WO2025001059A1 - 一种高强韧高导热压铸镁合金及其制备方法 - Google Patents

一种高强韧高导热压铸镁合金及其制备方法 Download PDF

Info

Publication number
WO2025001059A1
WO2025001059A1 PCT/CN2024/071478 CN2024071478W WO2025001059A1 WO 2025001059 A1 WO2025001059 A1 WO 2025001059A1 CN 2024071478 W CN2024071478 W CN 2024071478W WO 2025001059 A1 WO2025001059 A1 WO 2025001059A1
Authority
WO
WIPO (PCT)
Prior art keywords
magnesium alloy
pure
die
ingot
alloy
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CN2024/071478
Other languages
English (en)
French (fr)
Inventor
王卓
唐伟能
胡勇
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Baosteel Metal Co Ltd
Original Assignee
Baosteel Metal Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Baosteel Metal Co Ltd filed Critical Baosteel Metal Co Ltd
Priority to EP24829722.8A priority Critical patent/EP4733427A1/en
Publication of WO2025001059A1 publication Critical patent/WO2025001059A1/zh
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
    • 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

Definitions

  • the present invention relates to the technical field of magnesium alloy materials, and in particular to a high-strength, high-toughness and high-thermal-conductivity die-cast magnesium alloy and a preparation method thereof.
  • the cooling system structures of mobile phone mid-plates, laptop computer shells, 5G base station shells, car headlight bases, mobile energy storage devices, etc. not only require their materials to have the characteristics of low density and high strength, but also require them to have excellent thermal conductivity/heat dissipation performance.
  • Magnesium alloy is the metal material with the lowest density in the current engineering structural materials. At the same time, magnesium alloy has excellent thermal conductivity, damping performance and electromagnetic properties, so it is considered to be a very potential structural-functional integrated material. Because magnesium alloy has both lightweight characteristics and excellent physical properties, it has broad application prospects in the above-mentioned 3C products and automotive parts fields.
  • the thermal conductivity of pure magnesium at room temperature is about 154.5W/(m ⁇ K), but its yield strength is too low to be used as an engineering material.
  • Deformed magnesium alloys have excellent mechanical properties, but conventional extrusion, rolling, and forging of magnesium alloys are expensive, and it is impossible to produce magnesium alloy products with complex structures and shapes. Therefore, more than 80% of magnesium alloy products are formed by die casting. Die casting is the most widely used magnesium alloy casting process. It has the advantages of low manufacturing cost and the ability to form complex structural products. Products such as 3C product housings, 5G base station housings, car headlight bases, mobile energy storage equipment, etc. require their materials to have excellent thermal conductivity/heat dissipation and mechanical properties while being lightweight to ensure that the product has high working stability and service life.
  • Chinese patent CN105463280A discloses "a magnesium alloy with high thermal conductivity and its preparation method", and prepares a Mg-Al-RE-Mn die-casting magnesium alloy, the chemical composition mass percentage of which is: Al: 3.0-6.8%, Mn: 0.3-0.8%, mixed rare earth (La, Ce, Pr and Nd): 2.8-4.8%, and the rest is Mg.
  • the thermal conductivity of the alloy is greater than 100W/(m ⁇ K), but the patent does not mention the mechanical properties of the magnesium alloy.
  • Chinese patent CN107604228A discloses "High thermal conductivity and corrosion resistant die-cast magnesium alloy and its preparation method", and prepares Mg-Al-Ce-Mn-Be die-cast magnesium alloy, whose chemical composition mass percentage is: Ce: 3.5-5.0%, Al: 2.5-3.5%, Mn: 0.5%, Be: 0.05%, and the rest is Mg.
  • the thermal conductivity of the alloy is greater than 100W/(m ⁇ K), and the tensile strength is 250-260MPa, but key mechanical properties such as yield strength and elongation of magnesium alloy are not mentioned.
  • Chinese patent CN114351022A discloses "a high thermal conductivity magnesium alloy containing high solid solubility rare earth elements and its preparation method", and prepares a Mg-RE-Al casting magnesium alloy, whose chemical composition is: RE: 4-16% (mass percentage), Al: the atomic ratio of Al to RE is 0.3-4%, and the rest is Mg.
  • the thermal conductivity of the alloy is ⁇ 100W/(m ⁇ K), but the alloy contains a large amount of precious rare earth element Sm, the cost is high, and the mechanical properties are not mentioned.
  • the die-cast magnesium alloy materials reported in the prior art cannot simultaneously take into account high strength, toughness, high thermal conductivity and processing cost. Therefore, it is urgently necessary to carry out new die-cast magnesium alloy composition design and new molding technology research to develop new high-strength, toughness and high-thermal conductivity die-cast magnesium alloys to expand the application of magnesium alloys.
  • the purpose of the present invention is to provide a high-strength, high-toughness and high-thermal-conductivity die-cast magnesium alloy and a preparation method thereof, without adding expensive rare earth elements or other alloy elements, using a low-cost alloy formula, and ensuring that the alloy has good casting performance, to solve the problem that the existing magnesium alloy cannot take into account both high mechanical properties and high thermal conductivity at the same time;
  • the room temperature thermal conductivity of the magnesium alloy is 100-110W/(m ⁇ K), the room temperature yield strength is 140-150MPa, and the room temperature elongation is 8-12%; and magnesium alloy products with complex structures can be manufactured, the process is low-cost, easy to mass-produce, and can be widely used in heat dissipation/thermal conductive components in the fields of 3C products and automotive parts.
  • a high-strength, high-toughness and high-thermal-conductivity die-cast magnesium alloy the composition weight percentage of which is: Al: 2.5-4.0%, RE: 3.5-5.5%, Mn: 0.1-0.3%, Be: 0.002-0.003%, Ca: 0.1-1.0%, Gd: 0.05-0.3%, RE is one or both of La or Ce, and the balance includes Mg and other inevitable impurities; and the above elements also need to meet the following requirements at the same time:
  • the balance is Mg and other inevitable impurities.
  • the die-cast magnesium alloy matrix of the present invention has Al 11 RE 3 , Al 2 RE, Al 2 Ca, (Mg, Al) 2 Ca, Al 2 Gd and a needle-shaped Al 3 RE second phase uniformly distributed thereon.
  • the room temperature yield strength of the die-cast magnesium alloy of the present invention is 140-150 MPa, the elongation is 8-12%, and the thermal conductivity is 100-110 W/(m ⁇ K).
  • Al is the most commonly used alloying element in magnesium alloys, and Mg-Al alloys have good casting properties.
  • the atomic volume of Al is smaller than that of Mg.
  • Al atoms dissolve in Mg the lattice volume gradually decreases.
  • the valence electron difference between Al atoms and Mg atoms also leads to a significant reduction in the thermal conductivity of magnesium alloys when Al is dissolved in Mg.
  • the thermal conductivity of the commercial die-cast magnesium alloy AZ91D is only 51.2W/(m ⁇ K).
  • elements having strong affinity with Al such as La, Ce, Ca and Gd
  • Al 11 RE 3 elements having strong affinity with Al
  • Al 2 RE Al 2 Ca
  • (Mg, Al) 2 Ca Al 2 Gd second phases
  • a needle-shaped Al 3 RE new second phase is introduced.
  • This needle-shaped second phase is smaller in size than the Al 11 RE 3 second phase, has a more excellent second phase strengthening effect, and significantly improves the mechanical properties of the material.
  • These second phases not only improve the mechanical properties of the material, but also consume the Al element in the Mg matrix, increase the lattice volume, reduce the possibility of free electron scattering, and avoid the decrease in the thermal conductivity of the material caused by the solid solution of the Al element in the magnesium alloy.
  • the magnesium alloy simultaneously obtains high mechanical properties and high thermal conductivity.
  • the Al content is controlled within 2.5-4.0%.
  • La and Ce form a large amount of Al 11 RE 3 second phase and a small amount of Al 2 RE second phase with Al.
  • the added Al and RE elements are controlled to satisfy 0.7 ⁇ Al/RE ⁇ 0.8, so that Al and RE exist in the form of fine lamellar Al 11 RE 3 , extremely fine needle-shaped Al 3 RE second phase and granular Al 2 RE second phase.
  • the new second phase Al 3 RE is introduced, which has a more excellent second phase strengthening effect and significantly improves the mechanical properties of the material.
  • the formation of Al 11 RE 3 , Al 3 RE and Al 2 RE second phases greatly avoids the existence of Al in the form of solid solution atoms in the magnesium alloy, reduces the negative impact of the Al element on the thermal conductivity of the magnesium alloy, and thus This will not lead to a decrease in the thermal conductivity of the material, ensuring that the magnesium alloy has both excellent thermal conductivity and mechanical properties.
