Portevin-Le Chatelier Effect in Al-Zn-Mg-Cu-Zr Aluminum Alloy

Portevin-Le Chatelier (PLC) effect in a severely cold-rolled Al-Zn-Mg-Cu-Zr aluminum alloy (AA7055 type) plate before and after annealing was investigated. The results show that the sample annealed at 300℃ undergoes PLC effect, whereas the PLC effect is not observed in the deformed sample or the samples annealed at 110℃ or 200℃. The main precipitates in the sample annealed at 300℃ are the coarsened phases, while a mixture of small η' phases and η phases dominates in the sample annealed at 200℃. In the deformed sample and sample annealed at 110℃. GP zone are the main precipitates. The different flow behaviors are ascribed to the type of precipitates as well as the dislocation density differences.