A microalloyed magnesium alloy and its preparation method

Abstract

This invention discloses a high-performance, low-cost microalloyed magnesium alloy, comprising the following components by mass percentage: calcium 0.05-0.07%, manganese 0.009%, copper 1.33-1.46%, with the remainder being magnesium, additives, and unavoidable impurities. The preparation method includes the following steps: Step 1: Weigh the alloy raw materials according to the specified proportions and add them to a high-temperature melting furnace; Step 2: Subsequently, add either pure aluminum or pure zinc to the high-temperature furnace, melt in a sealed environment, vent the gas, remove slag, and obtain a liquid alloy; Step 3: Pour the liquid alloy into a preheated mold; Step 4: After cooling, remove the sample from the mold; Step 5: Grind the oxide scale on the sample surface with an angle grinder, and then perform homogenization treatment; Step 6: After homogenization treatment, quench the sample in water and perform low-temperature aging treatment. The materials selected in this invention are all alloying elements that are harmless to humans and the environment and are readily available. After heat treatment, dispersed and stable second-phase particles are obtained, which can effectively improve the mechanical properties of the alloy.

Description

Technical Field

[0001] This invention relates to the field of alloy preparation technology, and in particular to a microalloyed magnesium alloy and its preparation method. Background Technology

[0002] Magnesium (Mg) alloys are among the lightest metallic materials, attracting significant attention due to their low density, ease of recycling, excellent specific strength, and abundant reserves. However, their poor plasticity and low strength limit their widespread application in engineering fields. Improving the mechanical properties of magnesium alloys while maintaining a reasonable cost-performance ratio is a pressing challenge that needs to be addressed.

[0003] Currently, there are two main methods to improve the performance of magnesium alloys. One is to add a large amount of rare earth alloying elements, which can significantly improve the performance of magnesium alloys. However, rare earth elements are expensive, and adding rare earth elements will greatly increase the preparation cost of materials. The other is to add a large amount of other alloying elements, such as Zn, Al, Mn, Ca, etc. The addition of high alloying elements will produce many eutectic phases, and these eutectic phases are difficult to eliminate by heat treatment, which will significantly reduce the alloy performance. Moreover, the addition of high alloying elements will also significantly reduce the machinability of magnesium alloys. Summary of the Invention

[0004] 1. Technical problems to be solved

[0005] The purpose of this invention is to solve the problems in the prior art where adding rare earth elements greatly increases the material preparation cost and the addition of high alloying elements produces many eutectic phases that are difficult to eliminate by heat treatment and significantly reduce alloy performance. Therefore, this invention proposes a microalloyed magnesium alloy and its preparation method.

[0006] 2. Technical Solution

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A microalloyed magnesium alloy comprising the following percentages: calcium 0.05-0.07%, manganese 0.009%, copper 1.33-1.46%, with the remainder being magnesium, additives, and unavoidable impurities.

[0009] Preferably, the added element is either aluminum or zinc, or both.

[0010] Preferably, the percentage of the added elements is 0-1.06% aluminum and 0-0.87% zinc.

[0011] Preferably, the content of the unavoidable impurities does not exceed 0.05%.

[0012] This invention also proposes a method for preparing microalloyed magnesium alloy, comprising the following steps:

[0013] Step 1: Weigh pure magnesium, pure copper, magnesium-calcium master alloy, and magnesium-manganese master alloy according to the proportions, and add the various raw materials in sequence into a high-temperature melting furnace at 680-700℃ under the protection of argon atmosphere.

[0014] Step 2: Then add one of pure aluminum or pure zinc to the high-temperature furnace, or put both into the high-temperature furnace together and melt them in a sealed manner; then blow high-purity argon into the furnace and let it stand for 10 minutes. After all the raw materials have melted, exhaust the gas, remove the slag, and obtain the alloy liquid.

[0015] Step 3: The alloy liquid obtained in Step 2 is poured into a mold preheated to 250°C under an argon protective atmosphere to obtain a sample;

[0016] Step 4: After cooling, remove the sample obtained from Step 3 from the mold;

[0017] Step 5: Use an angle grinder to grind off the oxide scale on the surface of the sample from Step 4, and then put the sample into a high-temperature furnace for homogenization treatment.

