Synergetic deformation mechanisms in an Mg-Zn-Y-Zr alloy with intragranular LPSO structures

Deformation kink is one of the important strengthening mechanisms of the long-period-stacking-ordered (LPSO) phase containing magnesium (Mg) alloys, while the deformation twin is generally suppressed. To optimize the mechanical properties of LPSO containing Mg alloy by simultaneously exciting kink and twin, we successfully prepared the Mg-Zn-Y-Zr alloy featuring intragranular LPSO phase and free grain boundary LPSO phase by homogenization. We unraveled the corresponding strengthening and toughening mechanisms through transmission electron microscopy characterization and theoretical analysis. The high strength and good plasticity of the homogenized alloy benefit from the synergistic deformation mechanism of multiple kinking and twining in the grains. And the activation of kinking and twinning depends on the thicknesses of LPSO lamellae and their relative spacing. These results may shed light on optimizing the design of Mg alloys regulating the microstructure of LPSO phases.