Plastic deformation behavior of Mg12YZn with 18R long-period stacking ordered structure

The recent development of high-strength Mg alloys has focused on the role of the strengthening phase with a long-period stacking ordered (LPSO) structure. In this study, the plastic deformation behavior of Mg12ZnY with an 18R LPSO-structure was investigated using directionally solidified crystals. The (0001)<11<(2)over bar>0> basal slip was identified to be the dominant operative deformation mode in Mg12ZnY, whose critical resolved shear stress (CRSS) was estimated to be 10-30 MPa. When the stress was loaded parallel to the (0001) plane, where the Schmid factor for the basal slip is negligible, deformation kinks were initiated in the specimens and accommodated the compressive strain to some extent. These results showed that the plastic behavior of LPSO Mg12ZnY is highly anisotropic and, hence, the control of the microstructure is expected to be extremely important in order to improve the mechanical properties of the LPSO-phases in high-strength Mg alloys. (C) 2009 Elsevier Ltd. All rights reserved.