Magnesium alloy, preparation method thereof, magnesium product and preparation method of magnesium product

Abstract

The invention provides a magnesium alloy and a preparation method thereof, a magnesium product and a preparation method of the magnesium product. The magnesium alloy comprises a magnesium matrix as well as an aluminum element, a lanthanum element, a zinc element, a manganese element, an iron element, a silicon element, a copper element and a nickel element which exist in the magnesium matrix, in the magnesium alloy, the mass percentage of the aluminum element is 5.0%-8.0%; the mass percentage content of the lanthanum element is 1.0%-2.5%; the mass percentage content of the zinc element is 0.5%-1.5%; the mass percentage content of the manganese element is 0.1%-1.0%; the mass percentage content of the iron element is less than 0.004%; the mass percentage content of the silicon element is less than 0.05%; the mass percentage content of the copper element is less than 0.008%; the mass percentage content of the nickel element is less than 0.001%. According to the magnesium alloy provided by the invention, the yield strength, the tensile strength, the ductility and the casting fluidity of the magnesium alloy are improved by accurately controlling the types and the contents of all the elements in the magnesium alloy.

Description

Technical Field

[0001] This invention belongs to the field of magnesium alloy technology, and particularly relates to a magnesium alloy and its preparation method, magnesium products, and the preparation method of magnesium products. Background Technology

[0002] Currently, the new energy vehicle industry faces the dual technological challenges of high energy consumption and limited driving range, urgently requiring breakthroughs through material and process innovation. Against this backdrop, lightweighting technology has become one of the key pathways driving industry development. Magnesium alloys, due to their low density (1.74 g / cm³), excellent specific strength and specific stiffness, and outstanding vibration and noise reduction performance, demonstrate significant application potential in automotive lightweighting.

[0003] The service conditions of automotive structural components place higher demands on the performance of magnesium alloy materials. However, the comprehensive mechanical properties of the traditional die-cast magnesium alloys that are widely used at present, such as Mg-Al-Zn (AZ series), Mg-Al-Mn (AM series) and Mg-Al-RE (AE series), are still relatively limited and cannot meet the performance requirements of integrated die-cast structural components for new energy vehicles.

[0004] Therefore, there is an urgent need for a magnesium alloy material with excellent strength, toughness, and casting fluidity. Summary of the Invention

[0005] One objective of this invention is to provide a magnesium alloy to solve the problem of poor overall mechanical properties of existing magnesium alloys; a second objective is to provide a method for preparing a magnesium alloy; a third objective is to provide a magnesium product; and a fourth objective is to provide a method for preparing a magnesium product.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A magnesium alloy comprising: a magnesium matrix, and aluminum, lanthanum, zinc, manganese, iron, silicon, copper, and nickel elements present in the magnesium matrix;

[0008] In the magnesium alloy, the mass percentage of aluminum is 5.0%-8.0%; the mass percentage of lanthanum is 1.0%-2.5%; the mass percentage of zinc is 0.5%-1.5%; the mass percentage of manganese is 0.1%-1.0%; the mass percentage of iron is less than 0.004%; the mass percentage of silicon is less than 0.05%; the mass percentage of copper is less than 0.008%; and the mass percentage of nickel is less than 0.001%.

[0009] Based on the above technical means, by controlling the types of elements in magnesium alloys, the grain boundary morphology and dislocation movement can be optimized; at the same time, by precisely controlling the content of each element in magnesium alloys, the yield strength, tensile strength, elongation and casting fluidity of magnesium alloys can be improved.

[0010] Furthermore, the aluminum content is 6.0%-7.0% by mass; the lanthanum content is 1.2%-2.0% by mass; the zinc content is 0.8%-1.2% by mass; the manganese content is 0.2%-0.4% by mass; the iron content is less than 0.004% by mass; the silicon content is less than 0.05% by mass; the copper content is less than 0.008% by mass; and the nickel content is less than 0.001% by mass.

[0011] Based on the above-mentioned technical means, by precisely controlling the types and contents of each element in the magnesium alloy, the yield strength, tensile strength, elongation and casting fluidity of the magnesium alloy can be further improved.

[0012] Furthermore, the mass ratio of Al, La, and Zn elements in the magnesium alloy satisfies 1:(0.2-0.3):(0.1-0.2).

[0013] Based on the above technical means, the synergistic effect of the three elements is maximized, resulting in optimized yield strength, tensile strength, elongation and casting fluidity of magnesium alloys.

[0014] Furthermore, the magnesium alloy includes Mg 17 Al 12 Phase, the Mg 17 Al 12 The phase is distributed in a granular form along the grain boundaries in a eutectic manner; the Mg 17 Al 12 The phase particle size is ≤2.0μm.

[0015] Based on the above technical means, Mg 17 Al 12 The phase is distributed in a granular form along the grain boundaries in a eutectic form, which refines the matrix grain structure, thereby ensuring strength while improving the elongation of magnesium alloy.

[0016] Furthermore, the magnesium alloy includes Al 11 La3 phase, the Al 11 The particle size of the La3 phase is ≤1.8μm.

[0017] Based on the aforementioned technical means, AI 11The La3 phase can not only effectively hinder dislocation movement and grain boundary slip, but also provide nucleation sites for eutectic structures, promote nucleation, refine the microstructure, further suppress crack propagation, and improve the yield strength, tensile strength and elongation of magnesium alloys.

[0018] Furthermore, the magnesium alloy also includes an Al8Mn4La phase with a particle size ≤1.2μm.

[0019] According to the above technical means, the Al8Mn4La phase is distributed in a granular manner, which can play a role in second phase strengthening and precipitation strengthening, further improving the yield strength, tensile strength and elongation of magnesium alloy.

[0020] Furthermore, the magnesium alloy has a yield strength of 150-160 MPa, a tensile strength of 280-300 MPa, and an elongation of 15%-20%.

[0021] A second aspect of the present invention provides a method for preparing a magnesium alloy, comprising the following steps:

[0022] (1) In a protective atmosphere, raw materials including magnesium source, aluminum source, manganese source, zinc source and lanthanum source are melted and mixed to obtain a mixed melt;

[0023] (2) The magnesium alloy is obtained by refining the mixed melt;

[0024] In the magnesium alloy, the mass percentage of aluminum is 5.0%-8.0%; the mass percentage of lanthanum is 1.0%-2.5%; the mass percentage of zinc is 0.5%-1.5%; the mass percentage of manganese is 0.1%-1.0%; the mass percentage of iron is less than 0.004%; the mass percentage of silicon is less than 0.05%; the mass percentage of copper is less than 0.008%; and the mass percentage of nickel is less than 0.001%.

[0025] Based on the above-mentioned technical means, by precisely controlling the types and contents of each element in the magnesium alloy, the tensile strength, yield strength, elongation and casting fluidity of the magnesium alloy can be improved simultaneously.

