Die-casting Mg-Al-Zn-RE alloy material, preparation method and application thereof

Abstract

The application provides a die-casting Mg-Al-Zn-RE alloy material and a preparation method and application thereof, and belongs to the technical field of alloy materials. 11 The addition of Al elements can improve the fluidity of the die-casting magnesium alloy, Ce can refine the grains and precipitate Al 10 Ce2Mn7 precipitated phase, so as to improve the yield strength of the alloy material; trace amounts of Sb and Sr can obviously refine the grains of the alloy material, so as to improve the mechanical properties of the alloy material. The results of the examples show that the die-casting Mg-Al-Zn-RE alloy material provided by the application has a tensile strength of 270-300 MPa, a yield strength of 180-200 MPa and an elongation of 9-14% at room temperature.

Description

Technical Field

[0001] This invention relates to the field of alloy materials technology, and in particular to a die-cast Mg-Al-Zn-RE alloy material, its preparation method, and its application. Background Technology

[0002] Magnesium alloys are the lightest metallic structural materials, with a density only 2 / 3 that of aluminum alloys and 1 / 4 that of steel. They are among the most promising lightweight metallic materials, and their large-scale application is of great strategic significance for energy conservation, emission reduction, and alleviating the shortage of metal mineral resources in my country. The demand for lightweighting in both traditional and new energy vehicles is urgent, and magnesium alloys have enormous potential for automotive lightweighting. With the upgrading of materials and process equipment, small and medium-sized magnesium alloy parts are gradually shifting towards large and ultra-large sizes. Many key automotive magnesium alloy components are developing towards "ultra-large size," "structural integration," and "functional integration." The lightweighting effect of integrated ultra-large magnesium alloy components will be even more significant. The integrated molding technology for ultra-large magnesium alloy castings can greatly simplify the complex processes of multi-component production and connection, significantly improving component dimensional stability. This not only saves time and manufacturing costs but also reduces production line and labor costs, resulting in more significant energy conservation and emission reduction benefits, and has become an important future development trend. In June 2022, the HDC8800-ton die-casting machine, jointly developed by Merix Technologies and Haitian Metal, and currently the world's largest in mass production capacity, successfully mass-produced large automotive aluminum alloy rear floor components. In June 2023, Chongqing University, Merix Technologies, and Chongqing Boao successfully trial-produced two types of integrated ultra-large magnesium alloy die-cast parts, each with a projected area greater than 2.2m². 2 .

[0003] Magnesium alloy integrated die-cast components have enormous application potential in the automotive industry. However, with technological advancements, the requirements for the mechanical properties of these components are becoming increasingly stringent. Currently available magnesium alloy integrated die-cast components generally possess only average mechanical properties, which are insufficient to meet technical requirements. Therefore, improving the mechanical properties of magnesium alloy integrated die-cast components has become a pressing technical problem to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a die-cast Mg-Al-Zn-RE alloy material, its preparation method, and its application. The die-cast Mg-Al-Zn-RE alloy material provided by this invention has excellent mechanical properties, can strictly meet the requirements of automobile components, and does not require heat treatment, thus replacing certain die-cast aluminum alloy products.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a die-cast Mg-Al-Zn-RE alloy material, comprising the following chemical composition by mass percentage: Al: 8.0-8.5%, Ce: 1.0-1.6%, Zn: 0.5-0.9%, Mn: 0.21-0.28%, Sb: 0.18-0.36%, Sr: 0.06-0.12%, and the balance Mg; wherein the mass ratio of Sb to Sr is (2-4):1.

[0007] Preferably, the die-cast Mg-Al-Zn-RE alloy material comprises the following chemical composition by mass percentage: Al: 8.3-8.5%, Ce: 1.0-1.3%, Zn: 0.6-0.8%, Mn: 0.21-0.25%, Sb: 0.18-0.32%, Sr: 0.06-0.08%, and the balance Mg.

[0008] Preferably, the die-cast Mg-Al-Zn-RE alloy material comprises the following chemical composition by mass percentage: Al: 8.3%, Ce: 1.19%, Zn: 0.74%, Mn: 0.21%, Sb: 0.18%, Sr: 0.06%, and the balance Mg.

