Recrystallization Twinning in Stable Single Crystals of Cu-2%Al and Al-1%Mn Alloys

Abstract

The crystallographic aspects of recrystallization twinning have been characterized in {110}<001> and {110}<112>-oriented single crystals of Cu-2%wt.Al and Al-1%wt.Mn alloys. The samples were plane strain compressed to logarithmic strain of 0.52 and then lightly annealed. SEM/EBSD local orientation measurements on partly recrystallized samples demonstrate the appearance of a specific number of new orientation groups of recrystallized grains, which resulted from rotation of the deformed crystal orientations around axes lying near (but rarely at) selected the <111> directions. Then the primary nucleus can transform through the formation of a first generation recrystallization twin. The most frequent situation was that the twinning plane normal was situated near the rotation axis, around which the crystal lattice of the ‘primary nuclei’ rotates. Based on new algorithm to identify coherent and incoherent twin boundaries the influence of free surface on the intensity of annealing twinning was analyzed.