Crystal defects in a plastically deformed Mg-Zn-Y alloy were studied at the atomic scale by using aberration-corrected scanning transmission electron microscopy, thus providing important structural data on the material's deformation behavior and strengthening mechanisms. Atomic-scale structures of deformation stacking faults resulting from the dissociation of various types of dislocation were characterized experimentally and modelled. Suzuki segregation of Zn and Y along stacking faults formed by dislocation dissociation during plastic deformation at 300C was confirmed experimentally at the atomic level. The stacking-fault energy of the Mg-Zn-Y alloy was evaluated to be 4.0 to 10.3mJ/m2. The newly-formed nm-wide stacking faults, with their Zn/Y segregation in Mg grains, played an important role in the strength of this alloy at high temperatures.

Direct Observation of Dislocation Dissociation and Suzuki Segregation in a Mg-Zn-Y Alloy by Aberration-Corrected Scanning Transmission Electron Microscopy. Z.Yang, M.F.Chisholm, G.Duscher, X.Ma, S.J.Pennycook: Acta Materialia, 2013, 61[1], 350-9