High-strength heat-resistant Mg-Gd-Al-Cu-Sc alloy and preparation method thereof

Abstract

The invention relates to the technical field of non-ferrous metals, in particular to a high-strength heat-resistant Mg-Gd-Al-Cu-Sc alloy and a preparation method of the high-strength heat-resistant Mg-Gd-Al-Cu-Sc alloy. 3.0 to 5.0 wt% of Al; 0.5 to 1.2 wt% of Cu; 0.6 to 1.0 wt% of Sc; the manufacturing method comprises the steps of raw material weighing, raw material drying, crucible preparation, charging and melting, casting and the like, according to the scheme, Al, Cu and Sc elements are added into the Mg-Gd alloy, the structure and performance of the Mg-Gd alloy are improved through addition of the Al, Cu and Sc elements and solid solution-aging treatment, the grain refining effect is mainly achieved, the precipitation strengthening effect of a high-melting-point Mg5Gd (548 DEG C) precipitated phase is remarkably promoted, and the high-melting-point Mg5Gd (548 DEG C) precipitated phase can be obtained. Stable Al3Sc (1320 DEG C) and Al2Gd (950 DEG C) second phases are formed, and the second phase strengthening effect is achieved.

Description

Technical Field

[0001] The invention belongs to the field of nonferrous metal materials and forming, and in particular relates to a high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy and a preparation method thereof. Background Art

[0002] Following the research on Mg-Nd and Mg-Y series alloys, Mg-Gd alloys have also received extensive attention. Mg-Gd alloys have broad application prospects in aerospace, automotive, and 3C communications due to their high strength and good heat resistance. However, excessive addition of Gd elements in magnesium alloys will result in a large amount of residual second phases, which can easily cause stress concentration during tensile deformation, increase the brittleness of the material, and thus reduce the mechanical properties of the alloy. At the same time, when the Gd content exceeds a certain proportion, a network eutectic structure will form at the grain boundaries, further increasing the brittleness of the material. In addition, Gd is an expensive rare earth element, and excessive addition will significantly increase the cost of the alloy.

[0003] Studies have found that the mechanical properties and heat resistance of Mg-Gd alloys can be further improved by adding other elements such as Y, Nd, Sm, Sc and Zn. The addition of these elements can not only promote the formation and refinement of the precipitated phase, but also improve the microstructure and texture of the alloy, thereby improving the comprehensive performance of the alloy. How to reduce the Gd content while ensuring the precipitation strengthening ability of the alloy, and how to further improve the plasticity and corrosion resistance of the alloy by optimizing the alloying and heat treatment processes have been widely studied.

[0004] Therefore, designing a high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy to solve the above technical problems is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0005] The present invention aims to solve the technical problems in the related art to at least a certain extent. To this end, a high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy is developed and a preparation method thereof is provided, specifically the following technical solutions: A high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy, the alloy comprising the following metal elements in percentage by mass: Gd: 8.0~11.0 wt %; Al: 3.0~5.0 wt %; Cu: 0.5~1.2wt %; Sc: 0.6~1.0wt%; Mg and impurities: balance.

[0006] Specifically, the mass percentages of the metal elements are: Gd: 8%; Al: 3%; Cu: 0.5%; Sc: 0.6%, and Mg and impurities: the remainder.

[0007] Specifically, the mass percentages of the metal elements are: Gd: 9%; Al: 3.5%; Cu: 0.8%; Sc: 0.7%, and Mg and impurities: the remainder.

[0008] Specifically, the mass percentages of the metal elements are: Gd: 10%; Al: 4%; Cu: 1%; Sc: 0.8%, and Mg and impurities: the remainder.

[0009] Specifically, the mass percentages of the metal elements are: Gd: 11%; Al: 5%; Cu: 1.2%; Sc: 1%, Mg and impurities: balance.

