J, Vicens et al./Aerospace Science and Technology 7(2003)135-146 液b整 Fig 3.(a) HRTEM image of the contact zone between CL(upper part) and tl (lower part). (b) Enlargement of the precedent zone showing the turbostratic carbon and SiC nanocrystals in TL. of Al and Mg. The carbon layer(100 nm) also contains fibres can vary slightly from one batch to another [36]. The oxygen. A very thin silica layer(20 nm) was found at the dark sublayer(TL)is characterised by an enrichment in CL/matrix interface oxygen and significant quantities of Mg and Al compared The following conclusions can be derived from all these to the fibre surface. The chemical nature of the carbon results obtained in Nicalon/YMAS or MLAS composites. units phase CL is confirmed by EDX The carbon layer The fibre surface is oxygen enriched compared with the contains also oxygen, silicon, magnesium and aluminium fibre core. This is in agreement with previous results which elements, however the silicon content remains low. The have clearly shown an enrichment in oxygen at the surface matrix close to the carbon layer exhibits an enrichment in of the fibres, although the chemical content of Sic Nicalon silicon. The transition layer appears as a diffusion zone forJ. Vicens et al. / Aerospace Science and Technology 7 (2003) 135–146 139 Fig. 3. (a) HRTEM image of the contact zone between CL (upper part) and TL (lower part). (b) Enlargement of the precedent zone showing the turbostratic carbon and SiC nanocrystals in TL. of Al and Mg. The carbon layer (∼100 nm) also contains oxygen. A very thin silica layer (∼20 nm) was found at the CL/matrix interface. The following conclusions can be derived from all these results obtained in Nicalon/YMAS or MLAS composites. The fibre surface is oxygen enriched compared with the fibre core. This is in agreement with previous results which have clearly shown an enrichment in oxygen at the surface of the fibres, although the chemical content of SiC Nicalon fibres can vary slightly from one batch to another [36]. The dark sublayer (TL) is characterised by an enrichment in oxygen and significant quantities of Mg and Al compared to the fibre surface. The chemical nature of the carbon units phase CL is confirmed by EDX. The carbon layer contains also oxygen, silicon, magnesium and aluminium elements, however the silicon content remains low. The matrix close to the carbon layer exhibits an enrichment in silicon. The transition layer appears as a diffusion zone for