[0018] Step 6: After homogenization, the mixture is water-quenched and then placed back into a high-temperature furnace for low-temperature aging treatment.

[0019] Preferably, the heating temperature in step 5 is 420℃ and the holding time is 12h.

[0020] Preferably, in step 6, the low-temperature aging temperature is 200℃ and the holding time is 0.5h-16h.

[0021] 3. Beneficial effects

[0022] Compared with the prior art, the advantages of this invention are:

[0023] (1) In this invention, the selected materials are alloy elements that are not harmful to the human body and the environment and are easy to obtain. After heat treatment, dispersed and stable second phase particles are obtained, which can effectively improve the mechanical properties of the alloy.

[0024] (2) In this invention, a micro-alloyed magnesium alloy with both high performance and low cost was prepared, and the addition of different alloying elements can be controlled to meet different requirements for lightweight alloy materials.

[0025] (3) In this invention, the content of the added alloying elements is very low and no rare earth elements are used, which not only makes the cost low, but also facilitates the subsequent processing and deformation of the ingot, improves market competitiveness, and is easy to promote and use in industry.

[0026] (4) In this invention, the entire processing from casting to heat treatment is extremely simple and convenient, and it is easy to promote and apply in industrial production. Attached Figure Description

[0027] Figure 1 These are hardness dot plots of magnesium alloy materials under different conditions provided in Embodiments 1, 2, and 3 of the present invention, with error bars.

[0028] Figure 2 The image shows the scanning electron microscope (SEM) morphology of the second phase particles in the peak-aged state of the magnesium alloy material provided in Example 1 of the present invention.

[0029] Figure 3 Energy dispersive spectroscopy (EDS) of the second phase particles in the peak-aged state of the magnesium alloy material provided in Example 1 of the present invention;

[0030] Figure 4 This is a scanning electron microscope image of the second phase particles of the magnesium alloy material provided in Example 2 of the present invention under peak aging conditions.

[0031] Figure 5 Energy dispersive spectroscopy (EDS) of the second phase particles of the magnesium alloy material provided in Example 2 of the present invention under peak aging state;

[0032] Figure 6 The image shows the scanning electron microscope (SEM) morphology of the second phase particles in the peak-aged state of the magnesium alloy material provided in Example 3 of the present invention.

[0033] Figure 7 The energy spectrum (EDS) of the second phase particles in the peak-aged state of the magnesium alloy material provided in Example 3 of this invention. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0035] Example 1:

[0036] A microalloyed magnesium alloy comprising the following percentages of elements: calcium 0.05-0.07%, manganese 0.009%, copper 1.33-1.46%, with the remainder being magnesium, additives, and unavoidable impurities.

[0037] In this embodiment, the added element is either aluminum or zinc, or both, with the element percentage being 0-1.06% aluminum and 0-0.87% zinc; the unavoidable impurity content does not exceed 0.05%.

[0038] In this embodiment, a method for preparing a micro-alloyed magnesium alloy includes the following steps:

[0039] Step 1: Weigh pure magnesium, pure copper, magnesium-calcium master alloy, and magnesium-manganese master alloy according to the proportions, and add the various raw materials in sequence into a high-temperature melting furnace at 680-700℃ under the protection of argon atmosphere.

[0040] Step 2: Then add one of pure aluminum or pure zinc to the high-temperature furnace, or put both into the high-temperature furnace together and melt them in a sealed manner; then blow high-purity argon into the furnace and let it stand for 10 minutes. After all the raw materials have melted, exhaust the gas, remove the slag, and obtain the alloy liquid.

[0041] Step 3: The alloy liquid obtained in Step 2 is poured into a mold that has been preheated to 250°C under an argon protective atmosphere.

[0042] Step 4: After cooling, remove the sample obtained from Step 3 from the mold;

[0043] Step 5: Use an angle grinder to grind off the oxide scale on the surface of the sample from Step 4, and then put the sample into a high-temperature furnace for homogenization treatment. The heating temperature is 420℃ and the holding time is 12h.

