The microstructure of sigma 1140+SiC fibres

Transmission electron microscopy (TEM) studies have been carried out on ‘as-received’ SM1140+SiC fibres grown by CVD onto W wire cores. The transition between the W core and the SiC deposit is not abrupt in that there is a reaction zone present at the interface which actually consists of a silicide layer and a carbide layer. The SiC is subdivided into four concentric layers across the fibre diameter, each with a different morphology. The possible causes for the differences in the SiC morphology are discussed.