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CN-122013010-A - Mg-Ce-Zr series cast magnesium alloy and preparation method thereof

CN122013010ACN 122013010 ACN122013010 ACN 122013010ACN-122013010-A

Abstract

The invention provides a Mg-Ce-Zr series cast magnesium alloy and a preparation method thereof, belongs to the technical field of magnesium alloy materials, and solves at least one technical problem that the existing cast magnesium alloy is low in heat conductivity, or high in strength and high in heat conductivity can not be compatible, or the density of the magnesium alloy can not be controlled to the lowest level while the cast magnesium alloy is high in strength and high in heat conductivity. The Mg-Ce-Zr series cast magnesium alloy comprises, by weight, 0.5-2.5% of Ce, 0.35-0.55% of Zr, and the balance of magnesium and unavoidable impurities. The rare earth element Ce with small difference with the radius of the magnesium atom is selected, the Ce can refine grains, purify melt, improve fluidity and heat resistance in magnesium alloy, the rare earth element Ce with higher solid solubility can form second phases Mg 17 Ce 2 and CeMg 12 at the grain boundary, has less negative influence on heat conductivity, and improves strength by pinning the grain boundary.

Inventors

  • HE WEI
  • HE FEIYU
  • WU HONGFEI
  • CHEN ZHIQIANG
  • ZHANG XUDONG
  • YU ZEMIN
  • SHI LEI
  • HU WENXIN
  • LU YUMING
  • LIU FENG
  • GUO HE
  • YANG ZHENGHUA
  • WANG WEI
  • LI KUN
  • MA SHAOBO

Assignees

  • 包头稀土研究院

Dates

Publication Date
20260512
Application Date
20260210

Claims (10)

  1. 1. The Mg-Ce-Zr series cast magnesium alloy is characterized by comprising, by weight, 0.5-2.5% of Ce, 0.35-0.55% of Zr and the balance of magnesium and unavoidable impurities.
  2. 2. The magnesium alloy according to claim 1, wherein the magnesium alloy comprises, by weight, 1.0-2.0% of Ce, 0.40-0.50% of Zr, and the balance magnesium and unavoidable impurities.
  3. 3. A method for producing the magnesium alloy according to any one of claims 1 or 2, comprising the steps of: (1) Raw materials of magnesium ingots, mg-Ce intermediate alloy and Mg-Zr intermediate alloy are proportioned according to chemical components of the magnesium alloy, and the raw materials are preheated; (2) Melting the preheated magnesium ingot under the conditions of protective gas and 680-720 ℃ to obtain magnesium liquid; (3) Adding the preheated Mg-Ce intermediate alloy into the magnesium liquid under the conditions of protective gas and 700-800 ℃, heating to 740-780 ℃ after the magnesium liquid is completely melted, adding the Mg-Zr intermediate alloy, stirring, standing for the first time, refining and deslagging, and standing for the second time for cooling; (4) Pouring the furnace temperature to a custom iron mold after the furnace temperature is reduced to 700-720 ℃, and then air-cooling to room temperature to obtain a primary magnesium alloy ingot; (5) Heating the primary magnesium alloy ingot to 500-530 ℃, preserving heat for 5-8 hours, and then quenching; (6) And heating the quenched magnesium alloy to 200-230 ℃ and preserving heat for 10-20 hours, and then cooling to room temperature along with a furnace.
  4. 4. The method according to claim 3, wherein in the step (1), the mg—ce intermediate alloy is Mg-25wt.% Ce intermediate alloy, and the mg—zr intermediate alloy is Mg-25wt.% Zr intermediate alloy.
  5. 5. The method according to claim 3, wherein in the step (1), the preheating temperature is 150 to 350 ℃, and the preheating time is 2 to 6 hours.
  6. 6. The method according to claim 3, wherein in the step (3), the stirring time is 60-120 min, the first standing time is 60-90 min, the refining and deslagging are performed by using 99.99% pure argon, and the flow rate of the argon is 80-150 cm 3 /min.
  7. 7. The method according to claim 3, wherein in the step (2) and the step (3), the shielding gas is composed of SF 6 and N 2 , and the volume ratio of SF 6 to N 2 is 1:300-800.
  8. 8. The method of claim 7, wherein the volume ratio of SF 6 to N 2 is 1:350-650.
  9. 9. The method according to claim 3, wherein in the step (5), the primary magnesium alloy ingot after the heat preservation is cooled in boiling water.
  10. 10. The magnesium alloy according to any one of claims 1 or 2, or the magnesium alloy produced by the production method according to any one of claims 3 to 9, wherein the magnesium alloy has a tensile strength of 205 to 240mpa, a yield strength of 130 to 160mpa, an elongation of more than 10%, and a thermal conductivity of more than 125W/(m.k) at 20 to 200 ℃.

