Mg-Al-Ce high-strength heat-resistant magnesium alloy and preparation method thereof

Abstract

The invention discloses an Mg-Al-Ce high-strength heat-resistant magnesium alloy and a preparation method thereof, and belongs to the technical field of materials. The Mg-Al-Ce high-strength heat-resistant magnesium alloy comprises the following components in percentage by weight: 90.7-94.7 wt.% of Mg, 0.1-0.5 wt.% of Al, 0.1-0.5 wt. % of Al, 4.0 to 5.0 wt.%; % of Ce, 3.0 to 4.0 wt.%; %, and 0 to 0.1 wt.% of Mn. The preparation method of the Mg-Al-Ce high-strength heat-resistant magnesium alloy comprises the following steps that S1, burdening is conducted according to target alloy components, smelting is conducted under the protective atmosphere after preheating is conducted, and magnesium alloy melt with uniform components is obtained; s2, the magnesium alloy melt is subjected to rapid solidification, and a rapid solidification strip is formed; s3, the rapidly solidified strip is crushed, and alloy powder with the preset particle size is obtained; and S4, the alloy powder is subjected to hot press forming and hot extrusion, and a compact bar is obtained. On the premise of considering low cost and high process feasibility, comprehensive improvement of the strength, toughness and heat resistance of the magnesium alloy is achieved through structure refinement and multi-mechanism strengthening, and the magnesium alloy has important industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of materials technology, specifically relating to a Mg-Al-Ce high-strength heat-resistant magnesium alloy and its preparation method. Background Technology

[0002] With the continuous improvement of material performance requirements due to industrial development, lightweighting and high strength and toughness have become important research directions for metallic structural materials. Magnesium alloys, due to their low density, good specific strength, excellent damping properties and machinability, are regarded as highly promising lightweight structural materials, and have significant value in reducing equipment weight and energy consumption.

[0003] Currently, the main technical approaches to achieving high strength and heat resistance in magnesium alloys are as follows: One approach involves alloy systems incorporating medium-heavy rare earth elements (such as Gd, Y, and Nd) (see patents CN118581371A, CN115927939A, CN116949331A, CN117026042A, CN116121575A, CN115161528A, and CN114836664A). While this method can enhance high-temperature stability by utilizing rare earth phases, it significantly increases raw material costs and alloy density, weakening the lightweight advantage of magnesium alloys. Furthermore, these alloys generally rely on subsequent solution treatment and aging heat treatment to control their microstructure, leading to extended production cycles and further increased costs, thus hindering their large-scale industrial application.

[0004] Secondly, alloying can be achieved using light rare earth elements (such as Ce and La). Light rare earth elements have relatively low cost and density, but their solid solubility in a magnesium matrix is ​​extremely low. They readily combine with aluminum to form high-melting-point intermetallic compounds, such as Al₂Ce and Al₂O₃. 11 Ce3 and other brittle phases have melting points exceeding 1200℃. Traditional solution treatment and aging processes are insufficient to effectively refine and disperse these brittle phases, thus offering limited improvement to overall mechanical properties.

[0005] Thirdly, we are developing rare-earth-free alkaline earth magnesium alloys, such as Mg-Al-Ca, Mg-Al-Sr, and Mg-Al-Si systems. While these alloys are less expensive, they still have significant drawbacks: Mg-Al-Ca systems readily form coarse Mg2Ca and Al2Ca phases, impairing room-temperature plasticity and deteriorating casting processability. Typical Mg-Al-Sr alloys, such as AJ52 and AJ62, require high-temperature melting and casting, making die casting difficult, and their as-cast strength is generally low; the tensile strength of AJ52 prepared by gravity casting is only 150 MPa, with an elongation of approximately 6%. Mg-Al-Si systems, on the other hand, suffer from severely degraded mechanical properties due to the formation of coarse Mg2Si phases in their microstructure.

