5th International Conference on Advances in Solidification Processes (ICASP-5) 5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining (CSSCR-5)

The 3-D morphology, orientation selection and behind mechanism of magnesium alloy dendrite were investigated by performing multiscale mathematical simulations. The results showed that the α-Mg dendrite prefers to grow along <11-20> basal direction and <11-23> nonbasal direction, and the resultant 3-D dendritic morphology exhibits a typical 18-primary branch pattern. Such dendritic microstructure formation was found to be associated with the surface energy anisotropy in light of the hexagonal-close-packed (hcp) lattice structure of the α-Mg dendrite. An anisotropic function model describing the α-Mg dendrite growth was developed by combining the observed 3-D growth pattern, the spherical harmonics, and the calculated anisotropic strength via DFT-based atomistic simulations. Accordingly, the dendritic growth behavior and morphological evolution were further investigated by coupling the anisotropy function with the phase-field model. The simulated results on the 3-D dendritic morphology agreed well with those reconstructed from X-ray tomography experiment. Our investigations provides a deep understanding on the growth behavior of magnesium alloy dendrite from phenomenological descriptive picture to a more intrinsic predictive way.