Combined extrusion experiment (including direct and indirect extrusion) at 440 for
large amount of deformation was carried out with the solution treated AA7050 aluminum alloy.
Qualitative description and quantitative characterization were conducted employing electron
backscattered diffraction (EBSD) technique on the microstructure of typical regions with different
filler contents. These characteristic regions were filled at the following stages: ahead of filling (AF),
beginning of filling (BF), mid stage of filling (MF) and the end of filling (EF). EBSD results
showed that recrystallization fraction during direct extrusion were 8.3%, 13.5%, 9.3% and 11.2%,
for AF, BF, MF and EF, respectively. Recrystallization fraction during indirect extrusion were
15.5%, 9.1% 5.2% and 9.9%，for AF, BF, MF and EF, respectively. It shows that the mode and the
amount of deformation played an important role in DRX. DRX grains were formed continuously
during direct extrusion, while during indirect extrusion, fewer DRX grains generated, and only
originally generated DRX grains grew larger gradually.