[0009] Preferably, the mass ratio of Sb to Sr is 3:1.

[0010] This invention provides a method for preparing the die-cast Mg-Al-Zn-RE alloy material described above, comprising the following steps:

[0011] (1) Melt the alloy raw materials to obtain the alloy melt;

[0012] (2) The alloy melt obtained in step (1) is die-cast to obtain die-cast Mg-Al-Zn-RE alloy material.

[0013] Preferably, the alloy raw materials in step (1) include pure magnesium ingots, pure Al, pure Zn, pure Sb, Mg-Ce master alloy, Mg-Mn master alloy and Mg-Sr master alloy.

[0014] Preferably, the smelting in step (1) includes the following steps:

[0015] 1) Preheat the smelting furnace to obtain a preheated smelting furnace;

[0016] 2) Apply the release agent to the inner wall of the low carbon steel crucible, and then dry the low carbon steel crucible to obtain a dried low carbon steel crucible.

[0017] 3) Place the pure magnesium ingot into the dried low-carbon steel crucible obtained in step 2), and then place the dried low-carbon steel crucible into the preheated melting furnace obtained in step 1). Under a protective atmosphere, heat the furnace to 750-780°C. After the pure magnesium ingot melts, add pure Al, pure Zn, pure Sb, Mg-Ce master alloy, Mg-Mn master alloy and Mg-Sr master alloy in sequence. After the alloy raw materials are completely melted, remove the surface slag to obtain the preliminary alloy melt.

[0018] 4) Add a refining agent to the preliminary alloy melt obtained in step 3) for refining, and then perform slag removal treatment to obtain the alloy melt;

[0019] Steps 1) and 2) are not sequential.

[0020] Preferably, the protective atmosphere in step 3) is a mixture of CO2 and SF6; the volume ratio of CO2 to SF6 is 100:(0.5-2).

[0021] Preferably, the die-casting temperature in step (2) is 720-740°C, and the die-casting is carried out using a 650T die-casting machine.

[0022] This invention provides applications of the die-cast Mg-Al-Zn-RE alloy material described in the above technical solution or the die-cast Mg-Al-Zn-RE alloy material prepared by the preparation method described in the above technical solution in the automotive, aerospace and defense industries.

[0023] This invention provides a die-cast Mg-Al-Zn-RE alloy material, comprising the following chemical composition by mass percentage: Al: 8.0–8.5%, Ce: 1.0–1.6%, Zn: 0.5–0.9%, Mn: 0.21–0.28%, Sb: 0.18–0.36%, Sr: 0.06–0.12%, and the balance Mg; wherein the mass ratio of Sb to Sr is (2–4):1. In this invention, the addition of Al can improve the fluidity of the die-cast magnesium alloy, and the addition of Ce can refine the grains while precipitating Al at the grain boundaries. 11 The addition of Ce3 phase, Al2Ce and (Al,Mg)2Ce phase further improves the yield strength of the alloy material; the addition of Zn and Mn elements can form Al2CeZn2 and Al with Al and Ce respectively. 10The Ce2Mn7 precipitate phase can significantly improve the yield strength of the alloy material; the addition of trace amounts of Sb and Sr elements can significantly refine the grain size of the alloy material, thereby further improving the overall mechanical properties of the alloy material. The results of the examples show that the die-cast Mg-Al-Zn-RE alloy material provided by this invention has a tensile strength of 270–300 MPa, a yield strength of 180–200 MPa, and an elongation of 9–14% at room temperature, showing good application prospects in the automotive, aerospace, and defense industries. Attached Figure Description

[0024] Figure 1 The stress-strain curve of the die-cast Mg-Al-Zn-RE alloy material obtained in Example 1 of this invention;

[0025] Figure 2 The stress-strain curve of the die-cast Mg-Al-Zn-RE alloy material obtained in Example 2 of this invention is shown. Detailed Implementation

[0026] This invention provides a die-cast Mg-Al-Zn-RE alloy material, comprising the following chemical composition by mass percentage: Al: 8.0-8.5%, Ce: 1.0-1.6%, Zn: 0.5-0.9%, Mn: 0.21-0.28%, Sb: 0.18-0.36%, Sr: 0.06-0.12%, and the balance Mg; wherein the mass ratio of Sb to Sr is (2-4):1.

