Microstructural observation of pressureless sintered boron carbide

Abstract

Boron carbide ceramics (B₄C) were pressureless sintered at the temperature ranging from 2108^o C to 2227^oC in a Ar atmosphere containing gaseous metal species such as Al and Si. The microstructure of the pressureless sintered B₄C was observed with a transmission electron microscope (TEM) equipped with STEM-EDS. Some small and dark contrasts were observed occasionally at the triple points in the bright field images of the B₄C samples, which were identified as tungsten compounds by the STEM-EDS analysis. Other minor impurities such as Al and Si were also investigated.