FRACTURE MECHANISMS IN A STOICHIOMETRIC 3AL(2)O(3)2SIO(2) MULLITE

The mechanical behaviour from room temperature up to 1400 OC (strength , toughness, Young's modulus) of a 3Al(2)O(3) . 2SiO(2) dense mullite material containing 0.2 wt% alkali has been studied. Microstructure ha s been characterized by scanning electron microscopy (SEM) and transmi ssion electron microscopy (TEM). Toughness, bend strength and static Y oung's modulus have been determined from room temperature up to 1400 d egrees C. The influence of strain rate on fracture behaviour has been investigated and a correlation of the mechanical parameters to fractog raphic observations by SEM has been stated. A strong influence of load ing rate on microstructural modifications during fracture at 1300 degr ees C has been found.