Effect of segregated elements on the interactions between twin boundaries and screw dislocations in Mg

Abstract

Interactions of {101¯2} and {101¯1} twin boundaries (TBs), segregated by X (X = Sc, Y, or Nd), with screw partial dislocations were simulated using molecular dynamics (MD). In addition, mechanical tests were carried out on pure Mg and Mg–Y alloy. The MD simulation results suggested that the dislocations passed through the {101¯2} TB in all the models and that the shear strains for transmission in the Mg–X models were larger than that in the pure Mg model; in particular, the shear strain in the Mg–Y model was the largest. This corresponded to the experimental result that strain hardening was enhanced by Y addition. For interactions of a {101¯1} TB, some segregated atoms induced the emission of dislocations from the TB, whereas other segregated atoms locked the dislocation absorbed in the TB. As a result, the interaction behaviors of the {101¯1} TB were divided into five patterns. The interactions of this TB could be explained by the criterion of energy variations, as well as the interactions, of the {101¯2} TB, although segregation complicated the interactions of the {101¯1} TB.