HIGH PURITY ALUMINIUM-LITHIUM MASTER ALLOY BY MOLTEN SALT ELECTROLYSIS

Abstract
The aim of this work is to develop the economical production process of the Al-Li master alloy free from metallic sodium, calcium and potassium. This master alloy can be used for aluminium-lithium alloys for structual materials of aircrafts, automobiles and robots. Moreover the Al-Li master alloy with lithium content of 18-20wt. % is applicable to the blanket of fusion reactors and the active mass of batteries. This Al-Li master alloy can be produced by means of LiCl-KCl molten salt electrolysis in our novel process, where aluminium or some aluminium alloys are used as the cathode. Considering the diffusion coefficient of lithium in solid alloys, the Al-Li master alloy essentially free from other alkali metals can be produced with high current efficiency under the optimum cathode current density and duration of the electrolysis. The conventional lithium electrolysis gives sodium content of 6000-7000ppm when produced from LiCl containing 0.1% of sodium. whereas the new process gives sodium content below 5ppm in the Al-20wt.%Li master alloy.