Abstract:A synthetical mathematic model describing the collision coarsening of the dispersion droplets in the solidification process of monotectic alloys has been put forward. Numerical simulation has been carried out for Zn-pb alloy. It was found that when the average droplet radius is smaller than 1 μm, Brownian ripening plays important role and the influence of gravity level on the coarsening rate of droplet is very weak. Otherwise, gravitational and Marangoni coagulations are the main factors of collision coarsening.

Key words: Zn-Pb alloy solidification collision coarsening