[0026] Furthermore, the specific steps of the refining process include:

[0027] After adding a refining agent to the mixed melt and reacting, the mixture is allowed to stand for 20-40 minutes to obtain the magnesium alloy; wherein the reaction temperature is 720-740℃ and the reaction time is 5-15 minutes.

[0028] Preferably, the amount of the refining agent added is 1.0%-3.0% of the weight of the mixed melt.

[0029] Based on the above-mentioned technical methods, the refining effect is better, and the resulting magnesium alloy has better tensile strength, yield strength, elongation and casting fluidity.

[0030] A third aspect of the present invention provides a magnesium article comprising the magnesium alloy described in the first aspect above, or a magnesium alloy prepared by the preparation method described in the second aspect above.

[0031] Furthermore, the magnesium product has a yield strength of 130-160 MPa, a tensile strength of 250-300 MPa, and an elongation of 12%-20%.

[0032] A fourth aspect of the present invention provides a method for preparing magnesium products, comprising:

[0033] The magnesium alloy is subjected to melting and die casting processes in sequence to obtain the magnesium product.

[0034] Furthermore, the melting treatment temperature is 680-720℃; and / or,

[0035] The injection speed of the die casting process is 5-9 m / s, the injection pressure is 90-180 MPa, the vacuum degree is ≤100 mbar, and the mold temperature is 230-280℃.

[0036] Based on the above technical means, magnesium products have good surface smoothness and excellent yield strength, tensile strength, and elongation.

[0037] The beneficial effects of this invention are:

[0038] The magnesium alloy provided by this invention optimizes grain boundary morphology and dislocation movement by controlling the types of each element therein; at the same time, it improves the yield strength, tensile strength, elongation and casting fluidity of the magnesium alloy by precisely controlling the content of each element. Attached Figure Description

[0039] Figure 1 The stress-strain curve of the magnesium alloy obtained in Example 1 of this invention is shown.

[0040] Figure 2 Here is a SEM image of the magnesium alloy obtained in Example 1 of this invention;

[0041] Figure 3 This is a phase analysis diagram of the magnesium alloy obtained in Example 1 of the present invention;

[0042] Figure 4 These are test photos (700°C) of the casting fluidity of the magnesium alloy obtained in Example 1 and the Mg-Al-Mn die-cast magnesium alloy obtained in Comparative Example 1.

[0043] Figure 5 The stress-strain curves are for the bodies of ultra-large integrated die-cast parts produced by the magnesium alloy obtained in Example 1 and the Mg-Al-Mn die-cast magnesium alloy obtained in Comparative Example 1. Detailed Implementation

[0044] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0045] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0046] To further improve the overall performance of magnesium alloys, the inventors studied existing magnesium alloys (such as the AZ (Mg-Al-Zn), AM (Mg-Al-Mn), and AE (Mg-Al-RE) series) and found that the poor overall performance of existing magnesium alloys is due to: brittle Mg... 17 Al 12 High phase content tends to form a network distribution at grain boundaries, resulting in coarsening of the microstructure and reducing the elongation of magnesium alloys, or Al 11 The AE3 phase appears in clusters and lanceolate shapes, which cuts through the α-Mg matrix and leads to a decrease in the mechanical properties of magnesium alloys.

[0047] Based on this, the first aspect of the present invention provides a magnesium alloy, comprising: a magnesium matrix, and aluminum, lanthanum, zinc, manganese, iron, silicon, copper and nickel elements present in the magnesium matrix;

[0048] In magnesium alloys, the mass percentage of aluminum is 5.0%-8.0%; the mass percentage of lanthanum is 1.0%-2.5%; the mass percentage of zinc is 0.5%-1.5%; the mass percentage of manganese is 0.1%-1.0%; the mass percentage of iron is less than 0.004%; the mass percentage of silicon is less than 0.05%; the mass percentage of copper is less than 0.008%; and the mass percentage of nickel is less than 0.001%.

[0049] For example, the mass percentage of aluminum in the magnesium alloy is 5%, 5.2%, 5.4%, 5.6%, 5.8%, 6%, 6.2%, 6.4%, 6.6%, 6.8%, 7%, 7.2%, 7.4%, 7.6%, 7.8%, or 8%, or a range of any two of these values.

[0050] For example, the mass percentage of lanthanum in the magnesium alloy is 1.0%, 1.25%, 1.5%, 1.75%, 2%, 2.25%, or 2.5%, or a range of any two of these values.

[0051] For example, the mass percentage of zinc in the magnesium alloy is 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, or 1.5%, or a range of any two of these values.

[0052] For example, the mass percentage of manganese in the magnesium alloy is 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, or 1.0%, or a range of any two of these values.

[0053] For example, the mass percentage of iron in the magnesium alloy is 0.001%, 0.002%, 0.003%, or 0.0039%, or a range of any two of these values.

[0054] For example, the mass percentage of silicon in the magnesium alloy is 0.01%, 0.02%, 0.03%, or 0.04%, or a range consisting of any two of these values.

[0055] For example, the mass percentage of copper in the magnesium alloy is 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, or 0.007%, or a range of any two of these values.

[0056] For example, the mass percentage of nickel in the magnesium alloy is 0, 0.0002%, 0.0004%, 0.0006%, 0.0008%, or 0.0009%, or a range of any two of these values.

[0057] The magnesium alloy provided by this invention exhibits excellent yield strength, tensile strength, elongation, and casting fluidity. The reason is as follows:

[0058] On the one hand, the magnesium alloy forms Mg-Al eutectic phase, Al-La eutectic phase, and Al-Mn-La phase through the composite addition of Al, La, and Zn. These elements collectively optimize grain boundary morphology and dislocation movement, and form a solid solution strengthening effect, improving the yield strength, tensile strength, and elongation of the magnesium alloy. Simultaneously, Mn reacts with impurity elements (Fe, Si, etc.) to form stable compounds, reducing the cutting effect of impurities on the α-Mg matrix and improving the casting fluidity of the magnesium alloy. On the other hand, by limiting the Al content within a specific range, the Mg content is prevented from being affected by other elements. 17 Al 12 The phases are distributed in a network along the grain boundaries of the α-Mg matrix, thus avoiding a decrease in the elongation of the magnesium alloy; by limiting the content of La to a specific range, excessive coarsening of Al is avoided. 11 La3 phase, with a large amount of Al 11 La3 phases tend to aggregate into clusters and flaky structures, disrupting the α-Mg matrix and leading to a decrease in the strength and elongation of magnesium alloys. By limiting the Zn content to a specific range, a solid solution strengthening effect is achieved, preventing the formation of coarsened MgZn phases and thus reducing the elongation of the magnesium alloy. Similarly, limiting the Mn content to a specific range neutralizes impurities and prevents Mn segregation and inclusions, which severely impact the elongation of magnesium alloys. The synergistic effect of these two aspects results in a comprehensive improvement in the yield strength, tensile strength, elongation, and casting fluidity of magnesium alloys.

