The influence of interfacial reactions on the fracture toughness of TiAl2O3 interfaces

The effect of interfacial reactions on the fracture toughness of the bond between a reactive metal, Ti, and a relatively stable oxide αAl 2 O 3 , was studied for heat treatments at different temperatures. The microstructure, chemistry and fracture toughness of the interfaces were characterized using transmission electron microscopy and a continuous microscratch test. The formation of intermetallic compounds resulted in a deterioration in the interfacial fracture toughness, relative to an unreacted interface. The decrease in fracture toughness was related to the presence along the interface of a brittle intermetallic phase and cavities. The cavities were produced as a result of the volume change and the oxygen released during the formation of intermetallic compounds at temperatures of 600°C and above. The strongest interface exhibited little if any reaction between the Ti and the Al 2 O 3 .