Deformation-Induced Recrystallization of Magnesium Single Crystals at Ambient Temperature

Specially oriented magnesium single crystals were subjected to plane strain compression along the <112-bar0> direction in c-axis extension at ambient temperature. The samples exhibited outstanding formability deforming up to a logarithmic final strain of -1. Investigations by optical and orientation imaging microscopy revealed that massive {101-bar2} extension twinning at low strains consumed the whole sample and resulted in new soft orientations for slip. Observations also indicated that additional twinning took place in the completely twinned matrix by secondary and tertiary twinning events. At advanced stages of deformation newly formed, equiaxed small grains were observed within numerous bands related to former deformation twins. These "recrystallized" grains characterized by a low grain orientation spread of less than 1° generated new orientations, which led to a substantial weakening and randomization of the texture during deformation up to very large strains. The reported results in this paper are discussed with regard to the microstructure evolution arising from multiple twinning and continuous dynamic recrystallization at room temperature. (paper)