Octapod-shaped, nanosized, amorphous precipitates in a crystalline ferrite matrix

Abstract

The development of uniquely octapod-shaped nanosized amorphous silicon-nitride precipitates in a ferrite matrix was observed upon nitriding of Fe-4.5at.%Si alloy. The legs of the amorphous precipitate are oriented along 1 1 1-directions of the ferrite. The occurrence of such peculiarly shaped amorphous silicon-nitride precipitates, which experience a volume misfit of more than 100% with the surrounding ferrite, was attributed to precipitate growth influenced by long-range diffusion within the evolving highly anisotropic stress field around the developing precipitates after nucleation. © 2013 Copyright Taylor and Francis Group, LLC.