Kinetics of phase precipitation in Al–Mg–Si alloys subjected to equal-channel angular pressing during subsequent heating

Abstract

Effects of equal-channel angular pressing (ECAP) with subsequent aging on the microstructure and phase transformation of Al–Mg2Si alloys with combined (Sc + Zr) and (Sc + Hf) additions were studied. The microstructure processed by ECAP and the precipitation of phases of Al–Mg2Si alloys were thoroughly examined by transmission electron microscopy (TEM). An analysis of the precipitation and determination of the temperatures of these precipitations in Al–Mg2Si alloys after ECAP was carried out by DSC. It has been revealed that transition metals added to Al–Mg2Si alloys do not change the character of decomposition of the solid solution but shift the precipitation temperatures of the β'', β' and β phases to lower temperatures compared to the quenched state. Recovery processes have been revealed in the temperature range 200–600 °C based on the changes in hardness and electrical resistivity of Al–Mg2Si alloys with additions of transition metals (Sc + Zr) and (Sc + Hf) and without them after ECAP.