A compressive split-Hopkinson pressure bar was used to investigate the impact deformation behaviour of Al–Sc alloy under high strain rates of 1.2 x 103, 3.2 x 103 and 5.8 x 103/s, respectively, at -100C, 25C and 300C. It was shown that for a constant temperature, the flow stress, work hardening rate and strain rate sensitivity increase with increasing strain rate, while the activation volume decreases. Conversely, for a constant strain rate, the flow stress, work hardening rate and strain rate sensitivity decrease with increasing temperature, while the activation volume increases. It was found that the impact deformation behaviour of Al–Sc alloy could be accurately described using the Zerilli–Armstrong constitutive equation. Optical microscopic observations revealed that the specimens failed principally as the result of an adiabatic shearing mechanism. Furthermore, scanning electron microscopic observations showed that the fracture surfaces were characterised by a dimple-like structure, which indicates a ductile failure mode. Transmission electron microscopy observations indicated that the dislocation density and cell size were related to the strain rate, flow stress and temperature. Finally, the transmission electron microscopic observations suggest that the strengthening effect observed in the deformed Al–Sc alloy was the result of Al3Sc precipitates within the matrix and at the grain boundaries, which suppress dislocation motion and prompt an increase in the work hardening stress.

Impact Deformation Behaviour and Dislocation Substructure of Al–Sc Alloy. W.S.Lee, T.H.Chen, C.F.Lin, M.S.Chen: Journal of Alloys and Compounds, 2010, 493[1-2], 580-9