A phase-field study of lamellar eutectic growth with solid-solid boundary anisotropy

Abstract

Abstract The lamellar growth with solid-solid boundary anisotropy during directional solidification is studied by phase-field method. An anisotropy function with forbidden orientation is adopted. The influence of anisotropy on steady and unsteady lamellar morphology is analyzed. For the steady patterns, the locked and floating lamellae can be distinguished under current anisotropy function. The curve of tilted angle versus rotation angle of crystallographic orientation can be divided into a locked branch, a floating branch, and a “discontinuous angle jump” between the two branches in the simulation results. Because the locked lamellae have smaller contact angles, the growth undercooling of locked lamellae is smaller than that of floating lamellae. As rotation angle and lamellar spacing vary, the unsteady lamellar morphology exhibits three types of oscillations: floating oscillation, locked oscillation and mixed oscillation. Both rotation angle and lamellar spacing are the inducer of mixed oscillation. With the increase of lamellar spacing, the amplitude of oscillation increases regardless of the type of oscillation. Furthermore, a lamellar morphology transition map is obtained which gives a detailed exhibition of the influence of rotation angle and lamellar spacing.