Dark-field optical microscopy—a new technique to study recrystallization in commercial purity aluminium

A new technique to study recrystallization in commercial purity aluminium was evaluated. The samples that were compacted, sintered and hot extruded were annealed at 580 °C for various times to study recrystallization behaviour. The samples that were electropolished and etched were observed with a dark-field imaging technique in a Lietz optical microscope. The micrographs revealed an increase in fraction recrystallized with increase in annealing time. These images indicated recrystallized grains as white regions and the remaining deformed grains as black regions. The contrast in these images is quite distinct between the recrystallized grains and the reformed elongated grains.