THE EFFECTS OF MICROSTRUCTURE ON THE MECHANICAL-PROPERTIES OF AL2O3-NIAL COMPOSITES

In the present study, the room-temperature mechanical properties of Al 2O3-NiAl composites containing 0 to 100 vol.% NiAl are determined. The composites are prepared by attrition milling Al2O3 and NiAl powders t ogether followed by hot-pressing in vacuum. The Al2O3 and NiAl grains in the composites constrain each other's growth. Since the hardness of NiAl is lower than that of Al2O3, the hardness of the composites decr eases with the increase of NiAl content. The strength and toughness of the Al2O3-NiAl composites are higher than the values predicted by the rule of mixtures. The strengthening effect is mainly contributed by t he microstructural refinement. Because the Al2O3/NiAl interface is wea k, cracks propagate mainly along the interfaces. The fracture toughnes s is thus enhanced. (C) 1998 Elsevier Science S.A. All rights reserved .