CN-122013011-A - Rare earth magnesium aluminum alloy for battery box and preparation method thereof

Abstract

The invention belongs to the technical field of metal materials, and discloses a rare earth magnesium aluminum alloy for a battery box body and a preparation method thereof, wherein the rare earth magnesium aluminum alloy comprises, by mass, 7.0-9.5% of Al, 0.35-0.7% of Ca, 0.25-0.6% of Mn, 0.25-0.5% of La, 0.7-1.5% of Ce, 0.2-0.4% of Y, 0.1-0.3% of Zr, and the balance of magnesium and unavoidable impurities, the alloy has the yield strength of 280-340MPa, the tensile strength of 400-450MPa, the elongation of 6-14% and the ignition temperature of 780-870 ℃. According to the invention, calcium, manganese, lanthanum, cerium, yttrium and zirconium are added into the magnesium-aluminum alloy, so that the mechanical property and flame retardance of the magnesium-aluminum alloy are improved, and electrochemical corrosion is inhibited.

Inventors

• JIANG XIAONA
• HE JIALU
• CHEN XUEGANG
• SUN SHUO
• LI JUN
• ZHANG YINGHONG
• MA TINGTAO
• YANG BIN
• JING QI
• Ran Xiaoxu

Assignees

• 中国第一汽车股份有限公司

Dates

Publication Date

20260512

Application Date

20251022

Claims (10)

1. 1. The rare earth magnesium aluminum alloy for the battery box body is characterized by comprising, by mass, 7.0-9.5% of Al, 0.35-0.7% of Ca, 0.25-0.6% of Mn, 0.25-0.5% of La, 0.7-1.5% of Ce, 0.2-0.4% of Y, 0.1-0.3% of Zr, the balance of magnesium and unavoidable impurities, and having the yield strength of 280-340 MPa, the tensile strength of 400-450 MPa, the elongation of 6-14% and the ignition temperature of 780-870 ℃.
2. 2. The rare earth magnesium aluminum alloy for battery cases according to claim 1, wherein each component comprises, by mass, 7.5% -8.3% of Al, 0.35% -0.5% of Ca, 0.25% -0.4% of Mn, 0.25% -0.4% of La, 0.7% -1.1% of Ce, 0.2% -0.3% of Y, 0.1% -0.25% of Zr, and the balance Mg and impurity elements.
3. 3. The rare earth magnesium aluminum alloy for battery cases according to claim 1, wherein the ratio of La-Ce mischmetal is La: ce=1:3, and the total re content is lower than 2%.
4. 4. A rare earth magnesium aluminum alloy for a battery case according to claim 1, wherein the total content of impurities is not more than 0.003%.
5. 5. A method for producing a rare earth magnesium aluminum alloy for a battery case according to any one of claims 1 to 4, comprising the steps of: S1, raw material pretreatment, namely baking magnesium ingots, aluminum ingots, magnesium-calcium alloy, aluminum-manganese alloy, magnesium-lanthanum alloy, cerium-rich mixed rare earth, intermediate alloy Al-Zr and intermediate alloy Mg-Y for 2 hours at 140-170 ℃ according to the content of each component of the rare earth magnesium-aluminum alloy for the battery box body, and then crushing and sieving the materials through a 200-mesh sieve to obtain powder of each component of the raw materials; S2, gradient heat treatment, namely carrying out gradient smelting under the protection of Ar and 0.3 percent SF 6 , carrying out primary smelting on magnesium powder, aluminum powder and calcium powder at 700-730 ℃, continuously stirring by using a stirrer, then heating to 730-770 ℃, adding RE and Zr powder, and fully stirring by using the stirrer after the RE and Zr powder are completely melted; s3, high-pressure die casting treatment, namely adopting a die casting machine with the casting temperature of 650-690 ℃ and 900 tons to realize integral molding of the thin wall of the box body, wherein the wall thickness of the thin wall of the box body is 3mm, the die temperature is 220 ℃, and the injection speed is 4m/S; S4, double-stage solution treatment, namely placing the casting in a solid melting furnace, heating to 400-440 ℃, preserving heat for 6-10 h, then heating to 500-530 ℃, preserving heat for 1-2h, standing and cooling to obtain the rare earth magnesium aluminum alloy for the battery box body.
6. 6. The method for producing a rare earth magnesium aluminum alloy for a battery case according to claim 5, wherein in step S1, the baking temperature is set to 150 ℃.
7. 7. The method for producing a rare earth magnesium aluminum alloy for a battery case according to claim 5, wherein the preliminary melting temperature in step S2 is set to 715 to 725 ℃, and the temperature after the temperature rise is set to 740 to 755 ℃.
8. 8. The method for producing a rare earth magnesium aluminum alloy for a battery case according to claim 5, wherein in step S3, the casting temperature is set to 680 ℃.
9. 9. The method for preparing a rare earth magnesium aluminum alloy for a battery box according to claim 5, wherein in the step S4, the temperature of the solid melting furnace is 410-420 ℃ for the first time, and the heat preservation time is 8h.
10. 10. The method for preparing a rare earth magnesium aluminum alloy for a battery box according to claim 5, wherein in the step S4, the second heating temperature of the solid melting furnace is 510-540 ℃, and the heat preservation time is 2h.

