Achieving exceptional superplasticity in a bulk aluminum alloy processed by high-pressure torsion

Bulk specimens of an aluminum–magnesium–scandium alloy, in the form of small cylinders, were processed by high-pressure torsion at room temperature. Following processing, the microstructure was inhomogeneous with larger grains in the center and ultrafine grains of ∼130 nm at the periphery. Tensile testing after processing revealed the potential for achieving exceptional superplastic elongations but the measured elongations depended upon the positions of the specimens within the cylinder. The highest tensile elongation recorded in these experiments was 1600%.