Effect of the Reinforcement Volume Fraction on Mechanical Alloying of AA2124 – SiC Composite

Abstract

Mixtures of AA2124 aluminum alloy powder and SiC particles at volume fractions of 10 vol.% and 20 vol.% were milled in a high energy planetary ball mill under an argon atmosphere, for times of 2.5h to 60 h, aiming to produce Al alloy-SiC nanocomposites. Optical microscopy (MO) and scanning electron microscopy (SEM) were used to evaluate the morphological and microstructural evolution of the powder composite, occurred during mechanical alloying. The crystallite size was determined using the Williamson-Hall method to analyze the X-ray peak broadening. It was observed that increasing the volume fraction of SiC, the mechanical alloying stages were accelerated: a finer composite powder was obtained at a shorter milling time as well as the morphology of the particles became more equiaxed. The XRD analysis showed the reduction of crystallite size of the aluminum alloy matrix with increasing milling time and that this effect is more pronounced with high volume fraction of SiC. The results show that the increase in the volume fraction of reinforcement particles increases the work hardening and fracture occurrence in the aluminum alloy powder during the milling, affecting the structural evolution of the composite.