  • the cheap rare earth elements La and Ce also have the function of purifying the magnesium alloy melt. Too little La and Ce elements cannot form enough Al-RE second phase to improve material properties. When La and Ce are added in excess of 5.5%, the die-casting performance of the magnesium alloy is significantly reduced, and the melt fluidity becomes poor. Too much RE will also increase the material cost. Therefore, in the present invention, the amount of RE (La and Ce) is controlled at 3.5-5.5%.
  • the fine dispersed Al 2 Ca second phase and (Mg,Al) 2 Ca second phase formed by Ca element and Al in Mg-Al alloy can significantly improve the room temperature mechanical properties of magnesium alloy, while ensuring that the material has excellent plasticity and toughness.
  • the presence of Al 2 Ca as the second phase in magnesium alloy does not significantly reduce the thermal conductivity of the material.
  • Ca in magnesium alloy also has the effect of anti-oxidation and flame retardancy, inhibits the oxidation of the surface of magnesium alloy melt during die casting, and greatly reduces the inclusions in die-cast magnesium alloy.
  • too much Ca element will reduce the fluidity of magnesium solution during die casting, increase the tendency of hot cracking and brittleness, and reduce the mechanical properties of the material. Therefore, in the present invention, the content of Ca element is controlled at 0.1-1.0%.
  • Mn element in magnesium alloy is extremely low, which can effectively reduce the content of harmful elements such as Fe, Cu, Ni in magnesium alloy to improve the corrosion resistance of magnesium alloy.
  • an appropriate amount of Mn has the effect of refining the cast structure of magnesium alloy, which can improve the plasticity and toughness of the material and has a small negative impact on thermal conductivity.
  • adding more than 0.3% of Mn in the present invention will reduce the effect of grain refinement. Therefore, the content of Mn element is controlled to 0.1-0.3% in the present invention.
  • the affinity of Be to oxygen is greater than that of Mg to oxygen.
  • a very small amount of Be can form a dense oxide film on the surface of the magnesium alloy melt to prevent the magnesium alloy melt from oxidation.
  • the Be content is lower than 0.002%, the degree of oxidation of the magnesium alloy solution is significantly increased.
  • the Be content is higher than 0.003%, the microstructure of the material is significantly coarsened and the mechanical properties are reduced. Therefore, in the present invention, the Be content is controlled at 0.002-0.003%, the slag and inclusions in the magnesium alloy solution are reduced, the mechanical properties of the material are improved, and the inclusions and oxides are prevented from reducing the thermal conductivity of the material.
  • the Gd element added in the present invention can form the Al 2 Gd second phase with the Al element, thereby inhibiting the formation of the brittle phase Mg 17 Al 12 and avoiding a significant reduction in thermal conductivity.
  • the Al 2 Gd phase formed at the same time has a significant strengthening effect, which improves the strength of the magnesium alloy without significantly reducing the plasticity of the material.
  • the Al 2 Gd phase can also promote the heterogeneous nucleation process, improve the nucleation rate during the die casting solidification process, and reduce the thermal conductivity of the material. Too little Gd element cannot play a strengthening effect and inhibit the formation of Mg 17 Al 12 in magnesium alloy, and too much Gd element addition will reduce the die-casting performance of magnesium alloy. Therefore, in the present invention, the Gd element content is controlled to 0.05-0.3%.
  • the present invention obtains a die-cast magnesium alloy having both high strength and high toughness by controlling the composition while ensuring that the magnesium alloy has excellent casting properties.
  • the method for preparing the high-strength, high-toughness and high-thermal-conductivity die-cast magnesium alloy of the present invention comprises the following steps:
  • the ingredients are prepared according to the above magnesium alloy composition;
  • magnesium alloy flux to the obtained magnesium alloy melt, refining for 5 to 10 minutes, removing surface scum, and then heating to 700 to 720° C. and keeping the temperature for 10 to 15 minutes;
  • the refined magnesium alloy melt is cast into an ingot, which is then placed in a die-casting machine furnace to melt at 680-700°C.
  • the melt enters the mold through an injection system for filling, wherein the mold temperature is 200-250°C, the casting pressure is 100-110 MPa, and the injection speed is 3-5 m/s.
  • the magnesium alloy flux is RJ-2 flux and RJ-3 flux.
  • the protective gas is a mixed gas of CO 2 +SF 6 .
  • the pouring temperature is 680-700°C.
  • the furnace temperature is controlled at 680-700°C, and while ensuring that the magnesium alloy solution has good fluidity and filling properties, coarse dendrites are avoided to affect the mechanical properties of the material.
  • the temperature is lower than 680°C, the fluidity of the magnesium alloy solution deteriorates, and defects appear on the surface of the filled product.
  • the temperature is higher than 700°C, coarse dendrites appear in the microstructure of the filled product. The mechanical properties of the material are reduced.
  • the mold temperature is controlled at 200-250°C. Within this temperature range, the alloy is fully filled, defects such as cracks and pores are greatly reduced, and the material has excellent mechanical properties. When the temperature is lower than 200°C, due to the large temperature difference between the high-temperature melt and the mold temperature, defects appear on the surface of the filled product, and the plasticity of the product is reduced; when the mold temperature is higher than 250°C, the fine grain area on the product surface is reduced, and the mechanical properties are reduced.
  • the casting pressure is 100-110MPa to ensure normal filling of the product, making the material's microstructure dense, and having excellent mechanical properties and thermal conductivity.
  • the injection speed is controlled at 3-5m/s. If the injection speed is too low, the material cannot be completely filled into the mold. If the injection speed is too high, the material porosity is high, and the mechanical properties and thermal conductivity will be reduced.
  • the present invention has the following beneficial effects:
  • the high-strength, toughness and high-thermal conductivity magnesium alloy of the present invention adds Al, La, Ce, Ca and Gd elements to the magnesium matrix to form Al 11 RE 3 , Al 2 RE, Al 2 Ca, (Mg, Al) 2 Ca, Al 2 Gd second phases.
  • the added Al and RE elements are controlled to meet 0.7 ⁇ Al/RE ⁇ 0.8, and a needle-shaped Al 3 RE new second phase is introduced to improve the mechanical properties of the material with a more excellent second phase strengthening effect.
  • the formation of these second phases greatly avoids the presence of Al in the magnesium alloy in the form of solid solution atoms, reduces the negative impact of the Al element on the thermal conductivity of the magnesium alloy, and thus does not lead to a decrease in the thermal conductivity of the material.
  • the addition of the Gd element is combined with the Al element to form the Al 2 Gd second phase, thereby inhibiting the formation of the brittle phase Mg 17 Al 12 , and avoiding a significant decrease in thermal conductivity.
  • a magnesium alloy having both high thermal conductivity and high room temperature mechanical properties is obtained.
  • the alloy elements added in the present invention ensure the material properties while taking into account the die-casting manufacturability. Based on the composition design, the appropriate furnace temperature, mold temperature, casting pressure and injection speed are matched at the same time, so that the magnesium alloy has good fluidity and filling properties during die-casting, the product microstructure is dense and defect-free, the process cost is low, and complex structural products such as 3C housings, automotive parts, etc. with complex appearance structures can be mass-produced.
  • the room temperature thermal conductivity of the magnesium alloy obtained by the invention is 100-110 W/(m ⁇ K), the room temperature yield strength is 140-150 MPa, and the room temperature elongation is 8-12%.
  • the magnesium alloy composition of the embodiment of the present invention is shown in Table 1, and the rest is Mg and other inevitable impurities.
  • the ingredients are prepared according to the weight percentage of the magnesium alloy components designed;
  • the magnesium alloy ingot is placed in a 650T die-casting machine furnace and melted at 680°C.
