WO2022268034A1 - 高强铸造镁合金及其制备方法和应用 - Google Patents

高强铸造镁合金及其制备方法和应用 Download PDF

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WO2022268034A1
WO2022268034A1 PCT/CN2022/099890 CN2022099890W WO2022268034A1 WO 2022268034 A1 WO2022268034 A1 WO 2022268034A1 CN 2022099890 W CN2022099890 W CN 2022099890W WO 2022268034 A1 WO2022268034 A1 WO 2022268034A1
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magnesium alloy
casting
cast magnesium
strength cast
strength
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PCT/CN2022/099890
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English (en)
French (fr)
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王凯
吴海龙
莫雪妍
邵冲
朱小平
郑宗文
朱春雷
杨武强
高仕山
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河北钢研德凯科技有限公司
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C23/00—Alloys based on magnesium
    • C22C23/06—Alloys based on magnesium with a rare earth metal as the next major constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/02—Making non-ferrous alloys by melting
    • C22C1/03—Making non-ferrous alloys by melting using master alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/002—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working by rapid cooling or quenching; cooling agents used therefor
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/06—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of magnesium or alloys based thereon

Definitions

  • the present disclosure relates to the technical field of magnesium alloys, in particular to a high-strength cast magnesium alloy and its preparation method and application.
  • Magnesium alloys have the advantages of low density and high specific strength, and are widely used in the aerospace field. With the high requirements of engine R&D institutions for engine performance, higher requirements are put forward for the mechanical properties of materials, especially the tensile strength of cast magnesium alloys is required to be ⁇ 290MPa. However, the current cast magnesium alloy is difficult to reach the level of 290MPa stably.
  • magnesium alloy is very important.
  • some current magnesium alloys have low oxidation inclusions in the casting process, which greatly improves the casting process, they have problems such as loose casting and high segregation tendency, and it is difficult to be used for complex structures and multi-oil pipeline castings with pressure requirements. manufacture.
  • the present disclosure provides a high-strength cast magnesium alloy, mainly composed of the following components by mass percentage:
  • the high-strength cast magnesium alloy mainly consists of the following components by mass percentage:
  • the high-strength cast magnesium alloy mainly consists of the following components by mass percentage:
  • the unavoidable impurities include any one or more of Ag, Ni, Al, Mn, Cu, Fe, and Be;
  • the unavoidable impurities also include rare earth impurity elements, and the total amount of the rare earth impurity elements is ⁇ 0.4wt%.
  • the tensile strength of the high-strength cast magnesium alloy is ⁇ 285 MPa, and the yield strength is ⁇ 165 MPa.
  • the tensile strength of the high-strength cast magnesium alloy is ⁇ 290 MPa, and the yield strength is ⁇ 175 MPa.
  • the elongation of the high-strength cast magnesium alloy is ⁇ 5%.
  • the second phase in the as-cast structure of the high-strength cast magnesium alloy, is dispersedly distributed in the matrix; wherein, the second phase is fine needle-shaped, with a length of 1-6 ⁇ m and a width of 0.3-6 ⁇ m. 0.8 ⁇ m.
  • the volume fraction of the second phase is 8%-15%.
  • the second phase in the structure of the high-strength cast magnesium alloy after T6 heat treatment, is mainly distributed on the grain boundary; wherein, the second phase is in the form of an island-like second phase, and the island-like second phase
  • the contour length of the two phases is 5-13 ⁇ m.
  • the present disclosure also provides a method for preparing the above-mentioned high-strength cast magnesium alloy, which includes the following steps:
  • Magnesium, zinc, magnesium-gadolinium master alloy, magnesium-zirconium master alloy and magnesium-neodymium master alloy are used as raw materials, and after being proportioned, smelting and casting are carried out.
  • the casting includes any of sand casting and investment casting.
  • the method further includes: performing heat treatment on the casting obtained by casting; the heat treatment includes a T4 heat treatment regime or a T6 heat treatment regime.
  • the T4 heat treatment regime includes: heat preservation at 518-530°C for 8-16 hours, and water quenching;
  • the T6 heat treatment regime includes: heat preservation at 518-530°C for 8-16 hours, water quenching; Insulate at 208°C for 16-20 hours, then air-cool.
  • the method of smelting includes:
  • step (b) After all the materials in step (a) are melted, stir for 5-8 minutes to homogenize the alloy, then cool down to 740 ⁇ 5°C, remove the slag, sprinkle flux, raise the temperature of the alloy liquid to 760-780°C, and let it stand 10 ⁇ 15min.
  • the present disclosure also provides the application of the high-strength cast magnesium alloy described in any one of the above or the high-strength cast magnesium alloy prepared by the preparation method described in any one of the above in aerospace equipment.
  • the aerospace device includes an aerospace engine.
  • the aerospace device includes a casing of an aerospace engine transmission.
  • the present disclosure also provides the application of the high-strength cast magnesium alloy described in any one of the above or the high-strength cast magnesium alloy prepared by the preparation method described in any one of the above in electronic products, construction tools, and biomedicine.
  • Fig. 1 is the as-cast metallographic picture of the attached casting test rod of the casting of embodiment 5 of the present disclosure
  • Fig. 2 is the as-cast metallographic picture of the attached casting test rod of the casting of comparative example 3;
  • Fig. 3 is the metallographic picture of the T6 state of the cast test rod attached to the casting of Example 5 of the present disclosure
  • Fig. 4 is the T6 state metallographic picture of the attached casting test rod of the casting of comparative example 3;
  • FIG. 5 is an impedance fitting circuit diagram of the present disclosure
  • Example 6 is a physical photo of a certain engine drive system casing casting obtained in Example 5 of the present disclosure.
  • Fig. 7 is the segregation defect diagram of the X-ray non-destructive testing of the casing casting of a certain engine transmission system of Comparative Example 3;
  • Fig. 8 is a fluorescent non-destructive testing physical map showing the positions of loose defects of a casing casting of a transmission system of an engine obtained in Comparative Example 3;
  • Fig. 9 is a fluorescent non-destructive testing photograph of a casing casting of an engine transmission system prepared in Example 5 of the present disclosure.
  • High-strength cast magnesium alloy mainly composed of the following components by mass percentage:
  • EV31A alloy is a high-strength corrosion-resistant magnesium alloy. The tensile strength required in the standard AMS 4429A-2012 does not exceed 248MPa, and the yield strength does not exceed 145MPa.
  • Nd and Gd as strengthening elements can improve the strength of the alloy, but when the content of Nd exceeds 3.0%, the strengthening effect will no longer be significantly improved, but it will affect the casting performance of the alloy due to the high content of rare earth; Gd also has obvious strengthening However, when Gd exceeds 2.5%, the castings obtained by casting have a serious tendency to oxidize and slag, and there are visually visible oxidized slag defects. There are great hidden dangers in actual use, so it is not easy to exceed 2.5%.
  • the obtained cast magnesium alloy has high strength, heat resistance, corrosion resistance, and good formability.
  • the existing cast magnesium alloy its casting loose defects and segregation tendency are greatly reduced , the casting obtained by casting the casting magnesium alloy of the present disclosure is tested, and the loosening tendency is smaller compared with the EV31A alloy.
