Effect of copper concentration on the structure of intermetallics and graphite additives of Al-Cu/C powder composites

The structure of hypo-eutectic and eutectic Al-Cu/C powder composites, as well as the powders with composition in the region of equilibrium Al4Cu9 phase, were studied using X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and nuclear magnetic resonance (NMR) after high-energy ball milling of Al and Cu elemental powders with 5 wt.% of graphite additives and heat treatment at the temperature of 500 degrees C. Mechanical energy dose transferred into the powder composites during milling for 8 h was estimated to be 32 kJ/g and leads to the formation of the metastable disordered bcc-Al4Cu9 phase (A2 structural type) in a wide composition range. Effect of copper concentration on the peculiarities of its structure, chemical composition and the possibility of A2 -> D8(3) first range ordering after heat treatment has been examined. Graphite additives structure evolution after milling and heat treatment of copper-rich Al-Cu/C powder composites was also specified.