Hot deformation behaviour of aluminium alloy 6061/SiC_p MMCs made by powder metallurgy route

摘要

The hot deformation behaviour of a 20 vol.-%SiC particle reinforced Al alloy 6061 composite and Al alloy 6061, made via a powder metallurgy (PM) route and treated by a T4 temper, were studied by compression testing over a range of temperatures (300–500°C)and at strain rates of 0.005, 0.05, and 0.09 s-1. It was observed that the flow stresses of the composites were significantly higher than those of the alloy at lower deformation temperatures. However, the stress–strain curves of both the composite and the alloy showed significant softening during deformation at the lowest strain rate, the softening for the composite being faster than that of the alloy. The activation energy for hot deformation was determined for different strains, using a power law equation, and was found to change significantly with strain for both the alloy and the composite. This phenomenon was explained by the occurrence of dynamic precipitation and coarsening during deformation.