Description

Mg-Ce-Zr series cast magnesium alloy and preparation method thereof Technical Field The invention belongs to the technical field of magnesium alloy materials, and relates to a Mg-Ce-Zr series cast magnesium alloy and a preparation method thereof. Background With the rapid development of electronic technology, the electronic industry develops toward miniaturization, integration and high performance, so that the total power density and the heat productivity of electronic devices are greatly increased, the heat dissipation problem is more and more prominent, and particularly, the magnesium alloy is valued for the relatively low density and high heat conductivity of the magnesium alloy because of the characteristics of small density, high specific strength and high specific stiffness of the material required for complex structural members of heat dissipation systems of aerospace devices, portable electrical appliances, communication equipment, vehicles and other products which are sensitive to important requirements. The magnesium alloy can be divided into cast magnesium alloy and deformed magnesium alloy, the deformed magnesium alloy has higher strength and better mechanical property than cast magnesium alloy through deformation processes such as extrusion, rolling and forging, but has the defects of high processing cost, limited molding shape and the like, so that the wide application of the magnesium alloy as a magnesium alloy part with a complex shape or a fine structure is limited to a certain extent, and the cast magnesium alloy has the characteristics of good molding property and low cost, but is slightly insufficient in strength. Therefore, if a cast magnesium alloy with high strength and high heat conductivity can be developed, the material and the machining forming requirements of the complex structural part of the heat dissipation system can be met. The heat conductivity of pure magnesium is 158W/(m.K) at most, but the yield strength and the tensile strength of pure magnesium in an as-cast state are only 2.5MPa and 11.5MPa respectively, the mechanical property of the magnesium alloy is generally improved by adding alloy elements, and according to the heat conduction theory, the heat conductivity of a material is reduced by adding the alloy elements into a magnesium matrix, so that the obtaining of the cast magnesium alloy with high heat conductivity and high strength is a dilemma or needs to be balanced. The prior researches show that when the alloy element exists in the form of a second phase in the magnesium matrix, the negative influence on the heat conductivity is far lower than that when the alloy exists in the form of solid solution atoms, so that the alloy can meet the requirement of strengthening strength of the alloy, and meanwhile, the total amount of the alloy element is added as little as possible, the alloy forms a stable second phase instead of being solid-dissolved in the magnesium matrix, and the high heat conductivity can be maintained at the same time of high strength. In addition, since most of the alloying elements have a higher density than magnesium, it is also required to add as few alloying elements as possible in order to maintain the low density of the magnesium alloy. At present, most of cast magnesium alloys with high strength and high heat conduction are magnesium-zinc series alloys, such as patent CN100513606C, CN102719716A, CN101709418A, CN114351020A, wherein Zn is used as a main element for improving the mechanical property of the magnesium alloy through solid solution strengthening, other alloy elements are used for improving the strength and reducing the influence on the heat conduction property, in order to keep the high strength, the Zn content is mostly more than 1.0%, the upper limit is even more than 10%, and although the Zn content is less than 1.0%, other rare earth elements and heavy metal Th are also added. In a word, the cast magnesium alloy with high strength and high heat conductivity in the prior art has higher Zn content or total alloy mass, so that the density of the magnesium alloy is improved to different degrees. Disclosure of Invention In view of the above state of the art, the present invention provides a Mg-Ce-Zr-based cast magnesium alloy and a method for preparing the same, so as to achieve at least one of the objects that the cast magnesium alloy has high thermal conductivity, or both high strength and high thermal conductivity, or that the density of the magnesium alloy can be controlled to a minimum level while having both high strength and high thermal conductivity. The method is mainly realized by the following technical scheme: On the one hand, the invention provides a Mg-Ce-Zr series cast magnesium alloy, which comprises 0.5-2.5% of Ce, 0.35-0.55% of Zr and the balance of magnesium and unavoidable impurities in percentage by weight. Further, the magnesium alloy comprises, by weight, 1.0-2.0% of Ce, 0.40-0.50% of Zr, and the balance of ma