[0059] In one specific embodiment, the mass percentage of aluminum is 6.0%-7.0%; the mass percentage of lanthanum is 1.2%-2.0%; the mass percentage of zinc is 0.8%-1.2%; the mass percentage of manganese is 0.2%-0.4%; the mass percentage of iron is less than 0.004%; the mass percentage of silicon is less than 0.05%; the mass percentage of copper is less than 0.008%; and the mass percentage of nickel is less than 0.001%. The magnesium alloy's composition within this range further improves its yield strength, tensile strength, elongation, and casting fluidity.

[0060] In one specific embodiment, the mass ratio of Al, La, and Zn elements in the magnesium alloy satisfies 1:(0.2-0.3):(0.1-0.2). Within this range, the synergistic effect of the three elements is maximized, resulting in optimized yield strength, tensile strength, elongation, and casting fluidity of the magnesium alloy.

[0061] For example, the mass ratio of Al, La, and Zn in the magnesium alloy is 1:0.2:0.1, 1:0.2:0.15, 1:0.2:0.2, 1:0.25:0.1, 1:0.25:0.15, 1:0.25:0.2, 1:0.3:0.1, 1:0.3:0.15, or 1:0.3:0.2, or a range consisting of any two of these values.

[0062] In one specific embodiment, the magnesium alloy comprises Mg 17 Al 12 Phase, Mg 17 Al 12 The phase is distributed in a granular form along the grain boundaries in a eutectic manner; Mg 17 Al 12 The phase particle size is ≤2.0 μm. This invention limits the Al element content to achieve the desired Mg content. 17 Al 12 The phase is distributed in a granular form along the grain boundaries of the α-Mg matrix in a eutectic manner; and is distributed in a network with Mg 17 Al 12 In comparison, granular Mg 17 Al 12 The phase reduces the cleavage effect on the α-Mg matrix and refines the grain structure of the α-Mg matrix, thereby ensuring the strength of the magnesium alloy while improving its elongation.

[0063] For example, Mg 17 Al 12 The phase particle size is 0.1 μm, 0.3 μm, 0.5 μm, 0.7 μm, 0.9 μm, 1.1 μm, 1.3 μm, 1.5 μm, 1.7 μm, 1.9 μm or 2.0 μm, or a range of any two of these values.

[0064] In one specific embodiment, the magnesium alloy includes Al 11 La3 phase, Al 11 The particle size of the La3 phase is ≤1.8 μm. Al 11 The La3 phase has a grain size within this range, which can not only effectively hinder dislocation movement and grain boundary slip, but also provide nucleation sites for eutectic structures, refine the structure, further suppress crack propagation, and improve the yield strength, tensile strength and elongation of magnesium alloys.

[0065] For example, Al 11The particle size of the La3 phase is 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm or 1.8 μm, or a range of any two of these values.

[0066] In one specific embodiment, the magnesium alloy includes an Al8Mn4La phase with a particle size ≤1.2μm. The granular Al8Mn4La phase can play a role in second-phase strengthening and precipitation strengthening, further improving the yield strength, tensile strength and elongation of the magnesium alloy.

[0067] For example, the particle size of the Al8Mn4La phase is 0.1μm, 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1.0μm, 1.1μm or 1.2μm, or a range of any two of these values.

[0068] In addition, the magnesium alloy of the present invention also includes trace amounts of MgZn phase and Mg 32 (Zn,Al) 49 Phase, Mg4Zn7 phase. Trace amounts of MgZn phase, Mg 32 (Zn,Al) 49 The Mg4Zn7 phase can play a role in second-phase strengthening and precipitation strengthening, further improving the yield strength, tensile strength and elongation of magnesium alloys.

[0069] In one specific embodiment, the magnesium alloy has a yield strength of 150-160 MPa, a tensile strength of 280-300 MPa, and an elongation of 15%-20%. This magnesium alloy exhibits excellent yield strength, tensile strength, and elongation.

[0070] For example, the yield strength of the magnesium alloy is 150 MPa, 152 MPa, 154 MPa, 156 MPa, 158 MPa or 160 MPa, or a range of any two of these values.

[0071] For example, the tensile strength of the magnesium alloy is 280 MPa, 285 MPa, 290 MPa, 295 MPa or 300 MPa, or a range of any two of these values.

[0072] For example, the elongation of the magnesium alloy is 15%, 16%, 17%, 18%, 19%, or 20%, or a range of any two of these values.

[0073] A second aspect of the present invention provides a method for preparing a magnesium alloy, comprising:

[0074] (1) In a protective atmosphere, raw materials including magnesium source, aluminum source, manganese source, zinc source and lanthanum source are melted and mixed to obtain a mixed melt;

[0075] (2) After refining the mixed melt, a magnesium alloy is obtained;

[0076] In the magnesium alloy, the mass percentage of aluminum is 5.0%-8.0%; the mass percentage of lanthanum is 1.0%-2.5%; the mass percentage of zinc is 0.5%-1.5%; the mass percentage of manganese is 0.1%-1.0%; the mass percentage of iron is less than 0.004%; the mass percentage of silicon is less than 0.05%; the mass percentage of copper is less than 0.008%; and the mass percentage of nickel is less than 0.001%.

[0077] The method for preparing magnesium alloys provided by this invention achieves a combined improvement in tensile strength, yield strength, elongation, and casting fluidity of magnesium alloys by precisely controlling the types and contents of each element in the magnesium alloy.

[0078] In this invention, the aluminum source refers to the raw material providing aluminum, the magnesium source refers to the raw material providing magnesium, the manganese source refers to the raw material providing manganese, the zinc source refers to the raw material providing zinc, and the lanthanum source refers to the raw material providing lanthanum. The magnesium, aluminum, manganese, zinc, and lanthanum sources can be elemental or alloys.

[0079] The present invention does not specifically limit the type of protective atmosphere. In one embodiment, the protective atmosphere is selected from at least one of N2, CO2, and SF6 gases.

[0080] In one embodiment, the protective atmosphere is a mixture of CO2 and SF6, with a volume ratio of CO2 to SF6 of (180-200):1. Under this protective atmosphere, the mixed melt composition is homogeneous, elemental loss is minimal, and oxide inclusions are reduced.

[0081] It is conceivable that steps (1) and (2) of the present invention also include chemical composition analysis, and the test method refers to GB / T13748.

[0082] This invention does not specifically limit the equipment used to prepare the mixed melt; conventional smelting equipment in the art, such as a smelting furnace, is sufficient.

[0083] This invention does not impose any special limitations on the specific model and source of the smelting furnace; any commercially available smelting furnace known to those skilled in the art can be used.

