ABSTRACT
The stress-assisted martensitic transformation in ZrO2 ceramics contains both an athermal and an isothermal component. The thermodynamics and kinetics of the isothermal (thermally activated) transformation has been investigated in one MgO- and two Y2O3-ZrO2 alloys. In MgO-partially-stabilized ZrO2 with an appropriate thermal history, isothermal t⇒m and t⇒o transformations take place at room temperature over many months. In Y2O3-stabilized alloys, relatively rapid t⇒m transformation occurs at 300 to 800K within the residual stress fields of Vickers indentations. The transformation rate is controlled by the thermally activated, stress-assisted nucleation of the martensitic product.
