Effect of Ca and Nd on the microstructural development during dynamic and static recrystallization of indirectly extruded Mg-Zn based alloys

摘要

The present study examines the influence of Ca or Nd on the microstructure and texture modification during indirect extrusion and after subsequent annealing of Mg-Zn based alloys. The addition of such elements influence the recrystallization processes, i.e. dynamic (DRX) and static recrystallization (SRX), and leads to distinctive texture changes of samples extruded at different extrusion speeds. In the binary Mg-Zn alloys, the resulting texture after extrusion is the classical basal type texture, where there is an alignment of basal planes along the arc between the <10-10 and <11-20> poles. This development is independent of the extrusion speed, as the resulting microstructures are almost completely recrystallized. In the case of the Mg-Zn-Ca, there is a distinctive <10-11> component together with a <11-20> pole, while in the Mg-Zn-Nd alloy the so-called <11-21> rare-earth texture component and the <20-23> pole intensity are observed as DRX dominates the microstructural development. It is found that this distinctive behavior can be changed if partially recrystallized microstructures are subsequently annealed. This leads to an increase of the importance of SRX and a different resulting texture while maintaining a similar grain structure. Both recrystallization processes lead to different mechanical properties, yielding behavior and toughness as a result of the different texture development.