Assessing the Impact of Higher Quantity Density Mismatch Reinforcements and 3-Stepped T6 Treatment on Microstructure Dependent Properties of Al7075 Matrix Composite

There have been continuous efforts to study the load response behavior of composites made from low-density and naturally available reinforcements for structural applications. In the current research, an effort is made to cast a hybrid composite with natural reinforcement having a greater density in comparison to the other. One of the research projects focused on here is to determine the saturation level of the quantity of reinforcements and their effect on the mechanical properties of the composite. The granite powder particles (GrP) (2 wt. % fixed) and the particles of silicon nitride (Si ₃ N ₄ ) (3, 6 and 9 wt.%) have been dispersed in Al7075 alloy by double step stir casting technique to produce the three categories of composites. Microstructure showed that as the quantity of reinforcements increased, the level of agglomeration and porosity increased proportionately. The alloy and all composites were peak-aged to determine the peak-aging time and its corresponding VHN. The materials were further homogenized and subjected to three-step aging according to the optimal conditions derived from previous research. The findings demonstrated that the composite's hardness improved with the total number of reinforcements, while exhibiting the highest level of hardness. However, the specific strength of some composites was superior than the other. Also, the composite with Si ₃ N ₄ 6% displayed the best wear characteristics at both lower and higher load conditions as compared to the alloy and composites. The captured micrographs correlated with the test results to justify this fact.