Study On The Properties Of Extruded Wire Carbon Nanotubes Reinforced Aluminum Composites

0Vol%～5.3Vol%CNTs/Al composite wires were prepared with RotationalFriction Extrusion Processing(RFEP) was on the basis of the Friction Stir Processing(FSP) prepared carbon nanotubes reinforced aluminum matrix composite blocks. Theeffect of CNTs contents on macro morphology and microstructure of composite wireswere investigated. What’s more, the mechanical properties and the electricalproperties as well as thermal expansion properties were tested. The influence of CNTscontents on the composite properties was analyzed. Finally, the fracture mechanism,interface features and strengthen mechanism were studied.The results show that the composite wires formation is best when the volumefraction of CNTs is3.8%. The superficial cyclical peelings occured on the surface ofcomposite wires with increased the CNTs contents, but it can be removed bypolishing with sandpapers. CNTs were dispersed uniformly in the aluminum matrixand the compactness of the composite wires was superior to composite blocks by areascanning and microscopy observation on the longitudinal section of composite wireswith SEM. Some aligned carbon nanotubes were observed in composite wires withSEM and the uniform dispersed CNTs in the composite wires had an advantage overthe composite blocks.The addition of the CNTs significantly improves the micro-hardness andmechanical properties of the composite wires. With the same contents of CNTs, thecomposite wires were better than the composite bulks in terms of the tensile strength,but opposite to the ductility. When the addition of CNTs contents was5.3Vol%, theaverage micro hardness and tensile strength of composite wires was64.0HV and196.5MPa, an increase of1.7%,13.4%separately compared to the composite blocks,while the ductility and electrical resistivity decreased compared to the compositeblocks. The ductility and electrical resistivity was4%and4.381×10-8·m, adecreased of290%and35.1%separately compared to the composite blocks when theCNTs contents was5.3Vol%. The coefficient of thermal expansion (CTE) ofcomposite wires and composite blocks were reduced owing to the added carbonnanotubes. In addition, under the same contents of CNTs, the CTE of the compositewires had a little above the composite blocks. Finally, using RFEP methods can effectively improved the wettability betweenthe aluminum and carbon nanotubes. It would contribute improving the interfacestrength between aluminum matrix and reinforcement, the composite strength wouldbe enhanced. The strengthen mechanisms of carbon reinforced aluminum compositesincluded: CNTs beared the load, fine grain strengthened, dislocation strengthened andcoordination strengthened.