1993 Volume 34 Issue 10 Pages 930-936
Microstructure and fracture behavior of a SiC-whisker-reinforced Si3N4 composite have been investigated by transmission (TEM) and high-resolution electron microscopy (HREM) and micro-indentation fracture (MIF) technique. SiC whiskers (SiCw) are homogeneously dispersed in the Si3N4 matrix. Most of the SiCw have a β-type cubic structure with many twins and stacking faults. Amorphous layers of about 1 nm in thickness are observed at Si3N4 grain boundaries and Si3N4/SiCw interfaces. Cracks mainly propagate along the Si3N4 grain boundaries and Si3N4/SiCw interfaces in the indentation made at room temperature and 1200°C. Fracture toughening effects are due to multi-mechanism of crack deflection, bridging and microcracking.