  • the melt enters the mold through the injection system for filling.
  • the mold temperature is 216°C
  • the casting pressure is 105MPa
  • the injection speed is 3.5m/s.
  • the ingredients are prepared according to the weight percentage of the magnesium alloy components designed;
  • the magnesium alloy ingot is placed in a 650T die-casting machine furnace and melted at 692°C.
  • the melt enters the mold through the injection system for filling, wherein the mold temperature is 220°C, the casting pressure is 100 MPa, and the injection speed is 3 m/s.
  • the ingredients are prepared according to the weight percentage of the magnesium alloy components designed;
  • the magnesium alloy ingot is placed in a 650T die-casting machine furnace and melted at 700°C.
  • the melt enters the mold through the injection system for filling.
  • the mold temperature is 239°C
  • the casting pressure is 101MPa
  • the injection speed is 4m/s.
  • the ingredients are prepared according to the weight percentage of the magnesium alloy components designed;
  • magnesium alloy flux RJ-3 is added for refining for 9 minutes to remove surface scum, and finally the mixture is kept at 710°C for 15 minutes to cast into magnesium alloy ingots;
  • the magnesium alloy ingot is placed in a 650T die-casting machine furnace and melted at 695°C.
  • the melt enters the mold through the injection system for filling.
  • the mold temperature is 250°C
  • the casting pressure is 110MPa
  • the injection speed is 3.3m/s.
  • the ingredients are prepared according to the weight percentage of the magnesium alloy components designed;
  • the magnesium alloy ingot is placed in a 650T die-casting machine furnace and melted at 688°C.
  • the melt enters the mold through the injection system for filling.
  • the mold temperature is 208°C
  • the casting pressure is 108MPa
  • the injection speed is 4.3m/s.
  • the ingredients are prepared according to the weight percentage of the magnesium alloy components designed;
  • magnesium alloy flux RJ-2 is added to refine for 5 minutes, and the surface scum is removed, and finally the temperature is kept at 705°C for 11 minutes, and cast into a magnesium alloy ingot;
  • the magnesium alloy ingot is placed in a 650T die-casting machine furnace and melted at 690°C.
  • the melt enters the mold through the injection system for filling, wherein the mold temperature is 200°C, the casting pressure is 109 MPa, and the injection speed is 5 m/s.
  • the ingredients are prepared according to the weight percentage of the magnesium alloy components designed;
  • the magnesium alloy ingot is placed in a 650T die-casting machine furnace and melted at 695°C.
  • the melt enters the mold through the injection system for filling.
  • the mold temperature is 226°C
  • the casting pressure is 102MPa
  • the injection speed is 4.6m/s.
  • the magnesium alloy ingot is placed in a 650T die-casting machine furnace and melted at 698°C.
  • the melt enters the mold through the injection system for filling.
  • the mold temperature is 239°C
  • the casting pressure is 103MPa
  • the injection speed is 3.1m/s.
  • the ingredients are prepared according to the weight percentage of the magnesium alloy components designed;
  • the magnesium alloy ingot is placed in a 650T die-casting machine furnace and melted at 685°C.
  • the melt enters the mold through the injection system for filling.
  • the mold temperature is 203°C
  • the casting pressure is 104MPa
  • the injection speed is 3.9m/s.
  • the ingredients are prepared according to the weight percentage of the magnesium alloy components designed;
  • the magnesium alloy ingot is placed in a 650T die-casting machine furnace and melted at 689°C.
  • the melt enters the mold through the injection system for filling.
  • the mold temperature is 245°C
  • the casting pressure is 106MPa
  • the injection speed is 4.8m/s.
  • Comparative Examples 1 and 2 respectively use commercial grades AZ91D and AM60, and the molding process of these two grades of alloys is the traditional die-casting process.
  • the present invention adopts the design principle of high-strength, toughness and high-thermal conductivity magnesium alloy, and the molding process is the die-casting molding process.
  • the percentage content of the magnesium alloy composition is selected as follows: 9wt% Al, 1wt% Zn, and the rest is Mg;
  • a pure Mg ingot is placed in a crucible of a smelting furnace, heated to 695°C, and completely melted to form a melt under the protection of a mixed protective gas of CO2 and SF6 . Subsequently, a pure Al ingot and a pure Zn ingot are added, and stirred for 8 minutes in the mixed protective atmosphere. After the alloy is completely melted, a magnesium alloy flux RJ-2 is added and refined for 7 minutes to remove surface scum. Finally, the alloy is kept at 720°C for 15 minutes and cast into a magnesium alloy ingot. The magnesium alloy ingot is placed in a 650T die-casting machine furnace and melted at 680°C. The melt enters the mold for filling through the injection system, wherein the mold temperature is 206°C, the casting pressure is 105MPa, and the injection speed is 3.5m/s.
  • composition percentage of the magnesium alloy is selected as follows: 6wt% Al, 0.5wt% Mn, and the rest is Mg;
  • a pure Mg ingot is placed in a crucible of a smelting furnace, heated to 710°C, and completely melted to form a melt under the protection of a mixed protective gas of CO2 and SF6 . Subsequently, a pure Al ingot and pure Mn powder are added and stirred in the mixed protective atmosphere for 10 minutes. After the alloy is completely melted, a magnesium alloy flux RJ-2 is added and refined for 10 minutes to remove surface scum. Finally, the alloy is kept at 720°C for 10 minutes and cast into a magnesium alloy ingot. The magnesium alloy ingot is placed in a 650T die-casting machine furnace and melted at 700°C. The melt enters the mold for filling through the injection system, wherein the mold temperature is 209°C, the casting pressure is 105MPa, and the injection speed is 3.9m/s.
  • the ingredients are prepared according to the weight percentage of the magnesium alloy components designed;
  • the magnesium alloy ingot is placed in a 650T die-casting machine furnace and melted at 695°C.
  • the melt enters the mold through the injection system for filling, wherein the mold temperature is 220°C, the casting pressure is 100 MPa, and the injection speed is 3.5 m/s.
  • the ingredients are prepared according to the weight percentage of the magnesium alloy components designed;
  • the magnesium alloy ingot is placed in a 650T die-casting machine furnace and melted at 700°C.
  • the melt enters the mold through the injection system for filling.
  • the mold temperature is 230°C
  • the casting pressure is 103MPa
  • the injection speed is 3m/s.
  • the ingredients are prepared according to the weight percentage of the magnesium alloy components designed;
  • the magnesium alloy ingot is placed in a 650T die-casting machine furnace and melted at 710°C.
  • the melt enters the mold through the injection system for filling.
  • the mold temperature is 215°C
  • the casting pressure is 101MPa
  • the injection speed is 3.6m/s.
  • the room temperature thermal conductivity of the magnesium alloy of the present invention is 100-110 W/(m ⁇ K)
  • the room temperature yield strength is 140-150 MPa
  • the room temperature elongation is 8-12%.
  • the magnesium alloy obtained by the present invention has significantly improved room temperature mechanical properties and thermal conductivity compared with traditional AZ91D magnesium alloy and AM60B magnesium alloy.
  • the traditional die-cast AZ91D magnesium alloy and die-cast AM60B magnesium alloy are mainly composed of Al.
  • Gold element plays a role in solid solution strengthening and second phase (Mg 17 Al 12 ) strengthening to improve the room temperature yield strength of the material, while adding a small amount of Zn and Mn further improves the comprehensive mechanical properties of the material; however, this strengthening effect is limited, and more Al elements significantly reduce the thermal conductivity of the material when solid dissolved in the magnesium matrix.
  • the thermal conductivity of the die-cast AZ91D magnesium alloy in comparative example 1 and the die-cast AM60B magnesium alloy in comparative example 2 are both less than 65 W/(m ⁇ K), the room temperature yield strength is less than 150 MPa, and the elongation is less than 10%, that is, they cannot have both excellent mechanical properties and thermal conductivity.
  • Comparative Example 3 the Al content and RE content are low, and the second phase strengthening effect is weak, so the material yield strength is only 131 MPa, the elongation is 10%, and the thermal conductivity is 95 W/(m ⁇ K).
  • the Al/RE mass ratio is 1, more Al elements are dissolved in the Mg matrix or form more Mg 17 Al 12 phases, and the alloy elements have a more obvious negative impact on thermal conductivity. Therefore, the material has a yield strength of 138 MPa, an elongation of 11%, and a thermal conductivity of 90 W/(m ⁇ K).

