マグネシアの高温クリープ特性に及ぼすSiC微粒子の影響

抄録

Compressive creep experiments have been conducted with SiC/MgO nano-composites to understand the effects of SiC particles on the creep behaviors of MgO at high temperatures. The ranges of temperature and stress employed for the deformation studies were 1300°-1500°C and 5.8-40MPa, respectively. TEM and SEM observations were carried out to characterize the microstructures of crept specimens. Analyses of the stress exponents, activation energies and microstructures indicate that specimens with more than 10vol% SiC crept through grain boundary sliding which was accommodated by dislocations moving at the regions of grain boundaries. For the specimens with less than 5vol% SiC, the creep was controlled by dislocations moving between SiC particles. The obvious decrease in creep rate for nano-composites were mainly due to the retarded dislocation movement and the restrained diffusion flows by fine SiC particles dispersed uniformly within MgO matrix.