| As a model experiment, Cu powders were ball-milled in a tumbiling mill in order to investigate the morphological evolution of ductile metal powder during mechanical alloying. The change of particle morphology was studied by microscopic observations. The particle morphology of Cu powders changed from dendritic particles of feed metals to disk-shaped particles, and then to globular purticles, which was similar to the observation during mechanical alloying of the premix of ductile intemetalic systems. It was found that the morphological change was due to the pure mechanical effect rising from collsions between the tools and powders. The globular particles were formed by the characteristic agglomeration of disik-shaped particles, that is, enclosure, folding, infolding and file-up process. It was also found that the globular particies coarsened by agglomeration and/or by continuous wrapping of the disk-shaped particles. |
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