[0006] The key to improving the high-temperature performance of magnesium alloys lies in effectively controlling the morphology, size, and distribution of the high-temperature second phase. To this end, researchers have proposed various methods to improve the microstructure of the second phase, such as the technologies disclosed in patents CN 110468294A, CN200610095200, CN201910899941, CN117778844A, CN113755730A, CN117286379A, CN117845114A, CN117385245A, and CN116516225A. However, traditional casting processes are limited by cooling rates and solidification behavior, making it difficult to achieve effective refinement and uniform distribution of the second phase. Even with solution treatment followed by aging, only a small amount of medium and heavy rare earth elements can be dissolved into the matrix, while the large amount of high-temperature second phase already formed is difficult to redissolve. Therefore, its refinement and dispersion remain a significant challenge.

[0007] In summary, existing high-strength, heat-resistant magnesium alloys generally suffer from high costs, demanding forming processes, poor room-temperature performance, and insufficient high-temperature stability, severely restricting their widespread application. Therefore, providing a low-cost, high-strength, high-toughness, and high-temperature-resistant magnesium alloy preparation method, characterized by simple processes, controllable microstructure, and refined and uniform second-phase, to address the problems of reliance on expensive rare earth elements, complex heat treatment processes, and difficulty in synergistically improving room-temperature and high-temperature performance in existing technologies, has become a pressing technical problem for those skilled in the art. Summary of the Invention

[0008] One of the objectives of this invention is to provide a Mg-Al-Ce high-strength heat-resistant magnesium alloy that combines high strength with good toughness, thereby improving the overall performance of the material under high-temperature conditions.

[0009] The second objective of this invention is to provide a method for preparing Mg-Al-Ce high-strength heat-resistant magnesium alloy.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a Mg-Al-Ce high-strength heat-resistant magnesium alloy, comprising the following components: Mg 90.7~94.7 wt.%; Al 4.0~5.0 wt.%; Ce 3.0~4.0 wt.%; Mn 0~0.1 wt.%.

[0011] In some embodiments of the present invention, the impurity content of the Mg-Al-Ce high-strength heat-resistant magnesium alloy is less than or equal to 1 wt%.

[0012] The second aspect of this invention discloses a method for preparing the Mg-Al-Ce high-strength heat-resistant magnesium alloy, which includes the following steps: S1. Prepare the raw materials according to the target alloy composition, preheat them, and then melt them under a protective atmosphere to obtain a magnesium alloy melt with uniform composition; S2. The magnesium alloy melt is rapidly solidified to form a rapidly solidified strip; S3. The rapidly solidified strip is crushed to obtain alloy powder with a predetermined particle size; S4. The alloy powder is hot-pressed and hot-extruded to obtain a dense rod.

[0013] In some embodiments of the present invention, the smelting in step S1 specifically includes: S11. After preheating the raw materials of the main alloying elements magnesium and aluminum, they are heated and melted into a liquid state under the protection of a mixed gas of CO2 and SF6; S12. Add alloy raw materials containing Ce and Mn to the liquid alloy, keep it warm and stir to make the composition uniform.

[0014] In some embodiments of the present invention, in step S11, the preheating temperature is 190~210℃, preferably 200℃; The preheated raw materials of the main alloying elements magnesium and aluminum are heated and melted into a liquid state at 650~750℃; preferably 750℃. In the CO2 and SF6 mixture, the volume fraction of SF6 is less than or equal to 5%; preferably 1%.

[0015] In some embodiments of the present invention, in step S12, the liquid alloy is first heated to 740~760°C, and then alloy raw materials containing Ce and Mn are added.

[0016] In some embodiments of the present invention, the raw material for the alloying element magnesium is magnesium ingot, the raw material for the alloying element aluminum is aluminum ingot; the alloying raw material containing Ce is Mg-Ce or elemental Ce; and the alloying raw material containing Mn is Mg-Mn master alloy.

[0017] In some embodiments of the present invention, in step S2, the magnesium alloy melt is sprayed from a small hole at the bottom of the crucible onto a rapidly rotating cooling roller under a protective atmosphere by gas pressurization, and cooled and solidified to form a rapidly solidified strip with a thickness of 10-50 μm.

[0018] In some embodiments of the present invention, in step S3, the strip is crushed into powder with a particle size of 75~1000μm; preferably 500~700μm.

[0019] In some embodiments of the present invention, in step S4, the alloy powder is preheated in a mold and molded to form a green blank; then the green blank is subjected to at least one hot extrusion at a predetermined temperature.

