Microstructural characterization and mechanical properties of TiB2 reinforced Al6061 matrix composites produced using stir casting process

Particulate reinforced aluminum matrix composites are the most promising alternative for applications where the combination of high strength and ductility is essential. In the present study, Al-TiB2 composites with different amounts of reinforcement (3, 6 and 9 wt%) were fabricated using stir casting method. after optimizing the process parameters such as preheating temperature, stirring speed and duration. Microstructure, mechanical properties and the fracture surfaces of tensile specimens were studied. Optical microstructure of prepared composites showed a uniform distribution of reinforcements in matrix and also SEM analysis demonstrated the strong bonding between matrix and reinforcements which is the consequence of improved wettability due to K2TiF6 addition and preheating of TiB2 powder before adding to the melt. In addition to microstructure uniformity, the tensile strength of composites was improved with increasing the volume fraction of TiB2 reinforcement particles without any significant decrease in elongation. SEM micrographs from fractured surfaces of tensile specimens approved that the ductile fracture is occurred in Al6061 alloy in all of prepared composites through nucleation and coalescence of micro-voids.