Preparation Of Al-Li Master Alloy

As a kind of material with excellent propertities,Al-Li alloy was widely used in areospace stuctural materials.The troditional ingot metallurgy method wasn't satisfy the requirement of homogeneous composition,high recovery and short process.Two new preocess were investigated in production of Al-Li alloys in this paper.One is by molten salt electrolysis in Urea-LiCl,the other method is prepared by aluminothermic reduction with lithium peroxide.In Urea-LiCl molten salts,preparation of Al-Li master alloy at temperature lower than 393K.Li(I)can be formed coordination ion with urea and lower the melting point.The cyclic voltammetry experiments show that the reduction onset of Li(I)is 0.15V(vs.Li+/Li),and lithium element presents as AlLi phase.Tha mass content of lithium in alloy increased with increasing the electrolysis temperature and suitable treatment process.The maximum Li content was 6.87wt%.The images of the cross section show that lithium homogeneous diffused in aluminum and formed Al-Li alloy layers.Aluminum was used as a reducing agent to directly reduce the lithium peroxide to prepare the Al-Li master alloy in the KCl-LiCl molten salts.In the research on thermodynamic calculation,it's feasible to prepare Al-Li alloy by aluminothermic reduction with lithium peroxide at room temperature or higher.Li2O2 decomposed to form Li2O at 586K,then a spontaneous exothermic reaction occured between lithium oxide and alumina to form aluminum-lithium intermidate oxide in the DSC-TGA curves.Al-Li alloy can not be prepared under argon and vaccum atmosphere conditions due to the formation of aluminumlithium intermidate oxide.Al-Li alloy pellets with AlLi phase no less than 50 meshes can be obtained by aluminothermic reduction with Li2O2 in KCl-LiCl molten salt.The low temperature molten salt electrolysis and aluminothermic reduction method used in this paper provide a new direction and ideas for the preparation of Al-Li alloy.