Which of the following approaches is not a valid method of s

Which of the following approaches is not a valid method of strengthening (with respect to a flawed or fracture prone state) and toughenening a ceramic.

Solution

Toughening and strengthening mechanisms in ceramics based on nanocomposites based on Griffiths energy equilibrium equation and residual stresses around second phase nanoparticles despered in matrix grains. The residual thermal stresses around sperical despersed within concemtric sphere of matrix specifically analysed to clarify the effects of residual stresses in a toughening mechanism in the frontal process zone involving nanocracking and on the strengthening mechanism caused by nucleation of dislocation