3. The benefits and limits of superplasticity

3.1 Limits

These are essentially located at three levels linked to the material and the experimental deformation conditions: the material's microstructure and its evolution, the deformation rate and the temperature.

As already emphasized, the grain size of materials deformed under superplastic conditions must be small and remain relatively stable during deformation, which takes place at high temperature. Obtaining such structures may require the implementation of complex thermomechanical routines, leading to a high cost price. In the particular case of powder-metallurgy materials, this requires the use of ultra-fine powders and sintering procedures that do not involve excessive grain coarsening. Here again, these requirements can lead to high material costs....