[0027] The die-cast Mg-Al-Zn-RE alloy material provided by this invention comprises Al: 8.0% to 8.5% by mass percentage. As one embodiment of this invention, the mass percentage of Al in the die-cast Mg-Al-Zn-RE alloy material can be 8.0%, 8.1%, 8.2%, 8.3%, 8.4%, or 8.5%. In this invention, Al is one of the matrix elements of the alloy material, which can improve the fluidity of the die-cast magnesium alloy.

[0028] The die-cast Mg-Al-Zn-RE alloy material provided by this invention comprises Ce: 1.0% to 1.6% by mass percentage. As one embodiment of this invention, the mass percentage of Ce in the die-cast Mg-Al-Zn-RE alloy material can be 1.0%, 1.05%, 1.1%, 1.15%, 1.19%, 1.2%, 1.25%, 1.3%, 1.35%, 1.4%, 1.45%, 1.5%, 1.55%, or 1.6%. In this invention, the addition of Ce can refine the grains while precipitating Al at the grain boundaries. 11 The presence of Ce3 phase, Al2Ce and (Al,Mg)2Ce phase further improves the yield strength of the alloy material.

[0029] The die-cast Mg-Al-Zn-RE alloy material provided by this invention comprises Zn: 0.5% to 0.9% by mass percentage. As one embodiment of this invention, the mass percentage of Zn in the die-cast Mg-Al-Zn-RE alloy material can be 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.74%, 0.8%, 0.85%, or 0.9%.

[0030] The die-cast Mg-Al-Zn-RE alloy material provided by this invention comprises Mn: 0.21% to 0.28% by mass percentage. As one embodiment of this invention, the mass percentage of Mn in the die-cast Mg-Al-Zn-RE alloy material can be 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, or 0.28%.

[0031] In this invention, the addition of Zn and Mn elements can form Al2CeZn2 and Al with Al and Ce respectively. 10 Ce2Mn7 precipitates can also significantly improve the yield strength of alloy materials.

[0032] The die-cast Mg-Al-Zn-RE alloy material provided by this invention comprises Sb: 0.06% to 0.36% by mass percentage. As one embodiment of this invention, the mass percentage of Sb in the die-cast Mg-Al-Zn-RE alloy material can be 0.18%, 0.20%, 0.22%, 0.24%, 0.26%, 0.28%, 0.30%, 0.32%, 0.34%, or 0.36%.

[0033] The die-cast Mg-Al-Zn-RE alloy material provided by this invention comprises Sr: 0.06% to 0.12% by mass percentage. As one embodiment of this invention, the mass percentage of Sr in the die-cast Mg-Al-Zn-RE alloy material can be 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, or 0.12%.

[0034] In this invention, the mass ratio of Sb to Sr is (2-4):1. As one embodiment of this invention, the mass ratio of Sb to Sr can be 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1, 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 3.9:1, or 4.0:1.

[0035] In this invention, the addition of trace amounts of Sb and Sr elements and the control of their dosage relationship can significantly refine the grains of the alloy material, thereby further improving the comprehensive mechanical properties of the alloy material. When the mass ratio of Sb to Sr is in the range of (2 to 4): 1, the mechanical properties of the die-cast Mg-Al-Zn-RE alloy material are better than those in other ranges.

[0036] The die-cast Mg-Al-Zn-RE alloy material provided by this invention comprises the balance Mg by weight percentage. In this invention, Mg is the matrix material of the alloy material.

[0037] The die-cast Mg-Al-Zn-RE alloy material provided by the present invention preferably further includes impurities by weight percentage. In the present invention, the weight percentage of the impurities is preferably ≤0.01%. The present invention does not specifically limit the types of impurities, which are impurities that are unavoidable in the preparation of alloy materials and are well known to those skilled in the art.

