Crack bifurcation was observed in laminar ceramic composites when crac
ks entered thin Al2O3 layers sandwiched between thicker layers of Zr(1
2Ce)O-2. The Al2O3 layers contained a biaxial, residual, compressive s
tress of approximate to 2 GPa developed due to differential contractio
n upon cooling from the processing temperature. The Zr(12Ce)O-2 layers
were nearly free of residual, tensile stresses because they were much
thicker than the Al2O3 layers. The ceramic composites were fabricated
by a green tape and codensification method. Different specimens were
fabricated to examine the effect of the thickness of the Al2O3, layer
on the bifurcation phenomena. Bar specimens were fractured in four-poi
nt bending. When the propagating crack encountered the Al2O3 layer, it
bifurcated as it approached the Zr(12Ce)O-2/ Al2O3 interface. After t
he crack bifurcated, it continued to propagate close to the center lin
e of the Al2O3 layer. Fracture of the laminate continued after the pri
mary crack reinitiated to propagate through the next Zr(12Ce)O-2 layer
. where it bifurcated again as it entered the next Al2O3 layer. If the
loading was stopped during bifurcation, the specimen could be unloade
d prior to complete fracture. Although the residual stresses mere near
ly identical in all Al2O3 layers, crack bifurcation was observed only
when the layer thickness was greater than approximate to 70 mu m.