Dislocation-induced Y segregation at basal-prismatic interfaces in Mg

TL;DR

This study uses atomistic simulations and experiments to analyze how yttrium segregates at various basal-prismatic interfaces in magnesium, revealing the influence of local stress and defects on segregation behavior.

Contribution

It provides the first detailed investigation of Y segregation at basal-prismatic interfaces in Mg, linking local structural features to segregation energetics.

Findings

Short coherent interfaces are more stable than disordered ones.

Y segregation correlates with local compressive hydrostatic stress.

Dislocations at interfaces enhance solute segregation.

Abstract

Solute segregation at twin boundaries in Mg has been widely investigated, yet this phenomenon has not been studied at the equally important basal-prismatic interfaces. To fill this critical gap, this work investigates the segregation behavior of Y at basal-prismatic interfaces with various structures using atomistic simulations. The calculated interfacial energies show that short coherent interfaces and long semi-coherent interfaces containing disconnections and dislocations are more energetically stable than disordered interfaces, which is supported by our experimental observations. The segregation energy of Y at these lowest energy basal-prismatic interfaces shows a clear correlation with the atomic hydrostatic stress, highlighting the importance of local compressive stresses for segregation. In addition, sites around dislocations at the semi-coherent basal-prismatic interfaces demonstrate lower segregation energy, indicating that local defects such as interfacial dislocations can further enhance the segregation. In its entirety, this study indicates that the segregation of solutes can be affected by a number of different aspects of the local structure at complex interfaces in Mg alloys.