Optimization of Stir Casting Variables for Production of Multiwalled Carbon Nanotubes: AA7149 Composite

Combining liquefied metals with multiwalled carbon nanotube-aluminium alloy 7149 composites enables the creation of intricate designs and mass production was manufactured using mechanical stir casting, thixoforming, and T6 heat treatment. Taguchi with two factorial levels was chosen to investigate the optimum parameter and affect variables such as carbon nanotube concentration, magnesium wettability, and ring mechanical stir duration were used in addition to a robust design of experiments. The response variables were the S/N ratio, hardness, and ultimate tensile strength. The fourth DOE run resulted in an optimised nanocomposite with 107.8 HV hardness and 278.1 MPa tensile strength that contained 0.75 wt.% magnesium and 1% multiwalled carbon nanotube and stirred time of 10 minutes. The as-forged AA7149 alloy had a lower hardness value (76.3%) but a higher ultimate tensile strength value (108.4%). It was demonstrated that combining thixoforming and heat treatment improves the mechanical properties of multiwalled carbon nanotube produced under mechanical stir casting conditions.