Low-temperature superplasticity of Al–Mg–Sc alloy produced by friction stir processing

Ultrafine-grained (0.7 μm) Al–Mg–Sc alloy with an approximately random misorientation distribution and predominantly high-angle boundaries of 97% was produced by friction stir processing. A ductility of 235% was obtained at 200 °C. Increasing temperature from 200 to 300 °C resulted in an increase in superplasticity, optimum strain rate and strain rate sensitivity. Low temperature and high strain rate superplasticity with a ductility of 620% was achieved at 300 °C and 3 × 10−2 s−1. Abnormal grain growth occurred at 350 °C, resulting in the disappearance of superplasticity.