Abstract Gas atomization experiments are carried out with Cu-20wt%Co alloy. Powders with a fine dispersion of the Co-rich particles are obtained. A model has been developed to describe the solidification process of the atomized drops. The kinetic details of the microstructure evolution in the drops are calculated. It is indicated that the numerical results have a good accordance with the experimental ones. The microstructure development during the liquid-liquid decomposition is a result of the concurrent action of the nucleation, the growth of the minority phase droplets, the collision coagulations between the droplets and the spatial separation of phases. A bigger drop achieves a lower cooling rate and a lower nucleation rate of the minority phase droplets. It exhibits, therefore, a coarse Co-rich particle microstructure.
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