3-DIMENSIONAL DYNAMIC CALCULATION OF THE EQUILIBRIUM SHAPE OF A COHERENT TETRAGONAL PRECIPITATE IN MG-PARTIALLY STABILIZED CUBIC ZRO2

The equilibrium shape of a tetragonal precipitate coherently embedded in a cubic matrix is examined in three dimensions by a computer simula tion. Independent experimental data of Mg-partially stabilized ZrO2 ar e used as the input parameters. The equilibrium shape is obtained by d iffusional relaxation of an initially nonequilibrium spherical shape. The relaxation is described through a generalized field kinetic model which takes into account the transformation-induced elastic strain ari sing from a cubic --> tetragonal crystal lattice rearrangement. Withou t any a priori constraint on the geometry of the particle, the equilib rium shape is shown to be a rotation disk formed by two cones with the common base. It is far from the ellipsoidal shape assumed in the conv entional analytical calculations based on Eshelby's model.