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

Interactions of { 10 1 over bar 2} and { 10 1 over bar 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 { 10 1 over bar 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 { 10 1 over bar 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 { 10 1 over bar 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 { 10 1 over bar 2} TB, although segregation complicated the interactions of the { 10 1 over bar 1} TB.