Nonstationary analysis of the macrosegregation during the solidification in the space of the system Ge-Ga

The redistribution of solutes in the system Ge-Ga solidified under weightlessness conditions was analyzed taking into consideration, in particular, the nonstationary characteristics of the solidification velocity. Experimental data obtained by other authors in a space mission were used. The evolution of the Ga concentration during the solidification is compared with predictions from 3 models, resulting in a better fit for the proposed model. It is concluded that the growing process is controlled by a diffusion mechanism in the liquid before a front moving at increasing velocity.