[0038] In this invention, the addition of Al can improve the fluidity of die-cast magnesium alloys, and the addition of Ce can refine the grains while precipitating Al at the grain boundaries. 11 The addition of Ce3 phase, Al2Ce and (Al,Mg)2Ce phase further improves the yield strength of the alloy material; the addition of Zn and Mn elements can form Al2CeZn2 and Al with Al and Ce respectively. 10 Ce2Mn7 precipitates can significantly improve the yield strength of alloy materials; the addition of trace amounts of Sb and Sr elements can significantly refine the grains of alloy materials, thereby further improving the comprehensive mechanical properties of alloy materials.

[0039] This invention also provides a method for preparing the die-cast Mg-Al-Zn-RE alloy material described in the above technical solution, comprising the following steps:

[0040] (1) Melt the alloy raw materials to obtain the alloy melt;

[0041] (2) The alloy melt obtained in step (1) is die-cast to obtain die-cast Mg-Al-Zn-RE alloy material.

[0042] This invention involves melting alloy raw materials to obtain an alloy melt.

[0043] In this invention, the alloy raw materials preferably include pure magnesium ingots, pure Al, pure Zn, pure Sb, Mg-Ce master alloy, Mg-Mn master alloy, and Mg-Sr master alloy. This invention does not impose any specific limitations on the amount of the alloy raw materials used; it can be determined based on the technical knowledge of those skilled in the art, as long as the chemical composition of the obtained die-cast Mg-Al-Zn-RE alloy material meets the requirements.

[0044] In this invention, the alloy raw material is preferably subjected to grinding and drying treatment before smelting. The grinding method is preferably to use a grinding wheel to remove the oxide layer on the surface of the alloy raw material. The drying temperature is preferably 200–300°C; the drying time is preferably 20–60 minutes; and the drying is preferably carried out in a drying oven. As one embodiment of this invention, the drying temperature can be 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, or 300°C; and the drying time can be 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, or 60 minutes. This invention can remove oxides and moisture from the surface of the alloy raw material through grinding and drying treatment.

[0045] In this invention, the smelting preferably includes the following steps:

[0046] 1) Preheat the smelting furnace to obtain a preheated smelting furnace;

[0047] 2) Apply the release agent to the inner wall of the low carbon steel crucible, and then dry the low carbon steel crucible to obtain a dried low carbon steel crucible.

[0048] 3) Place the pure magnesium ingot into the dried low-carbon steel crucible obtained in step 2), and then place the dried low-carbon steel crucible into the preheated melting furnace obtained in step 1). Under a protective atmosphere, heat the furnace to 750-780°C. After the pure magnesium ingot melts, add pure Al, pure Zn, pure Sb, Mg-Ce master alloy, Mg-Mn master alloy and Mg-Sr master alloy in sequence. After the alloy raw materials are completely melted, remove the surface slag to obtain the preliminary alloy melt.

[0049] 4) Add a refining agent to the preliminary alloy melt obtained in step 3) for refining, and then perform slag removal treatment to obtain the alloy melt;

[0050] Steps 1) and 2) are not sequential.

[0051] The present invention preferably preheats the smelting furnace to obtain a preheated smelting furnace.

[0052] The present 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.

[0053] In this invention, the preheating temperature is preferably 480–520°C, more preferably 500°C; the preheating time is preferably 40–80 min, more preferably 60 min. Preheating facilitates subsequent smelting in this invention.

[0054] In this invention, the release agent is preferably applied to the inner wall of the low-carbon steel crucible, and then the low-carbon steel crucible is dried to obtain a dried low-carbon steel crucible.

[0055] In this invention, the release agent is preferably a mixture of boron nitride and alcohol in a mass ratio of 1:2. In this invention, the release agent is preferably applied evenly using a brush. This invention does not impose any particular limitation on the amount of release agent applied; it can be determined based on the technical knowledge of those skilled in the art. This invention, by applying a release agent, facilitates subsequent demolding.

[0056] The present invention does not have any special limitations on the specific drying operation. Based on the technical common sense of those skilled in the art, it is sufficient to dry the release agent.

