Superplasticity of rare-earth (RE) containing Mg-4Y-3RE (WE43) Mg alloy can be achieved upon processing by severe plastic deformation (SPD) and thermomechanical processing. In this regard, the reported investigations on the superplastic WE43 alloy processed by equal channel angular pressing (ECAP), friction stir processing (FSP), multi-axial forging (MAF), KoBo Extrusion, hot extrusion, and hot rolling were critically discussed in this monograph. Analysis of the reported works revealed that the SPD techniques are capable to refine the grain size of WE43 alloy down to the ultrafine grained (UFG) regime with good dispersion of secondary phases, leading to remarkable high strain rate superplasticity (HSRS). The thermomechanically processed WE43 alloy might also exhibit superplasticity, where both fine-grained and coarse-grained WE43 alloys exhibit superplasticity under proper temperatures and strain rates for the operation of dynamic recrystallization (DRX), grain boundary sliding (GBS), and solute drag creep mechanism (viscous glide). While raising the deformation temperature and grain refinement promotes HSRS, high deformation temperatures might deteriorate superplasticity because of the decrease in the amount of phases and the consequent grain coarsening. At the end, useful suggestions for future works were proposed, including focusing on the common SPD processes, unraveling the effects of processing parameters, characterization of the secondary phases, elucidating the microstructural refinement mechanisms, and metal additive manufacturing using friction stir engineering.
Hamed Mirzadeh (Fri,) studied this question.