Effects of Cu content and preaging on precipitation characteristics in aluminum alloy 6022

Abstract

Effects of Cu content and preaging treatments on precipitation sequence and artificial aging response in aluminum alloy 6022 were investigated using transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and hardness tests. It was found that Cu induces the formation of Q and its precursor metastable phases and has a beneficial effect on the kinetics of artificial aging. For the alloy with 0.07 wt pct Cu, the precipitation sequence is GP zones → needlelike ␤ Љ → rodlike ␤ Ј ϩ lathlike QЈ → ␤ ϩ Si. On the other hand, the precipitation sequence in the alloy with 0.91 wt pct Cu is GP zones → needlelike ␤ Љ → lathlike QЈ → Q ϩ Si. For the artificial aging condition of 20 minutes at 175 ЊC, which is the typical automotive paint bake condition, suitable preaging treatments were found to significantly reduce the detrimental effect of the natural aging on artificial aging response.

The Effects of Low Cu Additions and Predeformation on the Precipitation in a 6060 Al-Mg-Si Alloy

“…This is in good agreement with previous results showing that Cu additions enhance material hardness [10,24], and demonstrates that 0.10 wt% Cu addition is a quantity large enough to produce a measurable effect.…”

Formation Behavior of Nanoclusters in Al–Mg–Si Alloys with Different Mg and Si Concentration

“…Peak III, IV and V are described to the formation of ¢AA, ¢A metastable precipitates and the equilibrium precipitates ¢-(Mg 2 Si). These results are in good agreement with those of Miao et al 11) and Gaber et al 12) It is found that the peak area and peak temperature are changed depending on the Si concentration. In this paper, peak I corresponding to the formation of nanoclusters is mainly focused and discussed because nanoclusters play important roles in AlMgSi alloys.…”

Effect of Silver Addition on the β′-Phase in Al-Mg-Si-Ag Alloy

“…It would be interesting, for example, to compare the silver addition with reports about the effect of copper addition to this alloy on precipitation. [5][6][7] In our recent study, an Al-1.0 mass%Mg 2 Si-0.5 mass%Ag alloy showed good ductility at peak aged condition as compared with peak aged Al-1.0 mass%Mg 2 Si alloy. 3) On the other hand, a new grain boundary precipitate has been found in an Al-1.0 mass%Mg 2 Si-0.5 mass%Ag alloy by HRTEM method, 8) designated as a quaternary Al-Mg-Si-Ag compound (the Q Ag -phase), similar to the Q 0 -phase in Al-Mg-SiCu alloys.…”

“…3) On the other hand, a new grain boundary precipitate has been found in an Al-1.0 mass%Mg 2 Si-0.5 mass%Ag alloy by HRTEM method, 8) designated as a quaternary Al-Mg-Si-Ag compound (the Q Ag -phase), similar to the Q 0 -phase in Al-Mg-SiCu alloys. [5][6][7] An addition of silver to this alloy also seems to affect nucleation 4) according to a differential scanning calorimetric (DSC) analysis.…”