Published online by Cambridge University Press: 31 January 2011
The mechanisms of steady-slate creep in compression in a sintered SiC produced via sintering of β-SiC powders derived from gaseous reactants in a plasma are have been determined from (1) kinetic data within the ranges of temperature and constant stress of 1770–2020 K and 17–208 MPa, respectively, and (2) the results of transmission electron microscopy (TEM) and other microbeam characterization techniques. The stress exponent was 2.06 ± 0.04; the values of activation energy were 913 ± 13 and 630 ± 14 kJ/mol above and below, respectively, a knee of ∼∼ 1920 K. Gliding dislocations and B4C precipitates, which developed within the grains during creep, and their interaction were the dominant microstructural features of the crept material. Apparent nonmechanical pinning of the dislocations at the precipitates indicated that the latter attracted the dislocations rather than acting as classical obstacles to dislocation movement. A synthesis of this information leads to the conclusion that the controlling creep mechanisms in this SiC were grain boundary sliding accommodated by grain boundary diffusion at T < 1920 K and lattice diffusion at T > 1920 K. The parallel mechanism of dislocation glide also contributed to the total strain.