[0057] After obtaining the preheated melting furnace and the dried low-carbon steel crucible, the present invention preferably places pure magnesium ingots into the dried low-carbon steel crucible, and then places the dried low-carbon steel crucible into the preheated melting furnace. Under a protective atmosphere, the temperature is raised to 750-780°C. After the pure magnesium ingots melt, pure Al, pure Zn, pure Sb, Mg-Ce master alloy, Mg-Mn master alloy and Mg-Sr master alloy are added in sequence. After the alloy raw materials are completely melted, the surface slag is removed to obtain a preliminary alloy melt.

[0058] In this invention, the protective atmosphere is preferably a mixture of CO2 and SF6; the volume ratio of CO2 to SF6 is preferably 100:(0.5-2), more preferably 100:(1-1.5). This invention avoids metal oxidation by melting in a protective atmosphere.

[0059] In this invention, the preferred method for removing surface scum is to use a long-handled low-carbon steel spoon coated with a release agent. The release agent is preferably the same as described above and will not be repeated here. This invention reduces impurities by removing surface scum.

[0060] After obtaining the preliminary alloy melt, the present invention preferably adds a refining agent to the preliminary alloy melt for refining, and then performs slag removal treatment to obtain the alloy melt.

[0061] In this invention, the refining agent is preferably Refining Agent No. 5; the amount of the refining agent is preferably 2% of the total mass of the initial alloy melt; the refining agent is preferably dried; the drying treatment is preferably drying in a pit furnace at 250°C for 30 minutes. This invention removes oxides from the alloy melt by adding the refining agent, further reducing the impurity content.

[0062] In this invention, the refining agent is preferably added by using a long-handled low-carbon steel spoon to deliver the refining agent to the bottom of the preliminary alloy melt, stirring up and down for 2-3 minutes, and then rotating and stirring for 3-5 minutes. This method of addition ensures that the refining agent is mixed evenly.

[0063] In this invention, the refining temperature is preferably 740-750°C.

[0064] The present invention does not impose any special limitations on the specific operation of the slag removal process; it can be determined based on the technical common sense of those skilled in the art.

[0065] After obtaining the alloy melt, the present invention performs die casting on the alloy melt to obtain die-cast Mg-Al-Zn-RE alloy material.

[0066] In this invention, the temperature of the mold during die casting is preferably 180–250°C, more preferably 200–220°C. This invention avoids excessively rapid cooling of the alloy melt during die casting by increasing the mold temperature.

[0067] In this invention, the die-casting temperature is preferably 720–740°C; the die-casting is preferably performed using a 650T die-casting machine. This invention can directly obtain high-performance integrated die-cast ultra-large components through high-pressure die casting.

[0068] The preparation method provided by this invention is simple. High-performance integrated die-cast ultra-large components can be directly obtained through high-pressure die casting. The obtained ultra-large components have excellent mechanical properties and have good application prospects in the fields of automobiles, aerospace and defense.

[0069] This invention also provides the application of the die-cast Mg-Al-Zn-RE alloy material described in the above technical solution or the die-cast Mg-Al-Zn-RE alloy material prepared by the preparation method described in the above technical solution in the automotive, aerospace and defense industries.

[0070] The present invention does not impose any special limitations on the specific application method, which can be determined based on the technical common sense of those skilled in the art.

[0071] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0072] Example 1

[0073] A die-cast Mg-Al-Zn-RE alloy material, with the following chemical composition by mass percentage: Al: 8.3%, Ce: 1.19%, Zn: 0.74%, Mn: 0.21%, Sb: 0.18%, Sr: 0.06%, and balance Mg; wherein the mass ratio of Sb to Sr is 3:1;

[0074] The preparation method of the die-cast Mg-Al-Zn-RE alloy material comprises the following steps:

[0075] (1) Use a grinding wheel to remove the oxide layer on the surface of the alloy raw material, then dry it in a drying oven at 250°C for 30 minutes, and then melt it to obtain the alloy melt;

[0076] (2) The alloy melt obtained in step (1) is left to stand at 740°C for 30 minutes, and then the alloy melt is die-cast using a 650T die-casting machine to obtain a die-cast Mg-Al-Zn-RE alloy material. The die-cast Mg-Al-Zn-RE alloy material is rod-shaped. The temperature of the mold during die-casting is 200°C.

