A heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy and a preparation method thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA HANGFA SOUTH IND CO LTD
- Filing Date
- 2026-02-03
- Publication Date
- 2026-06-19
Smart Images
Figure CN122235547A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of metallic materials, specifically to a heat-resistant cast magnesium alloy and its preparation method. Background Technology
[0002] Magnesium alloys possess advantages such as low density, high specific strength, and high specific stiffness. In the aerospace field, replacing aluminum alloys and steel with magnesium alloys can significantly reduce the weight of structural components and bring significant economic benefits. Magnesium alloys are classified into cast magnesium alloys and wrought magnesium alloys according to their forming methods. Wrought magnesium alloys are generally formed through extrusion, rolling, and other methods. They exhibit excellent performance, with strength typically 30%-50% higher than cast magnesium alloys. However, wrought magnesium alloys require advanced equipment and technology, have long production cycles, and are 2-5 times more expensive than cast magnesium alloys. They are generally only suitable for manufacturing parts weighing less than ten kilograms and measuring several tens of centimeters, with relatively simple shapes, and are mostly used for small components. Cast magnesium alloys are generally formed through gravity casting and die casting. They are highly efficient, have a high yield rate, and are low in cost. They can also form complex structural components, with dimensions reaching several meters, and can manufacture structural components more than ten times the size of wrought magnesium alloys. If cast magnesium alloys can be used for large and complex aerospace components, they can bring significant weight reduction effects.
[0003] However, the aerospace field has high requirements for the strength of structural components under high temperature conditions. Magnesium alloys generally have poor mechanical properties under high temperature conditions. For example, the strength of commercially available AM and AZ series magnesium alloys will drop below 100MPa when they are used in an environment of 125℃. The strength of WE43 alloy also decays rapidly when it is used in an environment of 250℃~300℃. This greatly limits the further application of magnesium alloys in the aerospace field. There is an urgent need for high-temperature resistant magnesium alloys that can be used to make structural components. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy with good mechanical properties under high temperature environment and its preparation method.
[0005] The technical solution adopted by this invention to solve its technical problem is as follows: A heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy, containing Mg and unavoidable impurities, and also containing the following chemical elements in the following mass percentages: Gd: 6.5wt%~8.5wt%, Y: 1.5wt%~2.4wt%, Nd: 1.3wt%~2.2wt%, Zn: 0.8wt%~1.2wt%, Zr: 0.4wt%~0.6wt%.
[0006] Heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloys undergo solution treatment and aging treatment after casting. The solution treatment is carried out at 485℃~520℃ for 8h~15h, and then cooled in a coolant; The aging treatment is carried out at 215℃~235℃ for 6h~9h, followed by cooling in a coolant, then raising the temperature to 165℃~190℃ for 20h~36h, and then cooling in a coolant.
[0007] Preferably, the solution treatment is performed at 490℃~515℃ for 9h~14h, followed by cooling in a coolant.
[0008] Preferably, the aging treatment is performed at 220℃~230℃ for 7h~8h, followed by cooling in a coolant, then raising the temperature to 170℃~185℃ for 20h~40h, and finally cooling in a coolant.
[0009] Preferably, the coolant is water.
[0010] Preferably, the temperature is cooled to below 40°C.
[0011] Preferably, the total content of Si and Fe in the unavoidable impurities is less than 0.02 wt%.
[0012] Based on the same inventive concept, the present invention also provides a method for preparing the heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy, comprising: mixing raw materials uniformly, melting and casting to obtain a cast alloy; subjecting the cast alloy to solution treatment and aging treatment in sequence to obtain a heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy.
[0013] Preferably, the temperature of the alloy melt during casting is 710~730℃.
[0014] Preferably, the mold temperature before casting is 190~210℃.
[0015] Preferably, the mold is removed 50 to 70 minutes after pouring.
[0016] Preferably, the alloy is cooled in air after casting to obtain a cast alloy.
[0017] The present invention has the following beneficial effects: The heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy of this invention, by controlling the elemental composition and heat treatment process parameters, achieves tensile strength at 250 and 300 degrees Celsius that is more than 45% and 60% higher than WE43 (commercial heat-resistant magnesium alloy), respectively, and more than 20% and 25% higher than GWK series cast magnesium alloys with similar rare earth content, respectively. It meets the strength requirements of aerospace structural components operating at 250°C~300°C and can be used as a lightweight aerospace material.
