Electric-field-induced crack growth behavior in PZT/Al2O3 composites

Hard lead zirconate titanate (PZT) and PZT/Al2O3 composites were prepared a nd the alternating electric-field induced crack growth behavior of a precra ck above the coercive field was evaluated via optical and scanning electron microscopy. The crack extension in the 1.0 vol% Al2O3 composite was signif icantly smaller than that in monolithic PZT and the 0.5 vol% Al2O3 composit e. Secondary-phase Al2O3 dispersoids were found both at grain boundaries an d within grains in the composites. A large number of dispersoids were obser ved at the grain boundaries in the 1.0 vol% Al2O3 composite. It appears tha t the Al2O3 dispersoids reinforce the grain boundaries of the PZT matrix as well as act as effective pins against microcrack propagation.