Effect of pre-annealing on microstructure evolution ofTRC AA3003 aluminum alloy subjected to ECAP
(Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, 121 16 Prague 2, Czech Republic)
Abstract: An AA3003 aluminum alloy prepared by twin-roll casting was modified by a small amount of zirconium. Annealing at 450 °C led to precipitation of coherent Al3Zr phase and a simultaneous co-precipitation of Mn-rich α-Al(Mn,Fe)Si phase. Severe plastic deformation by equal channel angular pressing resulted in the grain refinement and increase of microhardness. Observation by electron back-scatter diffraction and in-situ transmission electron microscopy revealed influence of pre-annealing on microstructure changes during post-deformation heat treatment. Dislocation recovery and precipitation of α-Al(Mn,Fe)Si particles preceded recrystallization at 450 °C in material which was not annealed before deformation. The pre-deformation annealing enabled dynamic recovery during deformation as it depleted the solid solution from Mn atoms. Recrystallization was enhanced by Al3Zr precipitates.
Key words: aluminum alloy; Al3Zr; α-Al(Mn, Fe)Si; pre-annealing; recovery; recrystallization; microstructure evolution