The effects of pre-aging treatments on subsequent artificial aging response were investigated by means of transmission electron microscopy observations and hardness test in age hardened Al-3.95Cu-(1.32Mg)-0.52Mn-0.11 Zr alloys. In Al-3.95Cu-0.52Mn-0.11 Zr alloy, when the pre-aging temperature is 25 °C, the pre-aging treatment has no evident effect on the peak hardness of subsequent artificial aging, while a positive effect(increase of peak hardness) appears when pre-aging temperature is50 °C. However, in Al-3.95Cu-1.32Mg-0.52Mn-0.11 Zr alloy, it is found that whether the pre-aging temperature is 25 °C or 50 °C,the peak artificial aging hardness is lower than that of T6 treated alloy, that is to say, pre-aging treatment has a negative effect on the peak hardness of subsequent artificial aging in the alloys.
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