Crystallization Induced Sub-Grain Boundaries in Silicon Nitride

Abstract

The morphological , structural and chemical nature of internal interfaces in silicon nitride beta grains have been examined. Such interfaces or grain boundaries are produced as a result of the growth of the beta phase into an amorphous or glassy phase. This crystallization of the amorphous phase results in a topotactic type growth on the pre-existing crystalline phase. The crystallization of the glassy phase is interpreted in terms of classical crystal growth interface roughness models. The resulting interface that forms appears to behave in a self-similar manner as it maintains the same facets of the original grain and there are significant chemical changes across this interface as well. The collective nature of these observations suggests that the growth of the beta grains associated with the crystallization of a glassy phase, may fall into the general category of “Chemically Induced Grain Boundary Migration” (CIGM).The implications of identifying this phenomenon as a possible governing behavior in the microstructural evolution of silicon nitride are also discussed.