The fracture toughness and fatigue behavior of DRA

‘In this study, the fracture toughness and elevated-temperature tensile and fatigue behavior of discontinuously reinforced aluminum (DRA) were examined. The effects of heat treatment and specimen thickness on fracture toughness were studied in a 7093/SiC_p composite. The toughness of the DRA was lowest in the peak-aged condition, but increased considerably in the overaged condition. The highest toughness was obtained at a critical value of specimen thickness; this critical value was used to fabricate a laminated composite consisting of alternating layers of DRA and unreinforced alloy. Elevated-temperature tensile and fatigue behaviors were investigated in a 2080-T6/SiC_p composite at different volume fractions and particle sizes. Increasing reinforcement volume fractions resulted in increases in tensile and fatigue strength. Exposure tests for 300 h at 150°C produced no significant reduction in ultimate tensile strength or yield strength, indicating good thermal stability of the 2080 matrix. For more information, contact A.B. Pandey, Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson AFB, Ohio 45433; (937) 255-1320; fax (937) 255-3007; e-mail awadh.pandey@ml.afrl.af.mil.