Work-of-fracture of SiC-whisker reinforced Al2O3 composite at elevated temperatures

The work-of-fracture of a monolithic Al2O3 and a SiC whisker reinforced Al2O3 composite was evaluated from room temperature to 1270 degrees C at which both the materials maintained elasticity from a macroscopic view point. The work-of-fracture of the composite increased with elevating temperature, while that of the Al2O3 showed only a slight increment in this range of temperature. The increment of the work-of-fracture was reversibly proportional to the 2nd power of Delta T which was temperature difference from 1350 degrees C. This is the reason a compressive residual stress perpendicular to a whisker/matrix interface decreased with elevating temperature, and then the stress relaxation enhanced the toughening of the composite caused by the pulling-out of the SiC whiskers.