[0010] A method for preparing the high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy comprises the following steps: S1: weighing raw materials Weighing metal raw materials according to the weight percentage of alloy elements, the metal raw materials including high-purity Al ingots, Mg-Gd master alloys, high-purity Cu particles, and Mg-Sc master alloys; S2: Drying raw materials: The various metal raw materials weighed in step S1 are placed in a 140° C. drying oven for 20 minutes; S3: Crucible Preparation: Place the crucible in a 200-300℃ melting furnace for drying, and introduce a protective atmosphere into the furnace for 30 minutes; S4: Adding and melting The dried high-purity Al ingot, Mg-Gd master alloy, high-purity Cu particles and Mg-Sc master alloy obtained in step S2 are added into the crucible prepared in step S3, and then the temperature of the smelting furnace is continuously raised to 700-720° C., and a protective atmosphere is continuously introduced into the furnace. When all the metals in the crucible are melted, the scum on the liquid melt is removed for the first time; Controlling and maintaining the temperature of the smelting furnace at 710° C. for 30 minutes, and then stirring to ensure that the alloy components are fully mixed and uniformly mixed, and removing the slag for the second time; S5: Casting The liquid alloy obtained in step S4 is poured into a preheated metal mold and cooled naturally to obtain a cast Mg-Gd-Al-Cu-Sc alloy; S6: Homogenization Under protective atmosphere conditions, the cast Mg-Gd-Al-Cu-Sc alloy is kept at 420° C. for 10-16 hours for homogenization treatment; S7: Solution treatment The cast Mg-Gd-Al-Cu-Sc alloy after the homogenization treatment in step S6 is kept at 480-500° C. for 6-10 hours to complete the solid solution treatment, and then the alloy is cooled in water; S8: Aging treatment The aging treatment is performed on the solid solution Mg-Gd-Al-Cu-Sc alloy after the solid solution treatment, which mainly includes the following steps: S8-1 After aging treatment at 220℃ for 15-20 hours, some fine Mg5Gd precipitates completed rapid nucleation; S8-2 Aging treatment at 200°C for 25-55 hours causes the Mg5Gd precipitate to grow slowly; S9: Obtain high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy.

[0011] Specifically, in step S6, the cast Mg-Gd-Al-Cu-Sc alloy is kept at 420°C for 12 hours; in step S7, the solid solution Mg-Gd-Al-Cu-Sc alloy is kept at 480°C for 6 hours to complete the solution treatment; in step S8, the aging treatment is performed at below 220°C for 15 hours and at 200°C for 30 hours.

[0012] Specifically, in step S6, the cast Mg-Gd-Al-Cu-Sc alloy is kept at 420°C for 13 hours; in step S7, the cast Mg-Gd-Al-Cu-Sc alloy is kept at 480°C for 10 hours to complete solution treatment; in step S8, aging treatment is performed at 220°C for 17 hours and aging treatment is performed at 200°C for 35 hours.

[0013] Specifically, in step S6, the cast Mg-Gd-Al-Cu-Sc alloy is kept at 420°C for 15 hours; in step S7, the cast Mg-Gd-Al-Cu-Sc alloy is kept at 490°C for 9 hours to complete solution treatment; in step S8, aging treatment is performed at 220°C for 18 hours and at 200°C for 40 hours.

[0014] Specifically, in step S6, the cast Mg-Gd-Al-Cu-Sc alloy is kept at 420°C for 16 hours; in step S7, the cast Mg-Gd-Al-Cu-Sc alloy is kept at 500°C for 10 hours to complete solution treatment; in step S8, aging treatment is performed at 220°C for 20 hours and aging treatment is performed at 200°C for 45 hours.

[0015] The beneficial effects of the present invention include: In the technical solution of the present invention, the present invention adds Al, Cu and Sc elements to the Mg-Gd alloy, and improves the structure and performance of the Mg-Gd alloy by adding Al, Cu and Sc elements and solid solution-aging treatment, mainly achieving the effect of grain refinement, significantly promoting the precipitation strengthening effect of the high melting point Mg5Gd (548°C) precipitation phase, forming stable Al3Sc (1320°C) and Al2Gd (950°C) second phases, and playing a second phase strengthening effect. At the same time, some Al, Cu and Sc elements play a good solid solution strengthening effect, and a high-strength heat-resistant magnesium alloy is prepared based on the above mechanism. Since Cu, Sc and Al elements have a solid solution strengthening effect, they can refine the grain size and play a solid solution strengthening and aging strengthening effect, which has promotion significance for actual industrial production.

