A TEM study of the combined effect of severe plastic deformation and (Zr), (Sc+Zr)-containing dispersoids on an Al–Mg–Si alloy

The microstructural evolution with strain was investigated in a Zr-modified 6082 Al–Mg– Si alloy and in the same alloy added with 0.117 wt.% Sc, subjected to a multi-pass equal-channel angular pressing, up to a true strain of ~12. The role of fine Al3(Sc1-x,Zrx) dispersoids, pertaining Al–Mg– Si– (Sc– Zr) alloy, and Al3Zr dispersoids, pertaining to Al–Mg– Si– (Zr) alloy, was investigated by transmission electron microscopy techniques and discussed. Compared to the commercial parent alloy, Al– Mg– Si, block wall formation and propagation were favored by the presence of Sc– Zr containing dispersoids, while cell boundary evolution was less affected, Al3Zr dispersoids affected the microstructure in a similar way, but in a lesser extent. Mean misorientation across block walls increased with strain much more in the Sc– Zr containing alloy, reaching a plateau, starting from a true strain of ~8. Misorientation across cell boundaries continuously increased to ~8 and ~5 for the Sc– Zr and Zr containing alloy, respectively. The effect of the presence of Al3(Sc1-x,Zrx) and Al3Zr in the matrix, on the Mg2Si particle shearing and Si shrinking phenomena with strain, was also addressed and documented.