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.