Production and dispersion stability of ultrafine Al–Cu alloy powder in base fluid

In the present investigation, high-energy milling was carried out to synthesize ultrafine Al–Cu alloy powder from elemental Al and Cu powder. Elemental Al and Cu powders were milled in a high-energy planetary mill at a speed of 300 rpm and at 10:1 ball to powder weight ratio. Milling was carried out for 50 h in wet condition to prevent undue oxidation and agglomeration. Powder particles were characterized by X-ray diffraction (XRD), particle size analyzer, scanning electron microscope (SEM), and transmission electron microscope (TEM). It is found from XRD that nanostructured Al–Cu alloy prepared by high-energy milling resulted in a grain size of around 6.0 nm and lattice strain of about 1.43%. It is also found that the average particle size is around 4.0 μm after 50 h of milling. TEM shows that particles are irregular in shape and their size is around 200–300 nm. To study the dispersion stability, alloy powders were dispersed in de-ionized water and then zeta potential were measured at different pHs. The zeta potential value of the Al–Cu dispersion increases numerically from 49.00 (pH 4.96) to −90.60 (pH 9.50) when oleic acid is added. It is evident from different zeta potential values that stability is improved by the addition of oleic acid into the dispersion.