Effect of solute atoms on dislocation motion in Mg; An electronic structure perspective

Tsuru, Tomohito   ; Chrzan, D. C.*

Much of the world's future economy hedges on the ability to improve the efficiency of mechanical machines without sacrificing their performance. This requires the development of lighter and stronger structural alloys. Magnesium alloys are very promising for structural applications, but they suffer from a fatal flaw. The mobility of the dislocations is determined by the bonding within the alloy, and this bonding is best modeled using approaches rooted firmly in quantum mechanics. Here, we compute the electronic structure of a screw dislocation gliding on a prismatic plane within Mg as it passes over its Peierls barrier. We show that the ductility of Mg is increased because some substitutional additions strongly bind to and stabilize a compact core structure for screw dislocations that are formally able to glide on both the basal and prismatic planes.