Phase-field model simulations of alloy directional solidification and seaweed-like microstructure evolution based on adaptive finite element method

Abstract

Based on the multi-grain growth phase field model of multi-element single-phase system, the adaptive finite element method using non-uniform grid is studied to solve the problem. The Al-4wt.%Cu binary alloy is taken as an example to study the planar solidification process and morphological evolution during the initial transition phase of solidification were studied under the condition of large computational domain and thin interfacial layer thickness. The effects of disturbance and anisotropy intensity on the microstructure of the solidification, the influence of physical parameters such as temperature gradient and cooling rate on the interface morphology growth and evolution were quantitatively analyzed. The growth mechanism of the interface morphology during directional solidification and the transformation mechanism of seaweed tissue were discussed. The results show that under the condition of low temperature gradient and high cooling rate, the flat interface is unstable and forms cell or dendrites, and then the tip is continuously split to form seaweed structure morphology. The adaptive finite element method is one order of magnitude lower in computing time and storage space comparing to the finite difference method. When the system size is larger, the superiority of the adaptive finite element method can be better reflected, which facilitates the simulation of the large-scale multi-field coupled phase field model.