[0018] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description
[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 These are the tensile mechanical properties of the heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloys of Examples 1-5 of this invention at 300℃; Figure 2 These are transmission electron microscopy images and electron diffraction patterns of the heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy of Example 2 of this invention: Figure 2 (a) is a transmission electron microscope image of the alloy matrix microstructure; Figure 2 (b) is Figure 2 (a) Electron diffraction pattern of the precipitated β′ phase; Figure 2 (c) is Figure 2 (a) Electron diffraction pattern of the γ′ phase precipitated in the sample; Figure 2 (d) is a transmission electron microscope image of the alloy matrix microstructure; Figure 2 (e) is Figure 2 (d) Electron diffraction pattern of the LPSO phase; Figure 2 (f) is Figure 2 (d) Electron diffraction pattern of the precipitate at the grain boundary. Detailed Implementation
[0020] To make the objectives, solutions, and beneficial technologies of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. It should be noted that the embodiments described in this specification are merely illustrative of the invention and are not intended to limit the invention.
[0021] For simplicity, this paper only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an undefined range; and any lower limit can be combined with other lower limits to form an undefined range, just as any upper limit can be combined with any other upper limit to form an undefined range. Furthermore, although not explicitly stated, every point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can serve as its own lower or upper limit and be combined with any other point or individual value, or with other lower or upper limits, to form an undefined range.
[0022] In this description, it should be noted that, unless otherwise stated, "above" and "below" include the stated number, "multiple" in "one or more" means two or more, and "more than" in "one or more" means two or more.
[0023] Embodiments of the present invention provide a heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy, containing Mg and unavoidable impurities, and also containing the following chemical elements in the following mass percentages: Gd: 6.5wt%~8.5wt%, Y: 1.5wt%~2.4wt%, Nd: 1.3wt%~2.2wt%, Zn: 0.8wt%~1.2wt%, Zr: 0.4wt%~0.6wt%.
[0024] In embodiments of the present invention, the heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy undergoes solution treatment and aging treatment after casting. The solution treatment is carried out at 485℃~520℃ for 8h~15h, and then cooled in a coolant; The aging treatment is carried out at 215℃~235℃ for 6h~9h, followed by cooling in a coolant, then raising the temperature to 165℃~190℃ for 20h~36h, and then cooling in a coolant.
[0025] Gd, Y, and Nd all exhibit high maximum solid solubility in magnesium alloys, which decreases significantly with decreasing temperature. This method utilizes heat treatment to regulate the precipitated phases in the alloy, obtaining β′, γ′, and LPSO phases that can stably pin grain boundaries at high temperatures, thus achieving high strength and heat resistance. In particular, the heat-resistant Mg-Gd-Y-Nd-Zn-Zr magnesium alloy provided in this embodiment of the invention, with the addition of a certain amount of Nd element and a solution treatment method, promotes the formation of the LPSO phase during the solution treatment process. Combined with the regulation of two-stage aging, the precipitated β′ and γ′ phases in the alloy form a "grid-like" microstructure, effectively hindering grain boundary slip at high temperatures. This results in excellent high-temperature resistance, maintaining high tensile strength and yield strength even at 300℃.
[0026] In some embodiments of the present invention, the solution treatment is performed at 490°C to 515°C for 9 to 14 hours, followed by cooling in a coolant.
[0027] In some embodiments of the present invention, the aging treatment is performed at 220°C to 230°C for 7 to 8 hours, followed by cooling in a coolant, then raising the temperature to 170°C to 185°C for 20 to 40 hours, and finally cooling in a coolant.
[0028] In an embodiment of the present invention, the coolant is water.
[0029] In an embodiment of the present invention, the temperature is cooled to below 40°C.
[0030] In some embodiments of the present invention, the chemical element composition of the heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy is as follows: Gd: 6.5wt%~8.5wt%, Y: 1.5wt%~2.4wt%, Nd: 1.3wt%~2.2wt%, Zn: 0.8wt%~1.2wt%, Zr: 0.4wt%~0.6wt%, with the balance being Mg and unavoidable impurities.
