Microstructure and thermal stabilityof superplastic aluminium—lithium alloy after severe plastic deformation

Structure and phase composition of 1420 (Al-Mg-Li-Zr) alloy obtained by equal channel angular pressing during mechanical tensile testing and annealing within the temperature range 423–723 K were studied by means of TEM and XRDA. It was revealed that structural changes of the alloy after the mechanical tests corresponded to two stages of the deformation. The alloy structure was unstable due to its non-equilibrium nature and came to the equilibrium state during the annealing. Changes in the grain size and phase composition during the alloy annealing resulted in a significant decrease of its hardness.