Ductile Phase Toughening of Brittle Intermetallics

Abstract

AbstractOne method of imparting damage tolerance into intermetallic compounds is to introduce ductile particles in a fine uniform distribution. Systematic criteria are given as to the necessary requirements for such ductile phase reinforced systems. Two composite systems, Cr2Nb/Nb and Nb3Al/Nb were selected for further evaluation. Both microstructural evaluations as well as thermal stability were demonstrated in both systems. Small cracks introduced via micro-hardness indentations were measured as a function of precipitate size. In Cr2Nb/Nb the crack lengths decreased with increasing particle size which was explained through increasing effectiveness of ductile particles with minimum effective particle radii calculated at 6-10 μm. Larger particles along with poor ductile phase distributions led to lower damage tolerance in aged Nb3Al/Nb. By maintaining uniform ductile particle distributions, intermetallic compounds possessing superior damage tolerance have been demonstrated.