Effect of cold plastic deformation and subsequent aging on the strength properties of Al-Mg2Si alloys with combined (Sc + Zr) and (Sc + Hf) additions

Abstract

Effects of equal-channel angular pressing (ECAP) and rotary swaging (RS) with subsequent aging on the strength properties of Al-Mg2Si alloys with (Sc + Zr) and (Sc + Hf) additions were studied. The microstructure of deformed alloys was examined by optical and transmission electron microscopy (TEM). Mechanical properties were characterized by hardness measurements and tensile testing. It was found that the strength properties of Al-Mg2Si alloys were remarkably improved due to the structure refinement during cold deformation and the acceleration of the kinetics precipitation of the βʹ and βʹʹ phases during aging of deformed alloys. It is found an accelerated decomposition of the supersaturated aluminum-based solid solution in the presence of hafnium. Nearly the same values of hardness and tensile strength of Al-Mg2Si alloys with transition metals additions have been accounted for the more intense decomposition of the solid solution with hafnium has compensated by a larger amount of hardening phases (βʹʹ and βʹ) in alloys with zirconium. For all alloys the highest hardness was achieved after cold deformation and remained nearly the same after 2 h of aging.