[0084] This invention does not specifically limit the method for preparing the mixed melt. In one embodiment, the steps for preparing the mixed melt include:

[0085] 1) In a protective atmosphere, the magnesium source is subjected to initial melting treatment to obtain magnesium melt.

[0086] 2) Add aluminum, manganese, zinc and lanthanum sources to the magnesium melt for secondary melting to obtain a mixed melt.

[0087] The present invention does not specify the temperature of the initial melting treatment; it is sufficient to completely melt the magnesium source. In one embodiment, the temperature of the initial melting treatment is 680-720°C.

[0088] The present invention does not specify the temperature of the secondary melting process; it is sufficient to completely melt the aluminum source, manganese source, zinc source and lanthanum source. In one embodiment, the temperature of the secondary melting process is 730-770°C.

[0089] To further improve the overall performance of magnesium alloys, the specific steps of the refining process can be controlled.

[0090] In one specific implementation, the refining process includes the following steps:

[0091] After adding a refining agent to the mixed melt and reacting, the mixture is allowed to stand for 20-40 minutes to obtain a magnesium alloy. The reaction temperature is 720-740℃ and the reaction time is 5-15 minutes. Within this range of reaction temperature and time, the refining effect is better, and the resulting magnesium alloy has better tensile strength, yield strength, elongation, and casting fluidity. Within this range of standing time, impurities in the mixed melt are allowed to settle sufficiently, resulting in a more uniform composition of the magnesium alloy.

[0092] For example, the settling time is 20 min, 24 min, 28 min, 32 min, 36 min, or 40 min, or a range of any two of these values.

[0093] For example, the reaction temperature is 720°C, 722°C, 724°C, 726°C, 728°C, 730°C, 732°C, 734°C, 736°C, 738°C, or 740°C, or a range of any two of these values.

[0094] For example, the reaction time is 5 min, 7 min, 9 min, 11 min, 13 min or 15 min, or a range of any two of these values.

[0095] In one specific embodiment, the amount of refining agent added is 1.0%-3.0% of the weight of the mixed melt. Within this range, a balance between refining effect and economy can be achieved.

[0096] For example, the amount of refining agent added is 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8% or 3.0% of the weight of the mixed melt, or a range of any two of these values.

[0097] This invention does not specifically limit the type of refining agent; conventional refining agents in the art can be used.

[0098] In one embodiment, the refining agent in the refining process contains at least one of sodium chloride, magnesium chloride, magnesium fluoride, potassium chloride, barium chloride, and calcium fluoride. Preferably, the refining agent comprises a mixture of magnesium chloride, potassium chloride, barium chloride, and calcium fluoride, wherein the mass ratio of magnesium chloride, potassium chloride, barium chloride, and calcium fluoride in the mixture is 30:26:22:22. The above-mentioned refining agent has a good purification effect on the melt.

[0099] In addition, after refining, the present invention also undergoes slag removal.

[0100] This invention does not specify a particular method for slag removal, as long as it can remove floating slag.

[0101] This invention does not impose specific limitations on the conditions for magnesium alloy die casting, and those skilled in the art can make adjustments according to specific needs.

[0102] Furthermore, to test the performance of the magnesium alloy, the present invention also subjectes the prepared magnesium alloy to die-casting treatment; wherein the die-casting temperature is 700-740℃, the injection speed is 3-5m / s, the injection specific pressure is 50-100MPa, the vacuum degree is 20-60mbar, and the mold temperature is 250-270℃. Within this range, the process and material properties are effectively matched, the magnesium alloy filling is excellent, and the surface finish of the obtained material specimens is good.

[0103] For example, the temperature for die casting of the test piece is 700°C, 705°C, 710°C, 715°C, 720°C, 725°C, 730°C, 735°C or 740°C, or a range of any two of these values.

[0104] For example, the injection velocity is 3 m / s, 3.5 m / s, 4 m / s, 4.5 m / s, or 5 m / s, or a range of any two of these values.

[0105] For example, the injection pressure is 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa or 100 MPa, or a range of any two of these values.

[0106] For example, the vacuum level is 20 mbar, 30 mbar, 40 mbar, 50 mbar or 60 mbar, or a range of any two of these values.

[0107] For example, the mold temperature is 250°C, 252°C, 254°C, 256°C, 258°C, 260°C, 262°C, 264°C, 266°C, 268°C, or 270°C, or a range of any two of these values.

[0108] The injection speed of this invention refers to the speed at which the injection punch of the die casting machine moves as it pushes the magnesium alloy melt through the pressure chamber and fills the mold cavity.

[0109] The mold temperature of this invention refers to the working temperature at which the surface of the mold cavity is heated and maintained before and during the die casting production process.

[0110] A third aspect of the present invention provides a magnesium article comprising the above-described magnesium alloy, or a magnesium alloy prepared by the above-described preparation method. This magnesium article exhibits excellent yield strength, tensile strength, and elongation.

[0111] This invention does not specifically limit the types of magnesium products, such as small, medium and large integrated die-cast parts, etc.

[0112] In one specific embodiment, the magnesium product has a yield strength of 130-160 MPa, a tensile strength of 250-300 MPa, and an elongation of 12%-20%. This magnesium product has excellent yield strength, tensile strength, and elongation.

[0113] For example, the yield strength of the magnesium product is 130 MPa, 135 MPa, 140 MPa, 145 MPa, 150 MPa, 155 MPa or 160 MPa, or a range of any two of these values.

[0114] For example, the tensile strength of the magnesium product is 250 MPa, 255 MPa, 260 MPa, 265 MPa, 270 MPa, 275 MPa, 280 MPa, 285 MPa, 290 MPa, 295 MPa or 300 MPa, or a range of any two of these values.

[0115] For example, the elongation of the magnesium product is 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%, or a range of any two of these values.

[0116] A fourth aspect of the present invention provides a method for preparing magnesium products, comprising:

[0117] Magnesium alloys are sequentially melted and die-cast to obtain magnesium products.

[0118] This invention does not impose specific limitations on the conditions for melting and die casting, and those skilled in the art can make adjustments according to specific needs.

[0119] In one specific embodiment, the melting temperature is 680-720°C. Within this temperature range, magnesium alloy die casting can be achieved.

[0120] For example, the melt temperature is 680°C, 685°C, 690°C, 695°C, 700°C, 705°C, 710°C, 715°C, or 720°C, or a range of any two of these values.

[0121] In one specific embodiment, the injection speed of the first die-casting process is 5-9 m / s, the injection pressure is 90-180 MPa, the vacuum degree is ≤100 mbar, and the mold temperature is 230-280℃. Within this range, the process and material properties are effectively matched, the magnesium alloy filling is excellent, the obtained product has a good surface finish, and better yield strength, tensile strength, and elongation.

