Effect of processing on the fracture characteristics of a 6092 Al composite reinforced with SiCp

The evolution of microstructure and mechanical properties of a 17.5 vol.% SiCp reinforced 6092 Al composite has been studied as a function of post-fabrication processing. It has been found that control of particulate distribution, matrix grain and sub-structure, and the matrix precipitate state can be utilized effectively to optimize strength-toughness relationships in these composites. Depending on the specific microstructural condition, the composite can display a wide range of properties ranging from strong, brittle behavior with K-controlled failure on the one hand, to a soft, tough behavior showing slow, stable crack growth with a steep J(R)-curve on the other hand. This demonstrates that by appropriate microstructural control, substantially larger intrinsic toughenesses may be obtained in Al-SiCp composites than previously thought.