Nanodefect-Mediated Strengthening and Deformation Mechanisms in Magnesium Alloys: A Critical Review

Nanodefect engineering has emerged as an effective strategy to address the inherent strength-ductility trade-off and limited damage tolerance of wrought and cast magnesium alloys through controlled manipulation of their defect structures. Recent advances demonstrate that introducing and tailoring nanoscale defects can significantly enhance mechanical performance and, under appropriate defect architectures and processing conditions, may enable improved strength-ductility balance. This review provides a concise, mechanism-oriented overview of nanodefect-mediated strengthening in Mg alloys, focusing on the roles of nanograins, nanoprecipitates, nanotwins, and nano-stacking faults. Grain refinement via severe plastic deformation and other processing routes enhances strength through Hall-Petch effects while modifying texture and activating non-basal slip. Concurrently, nanoscale precipitates contribute through dislocation shearing and Orowan bypassing, whereas planar defects such as nanotwins and stacking faults introduce high-density interfaces that both impede dislocation motion and facilitate plastic accommodation. Emphasis is placed on the synergistic interactions among these defect populations, which govern strain hardening, deformation stability, and the overall strength-ductility balance. The review underscores that tailored defect architectures, achieved through integrated processing and alloy design, provide a viable pathway for developing next-generation Mg alloys with improved and tunable mechanical performance.