[0016] Secondly, in the scheme of the present invention, due to the addition of cheap metal elements aluminum and copper, the amount of Gd added can be reduced while ensuring strength and ductility, which reduces the production cost to a certain extent and has good development prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 This is a peak aging state scanning microstructure diagram of the Mg-10Gd-4Al-1Cu-0.8Sc alloy prepared in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. Figure 1 The alloy peak aging state scanning organization diagram can be observed, and the specific implementation method is as follows: Embodiment 1: Embodiment 1 of the present invention provides a high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy, in which the components and their weight percentages are: Gd: 8%; Al: 3%; Cu: 0.5%; Sc: 0.6%, and Mg and impurities: the remainder.

[0021] A method for preparing the above-mentioned high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy comprises the following steps: S1: weighing raw materials Weighing metal raw materials according to the weight percentage of alloy elements, the metal raw materials include high-purity Al ingots (Al content> 99.9%), Mg-Gd master alloy, high-purity Cu particles (Cu content> 99.9%), and Mg-Sc master alloy; S2: Drying raw materials: The various metal raw materials weighed in step S1 are placed in a 140° C. drying oven for 20 minutes; S3: Crucible Preparation: Place the crucible in a 200-300℃ melting furnace for drying, and introduce a protective atmosphere of 99% CO2+1% SF6 mixed gas into the furnace for 10 minutes; S4: Adding and melting The dried high-purity Al ingot, Mg-Gd master alloy, high-purity Cu particles and Mg-Sc master alloy obtained in step S2 are added into the crucible prepared in step S3, and the temperature of the smelting furnace is continuously raised to 700-720° C., and a protective atmosphere of 99% CO2+1% SF6 mixed gas is continuously introduced into the furnace. When all the metals in the crucible are melted, the scum on the liquid melt is removed for the first time; The temperature of the smelting furnace is controlled and maintained at 710° C. for 30 minutes, and then stirred to ensure that the alloy components are fully mixed, and the slag is removed for the second time; S5: Casting The liquid alloy obtained in step S4 from which the slag is removed is poured into a metal mold and cooled naturally to obtain a cast Mg-Gd-Al-Cu-Sc alloy; The metal mold should be preheated to 140℃-180℃ before use, and the preheating time is 50 minutes to keep the mold dry; S6: Homogenization Under the condition of protective atmosphere Ar gas, the cast Mg-Gd-Al-Cu-Sc alloy is kept at 420° C. for 12 hours for homogenization treatment; S7: Solution treatment The cast Mg-Gd-Al-Cu-Sc alloy after the homogenization treatment in step S6 is kept at 480° C. for 6 hours to complete the solid solution treatment, and then the alloy is cooled in water; S8: Aging treatment The aging treatment of the as-cast Mg-Gd-Al-Cu-Sc alloy after the solution treatment mainly includes the following two steps: S8-1 was aged at 220℃ for 15 hours, and some fine Mg5Gd precipitates completed rapid nucleation; S8-2 was aged at 200°C for 30 hours to allow the Mg5Gd precipitate phase to grow slowly, and then cooled to room temperature in water to obtain a high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy with a tensile strength of 219.4 MPa and an elongation of 14.5%.

[0022] S9: Obtain high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy. Example

[0023] Embodiment 2 of the present invention provides a high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy, in which the components and their weight percentages are: Gd: 9; Al: 3.5Cu: Cu: 0.8%; Sc: 0.7%, Mg and impurities: balance.