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

一种高强韧高导热压铸镁合金及其制备方法，其成分重量百分比为：Al：2.5～4.0％，RE：3.5～5.5％，Mn：0.1～0.3％，Be：0.002～0.003％，Ca：0.1～1.0％，Gd：0.05～0.3％，RE为La或Ce中的一种或两种，余量包括Mg和其它不可避免的杂质；且上述元素还需要同时满足：0.7≤Al/RE≤0.8。通过引入新的针状Al3RE第二相，以更加优异的第二相强化效果提高材料的力学性能。结合第二相的形成降低了Al元素对镁合金导热性能的负面影响，同时，抑制脆性相Mg17Al12的生成，避免了热导率的显著降低，从而获得同时兼顾高导热性和高室温力学性能的镁合金。所得镁合金的室温屈服强度为140～150MPa，延伸率为8～12％，热导率为100～110W/(m·K)。

Description

一种高强韧高导热压铸镁合金及其制备方法 技术领域
本发明涉及镁合金材料技术领域，特别涉及一种高强韧高导热压铸镁合金及其制备方法。
背景技术
手机中板、笔记本电脑壳体、5G基站外壳、汽车车灯底座、移动储能设备等散热系统结构，不仅需要其材料具有密度小、强度高的特点，还需要其具有优异的导热/散热性能。镁合金是目前工程结构材料使用中密度最小的金属材料，同时，镁合金的导热性能、阻尼性能及电磁性能均十分优异，因此被认为是一种极具潜力的结构-功能一体化材料。由于镁合金兼具轻量化特点及优良的物理性能，因此在上述3C产品及汽车零部件领域具有广泛的应用前景。
纯镁室温下的热导率约为154.5W/(m·K)，但是屈服强度较低无法作为工程材料使用。变形镁合金具有优异的力学性能，但常规的挤压、轧制、锻造镁合金成本较高，且无法制备结构外形复杂的镁合金产品，因此超过80％的镁合金产品成型工艺为压铸。压铸是应用最广泛的一种镁合金铸造工艺，其具有制造成本低廉，且可以成型复杂结构产品的优势。3C产品外壳、5G基站外壳、汽车车灯底座、移动储能设备等产品在轻量化的同时需要其材质兼顾优异的导热/散热性能和力学性能，以保证产品具有高的工作稳定性和使用寿命。另外，这类产品通常具有复杂外形结构，考虑到成本因素，压铸成型工艺是理想选择。最常用的压铸镁合金AZ91D(Mg-9Al-1Zn)是在纯镁中添加一定含量的Al、Zn等元素以提高其力学性能，但其导热性能显著降低、热导率仅为51.2W/(m·K)，已经越来越无法满足镁合金产品需求，因此急需开展新型镁合金成分设计及成型技术研究，以发展高强韧高导热压铸镁合金产品。
中国专利CN105463280A公开了“一种具有高热导率的镁合金及其制备方法”，制备出Mg-Al-RE-Mn压铸镁合金，其化学成分质量百分比为： Al：3.0～6.8％，Mn：0.3～0.8％，混合稀土(La、Ce、Pr和Nd)：2.8～4.8％，其余为Mg。该合金的热导率大于100W/(m·K)，但是该专利并未提及镁合金的力学性能。
中国专利CN107604228A公开了“高导热耐腐蚀压铸镁合金及其制备方法”，制备出Mg-Al-Ce-Mn-Be压铸镁合金，其化学成分质量百分比为：Ce：3.5～5.0％，Al：2.5～3.5％，Mn：0.5％，Be：0.05％，其余为Mg。该合金的热导率大于100W/(m·K)，抗拉强度250～260MPa，并未提及镁合金屈服强度、延伸率等关键力学性能指标。
中国专利CN114351022A公开了“一种含有高固溶度稀土元素的高导热镁合金及其制备方法”，制备出了一种Mg-RE-Al铸造镁合金，其化学成分为：RE：4～16％(质量百分数)，Al：Al与RE的原子比为0.3～4％，其余为Mg。该合金的热导率≥100W/(m·K)，然而该合金中有大量贵重稀土元素Sm，成本较高，且未提及力学性能。
现有技术中报道的压铸镁合金材料无法同时兼顾高强韧、高导热及加工成本，因此急需开展新型压铸镁合金成分设计及新型成型技术研究，以发展新型高强韧高导热压铸镁合金，以扩展镁合金的应用。
发明内容
本发明的目的在于提供一种高强韧高导热压铸镁合金及其制备方法，在不添加价格昂贵的稀土元素或其它合金元素的前提下，采用低成本的合金配方，在保证合金具有良好铸造性能的前提下，解决现有镁合金无法同时兼顾高力学性能和高导热性能的问题；该镁合金的室温热导率为100～110W/(m·K)，室温屈服强度为140～150MPa，室温延伸率为8～12％；且可制造结构复杂的镁合金产品，该工艺成本低廉，便于规模化量产，可广泛用于3C产品、汽车零部件领域的散热/导热组件。
为达到上述目的，本发明的技术方案是：
一种高强韧高导热压铸镁合金，其成分重量百分比为：Al：2.5～4.0％，RE：3.5～5.5％，Mn：0.1～0.3％，Be：0.002～0.003％，Ca：0.1～1.0％，Gd：0.05～0.3％，RE为La或Ce中的一种或两种，余量包括Mg和其它不可避免的杂质；且上述元素还需要同时满足：
0.7≤Al/RE≤0.8。
优选的，余量为Mg和其它不可避免的杂质。
本发明所述压铸镁合金基体上均匀分布有Al11RE3、Al2RE、Al2Ca、(Mg,Al)2Ca、Al2Gd和针状Al3RE第二相。
本发明所述压铸镁合金的室温屈服强度为140～150MPa，延伸率为8～12％，热导率为100～110W/(m·K)。
Al元素是镁合金中最常用的合金元素，Mg-Al系合金具有良好的铸造性能。然而Al的原子体积小于Mg的原子体积，随着Al原子固溶于Mg中，晶格体积逐渐降低。晶格体积越小，自由电子发生散射的可能性越大，对热导率的负面作用越明显。另外，Al原子与Mg原子之间价电子差也导致了Al固溶于Mg中时会显著降低镁合金的热导率。如商业压铸镁合金AZ91D的热导率仅为51.2W/(m·K)。
本发明中，通过添加La、Ce、Ca和Gd等与Al具有较强亲和力的元素，使其形成Al11RE3、Al2RE、Al2Ca、(Mg,Al)2Ca、Al2Gd第二相，并引入了针状Al3RE新第二相，这种针状的第二相比Al11RE3第二相尺寸更小，具有更加优异的第二相强化效果，显著提高材料的力学性能。这些第二相不仅提高了材料力学性能，同时消耗了Mg基体中的Al元素，提高了晶格体积，降低了自由电子发生散射的可能性，避免了由于Al元素固溶于镁合金时导致材料热导率的下降。从而使镁合金同时获得高力学性能和高导热性能。
在Mg-Al系合金中，Al元素含量低于2.5％时影响压铸性能，镁熔体流动性较差；Al元素高于4％时热导率显著降低，因此，本发明中将Al元素含量控制在2.5～4.0％。
La和Ce与Al形成大量的Al11RE3第二相和少量的Al2RE第二相，其中，控制加入的Al和RE元素满足0.7≤Al/RE≤0.8，使得Al和RE以细小层片状的Al11RE3、极细针状Al3RE第二相和颗粒状的Al2RE第二相形式存在，在原有Al11RE3、Al2RE第二相存在的基础上，引入新的第二相Al3RE，起到更加优异的第二相强化效果，显著提高材料的力学性能。且Al11RE3、Al3RE和Al2RE第二相形成，极大程度避免了Al以固溶原子形式存在于镁合金当中，降低了Al元素对镁合金导热性能的负面影响，从 而不会导致材料热导率的降低，保证镁合金兼具优异导热性能和力学性能。廉价的稀土元素La和Ce还具有净化镁合金熔体的作用。La和Ce元素太少无法形成足够多的Al-RE第二相以提高材料性能，当La和Ce添加超过5.5％时，镁合金压铸性能显著降低，熔体流动性变差，过多的RE也会提高材料成本，因此，本发明中将RE(La和Ce)的量控制在3.5～5.5％。
