Growth Behaviors of #delta#'-PEZ in the Al-Li-Sc Alloy

摘要

#delta#'-PEZ growth behaviors in Al-Li alloys at various aging conditions were investigated mainly by TEM observations. The widths of PFZs were increased with aging time and aging temperature and their growth is proportional to the square root of aging time. The alloy containing Sc showed a smaller value of growth rate constant and larger activation energy for the PFZ growth than those of other Sc-free alloys. These facts indicate that diffusion process of Li solutes via vacancies could be precluded or limited by Sc in solution. In the Sc containing alloy, high density of dislocations surrounded by coarsened Al_3Sc particles were observed in the overaged condition. These dislocations can be closely linked to the reduction of growth rate of the PFZ, considering that they provide sink sites for lattice vacancies, finally leading to suppress the diffusion of Li solutes toward grain boundaries.