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

Natural convective effects on dendritic primary spacing and morphology, in directional dendritic solidification of Al-Cu binary alloys, have been studied experimentally as a function of density gradient orientation in the interdendritic liquid relative to the gravity vector. Diffusion controlled experiments in a microgravity environment have been used as a reference. In a previous paper [Dupouy et al., Acta Met. 37 (1989) 1143], the convective effects in terms of segregations were predicted and analysed. In the present paper, morphological aspects are discussed: it is found that the development of lateral dendritic branches is strongly affected by the flow configuration.