Densification, β→α transformation and nanoindentation studies of SiCW/SiC composites fabricated by spark plasma sintering
Polycarbosilane-derived SiCW/SiC composites were processed by spark plasma sintering (SPS). Whisker-reinforced composites were densified with faster rates to a maximum density of ~ 98%, indicative of positive influence of SiC whiskers on densification behavior. Electron backscattered diffraction study confirmed the presence of twins in the sintered composites. A misorientation angle of 60° resembled to {111} twin boundaries. Twin density was found to increase with SPS temperature and whisker contest. Twin boundaries were found to be responsible for β→α SiC transformation. Hardness increased sharply with the increase in whisker content and a decrease in grain size. The maximum hardness of 23.4 GPa was observed in 20% SiCW/SiC composite. Nanoindentation study reflects the positive effect of whiskers on hardness and elastic modulus.