EFFECT OF MICROSTRUCTURE ON TENSILE AND FRACTURE PROPERTIES OF ALUMINUM-ALLOYS WITH HIGH LITHIUM CONTENT

The microstructure and mechanical properties of alloys containing simi lar to 4%Li, 0-2%Mg, and 0.06-0.12%Zr (all wt-%) have been evaluated. Alloys prepared by both ingot casting and spray casting have been inve stigated and these have been processed to give a range of grain struct ures, including equiaxed recrystallised, lamellar recrystallised, part ially recrystallised, and unrecrystallised. Unrecrystallised and parti ally recrystallised ingot alloys have improved strength and fracture e nergy when compared with coarse grained recrystallised ingot alloys. T he contributions to increased strength have been assessed by consideri ng grain size, dispersoid content, substructure, and crystallographic texture. The contributions to increased fracture energy have been disc ussed in terms of the fracture mode after various heat treatments.