Ca元素在Mg-Al合金中与Al形成的细小弥散的Al2Ca第二相以及(Mg,Al)2Ca第二相，可以显著提高镁合金的室温力学性能，同时保证材料具有优异的塑性和韧性。另外，以第二相Al2Ca存在于镁合金中并不会显著降低材料的导热性能。另外，Ca在镁合金中还具有防氧化阻燃的效果，抑制了压铸时镁合金熔体表面的氧化，大大降低了压铸镁合金中夹杂物。然而，过多的Ca元素会降低压铸时镁溶液的流动性，增大热裂倾向和脆性，降低材料的力学性能。因此，本发明中将Ca元素含量控制在0.1～1.0％。
Mn元素在镁合金中的固溶度极低，可以有效降低镁合金中Fe、Cu、Ni等有害元素的含量，以提高镁合金的耐蚀性能。另外，适量的Mn具有细化镁合金铸态组织的作用，可提高材料的塑性和韧性，对导热性能负面影响也较小。但是，本发明中添加超过0.3％的Mn会降低细化晶粒的效果，因此，本发明中将Mn元素含量控制在0.1～0.3％。
Be与氧气的亲和力大于Mg与氧气的亲和力，极少量的Be可以在镁合金熔体表面形成致密的氧化膜，防止镁合金熔体氧化。当Be含量低于0.002％时，镁合金溶液氧化程度明显提高，当Be含量高于0.003％时，材料显微组织明显粗化，力学性能降低。因此，本发明中将Be含量控制在0.002～0.003％，减少镁合金溶液中的浮渣和夹杂物，提高材料的力学性能的同时避免夹杂物和氧化物降低材料的热导率。
Gd元素加入Mg-Al合金中，常规的Mg-Al合金晶界处在凝固过程中析出大量的网状Mg17Al12第二相，这些在晶界分布的第二相严重破坏了镁基体点阵的周期性排列，并对自由电子形成散射作用，降低了材料的热导率。本发明中添加Gd元素可以与Al元素形成Al2Gd第二相，从而抑制脆性相Mg17Al12的生成，避免了热导率的显著降低。同时形成的Al2Gd相具有明显的强化效果，在提高镁合金强度的同时不明显降低材料的塑性。另外，Al2Gd相还能促进异质形核过程，提高压铸凝固过程中的形核率，细 化晶粒尺寸和显微组织。太少的Gd元素在镁合金中无法起到强化效果和抑制Mg17Al12的生成的作用，过多的Gd元素加入会降低镁合金的压铸性能，因此，本发明中将Gd元素含量控制在0.05～0.3％。
因此，本发明通过成分控制，在保证镁合金具有优良的铸造性能的前提下，获得了兼顾高强度、高韧性的压铸镁合金。
本发明所述高强韧高导热压铸镁合金的制备方法，包括以下步骤：
1)配料
以纯Mg锭、纯Al锭、纯La锭、纯Ce锭、纯Mn粉和Mg-Ca、Mg-Gd、Al-Be中间合金作为原料，按上述镁合金成分进行配料；
2)熔炼
将纯Mg锭放入坩埚中，升温至680～710℃，在保护气保护下完全熔化，随后加入纯Al锭、纯Mn粉，在保护气氛下搅拌至合金完全熔化，然后升温至740～750℃，再依次添加纯La锭、纯Ce锭，在保护气氛下搅拌至合金完全熔化，随后降温至690～710℃加入Al-Be、Mg-Ca及Mg-Gd中间合金到所述熔体中，待中间合金完全熔化后，搅拌5～10min，获得镁合金熔体；
3)精炼
向获得的镁合金熔体中加入镁合金熔剂，精炼5～10min，除去表面浮渣，之后加热到700～720℃保温10～15min；
4)成型
将精炼后的镁合金熔体浇铸成铸锭，之后将铸锭放置于压铸机熔炉中至680～700℃熔化，熔体经过压射系统进入模具充型，其中模具温度200～250℃，铸造压力100～110MPa，压射速度为3～5m/s。
优选的，步骤3)中，所述镁合金熔剂为RJ-2熔剂和RJ-3熔剂。
优选的，步骤2)中，所述保护气为CO2+SF6的混合气体。
优选的，步骤4)中，所述浇注温度为680～700℃。
本发明在压铸成型工艺中，熔炉温度控制在680～700℃，在保证镁合金溶液具有良好流动性和充型性的同时避免材料出现粗大的枝晶以影响材料的力学性能，温度低于680℃时镁合金溶液流动性变差，充型产品表面出现缺陷，当温度高于700℃时充型产品显微组织中出现粗大的枝晶， 材料力学性能降低。
模具温度控制在200～250℃，此温度范围内合金充型完整，裂纹气孔等缺陷大幅度降低，材料具有优异的力学性能。温度低于200℃时，由于高温熔体与模具温度温差较大，导致充型产品表面出现缺陷，同时产品的塑性降低；当模具温度高于250℃时，产品表面细晶区范围减小，力学性能降低。
铸造压力100～110MPa，以保证产品正常充型，使材料的显微组织致密、力学性能和导热性能优异。
注射速度控制在3～5m/s，注射速度太低，材料无法完整充型，注射速度太高，材料孔隙率较高，力学性能和导热性能都会降低。
与现有技术相比，本发明的有益效果：
本发明所述高强韧高导热镁合金在镁基体中添加Al、La、Ce、Ca及Gd元素，使其形成Al11RE3、Al2RE、Al2Ca、(Mg,Al)2Ca、Al2Gd第二相，同时，控制加入的Al和RE元素满足0.7≤Al/RE≤0.8，引入了针状Al3RE新第二相，以更加优异的第二相强化效果提高材料的力学性能。且，这些第二相的形成极大程度避免了Al以固溶原子形式存在于镁合金当中，降低了Al元素对镁合金导热性能的负面影响，从而不会导致材料热导率的降低。结合Gd元素的添加与Al元素形成Al2Gd第二相，从而抑制脆性相Mg17Al12的生成，避免了热导率的显著降低。从而获得同时兼顾高导热性和高室温力学性能的镁合金。
本发明中添加的合金元素，在保证材料性能的同时，同时兼顾压铸可制造性。在成分设计上基础上，同时匹配适合的熔炉温度、模具温度、铸造压力和压射速度，使得镁合金压铸时具有良好的流动性和充型性，产品微观组织致密无缺陷，工艺成本低廉，可规模化生产复杂外形结构的3C壳体、汽车零部件等复杂结构件产品。
本发明获得的镁合金室温热导率为100～110W/(m·K)，室温屈服强度为140～150MPa，室温延伸率为8～12％。
具体实施方式
下面通过实施例对本发明的技术方案作详细说明，本实施例在本发明 技术方案为前提下进行实施，给出了详细的实施方式和具体的操作过程，但本发明的保护范围不限于下述的实施例。
本发明实施例的镁合金成分参见表1，其余为Mg以及其它不可避免的杂质。
实施例1
1)以纯Mg锭、纯Al锭、纯La锭、纯Ce锭、纯Mn粉、和Al-Be、Mg-Ca及Mg-Gd中间合金为原料，按此设计的镁合金成分的重量百分比进行配料；
2)将纯Mg锭放入熔炼炉的坩埚中，升温至700℃，在CO2和SF6的混合保护气的保护下完全熔化形成熔体，随后加入纯Al锭、纯Mn粉，在保护气氛下搅拌至合金完全熔化，然后升温至740℃，再依次将纯La锭、纯Ce锭，在保护气氛下搅拌至合金完全熔化，静置降温至710℃加入Al-Be、Mg-Ca及Mg-Gd中间合金到所述熔体中，待合金完全熔化后，搅拌5min，再加入镁合金熔剂RJ-2精炼10min，除去表面浮渣，最后在700℃保温15min，浇铸成镁合金铸锭；
