Microstructure, Densification, and Compressive Properties of Al-CNT Metal Matrix Composites Fabricated by Flake Powder Metallurgy and Conventional Sintering Process

In this study, flake-like aluminum reinforced with different volume fractions of carbon nanotubes (CNTs) was prepared by mechanical milling and conventional sintering at 600 °C under argon atmosphere. To this end, X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were used to investigate the microstructure of the powders and bulk composite samples. Compression tests were also conducted on the samples to determine their mechanical properties. The obtained results showed that flake powder metallurgy was an effective method for dispersing CNTs on the surface of Al particles. At the sintering temperature of 600 °C, the highest relative density was obtained for the composites. The compression test results showed that the amount of CNT less than 2 vol. % caused an increase in the yield and compressive strength values as well as Young's modulus. However, the values of the mentioned factors decreased in higher volume percentages. Finally, the contributions of the load bearing and grain size refinement strengthening mechanisms on the final strength of the composites were addressed.