  • the cast magnesium alloys of the present disclosure have better corrosion resistance, using the same standard (GB/T 10125-2012) salt spray test to measure, the average corrosion rate of the magnesium alloys of the present disclosure It can reach 0.029w, while the average corrosion rate of ZM2 alloy is 0.49w.
  • the disclosure optimizes and adjusts the alloy composition, so that the obtained magnesium alloy has high strength, heat resistance, corrosion resistance, and good formability. Compared with the existing magnesium alloy, the casting loose defect and segregation tendency are greatly reduced.
  • the content of Gd can be, for example, 2.1% to 2.47%, 2.1% to 2.4%, 2.1% to 2.2%, 2.15% to 2.47%, or 2.15% to 2.33%, such as 2.1%, 2.15%, 2.2%, 2.25%, 2.3%, 2.35%, 2.4%, 2.45%, 2.5%, etc.
  • the content of Zr can be, for example, 0.54% to 1.0%, 0.55% to 1.0%, 0.56% to 1.0%, 0.60% to 1.0%, 0.65% to 1.0%, or 0.54% to 0.65%, such as 0.5 %, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1.0%, etc.
  • the content of Zn can be, for example, 0.3% to 0.6%, 0.44% to 0.6%, 0.48% to 0.6%, 0.50% to 0.6%, 0.53% to 0.6%, or 0.44% to 0.53%, such as 0.3 %, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, etc.
  • the content of Nd can be, for example, 2.8% to 3.1%, 2.9% to 3.1%, 2.94% to 3.1%, 2.98% to 3.1%, or 3.04% to 3.1%, such as 2.7%, 2.75%, 2.8 %, 2.85%, 2.9%, 2.95%, 3.0%, 3.05%, 3.1%, etc.
  • the high-strength cast magnesium alloy mainly consists of the following components by mass percentage:
  • the high-strength cast magnesium alloy mainly consists of the following components by mass percentage:
  • the high-strength cast magnesium alloy mainly consists of the following components by mass percentage:
  • the unavoidable impurities include any one or more of Ag, Ni, Al, Mn, Cu, Fe and Be.
  • Ag content ⁇ 0.05wt%, Ni content ⁇ 0.001wt%, Al content ⁇ 0.01wt%, Mn content ⁇ 0.05wt%, Cu content ⁇ 0.007wt%, Fe Content ⁇ 0.005wt%, Be content ⁇ 0.001wt%.
  • the tensile strength of the high-strength cast magnesium alloy is ⁇ 285 MPa, and the yield strength is ⁇ 165 MPa. In some embodiments of the present disclosure, the tensile strength of the high-strength cast magnesium alloy is ⁇ 290 MPa, and the yield strength is ⁇ 175 MPa. In some embodiments of the present disclosure, the elongation of the high-strength cast magnesium alloy is ⁇ 5%. In some embodiments of the present disclosure, tensile strength ⁇ 230 MPa and yield strength ⁇ 155 MPa can be achieved at 250°C.
  • the second phase in the as-cast structure of the high-strength cast magnesium alloy, is dispersedly distributed in the matrix; wherein, the second phase is in the form of fine needles with a length of 1-6 ⁇ m, such as 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m; the width is 0.3-0.8 ⁇ m, such as 0.3 ⁇ m, 0.4 ⁇ m, 0.5 ⁇ m, 0.6 ⁇ m, 0.7 ⁇ m, 0.8 ⁇ m.
  • the volume fraction of the second phase in the as-cast structure, is 8% to 15%, such as 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%.
  • the second phase in the structure of the high-strength cast magnesium alloy after T6 heat treatment, is mainly distributed on the grain boundary; wherein, the second phase is in the form of an island-like second phase, and the The contour length of the island-like second phase is 5-13 ⁇ m, such as 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m, 10 ⁇ m, 11 ⁇ m, 12 ⁇ m, 13 ⁇ m.
  • the present disclosure also provides a method for preparing a high-strength cast magnesium alloy, which includes the following steps:
  • Magnesium, zinc, magnesium-gadolinium master alloy, magnesium-zirconium master alloy and magnesium-neodymium master alloy are used as raw materials, and after being proportioned, smelting and casting are carried out.
  • the casting includes any of sand casting and investment casting. In some embodiments of the present disclosure, the investment casting is investment investment casting.
  • it also includes: performing heat treatment on the casting obtained by casting; the heat treatment includes a T4 heat treatment regime (T4 heat treatment) or a T6 heat treatment regime (T6 heat treatment).
  • the heat treatment includes a T4 heat treatment regime (T4 heat treatment) or a T6 heat treatment regime (T6 heat treatment).
  • the T4 heat treatment system includes: 518-530°C heat preservation for 8-16h, water quenching, for example, the temperature of the T4 heat treatment system is 519-528°C, 520-527°C or 521-525°C, and the time It is, for example, 9 to 15h, 10 to 14h or 11 to 13h.
  • the T6 heat treatment system includes: holding at 518-530°C for 8-16 hours, quenching water, for example, the temperature of the T6 heat treatment system is 519-528°C, 520-526°C or 521-524°C , the time is, for example, 9 to 15 hours, 10 to 14 hours or 11 to 13 hours.
  • after the T4 heat treatment regime or the T6 heat treatment regime it is kept at 200-208° C. for 16-20 hours, and then air-cooled.
  • the T4 heat treatment system Compared with the T6 heat treatment system, the T4 heat treatment system has more solute atoms dissolved into the matrix structure, so that the strength of the alloy in the T4 state is higher than that of the T6 state, but due to the large amount of solute atoms dissolved, the plasticity of the alloy in the T4 state below the T6 state. According to different use conditions, the appropriate heat treatment system can be selected according to actual needs to meet different use needs.
  • the method of smelting includes:
  • step (b) After all the materials in step (a) are melted, stir for 5-8 minutes to homogenize the alloy, then cool down to 740 ⁇ 5°C, remove the slag, sprinkle flux, raise the temperature of the alloy liquid to 760-780°C, and let it stand 10 ⁇ 15min. Among them, a layer of flux is sprinkled to cover the alloy liquid.
  • the temperature is lowered to the casting temperature for casting.
  • removing slag includes: removing slag on the surface of the sprue, baffle, crucible wall and alloy liquid.
  • the heating and melting of magnesium includes: putting magnesium preheated to above 200° C. into a preheated melting furnace (such as a crucible), sprinkling an appropriate amount of flux on the charge, and heating and melting.
  • a preheated melting furnace such as a crucible
  • the magnesium is pure magnesium ingot
  • the magnesium-gadolinium master alloy is magnesium-30 gadolinium alloy
  • the magnesium-zirconium master alloy is magnesium-30 zirconium alloy
  • the zinc is pure Zinc particles
  • the magnesium-neodymium master alloy is magnesium-30 neodymium alloy.
  • the present disclosure also provides the application of any one of the above-mentioned high-strength cast magnesium alloys in aerospace equipment.
  • an aerospace device includes an aerospace engine.
  • the aerospace device is an aerospace engine.
  • the aerospace equipment is a casing of the aerospace engine transmission system.
  • the disclosure also provides the above-mentioned high-strength cast magnesium alloy or the high-strength cast magnesium alloy prepared by the above-mentioned preparation method in electronic products (such as mobile phone parts or casings, computer parts or casings, household appliances parts or casings), delivery tools (such as automobiles) Parts, high-speed train casings), biomedicine (such as tissue engineering scaffolds, bone implant materials).
