Autocatalytic transformation, materials softening and toughening of single and multi-phase CE-TZP ceramics

The influence of autocatalysis and transformation induced shear strain on the transformation plastic zone shape development on the surface of three-point bending Ce-TZP ceramics beam is studied by finite element method. The numerical analysis is based on the micromechanics constitutive model of transformation plasticity developed by Sun et al. (1991). In this model the stress strain curve of ceramics during transformation is controlled by two important microstructure related parameters: hardening coefficient alpha and shear parameter h sub 0 . The obtained results demonstrate the important role of autocatalysis and shear in the development of anomalous transformation zone morphology. The fascinating phenomena discovered in beam specimen by some researchers (Reyes-Morel and Chen, 1988; Reyes-Morel et al., 1988 and Sun et al., 1994) are first simulated in the present work