[0031] In embodiments of the present invention, the total content of Si and Fe among unavoidable impurities is less than 0.02 wt%.
[0032] The method for preparing the heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy according to the embodiments of the present invention includes: mixing raw materials evenly, melting and casting to obtain a cast alloy; subjecting the cast alloy to solution treatment and aging treatment in sequence to obtain the heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy.
[0033] In an embodiment of the present invention, the temperature of the alloy melt during casting is 710~730°C.
[0034] In an embodiment of the present invention, the mold temperature before casting is 190~210℃.
[0035] In an embodiment of the present invention, demolding is performed 50 to 70 minutes after pouring.
[0036] In an embodiment of the present invention, the alloy is cooled in air after casting to obtain a cast alloy.
[0037] Example The following examples describe the disclosure of this invention in more detail. These examples are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on weight. Unless otherwise stated, all reagents used in the examples are available commercially or synthesized using conventional methods and are ready for use without further processing. Unless otherwise stated, all instruments used in the examples are available commercially.
[0038] The No. 6 flux used in the magnesium alloys mentioned in each case was purchased from Ganzhou Rare Earth New Materials Co., Ltd.
[0039] Example 1 The heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy of this embodiment contains the following chemical elements in the following mass percentages: Gd: 6.5wt%, Y: 2.4wt%, Nd: 1.3wt%, Zn: 0.8wt%, Zr: 0.4wt%, with the balance being Mg and unavoidable impurities; the total amount of impurity elements Si and Fe is less than 0.02wt%.
[0040] The heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy of this embodiment is obtained by uniformly mixing raw materials, melting and casting to obtain an as-cast alloy, and then subjecting the as-cast alloy to solution treatment and aging treatment. Specific preparation methods include: 1) Smelting: The smelting furnace is preheated at 450℃ for 30 minutes; boron nitride and alcohol are mixed in a mass ratio of 1:2 to form a liquid mixture, which is then evenly coated on a low-carbon steel crucible with a brush. The crucible is placed in the smelting furnace, and then the temperature of the smelting furnace is raised to 720℃ under the protection of a CO2+SF6 (volume ratio 100:1) mixed gas. Mg ingots, Mg-Gd master alloy, Mg-Y master alloy, Mg-Nd master alloy and Zn ingot are added in sequence. 2) Refining: Under the protection of a CO2+SF6 (volume ratio 100:1) mixed gas, raise the furnace temperature to 780℃, add the Mg-Zr master alloy, and after the alloy melts, use a slag-removing spoon coated with boron nitride alcohol mixture to remove the slag from the melt; add No. 6 flux for magnesium alloy, the amount of flux is 2wt% of the total mass of the magnesium alloy melt, and use the stirring head of the stirrer to send it to the bottom of the crucible to stir the melt for 3 minutes, then send the stirring head to the upper part of the crucible to stir the melt for 2 minutes; after refining, let the alloy melt stand at 720℃ for 20 minutes, and then thoroughly remove the slag; 3) Casting: The permanent metal mold is coated evenly with a mixture of boron nitride and alcohol in a mass ratio of 1:2, placed in a pit furnace, preheated at 200°C for 1 hour, and the alloy melt is poured into the permanent metal mold. After casting for 1 hour, the mold is demolded and cooled to room temperature in air to obtain the cast Mg-Gd-Y-Nd-Zn-Zr magnesium alloy. 4) Solution treatment: The obtained as-cast Mg-Gd-Y-Nd-Zn-Zr magnesium alloy was subjected to solution treatment at 500℃ for 9 hours, and then cooled to room temperature in water at about 25℃ to finally obtain the solution-treated Mg-Gd-Y-Nd-Zn-Zr magnesium alloy. 5) Two-stage aging treatment: The obtained solid solution Mg-Gd-Y-Nd-Zn-Zr magnesium alloy is held at 225℃ for 7 hours, then cooled to room temperature in water at about 25℃, and then held at 180℃ for 24 hours, and then cooled to room temperature in water at about 25℃ to obtain heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy products.
