Melting and casting of lithium containing aluminium alloys

摘要

The alloying of traditional aluminium with lithium metal has provided a new class of high strength aluminium alloys. These lithium containing aluminium alloys offers exceptional properties for weight critical and aerospace applications. By altering the chemistry of aluminium-lithium (Al-Li) alloys many different grades have been developed for specific needs such as damage tolerant alloys, medium strength and high strength alloys. However, regardless of their remarkable potential in aerospace applications, the Al-Li alloys could not runaway commercially analogue to traditional aluminium alloys. This article describes the processing necessities of melting and casting route of Al-Li alloys, and discusses the published work with reference to practical difficulties. The proposed methods in literature such as melting under specialised fluxes, use of lithium master alloys, vacuum or inert gas melting have been thoroughly examined. The known procedures for degassing and melt refining, casting practices, and the feasibility of various materials to hold the Al-Li melts have also been evaluated and compared with the ones used for traditional aluminium alloys. This study concluded that melting and casting practices used for traditional aluminium alloys could not be adopted as it is for Al-Li alloys due to rapid oxidation of lithium metal in furnace environment.