[0020] Preferably, the alloy powder is added to a mold that has been preheated to 240~260℃, kept at that temperature for 2~10 minutes, and then molded.

[0021] Preferably, the green blank is hot-pressed under a pressure of 250~350 MPa for 1~5 minutes.

[0022] Preferably, the hot extrusion is a two-pass extrusion, with the first pass having an extrusion ratio of 2-5 and the second pass having an extrusion ratio of 20-30, and the extrusion temperature being 300-400℃.

[0023] The matrix structure of the alloy described in this invention is Mg-Al-Ce, where Ce is the rare earth element with the lowest cost and lowest density. Its elemental melting point (798°C) is moderate. When Ce is added directly to the high-temperature molten magnesium alloy in elemental form during the smelting process, the difficulty of the smelting process can be effectively reduced.

[0024] By benchmarking against AE42 alloy and implementing composition optimization, this invention controls the Ce content to 2.0~4.0 wt.%, a range designed to introduce sufficient high-temperature second-phase Al. 11 Ce3. This phase has the characteristics of high melting point, high hardness, high elastic modulus and low coefficient of thermal expansion. It can be used as an effective reinforcing phase in magnesium matrix, which not only helps to improve the room temperature mechanical properties of the alloy, but also significantly improves its high temperature performance.

[0025] Furthermore, the alloy composition of this invention ensures that it primarily participates in the formation of the high-temperature Al phase by precisely controlling the low Al content. 11 Ce3, to minimize the formation of the low-temperature phase β-Mg from excess Al atoms. 17 Al 12 This phase avoids damage to the high-temperature performance of the alloy, allowing the alloy to maintain higher strength at high temperatures.

[0026] To achieve the aforementioned organizational advantages and further enhance performance, this invention employs a rapid solidification process. The core function of this process lies in dual refinement: on the one hand, it significantly refines the magnesium matrix grains; on the other hand, it refines the aforementioned high-temperature strengthening phase Al. 11 Ce3 is fully refined and its dispersion is promoted. This uniformly dispersed fine-grained structure, combined with the high volume fraction of high-temperature strengthening phases, together form a stable framework that resists high-temperature deformation and failure, thereby fundamentally improving the overall mechanical properties of the alloy, especially its high-temperature strength and creep resistance.

[0027] Compared with the prior art, the present invention has the following beneficial effects: This invention is scientifically designed and ingeniously conceived. While taking into account both low cost and high process feasibility, this invention achieves a comprehensive improvement in the strength, toughness, and heat resistance of magnesium alloys through microstructure refinement and multi-mechanism strengthening, and has significant industrial application value.

[0028] The method of this invention is highly operable, with a stable and reliable process flow, enabling large-scale continuous industrial production and overcoming the limitations of existing technologies that are complex and difficult to scale up.

[0029] This invention selects Ce, the light rare earth element with the lowest cost, as the rare earth element source, and uses it together with Al as the third and second largest additive elements. This significantly reduces the cost of raw materials and improves the economic efficiency and market competitiveness of the product while ensuring the performance of the alloy.

[0030] This invention combines composition optimization with a rapid solidification process to obtain extruded bars with an ultrafine grain structure. The coarse high-temperature phases in the microstructure are effectively refined, and their morphology and distribution are improved, laying a structural foundation for performance enhancement. Specific microstructure data are shown in Table 1.

[0031] This invention utilizes multiple strengthening mechanisms, including grain refinement and second-phase strengthening, to significantly improve the mechanical properties of the alloy under both room temperature and high temperature conditions. Particularly noteworthy is the alloy's excellent symmetry in mechanical properties, exhibiting no tensile-compressive asymmetry issues and significantly enhanced reliability. Detailed performance data are shown in Table 2. Attached Figure Description

[0032] Figure 1 Metallographic diagram of the rapidly solidified extruded bar prepared in alloy example 1 of the present invention; Figure 2 The image shows the tensile and compressive stress-strain curves of the rapidly solidified extruded bar prepared in Example 1 of this invention at room temperature. Figure 3 The tensile stress-strain curves of the rapidly solidified extruded bar prepared in Example 1 of the present invention at 150°C and 200°C are shown. Figure 4 The image shows the as-cast metallographic structure of Comparative Example 1. Detailed Implementation

[0033] All features disclosed in this specification, or steps in all disclosed methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

[0034] Any feature disclosed in this specification, unless otherwise stated, may be replaced by other equivalent or similar features. That is, unless otherwise stated, each feature is merely one example of a series of equivalent or similar features.

