Light ion irradiation creep of SCS-6 silicon carbide fibers in the temperature range 450--1100 C

Creep tests were conducted in torsion on Textron SCS-6 trademark silicon carbide (SiC) fibers during irradiation with light ions in the temperature range 450--1100 C up to doses of 0.06 dpa. The fibers, produced by chemical vapor deposition (CVD), should be representative of a SiC/SiC composite matrix produced by chemical vapor infiltration (CVI). For temperatures between 450 and 600 C, the irradiation creep curves were characterized by long lasting strain transients during which the creep rate slowed down before reaching approximately steady state values. On a decrease in temperature the creep rate increased. For temperatures between 900 and 1100 C, the transient creep regime was negligible. The creep rates reached constant values shortly after starting the irradiation and increased with temperature. The activation energy was E = 0.55 ± 0.15 eV. The results are discussed in terms of concentration and mobility of point defects and the change of these quantities with temperature