Since Clegg et al 1 were successful in producing weak interfaces in laminated ceramic composites to obtain a noncatastrophic failure, several studies were done presenting ceramics with laminar structures as an effective alternative to overcome the typical brittleness of monolithic ceramics, to avoid catastrophic failure, to modify the crack path, and to increase fracture toughness. One approach widely used for ceramic laminates is to generate compressive residual stresses in layers due to different coefficients of thermal expansion (CTE), considering interfaces with strong adhesion. The idea is to achieve high levels of compressive stresses in these layers to control or oppose crack propagation, activating toughening mechanisms as crack arresting, crack bifurcation, and microcracking. Thus, it is possible for laminates to enhance fracture toughness and to absorb more energy during failure, compared to reference monolithic ceramics. 2-11. Another way to enhance toughness in laminates is to produce weak interfaces or layers to cause crack deflection. This behavior strongly depends on the fracture energy and Young's modulus of weak and strong layers of the composite. The volume fraction of pores and the pore interaction have an important contribution to ensure that crack continues

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The mechanical performance of ceramic matrix composites (CMC) is strongly related to the properties of the reinforcement. In case of the polycrystalline alumina Nextel® 610, these are dominated by the grain structure of the fiber. Within this study we show, that the surrounding matrix material and the processing conditions exert a high impact on the microstructure of the fibers. Therefore, different matrices and manufacturing methods can result in different fiber structures and performances.

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