[0077] The smelting in step (1) consists of the following steps:

[0078] 1) Preheat the smelting furnace at 500℃ for 60 minutes to obtain the preheated smelting furnace;

[0079] 2) Boron nitride and alcohol are mixed in a mass ratio of 1:2 to form a release agent. The release agent is evenly applied to the inner wall of the low carbon steel crucible using a brush. Then the low carbon steel crucible is dried to obtain a dried low carbon steel crucible.

[0080] 3) Place the pure magnesium ingot into the dried low-carbon steel crucible obtained in step 2), and then place the dried low-carbon steel crucible into the preheated melting furnace obtained in step 1). Under a protective atmosphere, heat to 780°C. After the pure magnesium ingot melts, add pure Al, pure Zn, pure Sb, Mg-Ce master alloy, Mg-Mn master alloy, and Mg-Sr master alloy in sequence. After the alloy raw materials are completely melted, use a long-handled low-carbon steel spoon coated with a release agent to remove the surface slag and obtain a preliminary alloy melt. The protective atmosphere is a mixture of CO2 and SF6, with a volume ratio of CO2 to SF6 of 100:1.

[0081] 4) Control the temperature of the preliminary alloy melt to 750℃, add a refining agent to the preliminary alloy melt obtained in step 3) for refining, and then perform slag removal treatment to obtain the alloy melt; the refining agent is No. 5 refining agent; the amount of the refining agent is 2% of the total mass of the preliminary alloy melt; the refining agent is dried in a pit furnace at 250℃ for 30 minutes; the refining agent is added by using a long-handled low carbon steel spoon to send the refining agent to the bottom of the preliminary alloy melt, stirring up and down for 2 minutes, and then rotating and stirring for 3 minutes.

[0082] The die-cast Mg-Al-Zn-RE alloy material obtained in Example 1 was subjected to a room temperature mechanical tensile test. The test method was as follows: two groups (denoted as 1# and 2#) of the die-cast Mg-Al-Zn-RE alloy material obtained in Example 1 were processed into standard room temperature tensile specimens according to the national standard GB / T228.1-2021, and tensile tests were performed on a CMT-5105 room temperature tensile testing machine. Tensile conditions: The surface of the die-cast Mg-Al-Zn-RE alloy material specimens was polished with sandpaper, and tensile tests were performed at a rate of 3.6 mm / min. The obtained stress-strain curves are shown below. Figure 1 As shown in Table 1, the mechanical properties are as follows:

[0083] Table 1 Mechanical properties of the die-cast Mg-Al-Zn-RE alloy material obtained in Example 1

[0084] 1# 297 196 11.6 2# 285 187 10.4

[0085] Depend on Figure 1 As can be seen from Table 1, under room temperature conditions, the room temperature tensile strength and yield strength of the die-cast Mg-Al-Zn-RE alloy material obtained in Example 1 are at a high level; the yield strength of the rod-shaped die-cast Mg-Al-Zn-RE alloy material is as high as 196 MPa, the tensile strength reaches 297 MPa, and the elongation is 11.6%.

[0086] Example 2

[0087] A die-cast Mg-Al-Zn-RE alloy material, with the following chemical composition by mass percentage: Al: 8.3%, Ce: 1.19%, Zn: 0.74%, Mn: 0.21%, Sb: 0.18%, Sr: 0.06%, and balance Mg; wherein the mass ratio of Sb to Sr is 3:1;

[0088] The preparation method of the die-cast Mg-Al-Zn-RE alloy material comprises the following steps:

[0089] (1) Use a grinding wheel to remove the oxide layer on the surface of the alloy raw material, then dry it in a drying oven at 250°C for 30 minutes, and then melt it to obtain the alloy melt;

[0090] (2) The alloy melt obtained in step (1) is allowed to stand at 740°C for 30 minutes, and then the alloy melt is die-cast using a 650T die-casting machine to obtain die-cast Mg-Al-Zn-RE alloy material. The die-cast Mg-Al-Zn-RE alloy material is plate-shaped (with thicknesses of 3mm, 4mm and 5mm respectively); the temperature of the mold during die-casting is 200°C.

