 660-720 °C; The in-situ primary forging process has a forging temperature of 600-650 °C, a forging specific pressure of 50-300 MPa, a starting forging time of 2-20 s, and a pressure maintaining time of 2-20 s; The in-situ secondary forging pre-deformation process has a forging temperature of 250-480 °C, a forging specific pressure of 50-500 MPa, a pressure maintaining time of 0-10 s, and a deformation of 10-70 %; The heat treatment includes a solution treatment and an aging treatment, the solution treatment has a temperature of 490-530 °C and a time of 0.2-20 h, and the aging treatment has a temperature of 160-190 °C and a time of 2-30 h.

9. The method of producing an Al-Cu based aluminum alloy according to claim 5, wherein The forming process includes the following steps: The forming process includes a die casting process and an aging treatment, the die casting process has a temperature of 660-720 °C and a die casting speed of 0.23-2.5 m / s, and the aging treatment has a temperature of 160-190 °C and a time of 2-30 h; or The forming process includes a vacuum die casting process and a heat treatment, the vacuum die casting process has a temperature of 660-700 °C, a vacuum degree of 20-80 mbar, a injection speed of 2-5 m / s, and a casting pressure of 80-120 MPa, and the heat treatment includes a solution treatment and an aging treatment, the solution treatment has a temperature of 480-520 °C and a time of 0.2-6 h, and the aging treatment has a temperature of 160-190 °C and a time of 2-30 h.

10. An aluminum alloy structural member, characterized by, The material of at least part of the aluminum alloy structural member is the Al-Cu aluminum alloy according to any one of claims 1-4 or the Al-Cu aluminum alloy prepared by the preparation method according to any one of claims 5-9.

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