HREM study of the tetragonal/monoclinic interfacial fine structure in ZrO2 associated with the martensitic transformation

Y2O3, 3 vol%, stabilized tetragonal zirconia polycrystals (3Y-TZP) were chosen for the study of the interfacial fine structures resulting from the martensitic transformation of ZrO2. HREM observations revealed for the first time that there exists a transition area in-between the transformed martensitic phase (m-ZrO2) and the parent tetragonal phase (t-ZrO2). The dynamic process of this transformation induced by electron beams of variable intensity and its progression suggests that there may exist two different mechanisms with regard to nucleation and grain growth. The former is governed by the thermal stress produced by electron irradiation, whereas the latter is controlled by electron irradiation. Finally, a comparison of the nature of the twins formed during various transformation conditions was made.