Tribological and Mechanical Properties of Al(Cu)/MWCNT Nanocomposite Prepared by Mechanical Alloying and Hot Extrusion

Abstract

The bulk Al–Cu-multiwall carbon nanotube (MWCNT) nanocomposite was prepared using mechanical alloying (MA) and hot extrusion processes. Al–4 wt % Cu powder mixture was first milled for 20 h to form the nanostructured Al(Cu) solid solution. The MWCNT was then added to the Al(Cu) powder mixture and further milled for 5 h. X-Ray Diffraction (XRD) and Differential Thermal Analysis (DTA) were performed to study the phase transformations during mechanical alloying and hot extrusion. Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) were also employed to study the samples microstructure. Mechanical properties of the bulk Al(Cu)/CNT nanocomposite were also studied using room and high temperature compression and wear tests. The results showed that after 20 h of mechanical alloying, a supersaturated Al(Cu) solid solution with the average grain size of 25 nm was achieved. Homogenous distribution of CNTs in the Al(Cu) supersaturated matrix was obtained. CNTs retained their tubular structure after 5 h milling time. Hot extrusion process at 550°C also led to the formation of bulk samples with nearly full density. The average yield and compressive strength of the Al(Cu)/CNT nanocomposite were found to be around 450 and 590 MPa at room temperature. The bulk nanocomposite showed suitable thermal stability by keeping its strength up to 300°C.