A model based on the population dynamics method（PDM） was used to analyze the solidification behaviors of the Al-12Zn alloy droplets produced by gas atomization

and effects of the initial gas velocity and the melting temperature on the solidification process of single droplet were approached. The results show that the droplet undergoes five different thermal stages

i.e. liquid phase cooling

nucleation and recalescence

grain growth

eutectic solidification

solid phase cooling. The solid phase fraction in a droplet with a given size can be decreased with increasing in initial gas velocity or in melting temperature at the same flight distance.