Numerical modeling of grain refinement during solidification of Mg-4Y-3Nd (wt.%) alloy via mesh-anisotropy reduction algorithm. (December 2020)

• Record Type: Journal Article
• Authors: Pu, Zhenpeng; Wang, Lei; Liu, Dong-Rong
• Is Part Of: Materials today communications. Volume 25(2020)
• Publication Date: 2020-12
• Subjects: Solidification -- Grain refinement -- Magnesium alloy -- Nucleation -- Cellular automaton -- Mesh-anisotropy reduction; Materials science -- Periodicals; 620.11
• DOI: 10.1016/j.mtcomm.2020.101679
• Languages: English
• ISSNs: 2352-4928

Abstract

Graphical abstract: Highlights: A two-dimensional multi-component Cellular Automaton model is developed. A mesh-anisotropy reduction algorithm is proposed for interface curvature calculation. Initial alloy composition has limited influence on the predicted grain refinement under fast cooling condition. A high cooling rate at the time solidification begins is important to activate as many nuclei as possible. Abstract: Grain refinement during solidification of Mg-4Y-3Nd (wt.%) alloy is modeled and simulated in the present work. A two-dimensional multi-component cellular automaton (CA) model is developed, coupling with a mesh-anisotropy reduction (MAR) algorithm for interface curvature calculation. The concept of MAR is to estimate the curvatures based on an imaginary isotropic interface. The accuracy and feasibility of the developed model is validated by comparing the simulations with the analytical predictions and experimental data for both single and multi-dendrite growth. Influences of latent heat, cooling rate and initial alloy composition are studied. The latent heat release prevents the grain refinement. Only with the consideration of latent heat, the variation of grain size with initial composition is in line with Interdependency theory. For alloys of high solute content, a compromise between the growth restriction and solute suppressed nucleation makes the grain refinement less dependent on the initial alloy composition under a fast cooling condition. Since the in-situ formed Al2 RE nucleant particles have large sizes and high nucleation potency, only initial transient nucleation is found. A high cooling rate at the time solidification begins is important to activate as many nuclei as possible and promote grain refinement. With numerous highly-potent nuclei in melt, a grain refinement can be achieved within a wide range of cooling rate.