Published online by Cambridge University Press: 25 February 2011
Superplastic Sialons have very fine microstructures containing submicron grains and transient phases. Fabrication of these materials requires processing at relatively low temperatures. As a result, different stages of phase evolution, including oxide melt formation, nitride dissolution, a′ and β′-SiAlON nucleation, and Sialon growth with and without concurrent deformation, can be captured in the development of these materials. In addition, only very low flow stresses are required for large strain deformation which, in turn, allows grain boundary and liquid phase processes to be manifested in the deformation behavior. Highlights of investigation of these aspects are reviewed here to shed light on the phase relationship, microstructural development, and grain boundary characteristics of silicon nitride.