[0035] A Mg-Al-Ce high-strength heat-resistant magnesium alloy comprises the following components: Mg 90.7~94.7 wt.%; Al 4.0~5.0 wt.%; Ce 3.0~4.0 wt.%; Mn 0~0.1 wt.%.

[0036] The impurity content of the Mg-Al-Ce high-strength heat-resistant magnesium alloy is less than or equal to 1 wt%.

[0037] A method for preparing a Mg-Al-Ce high-strength heat-resistant magnesium alloy includes the following steps: S1. Prepare the raw materials according to the target alloy composition, preheat them, and then melt them under a protective atmosphere to obtain a magnesium alloy melt with uniform composition; S2. The magnesium alloy melt is rapidly solidified to form a rapidly solidified strip; S3. The rapidly solidified strip is crushed to obtain alloy powder with a predetermined particle size; S4. The alloy powder is hot-pressed and hot-extruded to obtain a dense rod.

[0038] The smelting process described in step S1 specifically includes: S11. The raw materials of the main alloying elements magnesium and aluminum are preheated at 190~210℃ and then heated and melted into a liquid state at 650~750℃, preferably 750℃, under the protection of a mixed gas of CO2 and SF6. The preheating temperature is preferably 200℃, and the heating temperature for melting into a liquid state is preferably 750℃. In the mixture of CO2 and SF6, the volume fraction of SF6 is less than or equal to 5%; preferably 1%.

[0039] S12. First, heat the liquid alloy to 740~760℃, preferably 750℃, then add alloy raw materials containing Ce and Mn elements to the liquid alloy, keep it warm and stir to make the composition uniform.

[0040] Among them, the raw material for the alloying element magnesium is magnesium ingot, and the raw material for the alloying element aluminum is aluminum ingot; the raw material for the alloy containing Ce is Mg-Ce or elemental Ce; and the raw material for the alloy containing Mn is Mg-Mn master alloy.

[0041] In step S2, the magnesium alloy melt is sprayed from a small hole at the bottom of the crucible onto a rapidly rotating cooling roller under a protective atmosphere and pressurized by gas, thereby cooling and solidifying to form a rapidly solidified strip with a thickness of 10-50 μm.

[0042] In step S3, the strip is crushed into powder with a particle size of 75~1000μm; preferably 500~700μm.

[0043] In step S4, the alloy powder is added to a mold that has been preheated to 240~260℃, held at that temperature for 2~10 minutes, and then pressed at 250~350 MPa for 1~5 minutes to form a green blank; the green blank is then subjected to at least one hot extrusion at a predetermined temperature.

[0044] The hot extrusion is a two-pass extrusion, with the first pass having an extrusion ratio of 2-5 and the second pass having an extrusion ratio of 20-30, and the extrusion temperature being 300-400℃.

[0045] Example 1 This embodiment discloses the Mg-4Al-4Ce high-strength heat-resistant magnesium alloy of the present invention, the elemental composition of which is as follows: The mass percentages are 91 wt% Mg, 4 wt.% Al, 3 wt.% Ce and 0.1 wt.% Mn, with the balance being unavoidable impurities.

[0046] The preparation method of the high-strength heat-resistant magnesium alloy in this embodiment is as follows: S1. Prepare the materials according to the target alloy composition. Preheat the magnesium ingot, aluminum ingot, Mg-Ce and Mg-Mn master alloy to about 200°C in a drying oven. Then, place the magnesium ingot and aluminum ingot into a crucible under the protection of CO2-1vol.%SF6 mixed gas and heat it to 500°C to melt it into a liquid state. Heat the liquid alloy to 750℃, then add Mg-Ce and Mg-Mn master alloys to the liquid alloy, keep it at the temperature and stir to make the composition uniform; after stirring, let it stand for 15 minutes and skim off the slag. S2. The skimmed magnesium alloy melt is transferred to a crucible preheated to 780°C, held at that temperature for 10 minutes, and protected with CO2. Then, using gas back pressure, the molten magnesium alloy solution is sprayed through a small hole at the bottom of the crucible onto a rapidly rotating cooling roller, which is in a CO2 atmosphere. After rapid solidification, a 30μm thick rapidly solidified strip is formed.