[0024] A method for preparing the above-mentioned high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy comprises the following steps: S1: weighing raw materials Weigh the metal raw materials according to the weight percentage of the alloying elements, the metal raw materials include high-purity Al ingots (Al content> 99.9%), Mg-Gd master alloy, high-purity Cu particles (Cu content> 99.9%), and Mg-Sc master alloy; S2: Drying raw materials: The various metal raw materials weighed in step S1 are placed in a 140° C. drying oven for 20 minutes; S3: Crucible Preparation: Place the crucible in a 200-300℃ melting furnace for drying, and introduce a protective atmosphere of 99% CO2+1% SF6 mixed gas into the furnace for 10 minutes; S4: Adding and melting The dried high-purity Al ingot, Mg-Gd master alloy, high-purity Cu particles and Mg-Sc master alloy obtained in step S2 are added into the crucible prepared in step S3, and the temperature of the smelting furnace is continuously raised to 700-720° C., and a protective atmosphere of 99% CO2+1% SF6 mixed gas is continuously introduced into the furnace. When all the metals in the crucible are melted, the scum on the liquid melt is removed for the first time; The temperature of the smelting furnace is controlled and maintained at 710° C. for 30 minutes, and then stirred to ensure that the alloy components are fully mixed, and the slag is removed for the second time; S5: Casting The liquid alloy obtained in step S4 and from which the slag is removed is poured into a metal mold and cooled naturally to obtain a cast Mg-Gd-Al-Cu-Sc alloy; The metal mold should be preheated to 140℃-180℃ before use, and the preheating time is 50 minutes to keep the mold dry; S6: Homogenization Under the condition of protective atmosphere Ar gas, the cast Mg-Gd-Al-Cu-Sc alloy is kept at 420° C. for 13 hours for homogenization treatment; S7: Solution treatment The cast Mg-Gd-Al-Cu-Sc alloy after the homogenization treatment in step S6 is kept at 480° C. for 10 hours to complete the solid solution treatment, and then the alloy is cooled in water; S8: Aging treatment The aging treatment of the as-cast Mg-Gd-Al-Cu-Sc alloy after the solution treatment mainly includes the following two steps: S8-1 was aged for 17 hours at a temperature below 220°C, and some fine Mg5Gd precipitates completed rapid nucleation; S8-2 was aged at 200°C for 35 hours, and the Mg5Gd precipitate phase grew slowly. Then it was cooled to room temperature in water to obtain a high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy with a tensile strength of 237.4 MPa and an elongation of 13.7%.

[0025] S9: Obtain high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy. Example

[0026] Embodiment 3 of the present invention provides a high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy, in which the components and their weight percentages are: Gd: 10%; Al: 4%; Cu: 1%; Sc: 0.8%, and Mg and impurities: balance.

[0027] A method for preparing the above-mentioned high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy comprises the following steps: S1: weighing raw materials Weighing metal raw materials according to the weight percentage of alloy elements, the metal raw materials include high-purity Al ingots (Al content> 99.9%), Mg-Gd master alloy, high-purity Cu particles (Cu content> 99.9%), and Mg-Sc master alloy; S2: Drying raw materials: The various metal raw materials weighed in step S1 are placed in a 140° C. drying oven for 20 minutes; S3: Crucible Preparation: Place the crucible in a 200-300℃ melting furnace for drying, and introduce a protective atmosphere of 99% CO2+1% SF6 mixed gas into the furnace for 10 minutes; S4: Adding and melting The dried high-purity Al ingot, Mg-Gd master alloy, high-purity Cu particles and Mg-Sc master alloy obtained in step S2 are added into the crucible prepared in step S3, and the temperature of the smelting furnace is continuously raised to 700-720° C., and a protective atmosphere of 99% CO2+1% SF6 mixed gas is continuously introduced into the furnace. When all the metals in the crucible are melted, the scum on the liquid melt is removed for the first time; Controlling and maintaining the temperature of the smelting furnace at 710° C. for 30 minutes, and then stirring to ensure that the alloy components are fully mixed and uniformly mixed, and removing the slag for the second time; S5: Casting The liquid alloy obtained in step S4 from which the slag is removed is poured into a metal mold and cooled naturally to obtain a cast Mg-Gd-Al-Cu-Sc alloy; The metal mold should be preheated to 140℃-180℃ before use, and the preheating time is 50 minutes to keep the mold dry; S6: Homogenization Under the condition of protective atmosphere Ar gas, the cast Mg-Gd-Al-Cu-Sc alloy is kept at 420° C. for 15 hours for homogenization treatment; S7: Solution treatment The cast Mg-Gd-Al-Cu-Sc alloy after the homogenization treatment in step S6 is kept at 490° C. for 9 hours to complete the solid solution treatment, and then the alloy is cooled in water; S8: Aging treatment The aging treatment of the as-cast Mg-Gd-Al-Cu-Sc alloy after the solution treatment mainly includes the following two steps: S8-1 was aged for 18 hours at a temperature below 220°C, and some fine Mg5Gd precipitates were rapidly nucleated; S8-2 was aged at 200°C for 40 hours, and the Gd (Mg5Gd) precipitated phase grew slowly. Then it was cooled to room temperature in water to obtain a high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy with a tensile strength of 273.4 MPa and an elongation at break of 12.4%.

