Superplasticity in an Al–Mg–Zr–Sc alloy produced by equal-channel angular pressing

The high-temperature plastic deformation of an Al–4.5 wt.% Mg–0.2 wt.% Zr–0.2 wt.% Sc alloy subjected to equal-channel angular pressing was studied, as well as its microstructure. The alloy exhibits high strain rate superplasticity in the temperature range of 573–798 K. Exceptionally high elongations to failure were achieved when testing at an initial strain rate of 4.5 × 10−2 s−1—2130% at 773 K and 1950% at 798 K. At these temperatures, the strain rate sensitivity parameter m exceeded the value of 0.6. The grain size after pressing was <1 μm. The microstructure exhibited exceptional stability, with the grain size <10 μm at a temperature as high as 798 K, due to the presence of Al3(ZrxSc1−x) precipitates.