[0047] S3. The rapidly solidified strip is crushed to obtain alloy powder of about 600 μm; S4. The alloy powder is hot-pressed and hot-extruded to obtain a dense rod.

[0048] The alloy powder is added to a cylindrical mold that has been preheated to about 250°C and held for 5 minutes. Then, it is pressed at 300 MPa for 3 minutes to form a green billet. The green billet is then extruded into a bar through two hot extrusions. The first hot extrusion has an extrusion ratio of 3 and the second hot extrusion has an extrusion ratio of 25. The extrusion temperature is 350°C and the holding time is 5 minutes.

[0049] For specific testing methods of room temperature performance, please refer to the national standard GB / T16865-2013 "Specimens and Methods for Tensile Testing of Wrought Aluminum, Magnesium and Their Alloys"; for high temperature tensile performance testing, please refer to the national standard GB / T 228.2-2015 "Metallic Materials - Tensile Testing - Part 2: High Temperature Test Methods". The alloy rapid-quenching extruded bar prepared in this embodiment exhibits the following mechanical properties at room temperature: yield strength 386 MPa, tensile strength 397 MPa, elongation after fracture 19%, and tension-to-compression ratio 0.97. At high temperatures, its properties change with increasing temperature: at 150℃, the yield strength is 177 MPa, the tensile strength is 180 MPa, and the elongation after fracture is 36%; at 200℃, the yield strength decreases to 105 MPa, the tensile strength is 113 MPa, and the elongation after fracture is 29%.

[0050] Table 1. Phase size, phase content, and phase distribution of Mg-4Al-4Ce rapidly quenched extruded bars.

[0051] The metallographic morphology of the alloy rapid quenching extrusion bar prepared in this embodiment is shown in the attached figure. Figure 1 As shown; the tensile and compressive stress-strain curves at room temperature are attached. Figure 2 As shown; the tensile stress-strain curves at 150℃ and 200℃ are attached. Figure 3 As shown.

[0052] From the appendix Figure 1 It can be seen that the alloy rapid quenching extrusion bar prepared in this embodiment has a uniform and fine ultrafine grain structure, providing a structural basis for fine grain strengthening and second-phase strengthening. (See attached...) Figure 2 It can be seen that the tensile and compressive stress-strain curves at room temperature highly overlap, with a tension-to-compression ratio of 0.97, confirming the absence of tension-compression asymmetry; the yield strength of 386 MPa, tensile strength of 397 MPa, and elongation after fracture of 19% demonstrate a good balance between strength and ductility. (See attached...) Figure 3 It can be seen that as the temperature increases to 150℃ and 200℃, the strength in the tensile curve decreases significantly (e.g., yield strength of 177 MPa at 150℃) while the elongation increases (reaching 36% at 150℃), indicating that the alloy still maintains a certain degree of plasticity at high temperatures, but its mechanical properties decrease with increasing temperature.

[0053] In summary, this magnesium alloy, through synergistic control of process and composition, achieves an ultrafine grain structure, effectively improving its comprehensive performance at both room temperature and high temperature, and eliminating tension-compression asymmetry.

[0054] Example 2 This embodiment discloses the Mg-Al-Ce high-strength heat-resistant magnesium alloy of the present invention, the elemental composition of which is as follows: The composition is 90.7 wt% Mg, 5 wt.% Al, 4 wt.% Ce and 0.1 wt.% Mn, with the balance being unavoidable impurities.

[0055] The preparation method of the high-strength heat-resistant magnesium alloy in this embodiment is as follows: S1. Prepare the materials according to the target alloy composition. Preheat the magnesium ingot, aluminum ingot, Mg-Ce and Mg-Mn master alloy to about 200°C in a drying oven. Then, place the magnesium ingot and aluminum ingot into a crucible under the protection of CO2-3vol.%SF6 mixed gas and heat it to 520°C to melt it into a liquid state. Heat the liquid alloy to 760℃, then add Mg-Ce and Mg-Mn master alloys to the liquid alloy, keep it at the temperature and stir to make the composition uniform; after stirring, let it stand for 15 minutes and skim off the slag. S2. The skimmed magnesium alloy melt is transferred to a crucible preheated to 780°C, held at that temperature for 10 minutes, and protected with CO2. Then, using gas back pressure, the molten magnesium alloy solution is sprayed through a small hole at the bottom of the crucible onto a rapidly rotating cooling roller, which is in a CO2 atmosphere. After rapid solidification, a 10μm thick rapidly solidified strip is formed.

