SIMPLE GEOMETRIC MODEL FOR ASSESSING WHISKER ORIENTATION IN AXISYMMETRICAL SIC-WHISKER-REINFORCED COMPOSITES

The nonuniform crystal structure of SiC whiskers complicates the interpretation of X-ray texture data collected from whisker-reinforced composites. A simple model for assessing whisker textures in alumina matrix composites which is able to account for the mixed polytype structure of SiC whiskers is discussed. Synchrotron X-ray radiation was used to quantitatively measure SiC whisker texture in hot-pressed and hot-forged Al2O3-SiC whisker composites. Pole figures of the 2.51 angstrom reflection ({111} cubic, (001) hexagonal) were obtained and compared to pole figures calculated from hypothetical whisker axis distributions describing the whisker orientation distribution within the axisymmetric composites. The X-ray data suggest that the degree of reinforcement phase texture in hot-worked specimens is dependent upon final specimen strain. The data also demonstrate that for conventionally hot-pressed composites the whiskers are angularly distributed about the compression plane, having an average orientation which does not approximate a two-dimensionally random distribution.