Structural characterization of Laves-phase MgZn2 precipitated in Mg-Zn-Y alloy

Structural characterization of Laves-phase MgZn2 precipitated in Mg-6 wt.%Zn-1 wt.%Y alloy was performed using a high-resolution transmission electron microscope (HRTEM). Plate- and rod-shaped precipitates with the Laves structure were observed in an aged sample at 200 A degrees C. An individual rod of the beta(2)' phase precipitated in the matrix contained several domains with various orientations. Numerous antiphase boundaries (APBs) and stacking faults (SFs) were observed in the beta(2)' precipitates. The stacking sequence of the 14C structure partially changed to that of the C15 structure due to the presence of a stacking fault. The orientation relationship between the C14 structure and the C15 structure in the beta(2)' precipitates was [11-20](C14)aEuro-[1-10](C15) and (0001)(C14)aEuro-(111)(C15). Modification of the stacking sequence based on the synchroshear mechanism was discussed.