The role of solute segregation and precipitation at dislocations to enhance continuous recrystallization

In dilute Al alloys with transition element additions, the equilibrium solvus can not be attained by standard heat treatment practice. Thus the matrix is inevitably supersaturated and this impurity level affects dislocation glide and climb suppressing dislocation annihilation during heat treatment. However, to obtain the near equilibrium solvus at low temperatures, the specimens were pre-strained to enhance precipitation at dislocations. When the matrix solute content is below 1 ppm, subsequent cold work and anneal resulted in continuously recrystallized fine grained microstructure. In this study, a uniform fine grain sized (1–2 μm) microstructure was obtained in commercial AA3003 Al alloy using this procedure.