EXPERIMENTAL-STUDY OF MORPHOLOGICAL STABILITY DURING DIFFERENT CONVECTION CONDITIONS

Morphological instabilities appearing at planar solid/liquid interface s have been studied under different convection conditions. The experim ents have been done with Ge crystals doped with Ga. In principal the w hole range from diffusion controlled growth to total mixing of the mel t has been covered. The results from two space experiments and from so me of the ground based runs, performed with little convection, fits we ll to the classical theory of Mullins and Sekerka. As the convection i ncreases the results deviate from the theory. The limit for the validi ty of the theory has been found. (C) 1997 International Astronautical Federation. Published by Elsevier Science Ltd.