IS THERE A DIFFERENCE BETWEEN DENDRITES OF A BINARY OR A TERNARY ALLOY? SOME ANSWERS BY PHASE-FIELD SIMULATIONS

摘要

Dendritic growth is best understood for pure substances growing into a uniformly supercooled environment. Under certain assumptions the standard growth theory can be applied to the directional growth of dendrites in a binary alloy. To apply the theory to technical multicomponent alloys so called 'binary equivalent' or 'pseudo-binary' models have been proposed. The basic question of 'Is there a difference between dendrites of a binary or ternary alloy?' has only partially been answered. A phase-field model applied to a ternary Fe-C alloy with a third fictive component will be used in this paper to compare ternary and binary equivalent phase-field simulations focussing on different component diffusivities. Results for directional dendritic solidification indicate negligible and relevant differences with respect to micro-segregation and micro-structure.