Refinement of precipitates and deformation substructure in an Al-Cu-Li alloy during heavy rolling at elevated temperatures

An Al-Cu-Li alloy has been severely deformed by rolling over a wide range of temperatures and the evolution of deformation substructure and precipitation examined. A high dislocation density is retained at all temperatures, with dislocations forming cell and subgrain arrangements. There is a greater extent of recovery and coarsening at the higher temperatures. Much finer precipitate particles are seen after rolling than after simple ageing, and grain boundary precipitation is much less extensive. Particle size is reduced both by extensive precipitation on dislocations and by the breakage of previously formed precipitates by the subsequent high strain. Material strength is increased by the presence of the deformation substructure and the fine precipitates, while ductility is improved only when extensive recovery has taken place. More severe deformation, controlling the extent of precipitation, is necessary to refine structures further.