The effect of transition metals on the structure and hardening of Al-Mg-Si alloys after cold plastic deformation

Abstract

The effects of equal-channel angular pressing (ECAP) and rotary swaging (RS) on the change in strength properties during aging at 170 ° C of Al-Mg-Si alloys doped with Sc, Zr and Hf additions was studied. The methods of measuring hardness, electrical resistivity, testing mechanical properties, light and transmission electron microscopy were used. The higher hardening effect compared to the initial state was found in the alloys after ECAP than after RS, whereas the strength properties (tensile strength and yield strength) were higher for alloys subjected to RS than ECAP. Al-Mg-Si alloys with the combined additives of scandium with zirconium and scandium with hafnium showed practically the same values of hardness and strength properties at tensile testing during aging. The reason is in the identical nature of the decomposition of the supersaturated solid solution. It is determined by the sequence of precipitation of the strengthening phase Mg2Si and (Sc1-x, Zrx) Al3 and (Sc1-x, Hfx) Al3 dispersoids which impede the movement of dislocations both in alloys after deformation and after aging.