NATURAL CONVECTIVE EFFECTS IN DIRECTIONAL DENDRITIC SOLIDIFICATION OF BINARY METALLIC ALLOYS - DENDRITIC ARRAY PRIMARY SPACING

This paper is concerned with the effect of natural convective patterns evidenced in a previous paper [Acta metall. 37,1143 (1989)], on the dendritic primary spacings. Primary spacings in normal gravity environment have been found to be much smaller than those measured in a microgravity environment, the latter being in good agreement with the diffusion controlled theoretical predictions. The scaling analysis of convective effects developed in the first paper allows us to propose a relationship, which gives the primary spacing as a function of the experimental parameters, in convective transport conditions of the solute in the liquid. This correlation is in good agreement with our experimental results, and those of the literature.