[0044] Step 6: After homogenization, the sample is water-quenched and then placed back into a high-temperature furnace for low-temperature aging treatment. The low-temperature aging temperature is 200℃ and the holding time is 0.5h-16h.

[0045] In this embodiment, the mechanical properties of this alloy were tested at room temperature. Figure 1 Yes, the hardness at peak aging is 71.08 HV; the yield strength is 161.28 MPa, the tensile strength is 255.02 MPa, and the elongation is 10.82%. Figure 2 Scanning electron microscope images and Figure 3 The energy spectrum shows that the dispersed second-phase particles are mainly distributed at the grain boundaries, and some second-phase particles are distributed inside the grains, playing a strengthening role. The second phase is mainly magnesium-copper phase.

[0046] In this embodiment, the selected materials are all alloying elements that are harmless to the human body and the environment and are very easy to obtain. After heat treatment, dispersed and stable second-phase particles are obtained, which can effectively improve the mechanical properties of the alloy.

[0047] In this embodiment, a micro-alloyed magnesium alloy with both high performance and low cost was prepared, and the addition of different alloying elements can be controlled to meet different requirements for lightweight alloy materials.

[0048] In this embodiment, the content of added alloying elements is very low and no rare earth elements are used, which not only reduces the cost but also facilitates the subsequent processing and deformation of the ingot, improving market competitiveness and making it easy to promote and use in industry.

[0049] In this embodiment, the entire processing from casting to heat treatment is extremely simple and convenient, making it easy to promote and apply in industrial production.

[0050] Example 2:

[0051] It has the implementation content of the above embodiments, wherein the specific implementation methods of the above embodiments can be referred to the above description, and the embodiments here will not be described in detail again; however, the difference between the embodiments in this application and the above embodiments is that:

[0052] In this embodiment, the magnesium alloy composition is Mg-0.8Zn-0.07Ca-1.35Cu-0.009Mn. The atomic percentages of each component in the alloy are: zinc 0.8%; calcium 0.07%; copper 1.35%; manganese 0.009%; unavoidable impurities do not exceed 0.05%, and the remainder is Mg.

[0053] The preparation method of this magnesium alloy is as follows:

[0054] Step 1: Weigh pure magnesium, pure copper, magnesium-calcium master alloy, magnesium-manganese master alloy and pure zinc according to the proportion, and add the various raw materials in sequence into a high-temperature melting furnace at 680-700℃ under the protection of argon atmosphere.

[0055] Step 2: Blow high-purity argon gas into the furnace and let it stand for 10 minutes until all the raw materials have melted. Then, exhaust the gas, remove the slag, and obtain the alloy liquid.

[0056] Step 3: The alloy liquid obtained in Step 2 is poured into a mold preheated to 250°C under an argon protective atmosphere to obtain a sample;

[0057] Step 4: After cooling, remove the sample obtained from Step 3 from the mold;

[0058] Step 5: Use an angle grinder to grind off the oxide scale on the surface of the sample from Step 4, and then put the sample into a 420℃ high-temperature furnace for homogenization treatment for 24 hours.

[0059] Step 6: After the homogenization process is completed, the alloy is water-quenched and then placed back into a high-temperature furnace for low-temperature aging treatment at 200℃ to obtain a high-performance magnesium alloy.

[0060] In this embodiment, the mechanical properties of this alloy were tested at room temperature. Figure 1Yes, the peak aged state has a hardness of 65.91 HV; a yield strength of 169.59 MPa; a tensile strength of 279.89 MPa; and an elongation of 12.95%. Figure 4 Scanning electron microscope images and Figure 5 The energy spectrum shows that a large number of spherical dispersed second-phase particles are distributed inside the grains, and a small amount of second-phase precipitates along the grain boundaries. The second phase is mainly copper-zinc phase, and calcium atom clusters appear together with the second phase to play a reinforcing role.

