Superplastic Deformation of a Mg-8% Li Alloy Processed at Room Temperature by ECAP

Significant phase refinement and dispersion were achieved in a cast Mg-8% Li alloy through processing by ECAP using a die having an internal channel angle of 135 deg and a pressing temperature of 293 K. Following extrusion and subsequent ECAP through 4 passes, the alloy exhibited superplasticity at a testing temperature of 473 K. A maximum fracture elongation of 1610% was attained with an initial strain rate of 1.5 x 10-4s-1. The strain rate sensitivities under the optimum superplastic conditions were measured as about 0.6. The maximum elongation achieved in this investigation is very high by comparison with most Mg alloys tested in tension at similar temperatures and strain rates.