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Lead lanthanum zirconate titanate (PLZT) ceramics were synthesized using a high energy mechanochemical processing technique, using tungsten carbide grinding vials and balls. The ceramic powders were prepared using the constituent oxide powders, which were subjected to high energy milling, without the use of any excess PbO in the starting composition. TEM studies revealed the formation of very fine particles of the order of 30 nm, due to the milling effect. Highly dense ceramics could be prepared via sintering which resulted in ultra-high strains in these piezoelectric samples of up to 0.25%, a value which has not been reported hitherto by any other known process. The effect of the reduction in particle size on the microstructure, mechanical and electrical properties of PLZT ceramics were studied and are discussed herein.

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The effect of temperature on fracture toughness of Timetal 834 titanium alloy plate under mode I and mixed mode I/III loading was investigated. Both mode I and mixed mode I/III fracture toughness values were initially found to increase as the temperature is increased from room temperature to 723 K. Beyond this temperature, both the fracture toughness values decreased up to 773 K and then showed a significant increase at 823 K. It was also observed that at room temperature, the fracture toughness under mixed mode I/III loading was higher than the corresponding mode I fracture toughness, whereas at 723, 748, and 773 K, the fracture toughness under mixed mode I/III loading was lower than the corresponding mode I fracture toughness, and at 823 K, the two toughness values were comparable. The results were explained on the basis of the occurrence of dynamic strain aging (DSA), change in fracture mechanism, and the nature of the deformation fields ahead of the crack tip under mode I and mixed mode I/III loading.