Description

Rare earth magnesium aluminum alloy for battery box and preparation method thereof Technical Field The invention belongs to the technical field of metal materials, and particularly relates to a rare earth magnesium aluminum alloy for a battery box body and a preparation method thereof. Background Under the background of the strict global energy saving and emission reduction policy and the rapid development of new energy automobiles, the automobile weight reduction has become an important development direction of the industry. Magnesium aluminum alloys (mg—al alloys) represent significant potential applications in a variety of fields by virtue of their low density (1.7-1.9 g/cm 3), high specific strength, excellent castability and electromagnetic shielding properties as an important representative of lightweight materials. Particularly in new energy automobiles, magnesium aluminum alloy is widely applied to various fields such as power systems, chassis suspension, automobile body structures, interior trim parts and the like. In the aspect of a power system, the magnesium aluminum alloy gearbox shell and the engine part can achieve a weight reduction effect of 20-40% (the weight reduction of 10% can reduce the energy consumption by 6-8%), meanwhile, the heat dissipation efficiency is improved, and after the magnesium aluminum alloy is adopted for the hub and the suspension part in the chassis system, the unsprung mass is reduced, the operability and NVH performance of a vehicle are improved, and the driving comfort is improved. For example, CN105296821B discloses a magnesium-aluminum alloy material and a preparation method thereof, wherein the magnesium-aluminum alloy material comprises 0.9-1.4% of zinc, 2.3-3.0% of magnesium, 0.3-0.6% of copper, 0.4-0.8% of boron, 0.3-0.7% of vanadium, 0.2-0.5% of lanthanum, 0.3-0.9% of molybdenum, 0.1-0.4% of tin, and the balance of aluminum and unavoidable impurities. The zinc magnesium aluminum alloy material prepared by the method has good corrosion resistance, the corrosion speed of the zinc magnesium aluminum alloy is less than 0.85 mg.cm -2•d-1, in addition, the tensile strength of the zinc magnesium aluminum alloy reaches 424-438 MPa, the yield strength reaches 290-306 MPa, and the zinc magnesium aluminum alloy material has good comprehensive performance, and is relatively suitable for high-performance power transmission parts, three-electric-system core parts (high-power motor rotor supports, batteries Bao Fangzhuang beams and the like) of new energy vehicles, special environment parts and the like. However, in the scheme, the content of expensive elements such as vanadium, lanthanum, molybdenum and the like is higher, the material cost is 3.2 times that of 6061 aluminum alloy, the high-temperature casting energy consumption at 1300 ℃ is 60% higher than that of aluminum alloy die casting, in addition, due to the characteristics of high strength and low toughness of the alloy, the defects such as fatigue crack and the like can occur under 10 7 times of cyclic load (frequency 50Hz, amplitude + -2 mm) and the like, so that the alloy cannot be used for a long time in practical application, and the flame retardance can not reach the practical requirement when the alloy is applied to three-electric system parts. Therefore, for the new energy automobile alloy parts, the required alloy not only meets the requirements of light weight and proper alloy strength, but also is an important index which cannot be ignored, and meanwhile, the cost is considered. For example, CN118531272A discloses a magnesium alloy for a battery box of a new energy automobile and a forming process thereof, and mainly provides a magnesium alloy section alloy system and an extrusion forming process thereof, wherein the alloy composition system is MG AL MN CE CA, and the mass percentages of the elements are 6.0-8.83% of Al, 0.35-0.65% of Mn, 0.14-0.16% of Ce, and the balance of Mg and unavoidable impurity elements; besides, the main steps of the extruded section comprise homogenization treatment, extrusion molding and isothermal aging treatment, the alloy system can form a large amount of fine and compact Mg 12 Ce phases by adding Ce, a large amount of Mg 12 Ce phases are distributed in a network shape at crystal boundaries, the precipitation of the second phases can play a role in refining recrystallized grains, the strong plasticity matching of the alloy can be effectively changed, so that the alloy meets the performance requirement of a battery box body, meanwhile, the addition of Ca and Ce has very important influence on the improvement of the flame retardance of the alloy, and the addition of Ca element and rare earth element has excellent effect on improving the flame retardance of the magnesium alloy mainly because the Ca element and Ce element can form a compact oxide film consisting of CeO 2 and CaO on the surface of the alloy, and compared with the compact oxide film of MgO, the flame retardan