[0041] Tensile tests were conducted on the obtained heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy products at different temperatures. The test method was as follows: the obtained products were prepared into rod-shaped tensile specimens according to the national standard (GB4338-2006). The specimen clamping section was 12 mm long and 10 mm in diameter, and the gauge length was 25 mm long and 5 mm in diameter. Tensile tests were performed on a high-temperature tensile testing machine CMT5305.
[0042] Tensile conditions: The sample surface was polished with sandpaper, held at the tensile temperature for 30 minutes, and then stretched at a tensile rate of 1.5 mm / min, with a strain rate of 10. -3 m / s, the results are shown in Table 1. The tensile test results of the heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy in Example 1 at 300℃ are shown in Table 1. Figure 1 .
[0043] Table 1. Tensile test results of heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy in Example 1 Example 2 The heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy of this embodiment contains the following chemical elements in the following mass percentages: Gd: 8.5wt%, Y: 1.5wt%, Nd: 2.2wt%, Zn: 1.2wt%, Zr: 0.6wt%, with the balance being Mg and unavoidable impurities; the total amount of impurity elements Si and Fe is less than 0.02wt%.
[0044] The heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy of this embodiment is obtained by uniformly mixing raw materials, melting and casting to obtain an as-cast alloy, and then subjecting the as-cast alloy to solution treatment and aging treatment. Specific preparation methods include: 1) Smelting: The smelting furnace is preheated at 450℃ for 30 minutes; boron nitride and alcohol are mixed in a mass ratio of 1:2 to form a liquid mixture, which is then evenly coated on a low-carbon steel crucible with a brush. The crucible is placed in the smelting furnace, and then the temperature of the smelting furnace is raised to 720℃ under the protection of a CO2+SF6 (volume ratio 100:1) mixed gas. Mg ingots, Mg-Gd master alloy, Mg-Y master alloy, Mg-Nd master alloy and Zn ingot are added in sequence. 2) Refining: Under the protection of a CO2+SF6 (volume ratio 100:1) mixed gas, raise the furnace temperature to 780℃, add the Mg-Zr master alloy, and after the alloy melts, use a slag-removing spoon coated with boron nitride alcohol mixture to remove the slag from the melt; add No. 6 flux for magnesium alloy, the amount of flux is 2wt% of the total mass of the magnesium alloy melt, and use the stirring head of the stirrer to send it to the bottom of the crucible to stir the melt for 3 minutes, then send the stirring head to the upper part of the crucible to stir the melt for 2 minutes; after refining, let the alloy melt stand at 720℃ for 20 minutes, and then thoroughly remove the slag; 3) Casting: The permanent metal mold is coated evenly with a mixture of boron nitride and alcohol in a mass ratio of 1:2, placed in a pit furnace, preheated at 200°C for 1 hour, and the alloy melt is poured into the permanent metal mold. After casting for 1 hour, the mold is demolded and cooled to room temperature in air to obtain the cast Mg-Gd-Y-Nd-Zn-Zr magnesium alloy. 4) Solution treatment: The obtained as-cast Mg-Gd-Y-Nd-Zn-Zr magnesium alloy was subjected to solution treatment at 500℃ for 11 hours, and then cooled to room temperature in water at about 25℃ to finally obtain the solution-treated Mg-Gd-Y-Nd-Zn-Zr magnesium alloy. 5) Two-stage aging treatment: The obtained solid solution Mg-Gd-Y-Nd-Zn-Zr magnesium alloy is held at 225℃ for 8 hours, then placed in water at about 25℃ to cool to room temperature, and then held at 180℃ for 30 hours, and then placed in water at about 25℃ to cool to room temperature to obtain heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy products.
[0045] Tensile tests were conducted on the obtained heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy products at different temperatures. The test method was as follows: the obtained products were prepared into rod-shaped tensile specimens according to the national standard (GB4338-2006). The specimen clamping section was 12 mm long and 10 mm in diameter, and the gauge length was 25 mm long and 5 mm in diameter. Tensile tests were performed on a high-temperature tensile testing machine CMT5305.
[0046] Tensile conditions: The sample surface was polished with sandpaper, held at the tensile temperature for 30 minutes, and then stretched at a tensile rate of 1.5 mm / min, with a strain rate of 10. -3 m / s, the results are shown in Table 2. The tensile test results of the heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy in Example 2 at 300℃ are shown in Table 2. Figure 1 .
