Suppressed negative influence of natural aging in SiCp/6092Al composites

In this study, effects of natural aging as an interlude on the mechanical properties of artificially aged SiCp/6092Al composite and 6092Al alloy were investigated using tension test, electrical conductivity test, differential scanning calorimetry and transmission electron microscopy. It was shown that the strength of both the composite and 6092Al alloy after artificial aging was decreased due to the precedent natural aging. Compared to 6092Al alloy, the composite had smaller strength decrement. However, qualitative analysis based on load transfer indicated that the negative influence of natural aging was stronger in the composite than in 6092Al alloy. Microstructure examinations showed that this conflict was caused by the different influence of natural aging on precipitation behaviors during artificial aging between the composite and 6092Al alloy. Compared to those in 6092Al alloy, not only was the cluster behavior during natural aging weaker, but also more NA clusters could become favorable nucleation sites for β'' phases in the composite. Therefore, the coarsening of the precipitates caused by precedent natural aging was weaker in the composite than in 6092Al alloy. Furthermore, more metastable phases containing Cu, named L phases, existed in the composite than in 6092Al alloy, which could also be responsible for the suppressed negative influence of natural aging.
Source: Materials Science and Engineering: A - Category: Materials Science Source Type: research