Dendritic array growth in the systems NH4Cl-H2O and [CH2CN]2-H2O:: the detachment of dendrite side arms induced by deceleration

Dendrite array adjustments have been measured in transparent material during the transient conditions attending deceleration. There is considerable hysteresis between the responses of dendrite tip radii and primary spacings to velocity changes and this promotes the dissolution of the necked regions, where side arms attach themselves to primary stems. Simple analyses of the transient dendritic dimensions are offered to illustrate a detachment mechanism. This phenomenon is relevant to the development of an equiaxed zone in metal castings. (C) 2002 Elsevier Science B.V. All rights reserved.