LPSO kink induces lattice rotation promotes basal slip and significantly elevates the plasticity of GW-series magnesium alloys

The study investigated the hot compression behavior of an Mg-Gd-Y-Zn-Zr alloy, revealing a unique deformation mechanism termed "kink deformation" within the LPSO (Long Period Stacking Ordered) phase inside the grain. This distinctive mode involves inducing lattice rotation and enhancing basal slip, thereby enhancing the compression deformability of the magnesium alloy significantly. The enhancement in plasticity due to the kink deformation of the LPSO phase is primarily attributed to the specific orientation relationship between LPSO and the matrix, which redistributes stress perpendicular to the basal plane, elevating shear stress along the <a> direction. Moreover, the basal plane of the grain rotates towards the direction facilitating easier slip initiation. The IGMA (intra-granular misorientation axis) analysis relies on kink-induced lattice rotation and Taylor-axis determination, enabling the determination of the slip mode of deformed grains by aligning the IGMA distribution between the Taylor-axis and rotating grains. The LPSO kink facilitates the onset of basal <a> slip alongside the rotation of <1-100> Taylor-axis, associated with the slip along the <11-20> direction of the (0001) plane. The lattice rotation of the <-12-10> Taylor-axis results from basal slip <a> induced by the combined slip of multiple Burgers vectors. This work effectively studied the lattice rotation and slip type corresponding to the Taylor-axis using IGMA analysis, and combined with microstructural characterization methods and micro-mechanical property testing, clarified the significant improvement of the plasticity of Mg-Gd-Y-Zn-Zr alloy by the kink of LPSO phase, providing new research ideas for alloy plastic deformation.