Extremely light (density $1.46 g/cm 3 ) and highly formable Mg-Li alloys have been drawing research interest; however, their relatively low strength is discouraging, and thus, an issue to be addressed. This paper processes and evaluates four Mg-Li alloys: the first, a basic alloy with a nominal composition of Mg-11%Li-1%Al-0.5%Zn; the second, an alloy with only Be added to the first; the third, an alloy with only Sc added to the first; and the fourth, with both Be and Sc added to the first. This research achieves a high strength of $240 MPa for Mg-Li alloys using the processes of solid solution treatment plus 90% heavy rolling. A subsequent natural aging process proceeded spontaneously and resulted in strength decay. Room temperature softening behavior is uncommon, but offers a convenient route for studying age-softening characteristics of metallic alloys.

Al-Si alloys, with excellent properties such as low weight, low thermal expansion coefficient, and high wear-resistance, are ideal materials for the automobile and aerospace industries. However, their applications have been hampered by the coarsening of the primary-Si particles in Al-Si alloys. In this study, the rolling-and-T6-treatments effect on A6061/Al 2 O 3 metal-matrix composites is investigated. The A6061/Al 2 O 3 metal-matrix composites with different amounts of reinforcing Al 2 O 3 particles are examined in the aspects of wear resistance and hardness. Upon the T6 treatment, the hardness is enhanced in all cases and is summarized. The results suggest that the increase of Al 2 O 3 particles reduce the wear rate. The possible reinforce mechanisms and the environmental temperature effects are discussed. This improvement in wear resistance is due to the particle size refinement of silicon at a high percentage-roll-reduction.