Influence of In Situ Titanium Diboride Particulate Reinforcement on Mechanical Properties of Aluminum-Silicon Based Metal Matrix Composites

摘要

Aluminum-silicon alloy reinforced with titanium diboride particles (2 wt.%, 5 wt.%, and 7 wt.%) were successfully synthesized using a stir-casting method. Dipotassium titanium hexafluoride and potassium tetrafluoroborate salts were used to obtain an in situ titanium diboride phase in a molten matrix. These in situ composites have shown significant improvements in their mechanical properties, such as Young's modulus, yield strength, ultimate tensile strength and micro-hardness compared to the base alloy. X-ray diffraction patterns of the obtained metal matrix composites confirms the formation of titanium diboride particles. The microstructures were studied using field-emission scanning electron microscopy. The in situ-formed titanium diboride particles were found uniformly distributed with good interfacial bonding. Reinforcement particles were predominantly in cubical, spherical, and hexagonal shapes. The fracture surfaces of the composites contained fine dimples, and some microcracks were generated and propagated through cleavage or facet zones.