PREPARATION OF NIAL TOUGHENED AL2O3 BY VACUUM HOT-PRESSING

Composites of Al2O3-NiAl containing up to 50 vol.-%NiAl were prepared by vacuum hot pressing at 1450 degrees C to give Al2O3-NiAl material o f > 98% theoretical density. The resulting composites were characteris ed in terms of hardness, strength, and toughness. For the 50 vol.-% co mposition, the hardness had deceased by 50% from the value for alumina ceramic, the strength increased by 60%, and the fracture toughness in creased by 160%. The increased toughness is mainly attributed to crack deflection mechanisms of toughening, and the strengthening effect to grain refinement. (C) 1996 The Institute of Materials.