TEM investigations of interfacial processes in SCS-6SiC/TiB2/Super α2 composites

Interfacial processes in SCS-6 SiC/TiB2/Super alpha(2) composites were investigated by means of analytical transmission electron microscopy (TEM). No reaction between the TiB2 coating and the carbon coating of the fibres can be found in the as-processed specimen. At the TiB2/matrix interface the TiB2 transforms into both a homogeneous layer and needles of TIE which are distributed in the matrix. This process takes place according to the reaction TiB2 + Ti = 2TiB. The TiB2 coating is consumed completely in the specimen heat treated at 900 degrees C for 64 h. At this time TiC and Ti3AlC form at the TiB/C-coating and the TiB/matrix interface, respectively. Prolonging the holding time at 900 degrees C, reaction layers thicken continuously following parabolic reaction kinetics. The paper additionally discusses the formation mechanisms of the reaction products. (C) 1999 Elsevier Science Ltd. All rights reserved.