Ultra-High Specific Strength of Mg-Li Alloy Via Rotary Swaging

Abstract

Ultralight Mg-Li alloys demonstrate significant potential for critical structural applications, yet their widespread adoption has been constrained by insufficient specific strength. Through multi-pass rotary swaging processing, we significantly enhance the mechanical properties of Mg-4Li alloy, achieving an exceptional specific strength of 214 kN·m/kg—far surpassing those of conventional binary Mg-Li alloys—alongside a yield strength of 277 MPa and a tensile strength of 343 MPa. This remarkable improvement stems from the formation of a refined nanograin structure. Comprehensive microstructural analysis identifies two primary strengthening mechanisms: (1) dislocation-mediated grain subdivision and (2) twin-twin intersection-induced grain refinement, which collectively contribute to the development of nanocrystalline domains. The achieved grain refinement efficiency demonstrates rotary swaging's unique capability in processing hard-to-refine Mg alloys, overcoming the intrinsic limitations of conventional thermo-mechanical methods. This breakthrough suggests new possibilities for developing ultrahigh-strength Mg-Li systems.

Keywords: Mg-Li alloy, rotary swaging, specific strength, Grain refinement