[0047] Table 2 Tensile test results of heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy in Example 2 Example 2: Transmission electron microscopy image of heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy as shown below. Figure 2 As shown. Figure 2 (a) is a transmission electron microscope image of the alloy matrix, showing multiple precipitates. Electron diffraction patterns were observed for the two most abundant precipitates, namely... Figure 2 (b) and Figure 2 (c) Electron diffraction pattern characteristics indicate Figure 2 (b) The precipitated phase is the β′ phase. Figure 2 (c) The precipitated phase is γ′ phase. Both of these are high-temperature heat-resistant phases that can hinder dislocation slip at high temperatures and improve the strength of the alloy. Figure 2 In (a), it can be seen that the β′ phase and γ′ phase form a “grid-shaped” microstructure for strengthening the alloy; Figure 2 (d) is a transmission electron microscope image of the alloy matrix microstructure. Figure 2 As can be seen in (d), the LPSO phase also exists in the matrix. Figure 2 (f) shows its electron diffraction pattern, proving that it is of the 14h type. The 14H-LPSO phase has good heat resistance, which can hinder non-basal plane slip and improve the heat resistance of the alloy. Figure 2 (e) shows the electron diffraction pattern of the precipitated phase at the grain boundary, indicating that it is a β phase and has a grain boundary pinning effect.
[0048] Example 3 The heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy of this embodiment contains the following chemical elements in the following mass percentages: Gd: 7.5wt%, Y: 1.9wt%, Nd: 2.0wt%, Zn: 1.0wt%, Zr: 0.5wt%, with the balance being Mg and unavoidable impurities; the total amount of impurity elements Si and Fe is less than 0.02wt%.
[0049] The heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy of this embodiment is obtained by uniformly mixing raw materials, melting and casting to obtain an as-cast alloy, and then subjecting the as-cast alloy to solution treatment and aging treatment. Specific preparation methods include: 1) Smelting: The smelting furnace is preheated at 450℃ for 30 minutes; boron nitride and alcohol are mixed in a mass ratio of 1:2 to form a liquid mixture, which is then evenly coated on a low-carbon steel crucible with a brush. The crucible is placed in the smelting furnace, and then the temperature of the smelting furnace is raised to 720℃ under the protection of a CO2+SF6 (volume ratio 100:1) mixed gas. Mg ingots, Mg-Gd master alloy, Mg-Y master alloy, Mg-Nd master alloy and Zn ingot are added in sequence. 2) Refining: Under the protection of a CO2+SF6 (volume ratio 100:1) mixed gas, raise the furnace temperature to 780℃, add the Mg-Zr master alloy, and after the alloy melts, use a slag-removing spoon coated with boron nitride alcohol mixture to remove the slag from the melt; add No. 6 flux for magnesium alloy, the amount of flux is 2wt% of the total mass of the magnesium alloy melt, and use the stirring head of the stirrer to send it to the bottom of the crucible to stir the melt for 3 minutes, then send the stirring head to the upper part of the crucible to stir the melt for 2 minutes; after refining, let the alloy melt stand at 730℃ for 20 minutes, and then thoroughly remove the slag; 3) Casting: The permanent metal mold is coated evenly with a mixture of boron nitride and alcohol in a mass ratio of 1:2, placed in a pit furnace, preheated at 200°C for 1 hour, and the alloy melt is poured into the permanent metal mold. After casting for 1 hour, the mold is demolded and cooled to room temperature in air to obtain the cast Mg-Gd-Y-Nd-Zn-Zr magnesium alloy. 4) Solution treatment: The obtained as-cast Mg-Gd-Y-Nd-Zn-Zr magnesium alloy was subjected to solution treatment at 515℃ for 10 hours, and then cooled to room temperature in water at about 25℃ to finally obtain the solution-treated Mg-Gd-Y-Nd-Zn-Zr magnesium alloy. 5) Two-stage aging treatment: The obtained solid solution Mg-Gd-Y-Nd-Zn-Zr magnesium alloy is held at 230℃ for 7 hours, then cooled to room temperature in water at about 25℃, and then held at 175℃ for 32 hours, and then cooled to room temperature in water at about 25℃ to obtain heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy products.
