Optimization of Powder Preheating and Process Parameters on Hardness and Porosity of Al–CNT–Mg Composites through Powder Metallurgy Using the Taguchi–ANOVA Method

Abstract

Aluminum-based nanocomposites are promising lightweight materials for engineering applications due to their high specific strength. Powder metallurgy combined with Taguchi L27 experimental design and ANOVA was used to evaluate the effects of the powder thermal preconditioning temperature, mixing time, and compaction pressure on the hardness, density, and porosity of Al–CNT–Mg composites. Composites containing 0.5 wt.% Carbon Nanotubes (CNTs) and 0.5 wt.% Mg were processed through low-energy ball milling, powder thermal treatment, compaction, and sintering. These treatments were applied as surface preconditioning steps to improve the initial condition of the aluminum particles, reduce adsorbed surface species, and enhance Al–Al interparticle contact before compaction. The optimum conditions were achieved at a temperature of 200 °C, mixing time of 6 h, and compaction pressure of 280 MPa, with the highest hardness of 100.38 HV, density of 2.20 g/cm3, and lowest porosity of 3.32%. The ANOVA results showed that the thermal preconditioning temperature was the most dominant factor, contributing 64.42% to the increase in hardness and 84.03% to the decrease in porosity. These findings indicate that controlled powder thermal conditions can be an effective surface preconditioning strategy to improve the densification and mechanical performance of Al–CNT–Mg composites.