[0028] S9: Obtain high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy. Example

[0029] Embodiment 4 of the present invention provides a high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy, in which the components and their weight percentages are: Gd: 11%; Al: 5%; Cu: 1.2%; Sc: 1%, and Mg and impurities: balance.

[0030] A method for preparing the above-mentioned high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy comprises the following steps: S1: weighing raw materials Weighing metal raw materials according to the weight percentage of alloy elements, the metal raw materials include high-purity Al ingots (Al content> 99.9%), Mg-Gd master alloy, high-purity Cu particles (Cu content> 99.9%), and Mg-Sc master alloy; S2: Drying raw materials: The various metal raw materials weighed in step S1 are placed in a 140° C. drying oven for 20 minutes; S3: Crucible Preparation: Place the crucible in a 200-300℃ melting furnace for drying, and introduce a protective atmosphere of 99% CO2+1% SF6 mixed gas into the furnace for 10 minutes; S4: Adding and melting The dried high-purity Al ingot, Mg-Gd master alloy, high-purity Cu particles and Mg-Sc master alloy obtained in step S2 are added into the crucible prepared in step S3, and the temperature of the smelting furnace is continuously raised to 700-720° C., and a protective atmosphere of 99% CO2+1% SF6 mixed gas is continuously introduced into the furnace. When all the metals in the crucible are melted, the scum on the liquid melt is removed for the first time; The temperature of the smelting furnace is controlled and maintained at 710° C. for 30 minutes, and then stirred to ensure that the alloy components are fully mixed, and the slag is removed for the second time; S5: Casting The liquid alloy obtained in step S4 from which the slag is removed is poured into a metal mold and cooled naturally to obtain a cast Mg-Gd-Al-Cu-Sc alloy; The metal mold should be preheated to 140℃-180℃ before use, and the preheating time is 50 minutes to keep the mold dry; S6: Homogenization Under the condition of protective atmosphere Ar gas, the cast Mg-Gd-Al-Cu-Sc alloy is kept at 420° C. for 16 hours for homogenization treatment; S7: Solution treatment The cast Mg-Gd-Al-Cu-Sc alloy after the homogenization treatment in step S6 is kept at 500° C. for 10 hours to complete the solid solution treatment, and then the alloy is cooled in water; S8: Aging treatment The aging treatment of the as-cast Mg-Gd-Al-Cu-Sc alloy after the solution treatment mainly includes the following two steps: S8-1 was aged at 220℃ for 20 hours, and some fine Mg5Gd precipitates completed rapid nucleation; S8-2 was aged at 200°C for 45 hours, and the Mg5Gd precipitate phase grew slowly. Then it was cooled to room temperature in water to obtain a high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy with a tensile strength of 269.4 MPa and an elongation of 12.2%.

[0031] S9: Obtain high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy.

[0032] The specific components and process parameters of Examples 1 to 4 are as follows: Mg-20Gd / g Al / g Cu / g Mg-10Sc / g Mg / g Total weight / g Tensile strength / MPa Elongation / % 1 440 24 4 48 284 800 219.4 14.5 2 400 28 6.4 56 309.6 800 237.4 13.7 3 360 32 8 64 336 800 273.4 12.4 4 320 40 9.6 80 350.4 800 269.4 12.2 The technical effects and advantages of the present invention are detailed in the content of the invention and will not be elaborated here.

[0033] The details not described in detail in the present invention are all conventional technical means known to those skilled in the art.

[0034] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy, characterized in that: The alloy contains the following metal elements in percentage by mass: Gd: 8.0~11.0 wt %; Al: 3.0~5.0 wt %; Cu: 0.5~1.2wt %; Sc: 0.6~1.0wt%; Mg and impurities: balance.

2. A high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy according to claim 1, characterized in that: The mass percentages of the metal elements are: Gd: 8%; Al: 3%; Cu: 0.5%; Sc: 0.6%, Mg and impurities: balance 3. The high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy according to claim 1, characterized in that: The mass percentage of the metal elements is: Gd: 9%; Al: 3.5%; Cu: 0.8%; Sc: 0.7%, Mg and impurities: balance 4. The high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy according to claim 1, characterized in that: The mass percentages of the metal elements are: Gd: 10%; Al: 4%; Cu: 1%; Sc: 0.8%, Mg and impurities: balance 5. The high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy according to claim 1, characterized in that: The metal elements are as follows by mass: Gd: 11%; Al: 5%; Cu: 1.2%; Sc: 1%, and Mg and impurities: the remainder.