[0050] Tensile tests were conducted on the obtained heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy products at different temperatures. The test method was as follows: the obtained products were prepared into rod-shaped tensile specimens according to the national standard (GB4338-2006). The specimen clamping section was 12 mm long and 10 mm in diameter, and the gauge length was 25 mm long and 5 mm in diameter. Tensile tests were performed on a high-temperature tensile testing machine CMT5305.
[0051] Tensile conditions: The sample surface was polished with sandpaper, held at the tensile temperature for 30 minutes, and then stretched at a tensile rate of 1.5 mm / min, with a strain rate of 10. -3 m / s, the results are shown in Table 3. The tensile test results of the heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy in Example 3 at 300℃ are shown in Table 3. Figure 1 .
[0052] Table 3. Tensile test results of heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy in Example 3 Example 4 The heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy of this embodiment contains the following chemical elements in the following mass percentages: Gd: 7.9wt%, Y: 1.8wt%, Nd: 1.7wt%, Zn: 1.1wt%, Zr: 0.5wt%, with the balance being Mg and unavoidable impurities; the total amount of impurity elements Si and Fe is less than 0.02wt%.
[0053] The heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy of this embodiment is obtained by uniformly mixing raw materials, melting and casting to obtain an as-cast alloy, and then subjecting the as-cast alloy to solution treatment and aging treatment. Specific preparation methods include: 1) Smelting: The smelting furnace is preheated at 450℃ for 30 minutes; boron nitride and alcohol are mixed in a mass ratio of 1:2 to form a liquid mixture, which is then evenly coated on a low-carbon steel crucible with a brush. The crucible is placed in the smelting furnace, and then the temperature of the smelting furnace is raised to 720℃ under the protection of a CO2+SF6 (volume ratio 100:1) mixed gas. Mg ingots, Mg-Gd master alloy, Mg-Y master alloy, Mg-Nd master alloy and Zn ingot are added in sequence. 2) Refining: Under the protection of a CO2+SF6 (volume ratio 100:1) mixed gas, raise the furnace temperature to 780℃, add the Mg-Zr master alloy, and after the alloy melts, use a slag-removing spoon coated with boron nitride alcohol mixture to remove the slag from the melt; add No. 6 flux for magnesium alloy, the amount of flux is 2wt% of the total mass of the magnesium alloy melt, and use the stirring head of the stirrer to send it to the bottom of the crucible to stir the melt for 3 minutes, then send the stirring head to the upper part of the crucible to stir the melt for 2 minutes; after refining, let the alloy melt stand at 720℃ for 20 minutes, and then thoroughly remove the slag; 3) Casting: The permanent metal mold is coated evenly with a mixture of boron nitride and alcohol in a mass ratio of 1:2, placed in a pit furnace, preheated at 200°C for 1 hour, and the alloy melt is poured into the permanent metal mold. After casting for 1 hour, the mold is demolded and cooled to room temperature in air to obtain the cast Mg-Gd-Y-Nd-Zn-Zr magnesium alloy. 4) Solution treatment: The obtained as-cast Mg-Gd-Y-Nd-Zn-Zr magnesium alloy was subjected to solution treatment at 490℃ for 14 hours, and then cooled to room temperature in water at about 25℃ to finally obtain the solution-treated Mg-Gd-Y-Nd-Zn-Zr magnesium alloy. 5) Two-stage aging treatment: The obtained solid solution Mg-Gd-Y-Nd-Zn-Zr magnesium alloy is held at 225℃ for 8 hours, then cooled to room temperature in water at about 25℃, and then held at 170℃ for 36 hours, and then cooled to room temperature in water at about 25℃ to obtain heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy products.
[0054] Tensile tests were conducted on the obtained heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy products at different temperatures. The test method was as follows: the obtained products were prepared into rod-shaped tensile specimens according to the national standard (GB4338-2006). The specimen clamping section was 12 mm long and 10 mm in diameter, and the gauge length was 25 mm long and 5 mm in diameter. Tensile tests were performed on a high-temperature tensile testing machine CMT5305.
