LAYERED COMPOSITES Vol. 38. No. I Figure 5. SEM micrograph of the polished cross-section of alumina/alumina(Y-TZP)laminated composite large number of perpendicularly oriented cracks are located in the alumina layers. This fact can be explained as follows on (a) The fraction of the zirconia which is monoclinic in the zirconia containing layer was determined polished specimens using Garvie's equation [61 and was found to be -80%6, During cooling dilatation takes place at 700-650oC range(Fig. 4)as a consequence of the t-m martensitic transfor mation of the coarse zirconia grain (b) Because of the strain mismatch(Ae) due to tetragonal to monoclinic zirconia trar esidual stress developed in the alumina layer according to equation Figure 6. SEM micrograph of the fracture surface alumina/alumina (Y-TZP)laminated composite