Synthesis, characterization, and mechanical properties of Al-Zn-Mg alloy-based hybrid metalmatrix composites reinforced with Si3N4/TiB2 particles processed through stir casting technique

In this study, the microstructural and mechanical properties of Al-Si3N4/TiB2 hybrid reinforced composites are examined. The aim is to investigate the impact of a novel combination of reinforcements (Si3N4/TiB2) on the mechanical behavior of hybrid metal matrix composites (HMMCs). The composites are produced by adding a fixed amount of Si3N4 (4 wt.%) and 2, 4, and 6 wt.% of TiB2, respectively, into molten AA7075 aluminum alloy using a liquid state stir casting process. The physical and mechanical properties of fabricated HMMCs are determined through the measurement of density, porosity, tensile strength, Brinell hardness, flexural, and impact strength. The microstructural study of HMMCs reveals a consistent distribution of microparticles within the matrix. Evidence of reinforcement particles in the HMMCs is confirmed through field emission scanning electron microscopy with energy-dispersive spectroscopy and X-ray diffraction analysis. The fabricated HMMCs with 4 wt.% Si3N4 and 6 wt.% TiB2 particulates demonstrated the greatest strength among others. The ultimate tensile strength, Brinell hardness, and flexural strength are improved by 59.36%, 95.59%, and 49.33%, respectively, compared to the base Al-Zn-Mg alloy. However, the increment in strength of HMMCs comes with the tradeoff of reduced ductility and impact resistance measured through the percentage elongation and energy absorbed by the samples.