Dynamics of banded structure formation in rapid solidification

Abstract

Motivated by widespread experimental observations of the ‘‘banded structure’’ in rapidly solidified alloys, we have studied numerically by Green’s-function method the dynamics of the planar interface under rapid directional solidification condition. We find that the formation of this structure can be explained and partially characterized quantitatively in terms of highly nonlinear ‘‘relaxation oscillations’’ of the interface whose spacings are controlled by latent heat diffusion but not by the thermal gradient. A comparison with experiment is presented for Al-Fe alloys.