[0091] The smelting in step (1) consists of the following steps:

[0092] 1) Preheat the smelting furnace at 500℃ for 60 minutes to obtain the preheated smelting furnace;

[0093] 2) Boron nitride and alcohol are mixed in a mass ratio of 1:2 to form a release agent. The release agent is evenly applied to the inner wall of the low carbon steel crucible using a brush. Then the low carbon steel crucible is dried to obtain a dried low carbon steel crucible.

[0094] 3) Place the pure magnesium ingot into the dried low-carbon steel crucible obtained in step 2), and then place the dried low-carbon steel crucible into the preheated melting furnace obtained in step 1). Under a protective atmosphere, heat to 780°C. After the pure magnesium ingot melts, add pure Al, pure Zn, pure Sb, Mg-Ce master alloy, Mg-Mn master alloy, and Mg-Sr master alloy in sequence. After the alloy raw materials are completely melted, use a long-handled low-carbon steel spoon coated with a release agent to remove the surface slag and obtain a preliminary alloy melt. The protective atmosphere is a mixture of CO2 and SF6, with a volume ratio of CO2 to SF6 of 100:1.

[0095] 4) Control the temperature of the preliminary alloy melt to 750℃, add a refining agent to the preliminary alloy melt obtained in step 3) for refining, and then perform slag removal treatment to obtain the alloy melt; the refining agent is No. 5 refining agent; the amount of the refining agent is 2% of the total mass of the preliminary alloy melt; the refining agent is dried in a pit furnace at 250℃ for 30 minutes; the refining agent is added by using a long-handled low carbon steel spoon to send the refining agent to the bottom of the preliminary alloy melt, stirring up and down for 2 minutes, and then rotating and stirring for 3 minutes.

[0096] Room temperature tensile tests were conducted on the die-cast Mg-Al-Zn-RE alloy materials with thicknesses of 3 mm, 4 mm, and 5 mm obtained in Example 2. The test method was as follows: The die-cast Mg-Al-Zn-RE alloy materials obtained in Example 2 were processed into standard room temperature tensile specimens according to the national standard GB / T228.1-2021, and tensile tests were performed on a CMT-5105 room temperature tensile testing machine. Tensile conditions: The specimen surface was polished with sandpaper, and tensile testing was performed at a rate of 3.6 mm / min. The resulting engineering stress-strain curves of the die-cast Mg-Al-Zn-RE alloy materials are shown below. Figure 2 As shown in Table 2, the mechanical properties of the die-cast Mg-Al-Zn-RE alloy material are as follows:

[0097] Table 2 Mechanical properties of the die-cast Mg-Al-Zn-RE alloy material obtained in Example 2

[0098] 3mm 271 196 9.1 4mm 265 180 10.3 5mm 267 173 12.3

[0099] Depend on Figure 2 As shown in Table 2, under room temperature conditions, the room temperature tensile strength and yield strength of the die-cast Mg-Al-Zn-RE alloy material obtained in Example 2 remain at a relatively high level. With the increase of the tensile specimen thickness, the yield strength of the die-cast Mg-Al-Zn-RE alloy material gradually decreases, the tensile strength decreases, and the elongation increases. When the tensile specimen thickness is 3 mm, the strength is relatively high, with a yield strength of 196 MPa and a tensile strength of 271 MPa. When the tensile specimen thickness is 5 mm, the elongation of the die-cast Mg-Al-Zn-RE alloy material is the highest, reaching 12.3%. Therefore, the die-cast Mg-Al-Zn-RE alloy material provided by this invention can strictly meet the requirements of automotive components and requires no heat treatment, thus replacing certain die-cast aluminum alloy products.

