COMPUTER SIMULATION OF POINT DEFECT TWIN BOUNDARY INTERACTIONS IN FACE CENTRED CUBIC METALS.

Abstract

A new method has been established to compute the variants of point defect clusters depending on their symmetry. Results are presented! for close- packed clusters of up to five point defects in cubic crystals. Interesting) relations among the variants of point defect clusters in two and three dimensiqnal lattice structures have been noted. Computer simulation techniques haye been employed to determine the relaxed structures and energies of sortie planar defects using manv-body potentials developed by Ackland et at. (198ir). The structures of some low index twin boundaries, e g. (130), (1j23), (140) and (114) in Copper, are explored 4? to examine their energy configurations. In (140) and (114) twin boundaries local atomic adjustments are made to obtain low interfacial energy. The atomic planes twin interface in all the cases. The interactions of coalesce at the vacancy with (1$0), (123), (140) and (114) boundaries are studied. For single vacancy the maximum binding energy for (123) and (114) boundary is observed when vacancy lies at the plane adjacen: to the interface. The structures and energies of (111), (001) and (110) twist boundaries with different misorientation angles in copper, silver, and investigated as well. It is observed that in-plane translations are flold necessary to establish low energy (110) twist boundary.