3)将镁合金铸锭置于650T压铸机熔炉中至680℃熔化，熔体经过压射系统进入模具充型，其中模具温度216℃，铸造压力105MPa，压射速度为3.5m/s。
所得压铸镁合金件性能如表3所示。
实施例2
1)以纯Mg锭、纯Al锭、纯La锭、纯Ce锭、纯Mn粉、和Al-Be、Mg-Ca及Mg-Gd中间合金为原料，按此设计的镁合金成分的重量百分比进行配料；
2)将纯Mg锭放入熔炼炉的坩埚中，升温至690℃，在CO2和SF6的混合保护气的保护下完全熔化形成熔体，随后加入纯Al锭、纯Mn粉，在保护气氛下搅拌至合金完全熔化，然后升温至741℃，再依次将纯La锭、纯Ce锭，在保护气氛下搅拌至合金完全熔化，静置降温至700℃加入Al-Be、Mg-Ca及Mg-Gd中间合金到所述熔体中，待合金完全熔化后， 搅拌6min，再加入镁合金熔剂RJ-3精炼7min，除去表面浮渣，最后在710℃保温12min，浇铸成镁合金铸锭；
3)将镁合金铸锭置于650T压铸机熔炉中至692℃熔化，熔体经过压射系统进入模具充型，其中模具温度220℃，铸造压力100MPa，压射速度为3m/s。
所得压铸镁合金件性能如表3所示。
实施例3
1)以纯Mg锭、纯Al锭、纯La锭、纯Ce锭、纯Mn粉、和Al-Be、Mg-Ca及Mg-Gd中间合金为原料，按此设计的镁合金成分的重量百分比进行配料；
2)将纯Mg锭放入熔炼炉的坩埚中，升温至710℃，在CO2和SF6的混合保护气的保护下完全熔化形成熔体，随后加入纯Al锭、纯Mn粉，在保护气氛下搅拌至合金完全熔化，然后升温至750℃，再依次将纯La锭、纯Ce锭，在保护气氛下搅拌至合金完全熔化，静置降温至705℃加入Al-Be、Mg-Ca及Mg-Gd中间合金到所述熔体中，待合金完全熔化后，搅拌10min，再加入镁合金熔剂RJ-2精炼10min，除去表面浮渣，最后在705℃保温11min，浇铸成镁合金铸锭；
3)将镁合金铸锭置于650T压铸机熔炉中至700℃熔化，熔体经过压射系统进入模具充型，其中模具温度239℃，铸造压力101MPa，压射速度为4m/s。
所得压铸镁合金件性能如表3所示。
实施例4
1)以纯Mg锭、纯Al锭、纯La锭、纯Ce锭、纯Mn粉、和Al-Be、Mg-Ca及Mg-Gd中间合金为原料，按此设计的镁合金成分的重量百分比进行配料；
2)将纯Mg锭放入熔炼炉的坩埚中，升温至695℃，在CO2和SF6的混合保护气的保护下完全熔化形成熔体，随后加入纯Al锭、纯Mn粉，在保护气氛下搅拌至合金完全熔化，然后升温至749℃，再依次将纯La 锭、纯Ce锭，在保护气氛下搅拌至合金完全熔化，静置降温至708℃加入Al-Be、Mg-Ca及Mg-Gd中间合金到所述熔体中，待合金完全熔化后，搅拌10min，再加入镁合金熔剂RJ-3精炼9min，除去表面浮渣，最后在710℃保温15min，浇铸成镁合金铸锭；
3)将镁合金铸锭置于650T压铸机熔炉中至695℃熔化，熔体经过压射系统进入模具充型，其中模具温度250℃，铸造压力110MPa，压射速度为3.3m/s。
所得压铸镁合金件性能如表3所示。
实施例5
1)以纯Mg锭、纯Al锭、纯La锭、纯Ce锭、纯Mn粉、和Al-Be、Mg-Ca及Mg-Gd中间合金为原料，按此设计的镁合金成分的重量百分比进行配料；
2)将纯Mg锭放入熔炼炉的坩埚中，升温至705℃，在CO2和SF6的混合保护气的保护下完全熔化形成熔体，随后加入纯Al锭、纯Mn粉，在保护气氛下搅拌至合金完全熔化，然后升温至748℃，再依次将纯La锭、纯Ce锭，在保护气氛下搅拌至合金完全熔化，静置降温至706℃加入Al-Be、Mg-Ca及Mg-Gd中间合金到所述熔体中，待合金完全熔化后，搅拌10min，再加入镁合金熔剂RJ-2精炼10min，除去表面浮渣，最后在720℃保温10min，浇铸成镁合金铸锭；
3)将镁合金铸锭置于650T压铸机熔炉中至688℃熔化，熔体经过压射系统进入模具充型，其中模具温度208℃，铸造压力108MPa，压射速度为4.3m/s。
所得压铸镁合金件性能如表3所示。
实施例6
1)以纯Mg锭、纯Al锭、纯La锭、纯Ce锭、纯Mn粉、和Al-Be、Mg-Ca及Mg-Gd中间合金为原料，按此设计的镁合金成分的重量百分比进行配料；
2)将纯Mg锭放入熔炼炉的坩埚中，升温至680℃，在CO2和SF6的 混合保护气的保护下完全熔化形成熔体，随后加入纯Al锭、纯Mn粉，在保护气氛下搅拌至合金完全熔化，然后升温至745℃，再依次将纯La锭、纯Ce锭，在保护气氛下搅拌至合金完全熔化，静置降温至690℃加入Al-Be、Mg-Ca及Mg-Gd中间合金到所述熔体中，待合金完全熔化后，搅拌5min，再加入镁合金熔剂RJ-2精炼5min，除去表面浮渣，最后在705℃保温11min，浇铸成镁合金铸锭；
3)将镁合金铸锭置于650T压铸机熔炉中至690℃熔化，熔体经过压射系统进入模具充型，其中模具温度200℃，铸造压力109MPa，压射速度为5m/s。
所得压铸镁合金件性能如表3所示。
实施例7
1)以纯Mg锭、纯Al锭、纯La锭、纯Ce锭、纯Mn粉、和Al-Be、Mg-Ca及Mg-Gd中间合金为原料，按此设计的镁合金成分的重量百分比进行配料；
2)将纯Mg锭放入熔炼炉的坩埚中，升温至700℃，在CO2和SF6的混合保护气的保护下完全熔化形成熔体，随后加入纯Al锭、纯Mn粉，在保护气氛下搅拌至合金完全熔化，然后升温至743℃，再依次将纯La锭、纯Ce锭，在保护气氛下搅拌至合金完全熔化，静置降温至695℃加入Al-Be、Mg-Ca及Mg-Gd中间合金到所述熔体中，待合金完全熔化后，搅拌8min，再加入镁合金熔剂RJ-2精炼8min，除去表面浮渣，最后在713℃保温11min，浇铸成镁合金铸锭；
3)将镁合金铸锭置于650T压铸机熔炉中至695℃熔化，熔体经过压射系统进入模具充型，其中模具温度226℃，铸造压力102MPa，压射速度为4.6m/s。
所得压铸镁合金件性能如表3所示。
实施例8
1)以纯Mg锭、纯Al锭、纯La锭、纯Ce锭、纯Mn粉、和Al-Be、Mg-Ca及Mg-Gd中间合金为原料，按此设计的镁合金成分的重量百分比 进行配料；
2)将纯Mg锭放入熔炼炉的坩埚中，升温至690℃，在CO2和SF6的混合保护气的保护下完全熔化形成熔体，随后加入纯Al锭、纯Mn粉，在保护气氛下搅拌至合金完全熔化，然后升温至744℃，再依次将纯La锭、纯Ce锭，在保护气氛下搅拌至合金完全熔化，静置降温至705℃加入Al-Be、Mg-Ca及Mg-Gd中间合金到所述熔体中，待合金完全熔化后，搅拌7min，再加入镁合金熔剂RJ-2精炼7min，除去表面浮渣，最后在720℃保温15min，浇铸成镁合金铸锭；
3)将镁合金铸锭置于650T压铸机熔炉中至698℃熔化，熔体经过压射系统进入模具充型，其中模具温度239℃，铸造压力103MPa，压射速度为3.1m/s。
所得压铸镁合金件性能如表3所示。
实施例9
1)以纯Mg锭、纯Al锭、纯La锭、纯Ce锭、纯Mn粉、和Al-Be、Mg-Ca及Mg-Gd中间合金为原料，按此设计的镁合金成分的重量百分比进行配料；