[0122] The injection speed of this invention refers to the speed at which the injection punch of the die casting machine moves as it pushes the magnesium alloy melt through the pressure chamber and fills the mold cavity.

[0123] The mold temperature of this invention refers to the working temperature at which the surface of the mold cavity is heated and maintained before and during the die casting production process.

[0124] For example, the injection velocity is 5 m / s, 5.5 m / s, 6 m / s, 6.5 m / s, 7 m / s, 7.5 m / s, 8 m / s, 8.5 m / s, or 9 m / s, or a range of any two of these values.

[0125] For example, the injection specific pressure is 90 MPa, 100 MPa, 110 MPa, 120 MPa, 130 MPa, 140 MPa, 150 MPa, 160 MPa, 170 MPa or 180 MPa, or a range of any two of these values.

[0126] For example, the vacuum level is 1 mbar, 10 mbar, 20 mbar, 30 mbar, 40 mbar, 50 mbar, 60 mbar, 70 mbar, 80 mbar, 90 mbar or 100 mbar, or a range of any two of these values.

[0127] For example, the mold temperature is 230°C, 235°C, 240°C, 245°C, 250°C, 255°C, 260°C, 265°C, 270°C, 275°C, or 280°C, or a range of any two of these values.

[0128] The present invention will be further described below through specific embodiments.

[0129] Example 1

[0130] The method for preparing the magnesium alloy in this embodiment includes the following steps:

[0131] (1) Prepare materials according to composition. Among them, Mg, Al and Zn are prepared in the form of pure magnesium, pure aluminum and pure zinc, Mn is prepared in the form of Mg-10Mn master alloy (that is, the mass percentage of Mn element in Mg-10Mn master alloy is 10%), and La is prepared in the form of Mg-30La master alloy (that is, the mass percentage of La element in Mg-30La master alloy is 30%).

[0132] (2) First, dry pure magnesium is placed in a melting furnace and a protective atmosphere (a mixture of CO2 and SF6, wherein the volume ratio of CO2 to SF6 is 200:1) is introduced for the first melting treatment to obtain magnesium melt. The melting temperature of the first melting treatment is 700℃. Then, pure aluminum, pure zinc, Mg-10Mn master alloy and Mg-30La master alloy are added to the magnesium melt and held at 760℃ for 1 hour (i.e., the second melting treatment). After melting, the mixture is stirred evenly. After the chemical composition analysis is qualified, the first alloy melt (i.e., the mixed melt) is obtained.

[0133] (3) At 730℃, a composite refining agent (a mixture of magnesium chloride, potassium chloride, barium chloride and calcium fluoride in a mass ratio of 30:26:22:22) was added to the first alloy melt for refining treatment. The proportion of the composite refining agent added was 1.0% of the total weight of the first alloy solution. After standing for 30 minutes, slag removal treatment was performed. After the chemical composition analysis was qualified, the second alloy melt was obtained.

[0134] (4) After the temperature of the second alloy melt drops to 720℃, test piece die casting is carried out to obtain magnesium alloy. The injection speed during test piece die casting is 4.5m / s, the injection pressure is 84.7MPa, the vacuum degree is 36mbar, and the mold temperature is 258℃.

[0135] The magnesium alloy of this embodiment includes: a magnesium matrix, and aluminum, lanthanum, zinc, manganese, iron, silicon, copper and nickel elements present in the magnesium matrix;

[0136] In the magnesium alloy, the mass percentage of aluminum is 6.6%; the mass percentage of lanthanum is 1.8%; the mass percentage of zinc is 1.1%; the mass percentage of manganese is 0.35%; the mass percentage of iron is 0.002%; the mass percentage of silicon is 0.02%; the mass percentage of copper is 0.003%; and the mass percentage of nickel is 0.0002%.

[0137] The weight percentages of Al, La, and Zn in the magnesium alloy are 1:0.27:0.17.

[0138] Example 2

[0139] This embodiment is basically the same as Embodiment 1, except that:

[0140] The magnesium alloy of this embodiment includes: a magnesium matrix, and aluminum, lanthanum, zinc, manganese, iron, silicon, copper and nickel elements present in the magnesium matrix;

[0141] In the magnesium alloy, the mass percentage of aluminum is 6.8%; the mass percentage of lanthanum is 1.5%; the mass percentage of zinc is 0.9%; the mass percentage of manganese is 0.3%; the mass percentage of iron is 0.002%; the mass percentage of silicon is 0.02%; the mass percentage of copper is 0.003%; and the mass percentage of nickel is 0.0002%.

[0142] The weight percentages of Al, La, and Zn in the magnesium alloy are 1:0.22:0.13.

[0143] Example 3

[0144] This embodiment is basically the same as Embodiment 1, except that:

[0145] The magnesium alloy of this embodiment includes: a magnesium matrix, and aluminum, lanthanum, zinc, manganese, iron, silicon, copper and nickel elements present in the magnesium matrix;

[0146] In the magnesium alloy, the mass percentage of aluminum is 6.3%; the mass percentage of lanthanum is 1.6%; the mass percentage of zinc is 1.0%; the mass percentage of manganese is 0.25%; the mass percentage of iron is 0.002%; the mass percentage of silicon is 0.02%; the mass percentage of copper is 0.003%; and the mass percentage of nickel is 0.0002%.

[0147] The weight percentages of Al, La, and Zn in the magnesium alloy are 1:0.25:0.16.

[0148] Example 4

[0149] This embodiment is basically the same as Embodiment 1, except that:

[0150] The magnesium alloy of this embodiment includes: a magnesium matrix, and aluminum, lanthanum, zinc, manganese, iron, silicon, copper and nickel elements present in the magnesium matrix;

[0151] In the magnesium alloy, the mass percentage of aluminum is 5.6%; the mass percentage of lanthanum is 2.2%; the mass percentage of zinc is 1.3%; the mass percentage of manganese is 0.5%; the mass percentage of iron is 0.002%; the mass percentage of silicon is 0.02%; the mass percentage of copper is 0.003%; and the mass percentage of nickel is 0.0002%.

[0152] The weight percentages of Al, La, and Zn in the magnesium alloy are 1:0.39:0.23.

[0153] Example 5

[0154] This embodiment is basically the same as Embodiment 1, except that:

[0155] The magnesium alloy of this embodiment includes: a magnesium matrix, and aluminum, lanthanum, zinc, manganese, iron, silicon, copper and nickel elements present in the magnesium matrix;

[0156] In the magnesium alloy, the mass percentage of aluminum is 7.5%; the mass percentage of lanthanum is 1.2%; the mass percentage of zinc is 0.6%; the mass percentage of manganese is 0.6%; the mass percentage of iron is 0.002%; the mass percentage of silicon is 0.02%; the mass percentage of copper is 0.003%; and the mass percentage of nickel is 0.0002%.

[0157] The weight percentages of Al, La, and Zn in the magnesium alloy are 1:0.16:0.08.

