Hi,
I only know the use of Lithium with aluminium as alloy, i.e. Al-li alloy, which about 10 % lighter and about 10 % stiffer then conventional aluminium alloy. The slats or leading edge of Eurofighter wing should be made from this alloy, I didn't sure if it comes true, since it was about six year ago as I made practical work there. I only know that teh great barrier for using Al-li alloys is their susceptibility to so called "inter-cristalline corrosion" and poor "impact behaviour".
regards