Microstructure and Toughening Mechanisms in an Al2O3 Ceramic Matrix Composite Dispersed with LiTaO3 Particles
LiTaO3 (5--25vol%) dispersed Al2O3 matrix composite (LTA) with high relative density were fabricated by hot pressing at 1300°C. The microstructure and mechanical properties of the composite were studied. The main results are as follows: Al2O3 was found to be phase compatible with piezoelectric LiTaO3 during high temperature sintering process. The relative density of the LTA composites was greatly improved by the addition of LiTaO3 particles. Domains are clearly discerned in LiTaO3 grains in the LTA composite, confirming that LiTaO3 particles remain ferroelectrics. 90 degree domains were observed in LiTaO3 grains constrained strongly by Al2O3 matrix, which has never been found in LiTaO3 single crystal before. Comparing with those of pure Al2O3, sintered at same temperature (1300°C), both the flexural strength and the fracture toughness of the composites are all enhanced. Domain switching is suggested as a new toughening mechanism in the ferroelectric particles dispersed structural ceramics.
Young-Jin Kim, Dong-Ho Bae and Yun-Jae Kim
Y. Zhou et al., "Microstructure and Toughening Mechanisms in an Al2O3 Ceramic Matrix Composite Dispersed with LiTaO3 Particles ", Key Engineering Materials, Vols. 297-300, pp. 2551-2556, 2005