[0158] Example 6

[0159] This embodiment is basically the same as Embodiment 1, except that:

[0160] The magnesium alloy of this embodiment includes: a magnesium matrix, and aluminum, lanthanum, zinc, manganese, iron, silicon, copper and nickel elements present in the magnesium matrix;

[0161] In the magnesium alloy, the mass percentage of aluminum is 6.5%; the mass percentage of lanthanum is 1.1%; the mass percentage of zinc is 1.4%; the mass percentage of manganese is 0.35%; the mass percentage of iron is 0.002%; the mass percentage of silicon is 0.02%; the mass percentage of copper is 0.003%; and the mass percentage of nickel is 0.0002%.

[0162] The weight percentages of Al, La, and Zn in the magnesium alloy are 1:0.17:0.22.

[0163] Example 7

[0164] This embodiment is basically the same as Embodiment 1, except that:

[0165] The magnesium alloy of this embodiment includes: a magnesium matrix, and aluminum, lanthanum, zinc, manganese, iron, silicon, copper and nickel elements present in the magnesium matrix;

[0166] In the magnesium alloy, the mass percentage of aluminum is 6.1%; the mass percentage of lanthanum is 2.0%; the mass percentage of zinc is 0.55%; the mass percentage of manganese is 0.35%; the mass percentage of iron is 0.002%; the mass percentage of silicon is 0.02%; the mass percentage of copper is 0.003%; and the mass percentage of nickel is 0.0002%.

[0167] The weight percentages of Al, La, and Zn in the magnesium alloy are 1:0.33:0.09.

[0168] Example 8

[0169] This embodiment is basically the same as Embodiment 1, except that:

[0170] The magnesium alloy of this embodiment includes: a magnesium matrix, and aluminum, lanthanum, zinc, manganese, iron, silicon, copper and nickel elements present in the magnesium matrix;

[0171] In the magnesium alloy, the mass percentage of aluminum is 6.8%; the mass percentage of lanthanum is 1.5%; the mass percentage of zinc is 0.6%; the mass percentage of manganese is 0.35%; the mass percentage of iron is 0.002%; the mass percentage of silicon is 0.02%; the mass percentage of copper is 0.003%; and the mass percentage of nickel is 0.0002%.

[0172] The weight percentages of Al, La, and Zn in the magnesium alloy are 1:0.22:0.09.

[0173] Example 9

[0174] This embodiment is basically the same as Embodiment 1, except that:

[0175] The magnesium alloy of this embodiment includes: a magnesium matrix, and aluminum, lanthanum, zinc, manganese, iron, silicon, copper and nickel elements present in the magnesium matrix;

[0176] In the magnesium alloy, the mass percentage of aluminum is 6.8%; the mass percentage of lanthanum is 1.5%; the mass percentage of zinc is 1.4%; the mass percentage of manganese is 0.35%; the mass percentage of iron is 0.002%; the mass percentage of silicon is 0.02%; the mass percentage of copper is 0.003%; and the mass percentage of nickel is 0.0002%.

[0177] The weight percentages of Al, La, and Zn in the magnesium alloy are 1:0.22:0.21.

[0178] Example 10

[0179] This embodiment is basically the same as Embodiment 1, except that:

[0180] The magnesium alloy of this embodiment includes: a magnesium matrix, and aluminum, lanthanum, zinc, manganese, iron, silicon, copper and nickel elements present in the magnesium matrix;

[0181] In the magnesium alloy, the mass percentage of aluminum is 6.8%; the mass percentage of lanthanum is 2.1%; the mass percentage of zinc is 1.0%; the mass percentage of manganese is 0.35%; the mass percentage of iron is 0.002%; the mass percentage of silicon is 0.02%; the mass percentage of copper is 0.003%; and the mass percentage of nickel is 0.0002%.

[0182] The weight percentages of Al, La, and Zn in the magnesium alloy are 1:0.31:0.15.

[0183] Example 11

[0184] This embodiment is basically the same as Embodiment 1, except that:

[0185] The magnesium alloy of this embodiment includes: a magnesium matrix, and aluminum, lanthanum, zinc, manganese, iron, silicon, copper and nickel elements present in the magnesium matrix;

[0186] In the magnesium alloy, the mass percentage of aluminum is 6.8%; the mass percentage of lanthanum is 1.2%; the mass percentage of zinc is 1.0%; the mass percentage of manganese is 0.35%; the mass percentage of iron is 0.002%; the mass percentage of silicon is 0.02%; the mass percentage of copper is 0.003%; and the mass percentage of nickel is 0.0002%.

[0187] The weight percentages of Al, La, and Zn in the magnesium alloy are 1:0.18:0.15.

[0188] Example 12

[0189] This embodiment is basically the same as Embodiment 1, except that:

[0190] The amount of refining agent added is 0.5% of the weight of the mixed melt.

[0191] Due to insufficient refining agent, the refining process in this comparative example was incomplete, and oxide inclusions remained in the melt, which affected the yield strength, tensile strength, and elongation of the magnesium alloy.

[0192] Comparative Example 1

[0193] This comparative example provides a Mg-Al-Mn die-cast magnesium alloy (AM60B), comprising: a magnesium matrix, and aluminum, manganese, beryllium, iron, silicon, copper and nickel elements present in the magnesium matrix;

[0194] In the magnesium alloy, the mass percentage of aluminum is 6.0%; the mass percentage of manganese is 0.38%; the mass percentage of beryllium is 0.001%; ​​the mass percentage of iron is 0.002%; the mass percentage of silicon is 0.02%; the mass percentage of copper is 0.003%; and the mass percentage of nickel is 0.0002%.

[0195] The preparation method of this Mg-Al-Mn die-cast magnesium alloy includes the following steps:

[0196] (1) Prepare materials according to the formula composition, wherein Mg and Al are prepared in the form of pure magnesium and pure aluminum, Mn is prepared in the form of Mg-10Mn master alloy (i.e., the mass percentage of Mn element is 10%), and Be is prepared in the form of Mg-5Be master alloy (i.e., the mass percentage of Be element is 5%).

[0197] (2) First, dry pure magnesium is placed in a melting furnace and a protective atmosphere (a mixture of CO2 and SF6, wherein the mass ratio of CO2 to SF6 is 200:1) is introduced for the first melting treatment to obtain magnesium melt. The first melting temperature is 700℃. Then, pure aluminum, Mg-10Mn master alloy and Mg-5Be master alloy are added to the magnesium melt and held at 760℃ for 1 hour (i.e., the second melting treatment). After melting, the metal liquid is stirred evenly. After the chemical composition analysis is qualified, the first alloy melt (i.e., the mixed melt) is obtained.

