The effect of SiC particle reinforcement on the creep behavior of 2080 aluminum

The influence of SiC particle reinforcement on the creep behavior of 2080 aluminum is investigated between 150 °C and 350 °C. The effect of particle size (F-280, F-600, and F-1000), volume fraction (10, 20, and 30 vol pct), and heat treatment (T6 and T8) on creep behavior is studied. In both the T6 and T8 conditions all composites are less creep resistant than similarly heat-treated monolithic materials when crept at 150 °C. These results contradict continuum mechanics predictions for steady-state creep rate, which predict composite strengthening. A high dislocation density is observed near SiC particles. It is proposed that strain localization near the reinforcements leads to microstructural breakdown and the subsequent reduction in creep resistance. When both materials are severely overaged or when they are tested at very high temperatures (350 °C), composite materials exhibit improved creep resistance relative to monolithic material. In these cases, the strengthening is consistent with continuum predictions for direct composite strengthening.