Superplastic deformation of Si3N4 based nanocomposites reinforced by nanowhiskers

A superplastic deformation of pre-sintered Si3N4-based nanocrystalline ceramics and Si3N4 nano-whisker reinforced composites has been investigated. Superplastic deformation tests have been carried out in the temperature range from 1500 to 1600°C under 56kN compression in nitrogen. During the tests, all nano-composites exhibited high rates of deformation (1.6-5.4×10-3s-1) corresponding to high activation energy in the range of 538-699kJ/mol. The composites enhanced by Si3N4 nano-whiskers exhibited the formation of anisotropic microstructure with anisotropic mechanical properties. The highest Vickers hardness ~19GPa and lowest coefficient of dry wear 0.39 was exhibited by the TiN-Si3N4 nano-composite.