Evolution of microstructures during isothermal annealing in hot-rolled Al-Mn alloys

Effect of annealing in hot-rolled Al-Mn alloys on evolution of microstructures was investigated using hardness measurement, electrical-resistivity measurement, backscattered electron images, and its image analysis. Electrical resistivity with annealing time exhibited that residual content of solute Mn and Fe atoms remained in hot-rolled alloys, and that their number was decreased during annealing. Analysis of backscattering electron image of scanning electron microscopy provided that a lot of precipitates grew by consumption of such solute atoms. We considered that the growth of precipitates during isothermal annealing affect recovery and recrystallization and then hardness behavior.