Mechanical properties of SiCw/Al composite degraded by thermal cycling

摘要

Mechanical properties of the SiCw/Al composite degraded by thermal cycling were examined using tensile tests and hardness measurements. Thermally cycled (TC) SiCw/Al was prepared through 100 thermal cycles between 200 and 300degreesC. Some of SiCw/Al were isothermally exposed (IE) at 300degreesC for 80 h for comparison. Fracture surface observation revealed the difference in fracture mechanism between the TC- and IE-SiCw/Al composites. Reduction of tensile strengths was greater in the TC-SiCw/Al than in the IE-SiCw/Al. The large reduction in the TC-SiCw/Al was caused by pulled-out whiskers, which was observed frequently in the fracture surfaces. While broken whiskers were observed markedly, indicating that whiskers of the IE-SiCw/Al carried external stress fully. The experimental results were verified theoretically using a shear-lag model for discontinuous fiber reinforced composites. Good agreement was found between experimental results and theoretical calculations. [References: 15]