Analytical investigation of grain boundaries of compressive deformed Al-doped sintered β-SiC

Series of analytical investigations were carried out to study the effect of deformation process at grain boundaries of Al-doped β-SiC (β-SiC[Al]). Three specimens, as-sintered, annealed and compressed β-SiC[Al] specimens were provided. Grain boundaries were observed by a high-resolution transmission electron microscope (HRTEM) and analytically investigated by energy dispersive X-ray spectroscopy (EDS) also electron energy loss spectroscopy (EELS) attached on a scanning transmission electron microscope (STEM). Glass phases Al-Si-O were commonly observed from the grain boundaries of the as-sintered specimen. It was also analyzed by EELS measurements that the amorphous phases were occasionally modified to form the fourfold coordinated aluminum-oxide by the compressive deformation. On the other hand, there were little traces of Al and O atoms observed from annealed specimen which suggests the vaporization of amorphous glass phase from the grain boundaries, due to the elevated temperature.