Relationship among elongation and work hardening behavior and dislocation characteristics of Al-Mg-Si series alloys

Dislocation multiplication and dynamic recovery in the tensile deformed Al-Mg-Si-Cu alloys were characterized by transmission electron microscope (TEM), to reveal the correlation between the dislocation characteristics and the elongation behaviors. 6016 (Al-0.4%Mg-1.0%Si-0.2%Cu (mass%)) and 6014 (Al-0.6%Mg-0.7%Si-0.1%Cu) alloys were aged at 363 K for 18 ks after solution treated and quenched into water. The maximum n-value of 6016 alloy was found higher than that in the 6014 alloy. The n-value reduction rate after reaching its maximum of 6016 alloy was found smaller than that of 6014 alloy. Furthermore, the dislocation multiplication on {111} plane and the formation of dislocation band were formed in 6016 alloy with more than 10% of tensile deformation. Therefore, the slip lines observed by scanning electron microscope (SEM) are finely formed. The homogeneous dispersion of slip lines are probably the cause of higher elongation of 6016 alloy than that of 6014 alloy. It is believed that suppression of the cross slip dislocation may contribute to a higher elongation.