Effects of CCEP and Sc on superplasticity of Al–5.6Mg–0.7Mn alloys

ABSTRACTTrace amount (0.3 wt%) of scandium is added to Al–5.6Mg–0.7Mn alloy to form uniformly distributed Al3Sc precipitates for producing a fine-grained and stable microstructure at high temperature through cross-channel extrusion process. Superplasticity and hot workability of the Sc-containing Al–5.6Mg–0.7Mn alloy, after extrusion, are also examined. The result indicates that Al–5.6Mg–0.7Mn alloys with and without 0.3 wt% Sc after extrusion of six passes at 300°C, fine-grained structures were observed with grain sizes of 1–2 µm and improvement of mechanical properties. Furthermore, Al3Sc phase can effectively retard recrystallization to increase the thermal stability and remain equiaxed. The elongation of Al–5.6Mg–0.7Mn alloy with Sc addition to failure is extended to 873% maximum at high temperature of 450°C at strain rate of 1 × 10−1 s−1after six passes in the CCEP.