Evaluation of structure and morphology of aluminum powder particles milled at different conditions

Micron sized aluminum powder was milled together with different process control agents (PCAs) including ethanol, graphite and stearic acid for various periods of time. The morphology of powder particles was characterized quantitatively using an image processing program and optical microscopy (OM). Work hardening effect on final particles morphology was evaluated by a number of structural characteristics such as dislocation density and crystallite size calculated by the modified Warren–Averbach method. Normal distribution curves for three morphological parameters of Feret diameter, aspect ratio and roughness, were obtained. The results showed that the type of PCA used during the milling operation was much more effective parameter on morphology, dislocation density and crystallite size of powder particles in comparison with the milling time. The specimens with higher work hardening characteristics showed smaller Feret diameter and aspect ratio. Also, ethanol as a liquid PCA found to be more effective comparing with other solid PCAs.