Research for the development of high specific strength Al-Li alloy by using new electrolysis method

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Al-Li alloy is a promising new material because it is lightest and strongest in all the aluminum alloy. However it is difficult to produce Al-Li alloy because metallic lithium is very active chemically and its density is only 1/5 of that of aluminum. This method, molten salt electrolysis, is considered to be excellent for producing Al-Li alloy as follows ;1.Dangerous metallic lithium is not used. Lithium content increases from zero to desired concentration by putting lithium into molten aluminum by using the electrolysis.2.Clean alloy is obtained because the molten salt acts as the flux and protects the alloy from air.3.It is possible to cut the cost of producing Al-Li alloy largely by using lithium carbonate as the source of lithium because lithium carbonate is less expensive and is not hygroscopic.Following results were obtained on the cathodic rection. The current efficiency of lithium deposition is excellent, at least higher than 90%. Content of farmful impurities, for example, potassium or sodium is very low level, about 10ppm which is almost same to that in pure aluminum. The Al-Li obtained was very clean and showed almost no deffects as cast.The results obtained on anodic reactions are follows ; Chlorine gas is evolved when chloride melt is used as the electrolyte. By adding lithium carbonate into chloride melt, anodic potential decreases drastically. It reaches almost 1.3V.No chlorine gas is evolved and the exhaust consists of large amount of carbon dioxide and small amount of carbon monoxide. This results are convenient for producing Al-Li alloy by using lithium carbonate.