[0056] S3. The rapidly solidified strip is crushed to obtain alloy powder of about 600μm; S4. The alloy powder is hot-pressed and hot-extruded to obtain a dense rod.

[0057] The alloy powder is added to a cylindrical mold that has been preheated to about 260°C and held for 5 minutes. Then, it is pressed into a green billet under a pressure of 350 MPa for 3 minutes. The green billet is then extruded into a bar through two hot extrusions. The first hot extrusion has an extrusion ratio of 5, the second hot extrusion has an extrusion ratio of 30, the extrusion temperature is 400°C, and the holding time is 5 minutes.

[0058] The alloy rapid-quenching extruded bar prepared in this embodiment exhibits the following mechanical properties at room temperature: yield strength 420 MPa, tensile strength 424 MPa, elongation after fracture 15%, and tension-to-compression ratio 0.95. At high temperatures, its properties change with increasing temperature: at 150°C, the yield strength is 147 MPa, the tensile strength is 149 MPa, and the elongation after fracture is 37%; at 200°C, the yield strength decreases to 96 MPa, the tensile strength is 104 MPa, and the elongation after fracture is 28%.

[0059] Comparative Example 1 A high-strength magnesium alloy of Mg-4Al-2Ce, wherein the alloy composition is 4 wt.% Al, 2.5 wt.% Ce and 0.1 wt.% Mn, 94.7 wt.% Mg, and the balance being unavoidable impurities.

[0060] Its preparation method is as follows: The raw materials are heated and melted according to the method of step S1 in Example 1 to obtain a magnesium alloy melt with uniform composition; Then, the ingot is obtained using conventional die casting. Specifically: Molten magnesium alloy is poured into the pressure chamber at a temperature controlled at 660–690℃. The mold is preheated to 180–250℃ and maintained at 200–300℃. A two-stage injection process is used: slow injection (0.2–0.4 m / s) smoothly propels the melt to the ingate; then, a high-speed injection (2–5 m / s) is applied, filling the cavity within tens of milliseconds, with an injection pressure of 30–80 MPa. Immediately after filling, a high pressure of 70–100 MPa is applied for pressure boosting and feeding, held for 4–12 seconds, and then the casting is ejected after cooling in the cavity for 20–40 seconds.

[0061] The AE42 ingot of this comparative example has a tensile yield strength, tensile strength, elongation, and tensile-to-compression ratio of 145 MPa, 230 MPa, 11%, and 1%, respectively. The tensile yield strength, tensile strength, and elongation of the ingot of this comparative example at 150 °C are 100 MPa, 160 MPa, and 22%, respectively.

[0062] Table 2 Comparison of mechanical properties between Example 1 and Comparative Example 1

[0063] According to the room temperature mechanical property data of Comparative Example 1, the mechanical properties of the AE42 ingot prepared by the ordinary die casting process are relatively low. In contrast, the rapidly quenched extruded bar prepared by advanced processes such as rapid solidification and powder hot extrusion in Example 1 of this invention has significantly improved room temperature mechanical properties: the tensile strength is increased by 241 MPa, the elongation is nearly doubled, the high-temperature yield strength at 150°C is increased by 77 MPa, and the high-temperature yield strength at 200°C is even slightly higher than the yield strength of the ingot in Comparative Example 1 at 150°C.

[0064] The magnesium alloy of this invention exhibits excellent mechanical properties without adding excessive amounts of expensive metal elements, while also possessing good economic efficiency and overall performance. Therefore, compared with existing commercial magnesium alloys, the high-strength, heat-resistant magnesium alloy involved in this invention has broader development prospects and application potential.

