Activation of non-basal slip and anomalous twinning in an additively manufactured Mg-Al-Zn alloy

The development of novel architectures in magnesium alloys through additive manufacturing represents an emerging and promising approach for achieving advanced lightweight, high-performance materials. In this study, laser powder bed fusion (LPBF) was employed to precisely tailor the intrinsic microstructure of a magnesium alloy, resulting in a significant enhancement of its mechanical properties, including a compressive strength of 630 MPa and a plastic strain of 9.2%. Detailed microstructural analysis reveals that the LPBF process facilitates the formation of a microscale closed-cellular structure characterized by a high aluminum solid-solution content, which is principally responsible for the enhanced performance. During plastic deformation, the closed-cellular architecture generates high stress concentrations at the phase boundaries, thereby promoting the activation of 〈c + a〉 dislocations. Furthermore, the Al-rich supersaturated solid solution inherent to the LPBF-fabricated alloy alters the prevailing mode of elemental segregation on deformation twin boundaries from zinc to aluminum. This shift markedly delays the activation of deformation twins, indicating that deformation twins contribute more substantially to the overall strength of the alloy than previously observed. Consequently, additive manufacturing is established as a novel and effective strategy for regulating deformation mechanisms, thereby advancing the design of next-generation high-performance magnesium alloys through precise microstructural control.