Investigation of microstructure, mechanical properties and fracture behaviour of AA8011/TiB₂ composites for...

This study investigates the microstructure, mechanical properties, and fracture behaviour of AA8011 aluminium matrix composites reinforced with TiB₂ particles. The composites containing 0, 3, 6, and 9 wt% TiB₂ were fabricated using the stir casting technique under optimized processing conditions. Structural and phase characterization were carried out using X-ray diffraction (XRD), while microstructural evaluation was performed through scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Mechanical behaviour was assessed by tensile and Vickers microhardness testing. The XRD results confirmed the presence of aluminium matrix and TiB₂ reinforcement phases without the formation of undesirable intermetallic compounds, indicating good chemical stability during processing. Density analysis revealed improved densification and reduced void content with increasing reinforcement percentage. Mechanical characterization showed progressive enhancement in tensile strength and hardness with the addition of TiB₂ particles, although ductility decreased at higher reinforcement levels. Microstructural observations demonstrated relatively uniform particle distribution and grain refinement, while fractographic analysis indicated a transition from ductile fracture in the base alloy to mixed ductile-quasi-brittle fracture behaviour in the reinforced composites. The results demonstrate that TiB₂ reinforcement effectively improves the overall mechanical performance of AA8011 aluminium composite.