[0065] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention used to illustrate the technical solutions of the present invention, and are not intended to limit the invention, nor are they intended to limit the patent scope of the present invention. Any modifications or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but which still solve the same technical problem as the present invention, should be included within the protection scope of the present invention; in addition, the direct or indirect application of the technical solutions of the present invention to other related technical fields are similarly included within the patent protection scope of the present invention.

Claims

1. A Mg-Al-Ce high-strength heat-resistant magnesium alloy, characterized by, The alloy comprises the following ingredients: Mg 90.7~94.7 wt.%; Al 4.0~5.0 wt.%; Ce 3.0~4.0 wt.%; Mn 0~0.1 wt.%.

2. The Mg-Al-Ce high-strength heat-resistant magnesium alloy according to claim 1, characterized in that, The Mg-Al-Ce high-strength heat-resistant magnesium alloy has an impurity content of less than or equal to 1 wt%.

3. The method of producing a Mg-Al-Ce high-strength heat-resistant magnesium alloy according to claim 1 or 2, characterized by, The method comprises the following steps: S1. Ingredients are prepared according to target alloy composition, and after preheating, melting is performed under a protective atmosphere to obtain a magnesium alloy melt with uniform composition; S2. The magnesium alloy melt is rapidly solidified to form a rapidly solidified strip; S3. The rapidly solidified strip is crushed to obtain alloy powder with a predetermined particle size; S4. The alloy powder is hot-pressed and hot-extruded to obtain a dense rod.

4. The method of producing Mg-Al-Ce high-strength heat-resistant magnesium alloy according to claim 3, characterized by, The melting in step S1 specifically comprises: S11. The raw materials of main alloy elements magnesium and aluminum are preheated and then heated and melted into a liquid state under a mixed gas of CO2 and SF6; S12. Alloy raw materials containing Ce elements and Mn elements are added to the liquid alloy, and the alloy is kept warm and stirred to make the composition uniform.

5. The method of producing Mg-Al-Ce high-strength heat-resistant magnesium alloy according to claim 4, characterized by, In step S11, the preheating temperature is 190~210℃, and preferably 200℃; The preheated raw materials of main alloy elements magnesium and aluminum are heated and melted into a liquid state at 650-750℃; preferably at 750℃; In the mixed gas of CO2 and SF6, the volume fraction of SF6 is less than or equal to 5%; preferably 1%.

6. The method of producing Mg-Al-Ce high-strength heat-resistant magnesium alloy according to claim 4, characterized by, In step S12, the liquid alloy is first heated to 740~760℃, and then alloy raw materials containing Ce elements and Mn elements are added.

7. The method of producing Mg-Al-Ce high-strength heat-resistant magnesium alloy according to any one of claims 4 to 6, characterized by, The raw materials of alloy element magnesium are magnesium ingots, the raw materials of alloy element aluminum are aluminum ingots, the alloy raw materials containing Ce elements are Mg-Ce or Ce single elements, and the alloy raw materials containing Mn elements are Mg-Mn intermediate alloys.

8. The method of producing Mg-Al-Ce high-strength heat-resistant magnesium alloy according to claim 3, characterized by, In step S2, the magnesium alloy melt is sprayed from the bottom hole of the crucible to a rapidly rotating cooling roller under a protective atmosphere through gas pressurization, and is cooled and solidified to form a rapidly solidified strip with a thickness of 10-50μm.

9. The method of producing Mg-Al-Ce high-strength heat-resistant magnesium alloy according to claim 3, characterized by, In step S3, the strip is crushed into powder with a particle size of 75~1000μm; preferably 500~700μm.

10. The method of producing Mg-Al-Ce high-strength heat-resistant magnesium alloy according to claim 3, characterized by, In step S4, the alloy powder is preheated and die-pressed in a mold to form a green body; and the green body is hot-extruded in at least one pass at a predetermined temperature; Preferably, the alloy powder is added to a mold preheated to 240~260℃, and after keeping warm for 2~10min, die-pressing is performed; Preferably, the hot-pressing is performed at a pressure of 250~350 MPa for 1~5min to form a green body; Preferably, the hot-extrusion is two-pass extrusion, the extrusion ratio of the first pass is 2~5, the extrusion ratio of the second pass is 20~30, and the extrusion temperature is 300~400℃.

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