[0061] Example 3:

[0062] It has the implementation content of the above embodiments, wherein the specific implementation methods of the above embodiments can be referred to the above description, and the embodiments here will not be described in detail again; however, the difference between the embodiments in this application and the above embodiments is that:

[0063] The composition of the magnesium alloy is Mg-0.96Al-0.87Zn-0.05Ca-1.46Cu-0.009Mn (the atomic percentages of each component in the alloy are: aluminum 0.96%; zinc 0.87%; calcium 0.05%; copper 1.46%; manganese 0.009%; unavoidable impurities do not exceed 0.05%, and the remainder is Mg).

[0064] In this embodiment, the magnesium alloy is prepared as follows:

[0065] Step 1: Weigh pure magnesium, pure copper, magnesium-calcium master alloy, magnesium-manganese master alloy, pure aluminum and pure zinc according to the proportions, and add the various raw materials in sequence into a high-temperature melting furnace at 680-700℃ under the protection of argon atmosphere.

[0066] Step 2: Blow high-purity argon gas into the furnace and let it stand for 10 minutes until all the raw materials have melted. Then, exhaust the gas, remove the slag, and obtain the alloy liquid.

[0067] Step 3: The alloy liquid obtained in Step 2 is poured into a mold preheated to 250°C under an argon protective atmosphere to obtain a sample;

[0068] Step 4: After cooling, remove the sample obtained from Step 3 from the mold;

[0069] Step 5: Use an angle grinder to grind off the oxide scale on the surface of the sample from Step 4, and then put the sample into a 420℃ high-temperature furnace for homogenization treatment for 24 hours.

[0070] Step 6: After the homogenization process is completed, the alloy is water-quenched and then placed back into a high-temperature furnace for low-temperature aging treatment at 200℃ to obtain a high-performance magnesium alloy.

[0071] In this embodiment, the mechanical properties of this alloy were tested at room temperature. Figure 1 Yes, the hardness at peak aging is 71.997 HV; the yield strength is 137.51 MPa, the tensile strength is 270.85 MPa, and the elongation is 13.26%. Figure 6 Scanning electron microscope images and Figure 7 The energy spectrum shows that a large number of second phases appeared inside the grains and at the grain boundaries. The second phases are mainly composed of aluminum, copper and zinc, and the clusters of copper atoms together with the second phases play a reinforcing role.

[0072] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A microalloyed magnesium alloy, characterized in that, It comprises the following components by mass percentage: calcium 0.05-0.07%, manganese 0.009%, copper 1.33-1.46%, with the remainder being magnesium, added elements, and unavoidable impurities. The added elements are either aluminum or zinc, or both, with the added elements comprising 0-1.06% aluminum and 0-0.87% zinc by mass. The unavoidable impurities do not exceed 0.05% by mass.

2. The method for preparing a microalloyed magnesium alloy according to claim 1, characterized in that, The following steps are involved: Step 1: Weigh pure magnesium, pure copper, magnesium-calcium master alloy, and magnesium-manganese master alloy according to the proportions, and add the various raw materials in sequence into a high-temperature melting furnace at 680-700℃ under the protection of argon atmosphere. Step 2: Then add one of pure aluminum or pure zinc to the high-temperature furnace, or put both into the high-temperature furnace together and melt them in a sealed manner; then blow high-purity argon into the furnace and let it stand for 10 minutes. After all the raw materials have melted, exhaust the gas, remove the slag, and obtain the alloy liquid. Step 3: The alloy liquid obtained in Step 2 is poured into a mold preheated to 250°C under an argon protective atmosphere to obtain a sample; Step 4: After cooling, remove the sample obtained from Step 3 from the mold; Step 5: Use an angle grinder to grind off the oxide scale on the surface of the sample from Step 4, and then put the sample into a high-temperature furnace for homogenization treatment. Step 6: After homogenization, the mixture is water-quenched and then placed back into a high-temperature furnace for low-temperature aging treatment.

3. The method for preparing a microalloyed magnesium alloy according to claim 2, characterized in that, The heating temperature for homogenization in step 5 is 420℃, and the holding time is 12h.

4. The method for preparing a microalloyed magnesium alloy according to claim 2, characterized in that, In step 6, the low-temperature aging temperature is 200℃, and the holding time is 0.5h-16h.

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