Molecular dynamic studies of the interaction of a/6⟨112⟩ Shockley dislocations with stacking fault tetrahedra in copper. Part II: Intersection of stacking fault tetrahedra by moving twin boundaries

Abstract

The interactions of moving twin boundaries with stacking fault tetrahedra (SFTs) have been studied by molecular dynamics. The results reveal a spectrum of processes occurring during these interactions. In general, they lead to damage of the parent SFT and formation of new defects in the twin lattice. The character of these defects depends on the nature of the twinning front, the size of the SFT and its orientation with respect to incoming dislocations. Typical structures that may be produced in the twin include product-SFTs, free vacancies, planar stacking faults bounded by partial dislocations, mutually linked stacking faults on non-coplanar {111} _T planes, small {111} _T tetrahedra and their partial forms. Dislocation mechanisms involved in the formation of these defects are being analyzed.

Keywords:

• stacking fault tetrahedra
• Shockley dislocation
• twinning transformation
• atomic structure
• defect structures
• deformation twinning
• dislocation interactions
• lattice defects
• molecular dynamic simulations
• strengthening mechanisms
• vacancies

Acknowledgements

This work was supported by the LANL Directed Research and Development Program. MN would like to thank the Los Alamos National Laboratory for this financial support during sabbatical leave. We also appreciate the helpful discussions with Professor John Hirth.