Parameters improving superplasticity

Several techniques have been developed to achieve ceramics and composites with fine microstructure  

The diffusion coefficients of the process controlling superplasticity may be enhanced or retarded by the addition of impurities or solute atoms or by the addition of secondary phases, normally used as sintering aids, which distribute along the grain boundaries and triple-point junctions of the grains. 

A plot of a versus the average grain size from (16.14) is shown in Fig. 16.5. From this it can be seen that the effect of the nanostructured character 

---