Atomic insights into the formation and micro-mechanical properties of micro-zones in Zr-based metallic glasses fabricated by selective laser melting

Understanding atomic-scale structural evolution mechanisms is crucial for linking microstructural forming to micro-mechanical properties of metallic glasses. In this study, the evolution of micro-zone formation (molten pool, remelted zone, and heat affected zone) during selective laser melting (SLM) was successfully revealed using the molecular dynamics (MD) simulation method. The results show that the molten pool exhibits a fully amorphous structure, while a small fraction of crystallization is present in the heat affected zone (HAZ) and remelted zone (RZ), characterized by a significant increase in the proportion of <0,3,6,4> and <0,4,4,6> Voronoi polyhedrons (VPs) of FCC structure. During the nanoindentation simulation, the activation, formation, propagation, and connection of shear transformation zones (STZs) contribute to the formation of shear bands, leading to a pile-up event around the indentation. This is further demonstrated by the displacement transformation of atoms undergoing effective shear strain. The experimental results reveal that the HAZ containing a composite microstructure of an amorphous matrix and Al 5 Ni 3 Zr 2 nanocrystals exhibited the peak hardness (H), maximum Elastic modulus (E), and optimal H/E ratio. • The formation and micro-mechanical properties of micro-zones in Zr-based MGs fabricated by SLM were systematically studied. • The atomic structure evolution characteristics of deformation were revealed. • The activation, formation, propagation, and connection of STZs contribute to the formation of the pile-up event.