6. A method for preparing the high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy according to any one of claims 1 to 5, characterized in that: The steps include: S1: weighing raw materials Weighing metal raw materials according to the weight percentage of alloy elements, the metal raw materials including high-purity Al ingots, Mg-Gd master alloys, high-purity Cu particles, and Mg-Sc master alloys; S2: Drying raw materials: The various metal raw materials weighed in step S1 are placed in a 140° C. drying oven for 20 minutes; S3: Crucible Preparation: Place the crucible in a 200-300℃ melting furnace for drying, and introduce a protective atmosphere into the furnace for 30 minutes; S4: Adding and melting The dried high-purity Al ingot, Mg-Gd master alloy, high-purity Cu particles and Mg-Sc master alloy obtained in step S2 are added into the crucible prepared in step S3, and then the temperature of the smelting furnace is continuously raised to 700-720° C., and a protective atmosphere is continuously introduced into the furnace. When all the metals in the crucible are melted, the scum on the liquid melt is removed for the first time; Controlling and maintaining the temperature of the smelting furnace at 710° C. for 30 minutes, and then stirring to ensure that the alloy components are fully mixed and uniformly mixed, and removing the slag for the second time; S5: Casting The liquid alloy obtained in step S4 is poured into a preheated metal mold and cooled naturally to obtain a cast Mg-Gd-Al-Cu-Sc alloy; S6: Homogenization Under protective atmosphere conditions, the cast Mg-Gd-Al-Cu-Sc alloy is kept at 420° C. for 10-16 hours for homogenization treatment; S7: Solution treatment The cast Mg-Gd-Al-Cu-Sc alloy after the homogenization treatment in step S6 is kept at 480-500° C. for 6-10 hours to complete the solid solution treatment, and then the alloy is cooled in water; S8: Aging treatment The aging treatment is performed on the solid solution Mg-Gd-Al-Cu-Sc alloy after the solid solution treatment, which mainly includes the following steps: S8-1 After aging treatment at 220℃ for 15-20 hours, some fine Mg5Gd precipitates completed rapid nucleation; S8-2 Aging treatment at 200°C for 25-55 hours causes the Mg5Gd precipitate to grow slowly; S9: Obtain high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy.

7. The method for preparing the high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy according to claim 6, characterized in that: In step S6, the cast Mg-Gd-Al-Cu-Sc alloy is kept at 420° C. for 12 hours; In step S7, the solid solution Mg-Gd-Al-Cu-Sc alloy is subjected to solution treatment by being kept at 480° C. for 6 hours; In step S8, aging treatment is performed at 220°C or less for 15 hours and at 200°C for 30 hours.

8. The method for preparing the high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy according to claim 6, characterized in that: In step S6, the cast Mg-Gd-Al-Cu-Sc alloy is kept at 420° C. for 13 hours; In step S7, the cast Mg-Gd-Al-Cu-Sc alloy is subjected to solution treatment by being kept at 480° C. for 10 hours; In step S8, aging treatment is performed at 220°C for 17 hours and at 200°C for 35 hours.

9. The method for preparing the high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy according to claim 6, characterized in that: In step S6, the cast Mg-Gd-Al-Cu-Sc alloy is kept at 420° C. for 15 hours; In step S7, the cast Mg-Gd-Al-Cu-Sc alloy is subjected to solution treatment by being kept at 490° C. for 9 hours; In step S8, aging treatment is performed at 220°C for 18 hours and at 200°C for 40 hours.

10. The method for preparing the high-strength and heat-resistant Mg-Gd-Al-Cu-Sc alloy according to claim 6, characterized in that: In step S6, the cast Mg-Gd-Al-Cu-Sc alloy is kept at 420° C. for 16 hours; In step S7, the cast Mg-Gd-Al-Cu-Sc alloy is subjected to solution treatment by being kept at 500° C. for 10 hours; In step S8, aging treatment is performed at 220°C for 20 hours and at 200°C for 45 hours.

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