Tensile Ductility of Liquid-Phase Sintered β-Silicon Carbide at Elevated Temperature

摘要

Nano-grain sized β-SiC was prepared with various additives by hot-pressing in Ar. The relative bulk densities were more than 95 %. As-sintered bodies were composed of equiaxed grains. Amorphous phase existed at grain boundaries in each as-sintered material. Tension tests were performed at the initial strain rates from 3 × 10~(-4) s~(-1) to 3 × 10~(-5) s~(-1) at 1973 - 2048 K. Tensile elongation more than 60 % was obtained. In deformed specimens, grain growth was observed. However, anisotropy of grain growth was not observed. The grain-boundary phase was vaporized during tension tests. The β phase of SiC was stable even after tension test. Therefore, critical deformation mechanism was thought to be grain-boundary sliding. Deformation behavior was influenced by the grain-boundary phase.