THE EFFECT OF SIC PARTICLE REINFORCEMENT ON THE CREEP-BEHAVIOR OF 2080-ALUMINUM

The influence of SiC particle reinforcement on the creep behavior of 2 080 aluminum is investigated between 150 degrees C and 350 degrees C. The effect of particle size (F-280, F-600, and F-1000), volume fractio n (10, 20, and 30 vol pet), and heat treatment (T6 and T8) on creep be havior 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 degrees C. These results contradict continuum mecha nics predictions for steady-state creep rate, which predict composite strengthening. A high dislocation density is observed near SiC particl es. It is proposed that strain localization near the reinforcements le ads to microstructural breakdown and the subsequent reduction in creep resistance. When both materials are severely overaged or when they ar e tested at very high temperatures (350 degrees C), composite material s exhibit improved creep resistance relative to monolithic material. I n these cases, the strengthening is consistent with continuum predicti ons for direct composite strengthening.