  • electronic products such as mobile phone parts or casings, computer parts or casings, household appliances parts or casings, delivery tools (such as automobiles) Parts, high-speed train casings), biomedicine (such as tissue engineering scaffolds, bone implant materials).
  • the high-strength cast magnesium alloy provided by the disclosure solves technical problems such as insufficient strength and poor casting performance of the cast magnesium alloy existing in the prior art. Meanwhile, the high-strength cast magnesium alloy provided by the present disclosure includes but not limited to the following advantages:
  • the present disclosure optimizes and adjusts the alloy composition, so that the obtained cast magnesium alloy has excellent mechanical properties, and at the same time improves the microporosity and segregation tendency in the casting performance, and ensures corrosion resistance and high temperature durability;
  • the tensile strength of the cast magnesium alloy of the present disclosure is ⁇ 290MPa, the yield strength is ⁇ 175MPa, and the elongation is ⁇ 5%; at 250°C, the tensile strength is ⁇ 230MPa, and the yield strength is ⁇ 155MPa;
  • the cast magnesium alloy of the present disclosure can meet the material selection requirements of a casing of an advanced aerospace engine transmission system.
  • the burnout rates of Gd and Nd elements in the smelting process are 10% and 12% respectively. According to the burnout rates, the charge ratio is set to obtain 5 groups of different components as shown in Table 1. The composition of the measured values of the alloy is shown in Table 1.
  • the inevitable impurities mentioned in Table 1 include any one or more of Ag, Ni, Al, Mn, Cu, Fe and Be, and the content of each impurity in the alloy does not exceed the following requirements: Ag content ⁇ 0.05wt %, Ni content ⁇ 0.001wt%, Al content ⁇ 0.01wt%, Mn content ⁇ 0.05wt%, Cu content ⁇ 0.007wt%, Fe content ⁇ 0.005wt%, Be content ⁇ 0.001wt%, other individual impurities ⁇ 0.01wt% %, other impurities generally ⁇ 0.1wt%.
  • the preparation method of the above-mentioned high-strength cast magnesium alloy comprises the following steps: using magnesium, zinc, magnesium-30 gadolinium alloy, magnesium-30 zirconium alloy and magnesium-30 neodymium master alloy as raw materials, according to the burning loss rate of Gd element and Nd element respectively After 10% and 12% batching of the furnace charge, melting and casting were carried out, and the sand casting magnesium alloy test rods were prepared respectively as sand casting 1#, sand casting 2#, sand casting 3#, sand casting 4# and sand casting 5#.
  • the method of smelting and casting comprises:
  • This example refers to the preparation method of Example 1. The only difference is that sand casting is replaced by investment casting, and precision casting 1#, precision casting 2#, precision casting 3#, precision casting 4#, precision casting 5# try stick.
  • the investment precision casting includes: after smelting according to the method of Example 1, cooling to 725-730°C for casting, and the temperature of the precision casting mold shell is 300°C.
  • the charge proportioning principle refers to Example 1, and the components of the obtained alloys are shown in Table 2 respectively.
  • the corresponding alloy casting prepared in Example 2 was treated to obtain the corresponding solid solution (T4) state high-strength cast magnesium alloy.
  • T4 casting number raw material heat treatment conditions X1 Precision Casting 1# 520 ⁇ 521°C for 8 hours, quenching X2 Precision Casting 2# 520 ⁇ 521°C for 8 hours, quenching X3 Precision Casting 3# 520 ⁇ 521°C for 8 hours, quenching X4 Precision Casting 4# 520 ⁇ 521°C for 8 hours, quenching X5 Precision Casting 5# 520 ⁇ 521°C for 8 hours, quenching
  • the preparation method of the above-mentioned solid solution (T4) state high-strength cast magnesium alloy comprises the following steps:
  • the corresponding alloy castings prepared in Example 2 were treated to obtain the corresponding solid solution + aging (T6) state high-strength cast magnesium alloy.
  • the preparation method of the high-strength cast magnesium alloy in the above solid solution+aging (T6) state comprises the following steps:
  • This embodiment provides a certain transmission casing casting made by high-strength casting magnesium alloy (this embodiment only takes the transmission casing casting in the aerospace field as an example), and the preparation method includes: according to the 4# alloy furnace charge of Embodiment 1 After proportioning and smelting, precision gravity casting of the investment mold is used to obtain a casing casting of a transmission system; the casting temperature is 745-750°C, and the mold shell temperature is 300°C; T6 heat treatment system is adopted after casting treatment. At the same time, a cast test rod is attached for testing.
  • Example 5 is only an example of a casting made of a high-strength cast magnesium alloy.
  • the application field of the high-strength cast magnesium alloy of the present disclosure is obviously not limited to aviation In the field of aerospace, it can be widely used in electronic products (such as mobile phone parts or casings, computer parts or casings, household appliances parts or casings), delivery tools (such as automobile parts, high-speed train casings), biomedicine (such as tissue engineering scaffolds, bone implant materials).
  • Comparative Example 1 provides the preparation of other cast magnesium alloys. According to the furnace charge ratio principle and smelting and casting methods of Example 1, sand casting 6#, sand casting 7#, sand casting 8#, and sand casting 9# are respectively produced. The sample is a sand-cast single-cast test bar, and the corresponding alloy components are shown in Table 5.
  • Comparative Example 2 refers to the preparation method of Comparative Example 1. The only difference is that sand casting is replaced by investment precision casting, and Precision Casting 6#, Precision Casting 7#, Precision Casting 8#, and Precision Casting 9# are prepared respectively. Investment casting conditions are the same as in Example 2.
  • the measured composition of the alloy of Comparative Example 2 is similar to that of Comparative Example 1, and the cast sample is a precision cast single-cast test rod.
  • Comparative Example 3 provides a transmission case casting made by casting magnesium alloy (this comparative example only takes the transmission case casting in the aerospace field as an example), and the preparation method includes: after batching and smelting according to the EV31A alloy composition, melting The casing casting of a certain transmission system was obtained by precise gravity casting of the mold; the casting temperature was 745-750°C, and the mold shell temperature was 300°C; T6 heat treatment system was adopted after casting treatment.
  • the measured composition of EV31A alloy is: Nd 2.86%, Gd 1.55%, Zn 0.5%, Zr 0.59%, the balance of magnesium and unavoidable impurities.
  • a cast test rod is attached for testing.
  • the second phase in the as-cast structure of Example 5 is fine needle-shaped, with a length of 1-6 ⁇ m and a width of 0.3-0.8 ⁇ m.
  • the second phase is dispersed in the matrix, and the volume of the second phase The fraction is 8% to 15%.
  • the matrix appears as an island-like second phase, which is mainly distributed on the grain boundary.
  • the contour length of the island-like second phase is 5-13 ⁇ m.
  • the second phase is strip-shaped, with a length of 3-10 ⁇ m and a width of 1-2 ⁇ m, mainly distributed near the grain boundary, and the phase relationship with the grain boundary is almost perpendicular, and the strip-shaped second phase
  • the volume fraction of the phase is 5% to 10%; after T6 heat treatment, a round rod-shaped second phase appears in the matrix, and the length of the round rod-shaped second phase is 8-15 ⁇ m and the width is 3-5 ⁇ m. state structure, the round rod-shaped second phase has low density and uneven distribution.
