Quasi-in-situ observing the rare earth texture evolution in an extruded Mg-Zn-Gd alloy with bimodal microstructure

The static recrystallization and associated texture evolution were investigated in an extruded Mg-Zn-Gd alloy with bimodal microstructure based on a quasi-in-situ electron back-scatter diffraction (EBSD) method. The typical rare earth (RE) texture formed during annealing, evolving from the bimodal microstructure with [101¯0] basal fiber texture that consisted of fine recrystallized (RXed) grains and coarse unrecrystallized (unRXed) grains elongated along the extrusion direction. In both RXed and unRXed regions, the RXed nucleation produced randomized orientations without preferred selection and the RXed grains with RE texture orientation had more intensive growth ability than those with basal fiber orientation, thereby leading to the preferred selection of RE texture orientation during grain growth. The relationships between stored strain energy, solute drag, grain growth and texture evolution are discussed in detail. This study provided direct evidence of the RE texture evolution in an extruded Mg-RE alloy, which assists in understanding the formation mechanisms for RE texture during extrusion and better developing wrought Mg alloys with improved formability.