[0198] (3) At 730°C, a refining agent (a mixture of magnesium chloride, potassium chloride, barium chloride, and calcium fluoride in a mass ratio of 30:26:22:22) was added to the first alloy melt for refining treatment. The proportion of the refining agent added was 1.0% of the total weight of the alloy solution. The solution was then slag removed and allowed to stand for 30 minutes. After the chemical composition analysis was qualified, the second alloy melt was obtained.

[0199] (4) After the second alloy melt reaches 720℃, the test piece is die-cast to obtain Mg-Al-Mn die-cast magnesium alloy; the injection speed during test piece die-casting is 4.5m / s, the injection specific pressure is 84.7MPa, the vacuum degree is 36mbar, and the mold temperature is 258℃.

[0200] Comparative Example 2

[0201] This comparative example provides a Mg-Al-Zn die-cast magnesium alloy (AZ91D), comprising: a magnesium matrix, and aluminum, zinc, manganese, beryllium, iron, silicon, copper and nickel elements present in the magnesium matrix;

[0202] In the magnesium alloy, the mass percentage of aluminum is 9.0%; the mass percentage of zinc is 0.7%; the mass percentage of manganese is 0.28%; the mass percentage of beryllium is 0.001%; ​​the mass percentage of iron is 0.002%; the mass percentage of silicon is 0.02%; the mass percentage of copper is 0.003%; and the mass percentage of nickel is 0.0002%.

[0203] The preparation method of this Mg-Al-Zn die-cast magnesium alloy includes the following steps:

[0204] (1) Prepare materials according to the formula composition, wherein Mg, Al and Zn are prepared in the form of pure magnesium, pure aluminum and pure zinc, Mn is prepared in the form of Mg-10Mn master alloy (i.e., the mass percentage of Mn element is 10%), and Be is prepared in the form of Mg-5Be master alloy (i.e., the mass percentage of Be element is 5%).

[0205] (2) First, dry pure magnesium is placed in a melting furnace and a protective atmosphere (a mixture of CO2 and SF6, wherein the mass ratio of CO2 to SF6 is 200:1) is introduced for the first melting treatment to obtain magnesium melt. The first melting temperature is 700℃. Then, pure aluminum, pure zinc, Mg-10Mn master alloy and Mg-5Be master alloy are added to the magnesium melt and held at 760℃ for 1 hour (i.e., the second melting treatment). After melting, the metal liquid is stirred evenly. After the chemical composition analysis is qualified, the first alloy melt (i.e., the mixed melt) is obtained.

[0206] (3) At 730℃, a refining agent (a mixture of magnesium chloride, potassium chloride, barium chloride and calcium fluoride in a mass ratio of 30:26:22:22) was added to the first alloy melt for refining treatment. The proportion of the refining agent added was 1.0% of the total weight of the alloy solution. The solution was then slag removed and allowed to stand for 30 minutes. After the chemical composition analysis was qualified, the second alloy melt was obtained.

[0207] (4) After the second alloy melt reaches 720℃, test piece die casting is carried out to obtain Mg-Al-Zn die casting magnesium alloy; the injection speed during test piece die casting is 4.5m / s, the injection specific pressure is 84.7MPa, the vacuum degree is 36mbar, and the mold temperature is 258℃.

[0208] Comparative Example 3

[0209] This comparative example is basically the same as Example 1, except that:

[0210] The magnesium alloy in this comparative example includes: a magnesium matrix, and aluminum, lanthanum, zinc, manganese, iron, silicon, copper and nickel elements present in the magnesium matrix;

[0211] In the magnesium alloy, the mass percentage of aluminum is 6.8%; the mass percentage of lanthanum is 0.8%; the mass percentage of zinc is 1.1%; the mass percentage of manganese is 0.35%; the mass percentage of iron is 0.002%; the mass percentage of silicon is 0.02%; the mass percentage of copper is 0.003%; and the mass percentage of nickel is 0.0002%.

[0212] The weight percentages of Al, La, and Zn in the magnesium alloy are 1:0.12:0.16.

[0213] This comparative example has a low La content, which is detrimental to Mg. 17 Al 12 Insufficient phase refinement, Mg 17 Al 12 The phases are distributed in a network pattern.

[0214] Comparative Example 4

[0215] This comparative example is basically the same as Example 1, except that:

[0216] The magnesium alloy in this comparative example includes: a magnesium matrix, and aluminum, lanthanum, zinc, manganese, iron, silicon, copper and nickel elements present in the magnesium matrix;

[0217] In the magnesium alloy, the mass percentage of aluminum is 6.8%; the mass percentage of lanthanum is 2.7%; the mass percentage of zinc is 1.1%; the mass percentage of manganese is 0.35%; the mass percentage of iron is 0.002%; the mass percentage of silicon is 0.02%; the mass percentage of copper is 0.003%; and the mass percentage of nickel is 0.0002%.

[0218] The weight percentages of Al, La, and Zn in the magnesium alloy are 1:0.40:0.16.

[0219] This comparative example has a high La content, which does not show a good match with Al and Zn. 11 The La3 phase forms in large quantities, appearing as clusters and needle-like structures.

[0220] Test case

[0221] 1. The actual chemical composition of the magnesium alloys prepared in the examples and comparative examples was tested. The test method was carried out in accordance with GB / T13748. The test results are shown in Table 1, expressed as mass percentage.

[0222] Table 1

[0223]

[0224] (2) Room temperature mechanical tensile tests were conducted on the magnesium alloys prepared in the examples and comparative examples. The test method was in accordance with GB / T228. The test equipment was a Zwick Z050 microcomputer-controlled electronic universal testing machine. The test rate was controlled by strain rate. The strain rate before yielding was 0.00025 / s, and the strain rate after yielding was 0.0067 / s. The test results of the magnesium alloys are shown in Table 2. The stress-strain curve of the magnesium alloy obtained in Example 1 is shown in Table 2. Figure 1 The magnesium alloys prepared in the examples and comparative examples were subjected to Mg treatment. 17 Al 12 Phase, Al 11 TEM scanning and particle size analysis of La3 phase and Al8Mn4La phase were performed using a TECNAI G2 F20 field emission transmission electron microscope. The test results are shown in Table 2. The SEM scanning and TEM phase analysis results of the magnesium alloy in Example 1 are shown in Table 2. Figure 2 , Figure 3 .

[0225] Depend on Figure 1 It can be seen that the magnesium alloy in Example 1 has a yield strength of 159 MPa, a tensile strength of 298 MPa, and an elongation of 19.5%, exhibiting excellent tensile mechanical properties.

[0226] Depend on Figure 2 , Figure 3It can be seen that in the magnesium alloy of Example 1, Mg 17 Al 12 Phase, Al 11 The La3 phase and trace amounts of Al8Mn4La phase are granular and short rod-shaped, and are dispersed on the α-Mg matrix. The particle size is very small, which strengthens the α-Mg matrix and effectively improves the yield strength, tensile strength and elongation of magnesium alloy.

