Strengthening and Thermal Stability of MgLiCa Alloys Processed by Severe Plastic Deformation

Magnesium-Lithium alloys have long been investigated for their potential to realize ultralightweight structural materials, however efforts have been limited by a combination of low strength and thermal stability at low homologous temperatures. We report the implementation of severe plastic deformation (specifically, high pressure torsion (HPT)) to refine the grains structures of Mg-3.5Li-0.6Ca (wt%) alloy to the sub-micrometer regime via the imposition of hydrostatic pressure and strain at ambient temperatures. The grain refinement results in increased hardness and strength while Mg₂Ca nanoprecipitates further strengthen the alloy and hinder grain boundary movement at elevated temperatures. Recrystallization curves as a function of strain applied during HPT with concurrent microstructural and hardness evolution are reported.