A review was presented of the role played by dislocation cores and planar faults in activating non-basal deformation modes, <c+a> pyramidal slip and deformation twinning, in hexagonal close-packed metals and alloys and in D019 intermetallic compounds. Differing mechanical behaviors arose from a competition between alternative defect structures that determined the deformation modes. The importance of using accurate atomistic defect models, which went beyond simple interatomic energy considerations, was emphasized.

Non-Basal Deformation Modes of HCP Metals and Alloys - Role of Dislocation Source and Mobility. M.H.Yoo, J.R.Morris, K.M.Ho, S.R.Agnew: Metallurgical and Materials Transactions A, 2002, 32[3A], 813-22