  • the mechanical properties of the test rods cast by the cast magnesium alloy of the present disclosure are significantly improved compared with other cast magnesium alloys, and the bulk properties are also slightly improved.
  • the elastic modulus of different test bars was tested, the elastic modulus of sand casting 4# in T6 state was 44.4MPa, the elastic modulus of T6 fine casting 4# was 45MPa, and the elastic modulus of casting body in T6 state was 45MPa , it can be seen that the cast magnesium alloy of the present disclosure can ensure the modulus of elasticity while improving the mechanical properties.
  • the cast magnesium alloy of the present disclosure can ensure or even improve the high cycle fatigue performance of the material while improving other mechanical properties.
  • the casting body of the T6 state obtained in embodiment 5 (tested from casting body sampling, sample size is 10mm*10mm*3.5mm) adopts conventional experimental method to carry out the polarization curve and the impedance of electrochemical experiment test sample, and test result is respectively See Table 8 to Table 9.
  • the alloy was soaked in 3.5wt% NaCl aqueous solution for hydrogen evolution test.
  • the total soaking time was 336h, and the average corrosion rate could reach 3.44mm/y.
  • test sequence of samples open circuit potential 60min; impedance 20min; polarization; room temperature 25°C.
  • the impedance fitting circuit diagram is shown in Figure 5.
  • Example 5 Metallurgical quality testing was carried out on a certain transmission casing casting obtained by casting in Example 5 and Comparative Example 3 respectively.
  • the test results showed that: the casting obtained in Comparative Example 3 had serious looseness and segregation defects; the casting obtained in Example 5 had more formability. Good, the appearance of the casting is complete, and there is no lack of casting at the thin wall. Under the same process, the loose defects are greatly reduced compared with Comparative Example 3, and no segregation is seen in the thin wall area on the side.
  • Fig. 6 is the physical photo of a transmission casing casting obtained by casting in Example 5.
  • the actual photo of a transmission casing casting obtained by casting in Comparative Example 3 is the same as that shown in Figure 6 of Example 5.
  • the casting obtained by casting in Comparative Example 3 had segregation defects as shown in Figure 7 at the thin wall circled in Figure 6, and loose defects at the thin-thick junction circled in Figure 8.
  • the photo of the fluorescent non-destructive testing of the casting obtained by casting in Example 5 is shown in FIG. 9 .
  • segregation defects are obtained through X-ray non-destructive testing, and the testing methods conform to HB/Z 60; loose defects are obtained through fluorescent non-destructive testing, and the testing methods conform to HB/Z 61.
  • the present disclosure provides a high-strength casting magnesium alloy and its preparation method and application.
  • the present disclosure optimizes and adjusts the composition of the alloy so that the obtained magnesium alloy has high strength, heat resistance, corrosion resistance, and good formability.
