Influences of solute concentration on uniform elongation and dislocation characteristics of Al-Mg and Al-Si alloys

Influences of solute atoms and their contents on the uniform elongation were investigated using Al-Mg and Al-Si alloys respectively. Dislocation characteristics of both alloys were examined by X-ray diffractometry and transmission electron microscopy. In the case of solute concentration ranging between 0.3 and 1.6 (mass%), it was found that the increase of solute concentration caused the decrease of the uniform elongation for the case of Al-Mg alloys, whereas the increase of that for the case of Al-Si alloys. It was suggested that the solute Mg in aluminum caused a strong interaction on dislocation with comparison to the solute Si, which probably caused the large increase of dislocation density during the tensile deformation. It is considered that the solute Si has stronger effect of decreasing the stacking fault energy of the aluminum alloy than the solute Mg. Thus, as for Al-Si alloys, the increase of the work-hardenability and the uniform elongation may occur by retardation of the dynamic recovery during the tensile deformation.