Solute strengthening strategies to design ductile Zn-alloys

Zinc is widely used in the steel industry as a coating material due to its excellent anticorrosive properties. However, its mechanical properties are still poorly understood. Its hexagonal close-packed crystalline structure leads to highly anisotropic elastic and plastic behavior. The latter arises from large differences in the activation stresses of the available slip systems. The Basal slip system activates readily at low applied shear stress, whereas the second most active system, Pyramidal II, requires stresses approximately an order of magnitude higher, resulting in poor ductility. This thesis aims to design a strategy to modify the relative activation of these slip systems through solute strengthening, with the goal of improving the ductility of zinc. To this end, we develop a multiscale modeling framework to study solute–dislocation interactions in Basal dislocations, starting from ab initio inputs. In addition, we develop a machine-learning interatomic potential that enables molecular dynamics and molecular statics simulations of zinc and, in particular, Pyramidal II dislocations. We assess the effects of various solute elements on the behavior and activation of Basal and Pyramidal II dislocations. Finally, we test the proposed strategy by modeling dislocations in the Zn–Al system, extending the machine-learning interatomic potential to this alloy. The thesis outlines a strategy for the design and further study of new zinc coating compositions, highlighting both the strengths and the limitations of the proposed approach.