Al2O3-NixAl Based Cermets Prepared by in-situ Reactions

Abstract

-The cermets, consisting of approximately equal volume of alumina and intermetallic compounds (NiAI, Ni3AI) with 2 -7 % of porosity, have been prepared by in-situ reactions under uniaxial pressure according to the reaction scheme xAI 2 0 3 + 3NiO + 5AI => (x+I)AI 2 0 3 + 3NiAI. Relatively high crack resistance (5 -60x10 5 Jm-2 ), depending on the composition and heat treatment schedule, was evaluated using an indentation method. Cracks propagate along the intermetallicceramic interfaces owing to their low strength.