  • the existing casting magnesium alloy has greatly reduced casting loose defects and segregation tendency, can meet the material selection requirements of a casing of an advanced aerospace engine transmission system, and has excellent application performance.

Abstract

本公开涉及镁合金技术领域，尤其是涉及高强铸造镁合金及其制备方法和应用。高强铸造镁合金，主要由按质量百分比计的如下组分组成：Gd 2.1％～2.5％、Zr 0.5％～1.0％、Zn 0.3％～0.6％、Nd 2.7％～3.1％、余量Mg和不可避免的杂质。本公开通过对合金成分进行优化调整，使得到的镁合金具有高强、耐热、耐蚀性能，并且成型性能良好，相较于现有的铸造镁合金，其铸造疏松缺陷以及偏析倾向大大降低，能够满足先进航空航天用发动机传动系统某机匣的选材要求。

Description

高强铸造镁合金及其制备方法和应用
相关申请的交叉引用
本公开要求于2021年06月22日提交中国专利局的申请号为CN202110693616.1、名称为“高强铸造镁合金及其制备方法和应用”的中国专利申请的优先权，其全部内容通过引用结合在本公开中。
技术领域
本公开涉及镁合金技术领域，尤其是涉及一种高强铸造镁合金及其制备方法和应用。
背景技术
镁合金具有低密度、高比强度等优点，被广泛应用于航空航天领域。随着发动机研发机构对发动机性能的高要求，对材料的力学性能提出了更高的要求，尤其是铸造镁合金抗拉强度要求≥290MPa。然而目前的铸造镁合金很难稳定达到290MPa的水平。
另外，对于镁合金其铸造性能至关重要。但目前的部分镁合金虽然在铸造过程中氧化夹杂较低使铸造工艺性大幅提升，但存在铸造疏松、偏析倾向较高等问题，很难用于复杂结构、有压力要求的多油路管路铸件制造。
由于目前镁合金材料上述性能的不足，使其在航空航天设备中的应用受到限制，亦限制了航空航天技术的进一步发展。
发明内容
本公开提供了高强铸造镁合金，主要由按质量百分比计的如下组分组成：
Gd 2.1％～2.5％、Zr 0.5％～1.0％、Zn 0.3％～0.6％、Nd 2.7％～3.1％、余量Mg和不可避免的杂质。
在一些实施方式中，所述高强铸造镁合金，主要由按质量百分比计的如下组分组成：
Gd 2.1％～2.4％、Zr 0.55％～1.0％、Zn 0.3％～0.6％、Nd 2.8％～3.1％、余量Mg和不可避免的杂质。
在一些实施方式中，所述高强铸造镁合金，主要由按质量百分比计的如下组分组成：
Gd 2.1％～2.3％、Zr 0.6％～1.0％、Zn 0.3％～0.6％、Nd 2.8％～3.1％、余量Mg和不可避 免的杂质。
在一些实施方式中，所述不可避免的杂质包括Ag、Ni、Al、Mn、Cu、Fe和Be中的任一种或多种；
Ag含量≤0.05wt％、Ni含量≤0.001wt％、Al含量≤0.01wt％、Mn含量≤0.05wt％、Cu含量≤0.007wt％、Fe含量≤0.005wt％、Be含量≤0.001wt％。
在一些实施方式中，所述不可避免的杂质还包括稀土杂质元素，所述稀土杂质元素总量＜0.4wt％。
在一些实施方式中，所述高强铸造镁合金的抗拉强度≥285MPa，屈服强度≥165MPa。
在一些实施方式中，所述高强铸造镁合金的抗拉强度≥290MPa，屈服强度≥175Mpa。
在一些实施方式中，所述高强铸造镁合金的延伸率≥5％。
在一些实施方式中，所述高强铸造镁合金的铸态组织中，第二相弥散分布在基体中；其中，所述第二相形态为细小针状，长度为1～6μm，宽度为0.3～0.8μm。
在一些实施方式中，所述铸态组织中，所述第二相的体积分数为8％～15％。
在一些实施方式中，所述高强铸造镁合金的T6热处理后的组织中，第二相主要分布在晶界上；其中，所述第二相形态为岛状第二相，所述岛状第二相的轮廓长度为5～13μm。
本公开还提供了上述高强铸造镁合金的制备方法，包括如下步骤：
采用镁、锌、镁-钆中间合金、镁-锆中间合金和镁-钕中间合金作为原料，按比例配料后，进行熔炼和浇铸。
在一些实施方式中，所述浇铸包括砂型铸造和熔模铸造中的任一种。
在一些实施方式中，所述方法还包括：对浇铸得到的铸件进行热处理；所述热处理包括T4热处理制度或T6热处理制度。
在一些实施方式中，所述T4热处理制度包括：于518～530℃保温8～16h，淬水；所述T6热处理制度包括：于518～530℃保温8～16h，淬水；然后于200～208℃保温16～20h，空冷。
在一些实施方式中，所述熔炼的方法包括：
(a)将镁升温熔化，待升温至745±5℃时，加入镁-钆中间合金，待完全熔化后，搅拌1～2min；升温至750～760℃，加入锌，继续升温至770～780℃，加入镁-锆中间合金和镁-钕中间合金；
(b)待步骤(a)物料全部熔化后，搅拌5～8min使合金均匀化，然后降温至740±5℃， 清除熔渣，撒入熔剂，将合金液升温至760～780℃，静置10～15min。
本公开还提供上文任一项所述的高强铸造镁合金或上文任一项所述的制备方法制得的高强铸造镁合金在航空航天设备中的应用。
在一些实施方式中，所述航空航天设备包括航空航天用发动机。
在一些实施方式中，所述航空航天设备包括航空航天用发动机传动系统的机匣。
本公开还提供上文任一项所述的高强铸造镁合金或上文任一项所述的制备方法制得的高强铸造镁合金在在电子产品、交工工具、生物医药中的应用。
附图说明
为了更清楚地说明本公开实施方式或现有技术中的技术方案，下面将对实施方式或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图是本公开的一些实施方式，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本公开实施例5的铸件的附铸试棒的铸态金相图片；
图2为比较例3的铸件的附铸试棒的铸态金相图片；
图3为本公开实施例5的铸件的附铸试棒的T6态金相图片；
图4为比较例3的铸件的附铸试棒的T6态金相图片；
图5为本公开的阻抗拟合电路图；
图6为本公开实施例5制得的某发动机传动系统机匣铸件的实物照片；
图7为比较例3的某发动机传动系统机匣铸件的X射线无损检测的偏析缺陷图；
图8为圈示比较例3制得的某发动机传动系统机匣铸件的疏松缺陷位置的荧光无损检测实物图；
图9为本公开实施例5制得的某发动机传动系统机匣铸件的荧光无损检测照片。
具体实施方式
下面将结合附图和实施方式对本公开的技术方案进行清楚、完整地描述，但是本领域技术人员将会理解，下列所描述的实施例是本公开一部分实施例，而不是全部的实施例，仅用于说明本公开，而不应视为限制本公开的范围。基于本公开中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本公开保护的范围。实施例中未注明条件者，按照常规条件或制造商建议的条件进行。所用试 剂或仪器未注明生产厂商者，均为可以通过市售购买获得的常规产品。
高强铸造镁合金，主要由按质量百分比计的如下组分组成：
Gd 2.1％～2.5％、Zr 0.5％～1.0％、Zn 0.3％～0.6％、Nd 2.7％～3.1％、余量Mg和不可避免的杂质。
现有镁合金用于航天航空领域重点关注减重，但目前常用的铸造镁合金如ZM2\ZM5\ZM6合金的力学性能较低，HB7780中要求的抗拉强度不超过230MPa。此外目前常用的铸造镁合金耐蚀性能较差，这进一步限制了镁合金铸件的使用环境。EV31A合金是一种高强耐蚀镁合金，标准AMS 4429A-2012中所要求的抗拉强度不超过248MPa，屈服强度不超过145MPa。