[0055] Tensile conditions: The sample surface was polished with sandpaper, held at the tensile temperature for 30 minutes, and then stretched at a tensile rate of 1.5 mm / min, with a strain rate of 10. -3 m / s, the results are shown in Table 4. The tensile test results of the heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy in Example 4 at 300℃ are shown in Table 4. Figure 1 .
[0056] Table 4. Tensile test results of heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy in Example 4 Example 5 The heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy of this embodiment contains the following chemical elements in the following mass percentages: Gd: 8.3wt%, Y: 1.9wt%, Nd: 2.0wt%, Zn: 1.0wt%, Zr: 0.5wt%, with the balance being Mg and unavoidable impurities; the total amount of impurity elements Si and Fe is less than 0.02wt%.
[0057] The heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy of this embodiment is obtained by uniformly mixing raw materials, melting and casting to obtain an as-cast alloy, and then subjecting the as-cast alloy to solution treatment and aging treatment. Specific preparation methods include: 1) Smelting: The smelting furnace is preheated at 450℃ for 30 minutes; boron nitride and alcohol are mixed in a mass ratio of 1:2 to form a liquid mixture, which is then evenly coated on a low-carbon steel crucible with a brush. The crucible is placed in the smelting furnace, and then the temperature of the smelting furnace is raised to 720℃ under the protection of a CO2+SF6 (volume ratio 100:1) mixed gas. Mg ingots, Mg-Gd master alloy, Mg-Y master alloy, Mg-Nd master alloy and Zn ingot are added in sequence. 2) Refining: Under the protection of a CO2+SF6 (volume ratio 100:1) mixed gas, raise the furnace temperature to 780℃, add the Mg-Zr master alloy, and after the alloy melts, use a slag-removing spoon coated with boron nitride alcohol mixture to remove the slag from the melt; add No. 6 flux for magnesium alloy, the amount of flux is 2wt% of the total mass of the magnesium alloy melt, and use the stirring head of the stirrer to send it to the bottom of the crucible to stir the melt for 3 minutes, then send the stirring head to the upper part of the crucible to stir the melt for 2 minutes; after refining, let the alloy melt stand at 720℃ for 20 minutes, and then thoroughly remove the slag; 3) Casting: The permanent metal mold is coated evenly with a mixture of boron nitride and alcohol in a mass ratio of 1:2, placed in a pit furnace, preheated at 200°C for 1 hour, and the alloy melt is poured into the permanent metal mold. After casting for 1 hour, the mold is demolded and cooled to room temperature in air to obtain the cast Mg-Gd-Y-Nd-Zn-Zr magnesium alloy. 4) Solution treatment: The obtained as-cast Mg-Gd-Y-Nd-Zn-Zr magnesium alloy was subjected to solution treatment at 515℃ for 9 hours, and then cooled to room temperature in water at about 25℃ to finally obtain the solution-treated Mg-Gd-Y-Nd-Zn-Zr magnesium alloy. 5) Two-stage aging treatment: The obtained solid solution Mg-Gd-Y-Nd-Zn-Zr magnesium alloy is held at 220℃ for 8 hours, then cooled to room temperature in water at about 25℃, and then held at 180℃ for 28 hours, and then cooled to room temperature in water at about 25℃ to obtain heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy products.
[0058] Tensile tests were conducted on the obtained heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy products at different temperatures. The test method was as follows: the obtained products were prepared into rod-shaped tensile specimens according to the national standard (GB4338-2006). The specimen clamping section was 12 mm long and 10 mm in diameter, and the gauge length was 25 mm long and 5 mm in diameter. Tensile tests were performed on a high-temperature tensile testing machine CMT5305.
[0059] Tensile conditions: The sample surface was polished with sandpaper, held at the tensile temperature for 30 minutes, and then stretched at a tensile rate of 1.5 mm / min, with a strain rate of 10. -3 m / s, the results are shown in Table 5. The tensile test results of the heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy in Example 5 at 300℃ are shown in Table 5. Figure 1 .
