The elastic modulus of aluminium-lithium alloys

Young's modulus measurements have been made on Al-Li alloys containing up to 32 at. % lithium, in an attempt to determine the cause of the high modulus that characterizes this potentially important alloy system. In alloys of commercial interest (7-11 at. %, 2-3 wt. % lithium), the modulus is in the range 79 to 83 GPa, the actual value depending on heat-treatment conditions. The major contribution to this increased modulus arises from lithium in solid solution. The Young's moduli of the Al3Li and AlLi intermetallic phases are estimated to be 96 GPa and 105 GPa respectively. Additions of magnesium to the Al-Li system produce a small decrease of the modulus; e.g., 4.5 at. % (4 wt. %) magnesium reduces the modulus by approximately 2 GPa.