Nd、Gd作为强化元素均有提高合金强度的作用，但Nd的含量超过3.0％后强化效果不再有明显提升，反而会因为稀土含量过高而影响合金的铸造性能；Gd同样有明显的强化作用，但Gd超过2.5％后浇铸得到的铸件氧化夹渣倾向严重，有目视可见的氧化夹渣缺陷，在实际使用时中存在很大隐患，故不易超过2.5％。
本公开通过对合金成分进行优化调整，使得到的铸造镁合金具有高强、耐热、耐蚀性能，并且成型性能良好，相较于现有的铸造镁合金，其铸造疏松缺陷以及偏析倾向大大降低，采用本公开的铸造镁合金浇铸得到的铸件经检验，相比较于EV31A合金的疏松倾向更小。相较于目前常用的铸造镁合金，本公开的铸造镁合金具有较好的耐蚀性能，使用相同标准(GB/T 10125-2012)盐雾实验测得，本公开的镁合金的平均腐蚀速率可达0.029w，而ZM2合金的平均腐蚀速率为0.49w。
本公开通过对合金成分进行优化调整，使得到的镁合金具有高强、耐热、耐蚀性能，并且成型性能良好，相较于现有的镁合金，其铸造疏松缺陷以及偏析倾向大大降低。
如在不同实施方式中，Gd的含量可以为例如2.1％～2.47％、2.1％～2.4％、2.1％～2.2％、2.15％～2.47％或2.15％～2.33％，诸如2.1％、2.15％、2.2％、2.25％、2.3％、2.35％、2.4％、2.45％、2.5％等等。在不同实施方式中，Zr的含量可以为例如0.54％～1.0％、0.55％～1.0％、0.56％～1.0％、0.60％～1.0％、0.65％～1.0％或0.54％～0.65％，诸如0.5％、0.55％、0.6％、0.65％、0.7％、0.75％、0.8％、0.85％、0.9％、0.95％、1.0％等等。在不同实施方式中，Zn的含量可以为例如0.3％～0.6％、0.44％～0.6％、0.48％～0.6％、0.50％～0.6％、0.53％～0.6％或0.44％～0.53％，诸如0.3％、0.35％、0.4％、0.45％、0.5％、0.55％、0.6％等等。在不同实施方式中，Nd的含量可以为例如2.8％～3.1％、2.9％～3.1％、2.94％～3.1％、2.98％～3.1％ 或3.04％～3.1％，诸如2.7％、2.75％、2.8％、2.85％、2.9％、2.95％、3.0％、3.05％、3.1％等等。在本公开的一些实施方式中，所述高强铸造镁合金，主要由按质量百分比计的如下组分组成：
Gd 2.1％～2.4％、Zr 0.55％～1.0％、Zn 0.3％～0.6％、Nd 2.8％～3.1％、余量Mg和不可避免的杂质。
在本公开的一些实施方式中，所述高强铸造镁合金，主要由按质量百分比计的如下组分组成：
Gd 2.1％～2.3％、Zr 0.6％～1.0％、Zn 0.3％～0.6％、Nd 2.8％～3.1％、余量Mg和不可避免的杂质。
在本公开的一些实施方式中，所述高强铸造镁合金，主要由按质量百分比计的如下组分组成：
Gd 2.1％～2.2％、Zr 0.6％～1.0％、Zn 0.3％～0.6％、Nd 2.9％～3.1％、余量Mg和不可避免的杂质。
在本公开的一些实施方式中，所述不可避免的杂质包括Ag、Ni、Al、Mn、Cu、Fe和Be中的任一种或多种。在本公开的一些实施方式中，所述合金中，Ag含量≤0.05wt％、Ni含量≤0.001wt％、Al含量≤0.01wt％、Mn含量≤0.05wt％、Cu含量≤0.007wt％、Fe含量≤0.005wt％、Be含量≤0.001wt％。
在本公开的一些实施方式中，所述高强铸造镁合金的抗拉强度≥285MPa，屈服强度≥165Mpa。在本公开的一些实施方式中，高强铸造镁合金的抗拉强度≥290MPa，屈服强度≥175Mpa。在本公开的一些实施方式中，高强铸造镁合金的延伸率≥5％。在本公开的一些实施方式中，在250℃下可达到抗拉强度≥230MPa，屈服强度≥155MPa。
在本公开的一些实施方式中，所述高强铸造镁合金的铸态组织中，第二相弥散分布在基体中；其中，所述第二相形态为细小针状，长度为1～6μm，诸如1μm、2μm、3μm、4μm、5μm、6μm；宽度为0.3～0.8μm，诸如0.3μm、0.4μm、0.5μm、0.6μm、0.7μm、0.8μm。在本公开的一些实施方式中，所述铸态组织中，所述第二相的体积分数为8％～15％，诸如8％、9％、10％、11％、12％、13％、14％、15％。
在本公开的一些实施方式中，所述高强铸造镁合金的T6热处理后的组织中，第二相主要分布在晶界上；其中，所述第二相形态为岛状第二相，所述岛状第二相的轮廓长度为5～13μm，诸如5μm、6μm、7μm、8μm、9μm、10μm、11μm、12μm、13μm。
本公开还提供了高强铸造镁合金的制备方法，包括如下步骤：
采用镁、锌、镁-钆中间合金、镁-锆中间合金和镁-钕中间合金作为原料，按比例配料后，进行熔炼和浇铸。
在本公开的一些实施方式中，所述浇铸包括砂型铸造和熔模铸造中的任一种。在本公开的一些实施方式中，所述熔模铸造为熔模精密铸造。
在本公开的一些实施方式中，还包括：对浇铸得到的铸件进行热处理；所述热处理包括T4热处理制度(T4热处理)或T6热处理制度(T6热处理)。
在本公开的一些实施方式中，所述T4热处理制度包括：518～530℃保温8～16h，淬水，例如T4热处理制度温度为519～528℃、520～527℃或521～525℃，时间为例如9～15h、10～14h或11～13h。在本公开的一些实施方式中，所述T6热处理制度包括：于518～530℃保温8～16h，淬水，例如T6热处理制度的温度为519～528℃、520～526℃或521～524℃，时间为例如9～15h、10～14h或11～13h。在本公开的一些实施方式中，在T4热处理制度或T6热处理制度后于200～208℃保温16～20h，空冷。
T4热处理制度与T6热处理制度相比，由于溶质原子更多的溶入基体组织，使合金在T4态的强度高于T6态强度，但由于溶质原子的大量溶入，使合金在T4态的塑性低于T6态。针对不同的使用情况，可根据实际需求选择适宜的热处理制度，以满足不同的使用需求。
在本公开的一些实施方式中，所述熔炼的方法包括：
(a)将镁升温熔化，待升温至745±5℃时，加入镁-钆中间合金，待完全熔化后，搅拌1～2min；升温至750～760℃，加入锌，继续升温至770～780℃，加入镁-锆中间合金和镁-钕中间合金；
(b)待步骤(a)物料全部熔化后，搅拌5～8min使合金均匀化，然后降温至740±5℃，清除熔渣，撒入熔剂，将合金液升温至760～780℃，静置10～15min。其中，撒入一层熔剂覆盖合金液。
在本公开的一些实施方式中，精炼静置完毕后，降温至浇铸温度进行浇铸。
在实际操作中，清除熔渣包括：清除浇嘴、挡板、坩埚壁及合金液表面上的熔渣。
在实际操作中，所述镁升温熔化包括：将预热至200℃以上的镁投入预热处理的熔炼炉(如坩埚)中，在炉料上撒上适量熔剂，升温熔化。
在本公开的一些实施方式中，所述镁为纯镁锭，所述镁-钆中间合金为镁-30钆合金，所述镁-锆中间合金为镁-30锆合金，所述锌为纯锌粒，所述镁-钕中间合金为镁-30钕合金。
本公开还提供了上述任意一种所述高强铸造镁合金在航空航天设备中的应用。
在本公开的一些实施方式中，航空航天设备包括航空航天用发动机。
在本公开的一些实施方式中，所述航空航天设备为航空航天用发动机。
在本公开的一些实施方式中，所述航空航天设备为所述航空航天用发动机传动系统某机匣。
本公开还提供上述高强铸造镁合金或上述制备方法制得的高强铸造镁合金在电子产品(诸如手机零件或壳体、计算机零件或壳体、家用电器零件或壳体)、交工工具(诸如汽车零件、高速列车壳体)、生物医药(诸如组织工程支架、骨骼植入材料)中的应用。
本公开提供的高强铸造镁合金，解决了现有技术中存在的铸造镁合金强度不足、铸造性能不佳等技术问题。同时，本公开提供的高强铸造镁合金包括但不限于以下优点：
