SWELLING BEHAVIOR AND TEM STUDIES OF SICF SIC COMPOSITES AFTER FUSIONRELEVANT HELIUM IMPLANTATION/

Helium implantation was carried out on SiCf/SiC (CVI) composites up to doses of 2500 appm, at temperatures of 1175 +/- 50 K. In this paper t he swelling behaviour of the implanted bending bars is reported. A sig nificant differential swelling effect after the alpha-implantation was evidenced by the matrix jutting out with respect to the fibre ends, a t the side surfaces of the implanted zone. A similar fibre shrinkage t ogether with slight expansion of the matrix was already reported for n eutron irradiated materials. However, after alpha-implantation this ef fect is enhanced by an increased swelling of the beta-SIC matrix. Thes e data are discussed in relation to microstructural observations by Tr ansmission Electron Microscopy. (C) 1998 Elsevier Science B.V. All rig hts reserved.