This proposal is for the continuation of research on transformation toughening in ZrO2-containig ceramics. Specifically, the research will focus on i) making dense transformation toughened Mg-PSZ with fine grain size, in contrast to the current generation of tough Mg- PSZ's which are course grained, porous, and contain unwanted second phases, ii)studying structure-property relationships in ternary Mg, Y-PSZ's, particularly probing the effect of particle morphology and hence coherency stresses, on the crack tip stress-induced transformation, iii) Studying the mechanics of stress-induced subcritical transformation which in "supertough" Mg-PSZ can occur before any visible surface microcracks, and iv) studying transformation around microhardness indents in Y-PSZ single crystals, particularly the dislocation-nucleated autocatalytic transformation.
