Numerische Modellierung der dendritischen Mikrostrukturentstehung in Legierungen Abschlussbericht fuer das Vorhaben COST 512/D22

This project has developed numerical modelling method for the simulation of dendritic microstructure formation in alloys. They are based on the generalized enthalpy method in a discrete formulation which includes the Gibb-Thomson equation, a discrete approximation of curvature and an attachment condition to control the transition of grid cells form metastable to multiphase state. Local equilibria are computed by maximizing the entropy potential function. Simulations have been performed with this model in binary systems. Growth of a free dendrite from a supercooled liquid was modelled in three dimensions in the system succinonitrile-acetone and the results were compared quantitatively with measurements from the literature. The formation of columnar dendrite arrays has been simulated in two dimensions and agrees qualitatively with measurements reported in the literature. The interaction between a free equiaxed dendrite and a columnbar front has been simulated in two dimensions and was interpreted in the light of theories for selection mechanisms of primary spacing. An accompanying empirical investigation by Dillinger Huettenwerke has provided measurements of dendrite arm spacing and has described the transition from columnar to equiaxed growth on steel samples obtained from continuously slab casting. The effect of several operational parameters has been studied. (orig.)SIGLEAvailable from TIB Hannover: F99B326 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman