Time-dependent interface stability during directional solidification of a single phase alloy (I) Comparison with experimental results

In situ observation on the interface instability and the solute transport boundary layer in front of the solid/liquid interface is carried out during the directional solidification of SCN-1.5 at% Salol. Based on this, and in combination with the experimental results of SCN-1.1 wt% Eth, SCN-0.43 wt% C152 alloys, the morphological instability of a solidifying planar interface is systematically investigated during directional solidification with and without the convection. It is found that the interface stability analysis in our previous paper describes correctly the time-dependent evolution of interface instability. Both the incubation time t_i for instability and the incubation time t_b for breakdown of the planar interface can be determined from the time-dependent instability solution, and the convection obviously shortens the incubation time t_i for instability and the incubation time t_b for breakdown of the planar interface. The steady-state instability solution overestimates the unit amplitude developing rate by an order of magnitude, as compared to the experimental value, while the time-dependent solution underestimates the experimental result.