Title: Effect of chemical composition on age-hardening behavior of 7003 aluminum alloys.
Abstract: The age-hardening behavior at various temperatures up to 453 K of the 7003 aluminum alloys with different compositions was studied by differential scanning calorimetry and transmission electron microscopy. The age-hardening behavior was affected by the amount of Zn and/or Mg contents. The incubation period of the age-hardening process became shorter and the peak hardness became higher with increasing the amount of Zn and/or Mg. The effects of Mg addition on the decreased incubation period and the increased peak hardness were greater by 2 to 7 times than those of Zn addition, compared in a unit mol%. The increase in Mg content at constant Zn concentration in Al–Zn–Mg alloys results in the increased amount of metastable precipitates with higher density and finer size. The increased amount of Mg, therefore, is effective to increase the age-hardenability of Al–Zn–Mg alloys.