Microstructure and mechanical properties of Al–Si–Cu–Fe alloy-based ceramic particle-reinforced nanocomposites and microcomposites and a modified model to predict the yield strength of nanocomposites

Abstract

The effects of volume fraction, size, and type of reinforcement particles on the microstructure and mechanical properties of Al–Si–Cu–(Fe) alloy matrix composites were investigated and an analytical model was modified to predict the yield strength of the particle-reinforced nanocomposites. Nano- and micro-particle-reinforced Al–Si–Cu-(Fe) matrix composites (N-AMCs and M-AMCs) were manufactured by adding two different types and sizes of reinforcement particles to Al–Si–Cu–(Fe) alloys at different volume fractions using a two-step stir casting method combined with a high-energy ball milling process and a high-pressure die-casting method. Microstructural analyzes of N-AMCs and M-AMCs were performed using SEM, EDX, and XRD. The Brinell hardness test and the tensile test were carried out to determine the mechanical properties of the N-AMCs and M-AMCs. The hardness of the N-AMCs and M-AMCs was continuously enhanced by increasing the volume fraction of the reinforcement particles, while the yield strength and ultimate tensile strength of the N-AMCs and M-AMCs were improved up to 1.5 vol.% and 4 vol.% of nano-particles and micro-particles, respectively. An analytical model was modified to predict the yield strength of N-AMCs by integrating the effective volume ratio of nano-particles into each strengthening mechanism. The results predicted by the modified model reached nearly 98% agreement with the experimental results up to 1.5 vol.% of the reinforcement particles. Nano-particles had a much greater effect on strengthening mechanisms compared to micro-particles.