Preparation method of a lithium-containing magnesium/aluminum matrix composite

Abstract

The present invention relates to a preparation method of a lithium-containing magnesium/aluminum matrix composite. The preparation method is performed according to the following steps: (1) preparing magnesium ingots or aluminum ingots, preparing lithium metal, and preparing flux and reinforcements; (2) heating the flux to prepare flux melt, and adding the reinforcements to the flux melt to prepare a liquid-solid mixture; (3) pouring the liquid-solid mixture in a normal-temperature crucible, and performing cooling to obtain a precursor; (4) preheating a crucible, adding raw materials, and performing melting to form a raw material melt; (5) controlling a temperature of the raw material melt to 973-993K, adding the lithium metal, performing stirring, adding the precursor, performing stirring and mixing, raising temperature to 993-1013K, and performing standing; and (6) scumming operation should be carried out, and performing temperature casting on composite melt.

What is claimed is: 
     
         1 . A preparation method of a lithium-containing magnesium/aluminum matrix composite, comprising the following steps:
 (1) preparing magnesium ingots or aluminum ingots as raw materials, preparing lithium metal, and preparing flux and reinforcements, wherein the flux contains components in percentage by mass of 65%-85% of lithium chloride, 15%-35% of lithium fluoride and less than or equal to 20% of lithium bromide, the reinforcements are elemental metal powder, rare earth oxide, carbide, boride or metal oxide, the elemental metal powder is W, Mo or Ni, the rare earth oxide is La 2 O 3 , CeO 2  or Y 2 O 3 , the carbide is TiC or SiC, the boride is ZrB 2 , and the metal oxide is MgO or SiO 2 , the reinforcements are 0.1%-30% of total volume of the raw materials, the reinforcements are 1%-50% of total volume of the flux, and the lithium metal is 0.1%-10% of total mass of the raw materials;   (2) putting the flux into a clay crucible or a graphite crucible, performing heating to 673-773K to make a flux melt, adding the reinforcements to the flux melt, and performing stirring to enable the reinforcements to uniformly disperse to make a liquid-solid mixture;   (3) pouring the liquid-solid mixture into the clay crucible or the graphite crucible at normal temperature, and performing cooling to normal temperature to obtain a precursor;   (4) preheating a crucible to 473-523K, then placing the raw materials in the crucible, and enabling the raw materials to melt at 923-1023 K to form a raw material melt, wherein if the raw materials are the magnesium ingots, the crucible is an iron crucible, and if the raw materials are aluminum ingots, the crucible is a graphite crucible;   (5) controlling a temperature of the raw material melt at 973-993K, putting the lithium metal wrapped with tin foil in the raw material melt, performing uniform stirring and mixing, adding a precursor, continuing to perform uniform stirring and mixing, raising temperature to 993-1013K, and performing standing to separate impurity components from composite components to form scumming and composite melt; and   (6) Scumming operation should be carried out on a surface of the composite melt, then reducing a temperature of the composite melt to 983±5K, and performing casting to prepare the lithium-containing magnesium/aluminum matrix composite.   
     
     
         2 . The preparation method of  claim 1 , wherein purity of the aluminum ingots is greater than or equal to 99.8%, purity of the magnesium ingots is greater than or equal to 99.85%, and purity of the lithium metal is greater than or equal to 99.8%. 
     
     
         3 . The preparation method of  claim 1 , wherein the reinforcements are in the form of fibers, particles or whiskers, wherein a particle size of the particles is 300 nm to 20 μm; the whisker has a diameter of 0.1-1 μm and a length of 10-100 μm; and the fibers have a diameter of 5-20 μm and a continuous length of 10-70 mm. 
     
     
         4 . The preparation method of  claim 1 , wherein in the step (2), a stirring speed is 100-200 r/min, and a time is 5-10 min. 
     
     
         5 . The preparation method of  claim 1 , wherein in the step (5), a stirring speed is 100-300 r/min, and a time is 2-15 min. 
     
     
         6 . The preparation method of  claim 1 , wherein in the step (5), a standing time is 10-20 min. 
     
     
         7 . The preparation method of  claim 1 , wherein in the step (1), magnesium ingots/aluminum ingots and other metal components are prepared as raw materials; when the step (4) is performed, the magnesium ingots/aluminum ingots and the other metal components are placed together in an iron crucible, melted, stirred and mixed uniformly to form a raw material melt; when the magnesium ingots and the other metal components are used as raw materials, the other metal components are one or more of aluminum metal, zinc ingots, manganese chloride, magnesium-rare earth alloys, magnesium-zirconium alloys and magnesium-silicon alloys, and the aluminum, zinc, manganese, rare earth, zirconium and silicon in other metal components account for less than or equal to 10% of total mass of the raw materials; and when aluminum ingots and other metal components are used as raw materials, the other metal components are one or more of magnesium metal, zinc ingots, aluminum-manganese alloys, aluminum-rare earth alloys, aluminum-copper alloys, aluminum-titanium alloys and aluminum-silicon alloys, and the magnesium, zinc, manganese, rare earth, copper, titanium and silicon in the other metal components account for less than or equal to 10% of total mass of the raw materials. 
     
     
         8 . The preparation method of  claim 1 , wherein in the lithium-containing magnesium/aluminum matrix composite, the reinforcement component accounts for 0.1%-22% of total volume.