Effect of Thermal Cycling on Fracture Mechanism in SiCp Reinforced Aluminum Cast Alloy

Abstract

The effects of thermal cycling on the fracture toughness of SiC particulate reinforced cast aluminum alloy have been studied. The results were discussed in terms of a microstructure controlled mechanism which is void growth, coalescence and debonding of SiC particle/matrix interface for fracture. The fracture toughness of thermally cycled material is twice larger than that of as received material. The measurements of 3D shape of fracture surfaces show that the crack blunting occured in front of the SiC particle clusters in the material with thermal cycling. The micro-mechanism of fracture is void coalescence and debonding of the SiC particle/matrix interface in this case. The behavior is basically consistent with void/inclusion models. A new formulation is proposed and its validity is demonstrated.