High strain rate superplasticity in an Al–Mg–Sc–Zr alloy processed via simple rolling

The superplastic behavior of Al–Mg–Sc–Zr samples with standard gauge size (18 mm by 6 mm) were prepared using simple rolling and were tested in the temperature range from 450 °C to 525 °C at strain rates ranging from 1.67×10^–3 s⁻¹ to 1×10^–1 s⁻¹. With proper deformation parameters, the Al–Mg–Sc–Zr alloy has an elongation to failure much higher than 300% and the maximum elongation is 740%. The Microstructure and dislocation substructure investigation using optical microscopy (OM) and transmission electron microscopy (TEM) revealed a dynamic recrystallization in it. The grain size and activation energy on the deformation mechanisms of superplastic is discussed. Results also show that these nano-scale Al₃(Sc_1−xZr_x) particles play an important role in the superplastic process. Al₆FeMn particles were found to induce the formation and growth of cavities, which can lead to the fracture of specimens.