A differential scanning calorimetry study of aluminum alloy 6111 with different pre-aging treatments

The effects of different pre-aging treatments on the precipitation behavior in Al alloy 6111 were studied using differential scanning calorimetry in conjunction with hardness measurements and transmission electron microscopy. Pre-aging treatments impose a significant effect on the alloy precipitation hardening behavior alloy. The GP zones formed during natural aging and pre-aging at 75 °C for 8 hours differ in size and/or structure. During subsequent artificial aging, a reversion process exists for the GP zones or clusters in the naturally aged sample. On the other hand, the GP zones or clusters formed during pre-aging are more stable and can act as nuclei for the precipitation of the main strengthening phase, β″, and hence enhance the artificial aging.