(1)本公开通过对合金成分进行优化调整，使得到的铸造镁合金具有优异力学性能，同时兼顾改善铸造性能中的显微疏松和偏析倾向，并保证耐腐蚀性能和高温持久性能等；
(2)本公开的铸造镁合金抗拉强度≥290MPa，屈服强度≥175MPa，延伸率≥5％；在250℃下可达到抗拉强度≥230MPa，屈服强度≥155MPa；
(3)本公开的铸造镁合金能够满足先进航空航天用发动机传动系统某机匣的选材要求。
实施例
实施例1
高强铸造镁合金的制备
经过多次实验验证，熔炼过程中Gd元素和Nd元素的烧损率分别是10％和12％，依照此烧损率设置炉料配比获得如表1所示的5组不同的成分，制得的合金实测值成分见表1。
表1不同高强铸造镁合金的实测成分
Figure PCTCN2022099890-appb-000001
Figure PCTCN2022099890-appb-000002
其中，表1中所指不可避免杂质包括Ag、Ni、Al、Mn、Cu、Fe和Be中的任一种或多种，合金中各杂质含量均不超过下述要求：Ag含量≤0.05wt％、Ni含量≤0.001wt％、Al含量≤0.01wt％、Mn含量≤0.05wt％、Cu含量≤0.007wt％、Fe含量≤0.005wt％、Be含量≤0.001wt％，其他单个杂质≤0.01wt％，其他杂质总体≤0.1wt％。
上述高强铸造镁合金的制备方法包括如下步骤：采用镁、锌、镁-30钆合金、镁-30锆合金和镁-30钕中间合金作为原料，按照Gd元素和Nd元素的烧损率分别是10％和12％进行炉料配料后，进行熔炼和浇铸，分别制备出砂型铸造镁合金试棒为砂铸1#、砂铸2#、砂铸3#、砂铸4#和砂铸5#。
所述熔炼和浇铸的方法包括：
(1)将坩埚预热至暗红色，炉料预热至200℃以上，加入预热的纯镁锭，在炉料上撒上适量熔剂，升温熔化。
(2)升温至745±5℃时，将镁-30钆合金直接加入到已经熔化的纯镁锭中，待其完全熔化后，搅拌1～2min；
(3)温度调整至750～760℃，加入纯锌粒；
(4)继续升温至770～780℃，缓慢地加入镁-30锆合金、镁-30钕合金；
(5)全部熔化后，捞底搅拌5～8min，使合金均匀化；
(6)待合金均匀化后，将温度降到740±5℃，进行精炼；停止搅拌，清除浇嘴、挡板(指有挡板坩埚)、坩埚壁和合金液表面上的熔渣，撒上一层覆盖熔剂；将合金液升温至760～780℃，静置10～15min；
(7)精炼静置完毕后，降温至浇铸温度725～730℃进行浇铸，浇铸得到砂铸试棒，砂型是室温，试棒尺寸为：平行端直径为Φ12，标距75mm。
实施例2
本实施例参考实施例1的制备方法，区别仅在于，将砂型浇铸替换为熔模精密铸造，分别制备出精铸1#、精铸2#、精铸3#、精铸4#、精铸5#试棒。熔模精密铸造包括：按照实施例1的方法熔炼后，降温至725～730℃进行浇铸，精铸模壳温度是300℃。其中，炉料配比原则参照实施例1，制得的合金实测值成分分别见表2。
表2不同高强铸造镁合金的实测成分
Figure PCTCN2022099890-appb-000003
实施例3
固溶(T4)状态高强铸造镁合金的制备
按照表3中热处理条件对实施例2制备获得的相应的合金铸件进行处理得到相应的固溶(T4)状态高强铸造镁合金。
表3不同固溶(T4)状态高强铸造镁合金的处理方法
T4铸件编号 原料 热处理条件
X1 精铸1# 520～521℃保温8h，淬水
X2 精铸2# 520～521℃保温8h，淬水
X3 精铸3# 520～521℃保温8h，淬水
X4 精铸4# 520～521℃保温8h，淬水
X5 精铸5# 520～521℃保温8h，淬水
上述固溶(T4)状态高强铸造镁合金的制备方法包括如下步骤：
将实施例2中制得的各个相应的合金试棒分别按照表3中的热处理制度进行处理后，得到相应的固溶(T4)状态高强铸造镁合金铸件。
也可对实施例1中制得的砂铸件进行同样的T4热处理。
实施例4
固溶+时效(T6)状态高强铸造镁合金的制备
按照表4中热处理条件对实施例2制备获得的相应的合金铸件进行处理得到相应的固溶+时效(T6)状态高强铸造镁合金。
表4不同固溶+时效(T6)状态高强铸造镁合金的处理方法
Figure PCTCN2022099890-appb-000004
上述固溶+时效(T6)状态高强铸造镁合金的制备方法包括如下步骤：
将实施例2中制得的各个相应的合金试棒分别按照表4中的热处理制度进行处理后，得到相应的固溶+时效(T6)状态高强铸造镁合金铸件。
也可对实施例1中制得的砂铸件进行同样的T6热处理。
实施例5
本实施例提供了采用高强铸造镁合金制得的某传动系统机匣铸件(本实施例仅以航 天领域的传动系统机匣铸件为例)，制备方法包括：按照实施例1的4#合金炉料配比熔炼后，熔模精密重力浇铸得到某传动系统机匣铸件；其中浇铸温度为745～750℃，模壳温度300℃；浇铸处理后采用T6热处理制度。同时附铸试棒用于检测。
需要说明的是，本公开的高强铸造镁合金在实施例5中的举例，仅为示例地举例以高强铸造镁合金为材料铸造的铸件，本公开高强铸造镁合金的应用领域显然并不仅限于航空航天领域，其可以广泛地应用于电子产品(诸如手机零件或壳体、计算机零件或壳体、家用电器零件或壳体)、交工工具(诸如汽车零件、高速列车壳体)、生物医药(诸如组织工程支架、骨骼植入材料)领域。
比较例1
比较例1提供了其他铸造镁合金的制备，按照实施例1的炉料配比原则以及熔炼和浇铸方法，分别制得砂铸6#、砂铸7#、砂铸8#、砂铸9#，所述试样为砂铸的单铸试棒，对应的合金实测值成分分别见表5。
表5不同铸造镁合金的实测成分
Figure PCTCN2022099890-appb-000005
比较例2
比较例2参考比较例1的制备方法，区别仅在于，将砂型浇铸替换为熔模精密铸造，分别制备出精铸6#、精铸7#、精铸8#、精铸9#。熔模精密铸造条件同实施例2。比较例2的合金实测成分与比较例1成分相近，所铸试样为精铸的单铸试棒。
比较例3
比较例3提供了采用铸造镁合金制得的某传动系统机匣铸件(本比较例仅以航天领域的传动系统机匣铸件为例)，制备方法包括：按照EV31A合金成分配料和熔炼后，熔模精密重力浇铸得到某传动系统机匣铸件；其中浇铸温度为745～750℃，模壳温度300℃；浇铸处理后采用T6热处理制度。EV31A合金实测成分为：Nd 2.86％，Gd 1.55％，Zn 0.5％，Zr 0.59％，余量镁和不可避免的杂质。同时附铸试棒用于检测。
实验例1
为了对比说明不同成分对镁合金的组织结构的影响，分别观察实施例和比较例的铸件的金相组织。图1和图2分别为实施例5和比较例3的铸件的附铸试棒的铸态金相图片；图3和图4分别为实施例5和比较例3的铸件的附铸试棒的T6态金相图片。从图中可知，实施例5的铸态组织中的第二相形态为细小针状，长度为1～6μm，宽度为0.3～0.8μm，第二相弥散分布在基体中，第二相的体积分数为8％～15％；经T6热处理后，基体中出现形态为岛状第二相，主要分布在晶界上，岛状第二相的轮廓长度为5～13μm。比较例3的铸态组织中第二相形态为条带状，长度为3～10μm，宽度为1～2μm，主要分布在晶界附近，且与晶界位相关系近乎垂直，条带状第二相的体积分数为5％～10％；经T6热处理后，基体中出现圆棒状第二相，圆棒状第二相长度为8～15μm，宽度为3～5μm，相比于实施例5的T6态组织，圆棒状第二相密度较低且分布不均匀。对实施例5和比较例3经T6热处理制度处理得到的某传动系统机匣铸件本体和附铸试棒等进行力学性能测试，测试结果分别见表6和表7，测试方法参考HB7780-2005，GB/T 22315-2008。
表6不同实施例的合金的T6态的力学性能测试结果
