Fractography of 3YPSZ/316L functionally graded composite subjected to indentation and flexural bending tests

In this paper, stainless-steel (AISI316L) and 3 mol% Y2O3-partially stabilized ZrO2 were used for fabrication of functionally graded material by spark plasma sintering. To make a temperature gradient in FGMs, a specific die configuration was utilized, which led to higher densification. In order to study the crack initiation and propagation behavior in the layered composites during bending and indentation tests, the section morphology of the layers was analyzed by optical microscopy and scanning electron microscopy. The results showed that cracks propagate through the PSZ matrix when there is no trace of steel. However, when cracks reach steel particles they grow around the particles and choose the interface of steel and matrix as a preferable route for propagation. Furthermore, the presence of small amounts of steel particles remained on the fracture surface, demonstrated that the steel particles can improve the fracture toughness of the composite.