Nonequilibrium effects during the ledgewise growth of a solid-liquid interface

L. M. FABIETTI; R. K. TRIVEDI

METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE

SPRINGER

Lugar: Berlin; Año: 1991 vol. 22 p. 1249 - 1258

1073-5623

Directional solidification studies have been carried out in the napthalene-camphor system in which the interface advances through the formation and motion of ledges. Growth conditions have been varied so as to characterize both the planar interface growth and the condition for the instability of the planar interface. It is found that the mechanisms of planar interface instability and the subsequent morphological development of the interface depend significantly on the crystallographic orientation of the interface. Appreciable interface kinetics effects are present during the growth of a planar interface, and experimental studies have been designed to quantitatively evaluate the nonequilibrium conditions at the interface. These nonequilibrium effects for the napthalene-camphor system have been determined experimentally and have been characterized by two response functions that describe the interface temperature and the interface composition in the liquid under nonequilibrium conditions. The interface kinetic law is found to be exponential, indicating that the growth of the interface occurs through the process of nucleation of new layers.