[0060] Table 5. Tensile test results of heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy in Example 5 Comparative Example 1 The cast magnesium alloy in this comparative example does not contain Nd, and the composition other than Mg is the same as in Example 1; specifically: Gd: 6.5wt%, Y: 2.4wt%, Zn: 0.8wt%, Zr: 0.4wt%, with the balance being Mg and unavoidable impurities; wherein the total amount of impurity elements Si and Fe is less than 0.02wt%.
[0061] The cast magnesium alloy in this comparative example was obtained by uniformly mixing raw materials, melting and casting to obtain an as-cast alloy, and then subjecting the as-cast alloy to solution treatment and aging treatment. The preparation method is basically the same as in Example 1, except that a Mg-Nd master alloy is not used and the amount of Mg ingot is increased accordingly.
[0062] The obtained heat-resistant cast magnesium alloy product was subjected to a tensile test at 300℃. The results showed that the tensile strength at 300℃ was 233MPa and the yield strength was 140MPa, which was 20% lower than that in Example 1.
[0063] Comparative Example 2 The elemental composition of the cast magnesium alloy in this comparative example is the same as that in Example 2.
[0064] The cast magnesium alloy in this comparative example was obtained by further solution treatment and aging treatment of the as-cast Mg-Gd-Y-Nd-Zn-Zr magnesium alloy obtained during the manufacturing process of Example 2. Specific details are as follows: Solution treatment: The as-cast Mg-Gd-Y-Nd-Zn-Zr magnesium alloy was solution treated at 540℃ for 10 hours, and then cooled to room temperature in water at about 25℃ to obtain a solution-treated Mg-Gd-Y-Nd-Zn-Zr magnesium alloy. Aging treatment: The obtained solid solution Mg-Gd-Y-Nd-Zn-Zr magnesium alloy was held at 200℃ for 24h, and then cooled to room temperature in water at about 25℃ to obtain the cast magnesium alloy product of this comparative example.
[0065] The obtained heat-resistant cast magnesium alloy product was subjected to a tensile test at 300℃. The results showed that the tensile strength at 300℃ was 225MPa and the yield strength was 136MPa, which was more than 20% lower than that in Example 2.
Claims
1. A heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy, containing Mg and unavoidable impurities, characterized in that, It also contains the following chemical elements in the following percentages by mass: Gd: 6.5wt%~8.5wt%, Y: 1.5wt%~2.4wt%, Nd: 1.3wt%~2.2wt%, Zn: 0.8wt%~1.2wt%, Zr: 0.4wt%~0.6wt%; After casting, solution treatment and aging treatment are also carried out: The solution treatment is carried out at 485℃~520℃ for 8h~15h, and then cooled in a coolant; The aging treatment is carried out at 215℃~235℃ for 6h~9h, followed by cooling in a coolant, then raising the temperature to 165℃~190℃ for 20h~36h, and then cooling in a coolant.
2. The heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy according to claim 1, characterized in that, The solution treatment involves treating at 490℃~515℃ for 9h~14h, followed by cooling in a coolant.
3. The heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy according to claim 1, characterized in that, The aging treatment is carried out at 220℃~230℃ for 7h~8h, followed by cooling in a coolant, then raising the temperature to 170℃~185℃ for 20h~40h, and then cooling in a coolant.
4. The heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy according to any one of claims 1 to 3, characterized in that, The coolant is water; the temperature is cooled to below 40°C.
5. The heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy according to claim 1, characterized in that, The total content of Si and Fe in the unavoidable impurities is less than 0.02 wt%.
6. The method for preparing the heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy according to any one of claims 1 to 5, characterized in that, include: The raw materials are mixed evenly and then melted and cast to obtain a cast alloy. The cast alloy is then subjected to solution treatment and aging treatment in sequence to obtain a heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy.
7. The method for preparing heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy according to claim 6, characterized in that, The alloy melt temperature during casting is 710~730℃.
8. The method for preparing heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy according to claim 6 or 7, characterized in that, The mold temperature before pouring is 190~210℃.
9. The method for preparing heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy according to claim 6 or 7, characterized in that, Demold 50-70 minutes after pouring.
10. The method for preparing heat-resistant Mg-Gd-Y-Nd-Zn-Zr cast magnesium alloy according to claim 6 or 7, characterized in that, After casting, the alloy is cooled in air to obtain the as-cast alloy.