Chemical Physics and Dynamics of Surfaces – Dynamics of interfaces – Control of solidification microstructures by feedback loop using a network of laser spots

Directional solidification in thin samples of a eutectic alloy CBr4-C2Cl6. The solid is two-phase, composed of two different crystalline phases α and β. Diffusive dynamics are at the origin of the periodic alternation of the lamellae of the two phases. A “laser multispot” device (Arryx, Bioryx) is used to locally heat the forehead and cause controlled disturbances.

(S. Akamatsu, K. Y. Lee, W. Losert, J. Cryst. Growth, 289, 331-338 (2006)). Collaboration with W. Losert, UMD.

The growth rate is downward (the film is accelerated), aligned with the thermal gradient axis (liquid at the bottom, solid at the top, the solid-liquid interface is seen in profile as a black line).