Verteilungskoeffizienten und Konzentrationsanreicherungen an der Phasengrenzfläche bei ebenem und zellularem Erstarren von Zinn-Zink-Legierungen

The experimental results of KRUMNACKER on the effective distribution coefficient k_eff and the concentration-profil at the solidification interface were examined. On the basis of this examination and some new calculations the depencence of the segregation coefficient on the solidification rate R and on the concentration C₀ is studied in the cases of planar and cellular solidification. — In the case of planar interface the dependence of k_eff on the solidification rate is that of the Burton-Prim-Slichter-theorie. The interface distribution coefficient is not a function of R, or C₀. Thus, the result od BRICE , basing on the same experiments, is not correct. It is impossible, to improve the model of BRICE by these values. — In the case of cellular growth the distribution depends on the diffusion in the diffusion layer at the interface and on the segregation in the grooves of the cells. Under the applied experimental conditions of a large diffusion-boundary-layer the diffusion determines the dependence of k_eff on the solidification rate also under the condition of cellular growth.