Deformation of dendrites by fluid flow during rapid solidification

Mechanical interactions between dendrites and their parent melt are normally considered insignificant. However, during rapid solidification the twin conditions of high How velocities and very fine dendrites required to produce mechanical damage may exist. A model for the skin stress resulting from flow around a family of realistically shaped dendrites is presented. We find that within a narrow undercooling range about a local minimum in the tip radius, mechanical deformation is likely. Experimental evidence is presented from a Cu-3 wt.% Sn alloy undercooled by 73 K which appears to show evidence of a deformed dendritic structure. (C) 2001 Elsevier Science B.V All rights reserved.