Copper-Graphite Composite Wire Made by Shear-Assisted Processing and Extrusion

Abstract

Copper-graphite composites wires are manufactured by a novel friction stir processing named Shear-Assisted Processing and Extrusion (ShAPE). Two types of precursors have been prepared respectively: a blend of copper and graphite powder; solid copper cylinders having pre-drill holes filled with graphite powder. The precursor material was consolidated and extruded in one step by ShAPE. Up to 800 mm long defect-free wires were produced. The metallographic inspection on both transverse cross-section and longitudinal cross-section confirms the good integrity of the ShAPE Cu-graphite wires. Energy dispersive spectroscopy and electron backscatter diffraction indicate the graphite particles were reduced to sub-micro size and uniformly dispersed in the copper matrix. The ultrafine graphite particle inhibits the grain growth thus improving the hardness. The processing temperature is below 550 °C which is much lower compared to conventional manufacturing methods.