LIGHT-ION IRRADIATION CREEP OF SIC FIBERS IN TORSION

Creep tests were conducted in torsion on TEXTRON type SCS-6(TM) silico n carbide (SiC) fibers during irradiation with 14 MeV deuterons for 45 0 degrees C, 600 degrees C and 800 degrees C. The fibers, produced by chemical vapor deposition (CVD), should be representative of the chemi cal vapor infiltrated (CVI) matrix of a SiC/SiC composite. SiC is know n to undergo irradiation induced swelling which occurs without an incu bation dose for temperatures below about 1000 degrees C [R.J. Price, J . Nucl. Mater. 33 (1969) 17]. Such swelling in SiC may mask the irradi ation creep strain in a tensile experiment, but plays a minor role in torsional creep tests. The torsional irradiation creep curves are char acterized by long lasting strain transients during which the creep rat e slows down before reaching approximately constant values. The steady state torsional creep rate (gamma)over dot(s) exhibited a linear depe ndence on stress and particle flux and it decreased when the temperatu re was increased. The temperature dependence of (gamma)over dot(s) in the range 450-800 degrees C is similar to that of swelling for neutron irradiated SiC. (C) 1998 Elsevier Science B.V. All rights reserved.