Competitive growth during directional solidification of a binary alloy with natural convection: two-dimensional phase-field study

Abstract

Due to the recent acceleration of phase-field simulations using a graphics processing unit (GPU), the mechanism of competitive growth among columnar grains has been better understood. In this study, the effects of natural convection, caused by the gravity driven buoyancy force, on the competitive growth of columnar grains during directional solidification of bi-crystal and polycrystal binary alloys are investigated by performing two-dimensional large-scale phase-field simulations using a GPU supercomputer. As a result, the downward flow accelerates and the upward flow decelerates the selection speed in competitive growth. It is also confirmed that these phenomena are caused by a characteristic liquid flow pattern at the converging and diverging grain boundaries.