AGE-HARDENING AND THE POTENTIAL FOR SUPERPLASTICITY IN A FINE-GRAINEDAL-MG-LI-ZR ALLOY

Experiments were conducted to determine the age-hardening characterist ics and the mechanical properties of an Al-5.5 pet Mg-2.2 pet Li-0.12 pet Zr alloy processed by equal-channel angular (ECA) pressing to give a very fine grain size of similar to 1.2 mu m. The results show that peak aging occurs more rapidly when the grain size is very fine, and t his effect is interpreted in terms of the higher volume of precipitate -free zones in the fine-grained material. Mechanical testing demonstra tes that the ECA-pressed material exhibits high strength and good duct ility at room temperature compared to conventional Al alloys containin g Li. Elongations of up to similar to 550 pet may be achieved at an el evated temperature of 603 K in the EGA-pressed condition, thereby conf irming that, in this condition, the alloy may be a suitable candidate material for use in superplastic forming operations.