PREDICTION OF DENDRITIC GROWTH AND MICROSEGREGATION PATTERNS IN A BINARY ALLOY USING THE PHASE-FIELD METHOD

A comprehensive model is developed for solving the heat and solute dif fusion equations during solidification that avoids tracking the liquid -solid interface. The bulk liquid and solid phases are treated as regu lar solutions and an order parameter (the phase field) is introduced t o describe the interfacial region between them. Two-dimensional comput ations are performed for ideal solutions and for dendritic growth into an isothermal and highly supersaturated liquid phase. The dependence upon various material and computational parameters, including the appr oach to conventional sharp interface theories, is investigated. Realis tic growth patterns are obtained that include the development, coarsen ing, and coalescence of secondary and tertiary dendrite arms. Microseg regation patterns are examined and compared for different values of th e solid diffusion coefficient.