2)将纯Mg锭放入熔炼炉的坩埚中，升温至710℃，在CO2和SF6的混合保护气的保护下完全熔化形成熔体，随后加入纯Al锭、纯Mn粉，在保护气氛下搅拌至合金完全熔化，然后升温至746℃，再依次将纯La锭、纯Ce锭，在保护气氛下搅拌至合金完全熔化，静置降温至694℃加入Al-Be、Mg-Ca及Mg-Gd中间合金到所述熔体中，待合金完全熔化后，搅拌7min，再加入镁合金熔剂RJ-2精炼6min，除去表面浮渣，最后在715℃保温11min，浇铸成镁合金铸锭；
3)将镁合金铸锭置于650T压铸机熔炉中至685℃熔化，熔体经过压射系统进入模具充型，其中模具温度203℃，铸造压力104MPa，压射速度为3.9m/s。
所得压铸镁合金件性能如表3所示。
实施例10
1)以纯Mg锭、纯Al锭、纯La锭、纯Ce锭、纯Mn粉、和Al-Be、Mg-Ca及Mg-Gd中间合金为原料，按此设计的镁合金成分的重量百分比进行配料；
2)将纯Mg锭放入熔炼炉的坩埚中，升温至705℃，在CO2和SF6的混合保护气的保护下完全熔化形成熔体，随后加入纯Al锭、纯Mn粉，在保护气氛下搅拌至合金完全熔化，然后升温至747℃，再依次将纯La锭、纯Ce锭，在保护气氛下搅拌至合金完全熔化，静置降温至698℃加入Al-Be、Mg-Ca及Mg-Gd中间合金到所述熔体中，待合金完全熔化后，搅拌5min，再加入镁合金熔剂RJ-2精炼5min，除去表面浮渣，最后在718℃保温15min，浇铸成镁合金铸锭；
3)将镁合金铸锭置于650T压铸机熔炉中至689℃熔化，熔体经过压射系统进入模具充型，其中模具温度245℃，铸造压力106MPa，压射速度为4.8m/s。
所得压铸镁合金件性能如表3所示。
对比例1、2分别选用商业牌号AZ91D与AM60，此两种牌号合金的成型工艺为传统压铸工艺。而本发明采用高强韧高导热镁合金设计原理，成型工艺为压铸成型工艺。
对比例1
选取镁合金成分百分含量为：9wt％Al，1wt％Zn，其余为Mg；
将纯Mg锭放入熔炼炉的坩埚中，升温至695℃，在CO2和SF6的混合保护气的保护下完全熔化形成熔体，随后加入纯Al锭、纯Zn锭，在混合保护气氛中搅拌8min，待合金完全熔化后，再加入镁合金熔剂RJ-2精炼7min，除去表面浮渣，最后在720℃保温15min，浇铸成镁合金铸锭；将镁合金铸锭置于650T压铸机熔炉中至680℃熔化，熔体经过压射系统进入模具充型，其中模具温度206℃，铸造压力105MPa，压射速度为3.5m/s。
对比例2
选取镁合金的成分百分含量为：6wt％Al，0.5wt％Mn，其余为Mg；
将纯Mg锭放入熔炼炉的坩埚中，升温至710℃，在CO2和SF6的混合保护气的保护下完全熔化形成熔体，随后加入纯Al锭、纯Mn粉，在混合保护气氛中搅拌10min，待合金完全熔化后，再加入镁合金熔剂RJ-2精炼10min，除去表面浮渣，最后在720℃保温10min，浇铸成镁合金铸锭；将镁合金铸锭置于650T压铸机熔炉中至700℃熔化，熔体经过压射系统进入模具充型，其中模具温度209℃，铸造压力105MPa，压射速度为3.9m/s。
对比例3
1)以纯Mg锭、纯Al锭、纯La锭、纯Ce锭、纯Mn粉、和Al-Be、Mg-Ca及Mg-Gd中间合金为原料，按此设计的镁合金成分的重量百分比进行配料；
2)将纯Mg锭放入熔炼炉的坩埚中，升温至703℃，在CO2和SF6的混合保护气的保护下完全熔化形成熔体，随后加入纯Al锭、纯Mn粉，在保护气氛下搅拌至合金完全熔化，然后升温至747℃，再依次将纯La锭、纯Ce锭，在保护气氛下搅拌至合金完全熔化，静置降温至695℃加入Al-Be、Mg-Ca及Mg-Gd中间合金到所述熔体中，待合金完全熔化后，搅拌5min，再加入镁合金熔剂RJ-2精炼5min，除去表面浮渣，最后在718℃保温15min，浇铸成镁合金铸锭；
3)将镁合金铸锭置于650T压铸机熔炉中至695℃熔化，熔体经过压射系统进入模具充型，其中模具温度220℃，铸造压力100MPa，压射速度为3.5m/s。
所得压铸镁合金件性能如表3所示。
对比例4
1)以纯Mg锭、纯Al锭、纯La锭、纯Ce锭、纯Mn粉、和Al-Be、Mg-Ca及Mg-Gd中间合金为原料，按此设计的镁合金成分的重量百分比进行配料；
2)将纯Mg锭放入熔炼炉的坩埚中，升温至705℃，在CO2和SF6的混合保护气的保护下完全熔化形成熔体，随后加入纯Al锭、纯Mn粉， 在保护气氛下搅拌至合金完全熔化，然后升温至740℃，再依次将纯La锭、纯Ce锭，在保护气氛下搅拌至合金完全熔化，静置降温至700℃加入Al-Be、Mg-Ca及Mg-Gd中间合金到所述熔体中，待合金完全熔化后，搅拌5min，再加入镁合金熔剂RJ-2精炼5min，除去表面浮渣，最后在718℃保温15min，浇铸成镁合金铸锭；
3)将镁合金铸锭置于650T压铸机熔炉中至700℃熔化，熔体经过压射系统进入模具充型，其中模具温度230℃，铸造压力103MPa，压射速度为3m/s。
所得压铸镁合金件性能如表3所示。
对比例5
1)以纯Mg锭、纯Al锭、纯La锭、纯Ce锭、纯Mn粉、和Al-Be、Mg-Ca中间合金为原料，按此设计的镁合金成分的重量百分比进行配料；
2)将纯Mg锭放入熔炼炉的坩埚中，升温至709℃，在CO2和SF6的混合保护气的保护下完全熔化形成熔体，随后加入纯Al锭、纯Mn粉，在保护气氛下搅拌至合金完全熔化，然后升温至739℃，再依次将纯La锭、纯Ce锭，在保护气氛下搅拌至合金完全熔化，静置降温至698℃加入Al-Be、Mg-Ca中间合金到所述熔体中，待合金完全熔化后，搅拌5min，再加入镁合金熔剂RJ-2精炼5min，除去表面浮渣，最后在718℃保温15min，浇铸成镁合金铸锭；
3)将镁合金铸锭置于650T压铸机熔炉中至710℃熔化，熔体经过压射系统进入模具充型，其中模具温度215℃，铸造压力101MPa，压射速度为3.6m/s。
所得压铸镁合金件性能如表3所示。
结合表3数据可知，本发明镁合金的室温热导率为100～110W/(m·K)，室温屈服强度为140～150MPa，室温延伸率为8～12％。本发明获得的镁合金较传统的AZ91D镁合金和AM60B镁合金，室温力学性能及导热性能明显提升。
而传统的压铸AZ91D镁合金和压铸AM60B镁合金是以Al为主要合 金元素，起到固溶强化和第二相(Mg17Al12)强化效果以提高材料的室温屈服强度，同时添加少量的Zn和Mn进一步提高材料的综合力学性能；然而这种强化效果有限，同时较多的Al元素固溶于镁基体时显著降低材料的热导率。
从表3对比例中可以看出，对比例1压铸AZ91D镁合金和对比例2压铸AM60B镁合金热导率均小于65W/(m·K)，室温屈服强度小于150MPa，延伸率小于10％，即无法兼具优异力学性能和导热性能。
对比例3中，Al含量及RE含量较低，第二相强化效果较弱，因此材料屈服强度仅为131MPa，伸长率10％，热导率为95W/(m·K)。
对比例4中，Al/RE质量比为1，较多的Al元素固溶于Mg基体或者形成较多的Mg17Al12相，合金元素对热导率负面影响较明显，因此材料屈服强度为138MPa，伸长率11％，热导率为90W/(m·K)。
对比例5中，未添加Gd元素，Al元素在晶界处形成较多的Mg17Al12相，因此材料屈服强度为139MPa，伸长率10.6％，热导率为91W/(m·K)。
表1           单位：重量百分比

表2

表3

Claims (8)

  1. 一种高强韧高导热压铸镁合金，其成分重量百分比为：Al：2.5～4.0％，RE：3.5～5.5％，Mn：0.1～0.3％，Be：0.002～0.003％，Ca：0.1～1.0％，Gd：0.05～0.3％，RE为La或Ce中的一种或两种，余量包括Mg和其它不可避免的杂质；且上述元素还需要同时满足：
    0.7≤Al/RE≤0.8。
  2. 如权利要求1所述的高强韧高导热压铸镁合金，其特征在于，余量为Mg和其它不可避免的杂质。
  3. 如权利要求1或2所述的高强韧高导热压铸镁合金，其特征在于，所述压铸镁合金基体上均匀分布有Al11RE3、Al2RE、Al2Ca、(Mg,Al)2Ca、Al2Gd和针状Al3RE第二相。
  4. 如权利要求1或2或3所述的高强韧高导热压铸镁合金，其特征在于，所述压铸镁合金的室温屈服强度为140～150MPa，延伸率为8～12％，热导率为100～110W/(m·K)。
  5. 如权利要求1～4任一项所述的高强韧高导热压铸镁合金的制备方法，其特征是，包括以下步骤：
    1)配料
    以纯Mg锭、纯Al锭、纯La锭、纯Ce锭、纯Mn粉和Mg-Ca、Mg-Gd、Al-Be中间合金作为原料，按权利要求1或2所述的镁合金成分进行配料；
    2)熔炼
    将纯Mg锭放入坩埚中，升温至680～710℃，在保护气保护下完全熔化，随后加入纯Al锭、纯Mn粉，在保护气氛下搅拌至合金完全熔化，然后升温至740～750℃，再依次添加纯La锭、纯Ce锭，在保护气氛下搅拌至合金完全熔化，随后降温至690～710℃加入Al-Be、Mg-Ca及Mg-Gd中间合金到所述熔体中，待中间合金完全熔化后，搅拌5～10min，获得镁合金熔体；
    3)精炼
    向获得的镁合金熔体中加入镁合金熔剂，精炼5～10min，除去表面浮渣，之后加热到700～720℃保温10～15min；
    4)压铸成型
    将精炼后的镁合金熔体浇铸成铸锭，之后将铸锭放置于压铸机熔炉中至680～700℃熔化，熔体经过压射系统进入模具充型，其中模具温度200～250℃，铸造压力100～110MPa，压射速度为3～5m/s。
  6. 如权利要求5所述的制备方法，其特征是，步骤3)中，所述镁合金熔剂为RJ-2熔剂和RJ-3熔剂。
  7. 如权利要求5所述的制备方法，其特征是，步骤2)中，所述保护气为CO2+SF6的混合气体。
  8. 如权利要求5所述的制备方法，其特征是，步骤4)中，所述浇注温度为680～700℃。
PCT/CN2024/071478 2023-06-28 2024-01-10 一种高强韧高导热压铸镁合金及其制备方法 Ceased WO2025001059A1 (zh)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP24829722.8A EP4733427A1 (en) 2023-06-28 2024-01-10 High-toughness and high-thermal-conductivity die-cast magnesium alloy and preparation method therefor

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202310772495.9 2023-06-28
CN202310772495.9A CN118773498A (zh) 2023-06-28 2023-06-28 一种高强韧高导热压铸镁合金及其制备方法

Publications (1)

Publication Number Publication Date
WO2025001059A1 true WO2025001059A1 (zh) 2025-01-02

Family

ID=92991794

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2024/071478 Ceased WO2025001059A1 (zh) 2023-06-28 2024-01-10 一种高强韧高导热压铸镁合金及其制备方法

Country Status (3)

Country Link
EP (1) EP4733427A1 (zh)
CN (1) CN118773498A (zh)
WO (1) WO2025001059A1 (zh)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN121183188B (zh) * 2025-11-25 2026-04-03 小米汽车科技有限公司 一种镁合金材料及其制备方法、车辆结构件

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101353746A (zh) * 2008-09-11 2009-01-28 上海交通大学 含Ca和重稀土Gd的压铸耐热镁合金及其制备方法
CN104032195A (zh) * 2014-06-26 2014-09-10 宝山钢铁股份有限公司 一种可高效挤压低成本高性能导热镁合金及其制备方法
CN105463280A (zh) 2015-12-14 2016-04-06 山东华盛荣镁业科技有限公司 一种具有高热导率的镁合金及其制备方法
CN107604228A (zh) 2017-08-30 2018-01-19 上海交通大学 高导热耐腐蚀压铸镁合金及其制备方法
CN108977711A (zh) * 2018-07-23 2018-12-11 上海交通大学 一种压铸镁合金材料及其制备方法
CN109207824A (zh) * 2017-06-29 2019-01-15 比亚迪股份有限公司 一种镁合金及其制备方法和手机
CN109881063A (zh) * 2019-04-17 2019-06-14 上海交通大学 一种高强韧高模量压铸镁合金及其制备方法
JP2020200492A (ja) * 2019-06-07 2020-12-17 株式会社戸畑製作所 マグネシウム合金およびマグネシウム合金を用いた鋳造構造部材
CN114351022A (zh) 2022-01-11 2022-04-15 上海交通大学 一种含有高固溶度稀土元素的高导热镁合金及其制备方法
CN115896574A (zh) * 2022-11-02 2023-04-04 青海盐湖工业股份有限公司 压铸镁合金及其制备方法
CN116219242A (zh) * 2021-12-02 2023-06-06 宝钢金属有限公司 一种高强韧高导热镁合金及其加工方法

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101353746A (zh) * 2008-09-11 2009-01-28 上海交通大学 含Ca和重稀土Gd的压铸耐热镁合金及其制备方法
CN104032195A (zh) * 2014-06-26 2014-09-10 宝山钢铁股份有限公司 一种可高效挤压低成本高性能导热镁合金及其制备方法
CN105463280A (zh) 2015-12-14 2016-04-06 山东华盛荣镁业科技有限公司 一种具有高热导率的镁合金及其制备方法
CN109207824A (zh) * 2017-06-29 2019-01-15 比亚迪股份有限公司 一种镁合金及其制备方法和手机
CN107604228A (zh) 2017-08-30 2018-01-19 上海交通大学 高导热耐腐蚀压铸镁合金及其制备方法
CN108977711A (zh) * 2018-07-23 2018-12-11 上海交通大学 一种压铸镁合金材料及其制备方法
CN109881063A (zh) * 2019-04-17 2019-06-14 上海交通大学 一种高强韧高模量压铸镁合金及其制备方法
JP2020200492A (ja) * 2019-06-07 2020-12-17 株式会社戸畑製作所 マグネシウム合金およびマグネシウム合金を用いた鋳造構造部材
CN116219242A (zh) * 2021-12-02 2023-06-06 宝钢金属有限公司 一种高强韧高导热镁合金及其加工方法
CN114351022A (zh) 2022-01-11 2022-04-15 上海交通大学 一种含有高固溶度稀土元素的高导热镁合金及其制备方法
CN115896574A (zh) * 2022-11-02 2023-04-04 青海盐湖工业股份有限公司 压铸镁合金及其制备方法

Also Published As

Publication number Publication date
EP4733427A1 (en) 2026-04-29
CN118773498A (zh) 2024-10-15

Similar Documents

Publication Publication Date Title
CN109518041B (zh) 一种同时改善压铸铝合金导热和力学性能的复合处理方法
CN105755340B (zh) 低成本高强高韧高导热变形镁合金及其制备方法
CN102618758B (zh) 一种低线收缩率铸造镁合金
CN109652685B (zh) 一种高导热高耐蚀铸造铝合金及其制备方法
CN111690849A (zh) Al-Si系压铸铝合金中富铁相的细化方法及合金
WO2011023060A1 (zh) 高强耐热铝合金材料及其制备方法
CN105779838B (zh) 一种高导热压铸镁合金及其制备工艺
CN101381833A (zh) 耐热铸造镁合金及其制备方法
CN102618760B (zh) 一种含铌的MgAlZn系耐热镁合金
CN102618762B (zh) 一种耐热镁合金
CN101353747A (zh) 压铸耐热镁合金及其制备方法
CN101012524A (zh) 压铸耐热镁合金
WO2011035654A1 (zh) Be-RE高强耐热铝合金材料及其制备方法
JP2020147780A (ja) 難燃性マグネシウム合金およびその製造方法
CN104073702A (zh) 一种稀土镁合金及其制备方法
WO2011035650A1 (zh) Ni-RE高强耐热铝合金材料及其制备方法
CN116179902B (zh) 一种高Fe含量的高导热压铸铝合金及其制备方法
WO2025001059A1 (zh) 一种高强韧高导热压铸镁合金及其制备方法
CN101191167B (zh) 一种含有稀土的镁合金及其制备方法
CN116219242B (zh) 一种高强韧高导热镁合金及其加工方法
CN111286658A (zh) 一种可压铸的高导热阻燃镁合金及其制备方法
CN108486446B (zh) 一种低膨胀镁合金及其制备方法
CN113151721B (zh) 一种高导热压铸镁合金及其制备方法
CN108118226A (zh) 一种高导热、耐蚀、耐热压铸镁合金及其制造方法
CN102618763A (zh) 一种耐热镁合金

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 24829722

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 2024829722

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 2024829722

Country of ref document: EP

Effective date: 20260121

ENP Entry into the national phase

Ref document number: 2024829722

Country of ref document: EP

Effective date: 20260121