[0100] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A die-cast Mg-Al-Zn-RE alloy material, comprising the following chemical composition by mass percentage: Al: 8.0~8.5%, Ce: 1.0~1.6%, Zn: 0.5~0.9%, Mn: 0.21~0.28%, Sb: 0.18~0.36%, Sr: 0.06~0.12% and balance Mg; wherein, The mass ratio of Sb to Sr is (2~4):1; The preparation method of the die-cast Mg-Al-Zn-RE alloy material includes the following steps: (1) Melt the alloy raw materials to obtain an alloy melt; (2) The alloy melt obtained in step (1) is die-cast to obtain die-cast Mg-Al-Zn-RE alloy material; The alloy raw materials in step (1) include pure magnesium ingots, pure Al, pure Zn, pure Sb, Mg-Ce master alloy, Mg-Mn master alloy and Mg-Sr master alloy; The smelting process in step (1) includes the following steps: 1) Preheat the smelting furnace to obtain a preheated smelting furnace; 2) Apply the release agent to the inner wall of the low carbon steel crucible, and then dry the low carbon steel crucible to obtain a dried low carbon steel crucible. 3) Place the pure magnesium ingot into the dried low-carbon steel crucible obtained in step 2), and then place the dried low-carbon steel crucible into the preheated melting furnace obtained in step 1). Under a protective atmosphere, heat the furnace to 750~780℃. After the pure magnesium ingot melts, add pure Al, pure Zn, pure Sb, Mg-Ce master alloy, Mg-Mn master alloy and Mg-Sr master alloy in sequence. After the alloy raw materials are completely melted, remove the surface slag to obtain the preliminary alloy melt. 4) Add a refining agent to the preliminary alloy melt obtained in step 3) for refining, and then perform slag removal treatment to obtain the alloy melt; Steps 1) and 2) are not sequential.

2. The die-cast Mg-Al-Zn-RE alloy material according to claim 1, characterized in that, By mass percentage, it includes the following chemical components: Al: 8.3~8.5%, Ce: 1.0~1.3%, Zn: 0.6~0.8%, Mn: 0.21~0.25%, Sb: 0.18~0.32%, Sr: 0.06~0.08% and balance Mg.

3. The die-cast Mg-Al-Zn-RE alloy material according to claim 1, characterized in that, The chemical composition, by mass percentage, includes the following: Al: 8.3%, Ce: 1.19%, Zn: 0.74%, Mn: 0.21%, Sb: 0.18%, Sr: 0.06%, and balance Mg.

4. The die-cast Mg-Al-Zn-RE alloy material according to claim 1, characterized in that, The mass ratio of Sb to Sr is 3:

1.

5. The method for preparing the die-cast Mg-Al-Zn-RE alloy material according to any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Melt the alloy raw materials to obtain an alloy melt; (2) The alloy melt obtained in step (1) is die-cast to obtain die-cast Mg-Al-Zn-RE alloy material; The alloy raw materials in step (1) include pure magnesium ingots, pure Al, pure Zn, pure Sb, Mg-Ce master alloy, Mg-Mn master alloy and Mg-Sr master alloy; The smelting process in step (1) includes the following steps: 1) Preheat the smelting furnace to obtain a preheated smelting furnace; 2) Apply the release agent to the inner wall of the low carbon steel crucible, and then dry the low carbon steel crucible to obtain a dried low carbon steel crucible. 3) Place the pure magnesium ingot into the dried low-carbon steel crucible obtained in step 2), and then place the dried low-carbon steel crucible into the preheated melting furnace obtained in step 1). Under a protective atmosphere, heat the furnace to 750~780℃. After the pure magnesium ingot melts, add pure Al, pure Zn, pure Sb, Mg-Ce master alloy, Mg-Mn master alloy and Mg-Sr master alloy in sequence. After the alloy raw materials are completely melted, remove the surface slag to obtain the preliminary alloy melt. 4) Add a refining agent to the preliminary alloy melt obtained in step 3) for refining, and then perform slag removal treatment to obtain the alloy melt; Steps 1) and 2) are not sequential.

6. The preparation method according to claim 5, characterized in that, In step 3), the protective atmosphere is a mixture of CO2 and SF6; the volume ratio of CO2 to SF6 is 100:(0.5~2).

7. The preparation method according to claim 5, characterized in that, In step (2), the die-casting temperature is 720~740℃, and a 650T die-casting machine is used for die-casting.

8. The application of the die-cast Mg-Al-Zn-RE alloy material according to any one of claims 1 to 4 or the die-cast Mg-Al-Zn-RE alloy material prepared by the preparation method according to any one of claims 5 to 7 in the automotive, aerospace and defense industries.

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