Fracture Toughness Evaluation of $2040-Al/Al_2O_3$ Particulate Composites by Instrumented Impact

Abstract

Composites consisting of an aluminium alloy (2024 Al) reinforced with 4 mu m sized $Al_2O_3$ particles were prepared by the casting route. Fracture energy, E, and dynamic fracture toughness, $K_{Id}$, values for composites and unreinforced alloys were evaluated by means of an instrumented impact test at temperatures varying from −196 to 100°C. The magnitude of the observed reduction is greater in the case of the fracture energy values that for the fracture toughness values as a result of the alumina additions. Furthermore, the dynamic fracture toughness of both composites and unreinforced alloys shows a negative dependence on temperature. By contrast, fracture energy values for the composites decrease with increase in temperature, whereas the fracture energy for the unreinforced alloy increases with increase in temperature. SEM examination of fracture surfaces of composites reveals multiple cracking of alumina particles