Figure PCTCN2022099890-appb-000006
Figure PCTCN2022099890-appb-000007
表7不同比较例的合金的T6态的力学性能测试结果
Figure PCTCN2022099890-appb-000008
从上表中可知，本公开的铸造镁合金浇铸的试棒力学性能较其它铸造镁合金明显提高，本体性能也略有提升。对不同试棒的弹性模量进行了测试，T6态砂铸4#的弹性模量为44.4MPa，T6态精铸4#的弹性模量为45MPa，T6态的铸件本体的弹性模量为45MPa，由此可知本公开的铸造镁合金在提高力学性能的同时，能够兼顾保证弹性模量。
此外，本公开的铸造镁合金在提高其余力学性能的同时，能够兼顾保证甚至提高材料的高周疲劳性能。
实验例2
对实施例5得到的T6态的铸件本体(从铸件本体取样进行测试，样品尺寸为10mm*10mm*3.5mm)采用常规实验方法进行了电化学实验测试样品的极化曲线和阻抗，测试结果分别见表8～表9。
在室温25℃，将合金浸泡于3.5wt％NaCl水溶液中进行析氢试验，总浸泡时间为336h，平均腐蚀速率可达3.44mm/y。
表8合金的极化曲线拟合结果
Figure PCTCN2022099890-appb-000009
表9合金的阻抗拟合结果
Alloys R1 R2 CPE 1 n 1 CPE 2 n 2 R3 x 2
实施例5 6.95 1239 1.38E-5 0.93 1.75E-3 1.02 492.2 7.95E-3
备注：样品的测试顺序：开路电位60min；阻抗20min；极化；室温25℃。阻抗拟合电路图如图5所示。
对实施例5得到的T6态的铸件本体(从铸件本体取样进行测试)进行加速盐雾试验，测试结果见表10。
表10盐雾试验测试结果(GB/T 20854-2007)
Figure PCTCN2022099890-appb-000010
从上述测试结果可知，本公开的高强铸造镁合金的腐蚀速率小，腐蚀电位可提升至-1.66V，和纯铝相当。
实验例3
分别对实施例5和比较例3浇铸得到的某传动系统机匣铸件进行冶金质量检测，检测结果显示：比较例3浇铸得到的铸件疏松及偏析缺陷较严重；实施例5浇铸得到的铸件成型性良好，铸件外观完整，薄壁处无欠铸等情况，在相同工艺情况下，其疏松缺陷相较于比较例3大大降低，侧面薄壁区域未见偏析情况。
图6为实施例5浇铸得到的某传动系统机匣铸件的实物照片。比较例3浇铸得到的某传动系统机匣铸件的实物照片同实施例5的图6所示。比较例3浇铸得到的铸件，在 图6所圈示的薄壁处存在如图7所示的偏析缺陷，在图8所圈示的薄厚相接处存在疏松缺陷。实施例5浇铸得到的铸件的荧光无损检测照片如图9所示。其中，偏析缺陷通过X射线无损检测测试得到，测试手段符合HB/Z 60；疏松缺陷通过荧光无损检测方式得到，检测方法符合HB/Z 61。
最后应说明的是：以上各实施例仅用以说明本公开的技术方案，而非对其限制；尽管参照前述各实施例对本公开进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本公开各实施例技术方案的范围。
工业实用性
本公开提供了一种高强铸造镁合金及其制备方法和应用，本公开通过对合金成分进行优化调整，使得到的镁合金具有高强、耐热、耐蚀性能，并且成型性能良好，相较于现有的铸造镁合金，其铸造疏松缺陷以及偏析倾向大大降低，能够满足先进航空航天用发动机传动系统某机匣的选材要求，具有优异的应用性能。

Claims (15)

  1. 高强铸造镁合金，其特征在于，主要由按质量百分比计的如下组分组成：
    Gd 2.1％～2.5％、Zr 0.5％～1.0％、Zn 0.3％～0.6％、Nd 2.7％～3.1％、余量Mg和不可避免的杂质。
  2. 根据权利要求1所述的高强铸造镁合金，其特征在于，主要由按质量百分比计的如下组分组成：
    Gd 2.1％～2.4％、Zr 0.55％～1.0％、Zn 0.3％～0.6％、Nd 2.8％～3.1％、余量Mg和不可避免的杂质。
  3. 根据权利要求1或2所述的高强铸造镁合金，其特征在于，主要由按质量百分比计的如下组分组成：
    Gd 2.1％～2.2％、Zr 0.6％～1.0％、Zn 0.3％～0.6％、Nd 2.9％～3.1％、余量Mg和不可避免的杂质。
  4. 根据权利要求1～3中任一项所述的高强铸造镁合金，其特征在于，所述不可避免的杂质包括Ag、Ni、Al、Mn、Cu、Fe和Be中的任一种或多种；
    Ag含量≤0.05wt％、Ni含量≤0.001wt％、Al含量≤0.01wt％、Mn含量≤0.05wt％、Cu含量≤0.007wt％、Fe含量≤0.005wt％、Be含量≤0.001wt％。
  5. 根据权利要求4所述的高强铸造镁合金，其特征在于，所述不可避免的杂质包括稀土杂质元素，所述稀土杂质元素总量＜0.4wt％。
  6. 根据权利要求1～5中任一项所述的高强铸造镁合金，其特征在于，所述高强铸造镁合金的抗拉强度≥285MPa，屈服强度≥165MPa；
    优选的，所述高强铸造镁合金的抗拉强度≥290MPa，屈服强度≥175Mpa；
    优选的，所述高强铸造镁合金的延伸率≥5％；
    优选的，所述高强铸造镁合金的铸态组织中，第二相弥散分布在基体中；其中，所述第二相形态为细小针状，长度为1～6μm，宽度为0.3～0.8μm；
    优选的，所述铸态组织中，所述第二相的体积分数为8％～15％；
    优选的，所述高强铸造镁合金的T6热处理后的组织中，第二相主要分布在晶界上；其中，所述第二相形态为岛状第二相，所述岛状第二相的轮廓长度为5～13μm。
  7. 权利要求1～6任一项所述的高强铸造镁合金的制备方法，其特征在于，包括如下步骤：
    采用镁、锌、镁-钆中间合金、镁-锆中间合金和镁-钕中间合金作为原料，按比例配 料后，进行熔炼和浇铸。
  8. 根据权利要求7所述的高强铸造镁合金的制备方法，其特征在于，所述浇铸包括砂型铸造和熔模铸造中的任一种。
  9. 根据权利要求7或8所述的高强铸造镁合金的制备方法，其特征在于，所述方法还包括：对浇铸得到的铸件进行热处理；所述热处理包括T4热处理制度或T6热处理制度。
  10. 根据权利要求8所述的高强铸造镁合金的制备方法，其特征在于，所述T4热处理制度包括：于518～530℃保温8～16h，淬水；所述T6热处理制度包括：于518～530℃保温8～16h，淬水；然后于200～208℃保温16～20h，空冷。
  11. 根据权利要求7～10中任一项所述的高强铸造镁合金的制备方法，其特征在于，所述熔炼的方法包括：
    (a)将镁升温熔化，待升温至745±5℃时，加入镁-钆中间合金，待完全熔化后，搅拌1～2min；升温至750～760℃，加入锌，继续升温至770～780℃，加入镁-锆中间合金和镁-钕中间合金；
    (b)待步骤(a)物料全部熔化后，搅拌5～8min使合金均匀化，然后降温至740±5℃，清除熔渣，撒入熔剂，将合金液升温至760～780℃，静置10～15min。
  12. 权利要求1～6任一项所述的高强铸造镁合金或权利要求7-11任一项所述的制备方法制得的高强铸造镁合金在航空航天设备中的应用。
  13. 根据权利要求12所述的应用，其特征在于，所述航空航天设备包括航空航天用发动机。
  14. 根据权利要求12或13所述的应用，其特征在于，所述航空航天设备包括航空航天用发动机传动系统的机匣。
  15. 权利要求1～6任一项所述的高强铸造镁合金或权利要求7-11任一项所述的制备方法制得的高强铸造镁合金在电子产品、交工工具、生物医药中的应用。
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