FERROELASTICITY OF T-ZIRCONIA .2. IN-SITU STRAINING IN A HIGH-VOLTAGEELECTRON-MICROSCOPE

The ferroelastic deformation of t'-ZrO2, the microstructure of which w as described in detail in Part I, was investigated by in situ deformat ion experiments in the high-voltage electron microscope at 1150 degree s C. During the experiments those two domain. variants with their c-ax es perpendicular to the [010] tensile direction were transformed into the third one with its c-axis parallel to the tensile direction, The s ubsequent 'switching' of the domains inside the colonies proceeds much faster than the penetration of the transformation front into a neighb oring colony. Therefore, the transformed region, exhibiting a unique t etragonal structure and containing residual defects, preferentially ex pands into the longitudinal directions of the colonies. The transforma tion of single domains proceeds instantaneously within the time resolu tion of the video tape recording.