Influence of heat treatment on the formation of ultrafine-grained structure of Al-Li alloys processed by SPD

In this study, binary Al-2.3wt%Li alloy, ternary Al-2.2wt%Li-0.1wt%Zr alloy and quaternary Al-2.2wt%Li-0.1wt%Zr-1.2wt%Cu alloy in the solution treated condition and additionally in aging condition were severely plastically deformed by rolling with cyclic movement of rolls (RCMR) method to produce ultrafine grained structure. Scanning transmission electron microscopy (STEM), scanning electron microscopy with EBSD detector (SEM/EBSD) were used for microstructural characterization and hardness test for a preliminary assessment of mechanical properties. The results shows, that the combination of aging treatments with RCMR deformation can effectively increase the hardness of Al-Li alloys. Second particles hinders the annihilation of dislocations in Al matrix during deformation leading to an increase of dislocation density. Significant amount of nanometric second particles in refined structure to ultrafine scale especially in Al-2.2wt%Li-0.1wt%Zr-1.2wt%Cu alloy effectively prevents the formation of high angle boundaries.