TRANSITION OF MECHANISMS CONTROLLING THE DISLOCATION-MOTION IN CUBIC ZRO2 BELOW 700-DEGREES-C

For cubic ZrO2 single crystals deformed in [112] direction, new experi mental data are presented on the flow stress and its strain rate sensi tivity as well as on the dislocation densities and the distances betwe en glide obstacles along the dislocations. A model is proposed to desc ribe the strong variation of the parameters of the plastic deformation below 1000 K. It assumes that the mechanisms controlling the dislocat ion motion change from the pinning by localized obstacles above a tran sition temperature, e.g. small precipitates or jogs, to the overcoming of the Peierls relief at lower temperatures. The model is in agreemen t with most of the experimental observations. (C) 1998 Acta Metallurgi ca Inc.