[0227] Table 2

[0228]

[0229] As shown in Table 2, the magnesium alloy prepared by this invention has excellent tensile mechanical properties, and its strength-ductility product (i.e., the product of tensile strength and elongation) significantly exceeds that of the comparative example.

[0230] (3) Casting fluidity tests were conducted on the magnesium alloys prepared in Examples 1-3 and the Mg-Al-Mn die-casting magnesium alloys prepared in Comparative Examples 1-2. The test methods were based on the casting fluidity test methods specified in Volume 3 of the Casting Handbook for Casting Non-ferrous Alloys. The test mold was a spiral fluidity sand mold (trapezoidal flow channel, 7mm wide at the top, 4mm wide at the bottom, and 7mm high). The test results are shown in Table 3 and... Figure 4 As shown.

[0231] Table 3

[0232]

[0233] As shown in Table 3, the magnesium alloy obtained by the present invention has excellent casting fluidity, and the flow distance is significantly higher than that of the Mg-Al-Mn die-cast magnesium alloy of Comparative Example 1.

[0234] (4) The magnesium alloys prepared in Examples 1-3 and the Mg-Al-Mn die-cast magnesium alloy prepared in Comparative Example 1 were used to trial-produce the front cabin product according to the die-casting production conditions for ultra-large integrated die-cast parts. The die-casting machine had a tonnage of 7000T, an injection pressure of 120MPa, an injection speed of 7m / s, a vacuum degree of 50mbar, a mold temperature of 250℃, and a melt temperature of 700℃. Samples were taken from key areas of the part body for tensile mechanical property testing. The test method was in accordance with GB / T 228. The test equipment was a Zwick Z050 microcomputer-controlled electronic universal testing machine. The test rate was controlled by the strain rate. The strain rate before yielding was 0.00025 / s, and the strain rate after yielding was 0.0067 / s. The test results of the part body samples are shown in Table 4 and Figure 5 As shown.

[0235] Table 4

[0236]

[0237] From Table 4 and Figure 5 It can be seen that the magnesium alloy obtained by this invention produces an ultra-large integrated die-cast front engine compartment for automobiles with excellent comprehensive mechanical properties. The yield strength, tensile strength and elongation of the near end, middle end and far end are significantly higher than those of the comparative example. The strength and plasticity are well matched, ensuring the reliability of the parts.

[0238] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A magnesium alloy characterized by, Comprise: a magnesium matrix, and aluminum element, lanthanum element, zinc element, manganese element, iron element, silicon element, copper element and nickel element present in the magnesium matrix; In the magnesium alloy, the mass percentage of the aluminum element is 5.0%-8.0%; the mass percentage of the lanthanum element is 1.0%-2.5%; the mass percentage of the zinc element is 0.5%-1.5%; the mass percentage of the manganese element is 0.1%-1.0%; the mass percentage of the iron element is less than 0.004%; the mass percentage of the silicon element is less than 0.05%; the mass percentage of the copper element is less than 0.008%; and the mass percentage of the nickel element is less than 0.001%.

2. The magnesium alloy according to claim 1, characterized by The mass percentage of the aluminum element is 6.0%-7.0%; the mass percentage of the lanthanum element is 1.2%-2.0%; the mass percentage of the zinc element is 0.8%-1.2%; the mass percentage of the manganese element is 0.2%-0.4%; the mass percentage of the iron element is less than 0.004%; the mass percentage of the silicon element is less than 0.05%; the mass percentage of the copper element is less than 0.008%; and the mass percentage of the nickel element is less than 0.001%.

3. The magnesium alloy according to claim 1 or 2, characterized in that, The mass ratio of the Al element, La element and Zn element in the magnesium alloy satisfies 1:(0.2-0.3):(0.1-0.2).

4. The magnesium alloy according to any one of claims 1 to 3, characterized in that, The magnesium alloy comprises Mg 17 Al 12 phases, the Mg 17 Al 12 phase is distributed in the form of eutectic along the grain boundaries in the form of particles; the Mg 17 Al 12 phase has a particle size of ≤ 2.0 μm.

5. The magnesium alloy according to any one of claims 1 to 4, characterized in that The magnesium alloy comprises Al 11 La3 phase, the Al 11 The particle size of the La3 phase is ≤ 1.8 μm.

6. The magnesium alloy according to any one of claims 1 to 5, characterized in that The magnesium alloy comprises an Al8Mn4La phase, and the particle size of the Al8Mn4La phase is ≤1.2μm.

7. The magnesium alloy according to any one of claims 1 to 6, characterized in that The yield strength of the magnesium alloy is 150-160MPa, the tensile strength is 280-300MPa, and the elongation is 15%-20%.

8. A method of producing the magnesium alloy according to any one of claims 1 to 7, characterized by, Comprise the following steps: (1) In a protective atmosphere, raw materials comprising a magnesium source, an aluminum source, a manganese source, a zinc source and a lanthanum source are melted and mixed to obtain a mixed melt; (2) The mixed melt is subjected to a refining treatment to obtain the magnesium alloy; In the magnesium alloy, the mass percentage of the aluminum element is 5.0%-8.0%; the mass percentage of the lanthanum element is 1.0%-2.5%; the mass percentage of the zinc element is 0.5%-1.5%; the mass percentage of the manganese element is 0.1%-1.0%; the mass percentage of the iron element is less than 0.004%; the mass percentage of the silicon element is less than 0.05%; the mass percentage of the copper element is less than 0.008%; and the mass percentage of the nickel element is less than 0.001%.

9. The method of claim 8, wherein the magnesium alloy is prepared by a method comprising: The specific steps of the refining treatment comprise: After adding a refining agent to the mixed melt for reaction, the mixed melt is allowed to stand for 20-40min to obtain the magnesium alloy; wherein the reaction temperature is 720-740℃ and the reaction time is 5-15min; Preferably, the amount of the refining agent added is 1.0%-3.0% of the weight of the mixed melt.

10. A magnesium article characterized in that, The magnesium alloy of any one of claims 1-7, or the magnesium alloy prepared by the preparation method of claims 8 or 9.

11. The magnesium article of claim 10, wherein, The magnesium product has a yield strength of 130-160 MPa, a tensile strength of 250-300 MPa, and an elongation of 12-20%.

12. A method of producing a magnesium article according to claim 10 or 11, characterized in that The method comprises the following steps: The magnesium alloy is sequentially subjected to a melting treatment and a die casting treatment to obtain the magnesium product.

13. The method of claim 12, wherein, The temperature of the melting treatment is 680-720 DEG C; and / or, The injection speed of the die casting treatment is 5-9 m / s, the injection specific pressure is 90-180 MPa, the vacuum degree is less than or equal to 100 mbar, and the mold temperature is 230-280 DEG C.

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