Synthesis and Characterization of Mg-Al-Zn Alloy-Based Bimodal Hybrid Composites with SiC and TiO₂

Magnesium and its alloys were highly reactive when it encountered with oxygen in air. The melting and casting processes were done in a protective atmosphere furnace. Initially, Al-Si/SiC/TiO₂ hybrid bimodal composites were prepared in the electric resistance furnace. Then, the developed hybrid composites used as a raw material along with pure Mg, Al and other alloying elements, in the Mg melting furnace to produce Mg-Al-Zn hybrid bimodal composites. Microstructural analysis depicted reasonably good distribution of the particles in the alloy metallic matrix. The SEM images showed the precipitation of β-Mg₁₇Al₁₂ along the α-Mg, which greatly affected the properties. To understand the nucleation and growth behavior of the precipitates, the cast samples were heat treated. The cast samples were solutionized for 24hrs at 420 °C followed by water quenching at 7 °C. After then the solution treated samples were aged for 8, 10, 12 hrs at 350 °C, 227 °C and 150 °C, respectively. The microstructure of aged samples was showed continuous and discontinuous precipitations of β-phase. Vickers hardness of solutionized sample was recorded 98 HV and aged at 350 °C, was 113 HV. On aging at 150 °C, the hardness was reduced to 104 HV, while aging at 227 °C, the hardness was found 116 HV. The tensile properties of solutionized sample showed better ultimate tensile strength (UTS) and yield strength (YS) value as compared to as-cast and aged conditions, and the values were 269 and 130 MPa.