作者: V. Laxmanan
DOI: 10.1016/0022-0248(86)90103-X
关键词:
摘要: A simple model describing “constrained” growth of an “array” cells or dendrites in a binary alloy melt, the presence imposed positive temperature gradient liquid, has been presented. The dendrite cell tip radius is calculated using marginal stability criterion proposed by Langer and Muller-Krumbhaar. results obtained are compared with predictions deriving from two other approaches: first approach adopts “ad hoc” assumption “minimum undercooling” at tips, second based on closely similar Trivedi. It shown that all three approaches predict radii, differing no more than 30%. All yield following relationship between radius, rt, conditions: σc = A(1 − s) where 2lcDL/Rr2t s DLGL/RΔT0 dimensionless parameters, constant whose value depends used to determine radius. Recent experimental data succinonitrile-acetone system have be good agreement these predictions. These comparisons also indicate during dendritic alloy, 1/(2π2), exactly twice σ∗ 1/(4π2) 0.0253 Muller-Krumbhaar for “free” supercooled pure melt. increase parameter, σc, may related transition morphology cellular structure, just few side branches (for which 0.50), “fully developed” structure → 0 GL/R 0).