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

摘要

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 Al-3(Sc1-x ,Zr-x) 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 degrees and -5 degrees for the Sc-Zr and Zr containing alloy, respectively. The effect of the presence of Al-3(Sc1-x ,Zr (x) ) and Al3Zr in the matrix, on the Mg2Si particle shearing and Si shrinking phenomena with strain, was also addressed and documented.