Speaker
Description
Magnesium alloys offer promising routes for weight reduction in structural applications, e.g. potentially leading to significant energy savings in the transportation sector. During Mg alloys solidification, primary dendrites typically solidify with a hexagonal close packed (hcp) structure, which has been relatively less explored than its cubic-symmetry counterparts. In this work, using thin-interface quantitative phase-field simulations as our main tool, we investigate some key mechanisms of microstructure selection during solidification of Mg alloys (e.g. Mg-Al, AZ31B). On the one hand, we compare the various formulations of solid-liquid interface energy anisotropy proposed in the literature (mainly based upon atomistic simulations [1,2]) and we discuss their implications in terms of preferred growth direction and inner grain morphologies. On the other hand, we simulate the columnar growth of bi-crystalline samples in a temperature gradient for a range of processing conditions and grain orientations, in order to explore the selection of grain boundaries, which have a predominant importance in hcp systems that exhibit relatively complex deformation mechanisms compared to fcc and bcc phases. Beyond the current application to Mg alloys, these simulations should bring deeper insight into the selection of hcp dendritic microstructures in solidification processing in general.
[1] D.Y. Sun, et al. "Crystal-melt interfacial free energies in hcp metals: A molecular dynamics study of Mg." Physical Review B 73 (2006) 024116.
[2] E. Asadi, M.A. Zaeem. "The anisotropy of hexagonal close-packed and liquid interface free energy using molecular dynamics simulations based on modified embedded-atom method." Acta Materialia 107 (2016) 337-344.
| Speaker Country | Spain |
|---|