Carbon nanotube (CNT) reinforced magnesium matrix composites: The effect of CNT ratio on their mechanical properties and corrosion resistance

In this study, mechanical properties and corrosion resistance of AZ61 and AZ91 magnesium matrix composites reinforced with 01, 0.2, and 0.5 wt% carbon nanotubes (CNTs) were investigated, detailly. CNTs have been successfully synthesized with 15–20 nm diameters by chemical vapor deposition (CVD) method and then, added to magnesium alloys by using the powder metallurgy (PM) technique. The composite compacts were consolidated by cold-pressing under 500 MPa pressure and sintered for 2 h at 500 °C under Ar atmosphere. The characterization studies of the unreinforced alloys and composites were carried out by scanning and transmission electron microscopes (SEM, TEM), electron dispersive spectroscope (EDS), Raman spectroscopy, and X-ray diffraction. The mechanical properties and corrosion behaviors of the composites have been compared with compression tests and potentiodynamic scanning (PDS) techniques, respectively. The results showed that the effect of CNTs reinforcement on strength increase was greater in AZ61 series samples than AZ91-based composites. The corrosion results of the presented study showed that the composites reinforced with lower CNTs (such as 0.1 or 0.2 wt%) and unreinforced alloys had better corrosion resistance than high CNTs (such as 0.5 wt%) containing structures. However, the most resistant structure to the corrosion for both AZ61 and AZ91 alloys were obtained in the composites reinforced with 0.2 wt% CNTs.