Effect of SiC content and milling time on the hardness and compressive strength of A380-based composites

The A380 alloy is generally preferred for automotive and structural applications owing to its superior castability; however, its use in high-load applications is limited by its mechanical properties. Powder metallurgy and the addition of ceramic nanoparticles offer a potential pathway to overcome these difficulties. In the present work, the synergistic effect of milling time (3, 6, 8, 10, and 12 h) and SiC nanoparticle content (0, 0.5, 1, and 2 wt%) on the microstructural evolution and mechanical response of A380-based nanocomposites was systematically investigated. The consolidated nanocomposites were produced by hot pressing at 510 °C under 50 MPa. The results indicated that a milling time of 10 h was optimal for producing a balanced particle size and a cold-welding effect. The addition of 0.5 wt% SiC and 10 h of milling time produced the highest mechanical properties among the nanocomposites processed in the present work, with a micro-Vickers hardness of approximately 80 HV and a compressive strength of approximately 282 MPa. However, excessive addition of SiC nanoparticles (>0.5%) and milling time (>10 h) resulted in nanoparticle agglomeration and inferior densification, leading to reduced mechanical response. The present work established a specific processing condition for optimizing the hardness and strength of hot-pressed A380-based nanocomposites.