Effects of particulate volume fraction on cyclic stress response and fatigue life of AZ91D magnesium alloy metal matrix composites

In this work, both AZ91D monolithic and AZ91D/SiCp composites prepared by squeeze casting followed by hot extrusion are tested under fully reversed strain-controlled loading conditions. The effects of SiCp volume fraction (i.e. Vf=0%, 5%, 15%, 25%, and 30%) and the imposed strain amplitude on the strain-controlled fatigue life and properties are examined. Increasing the SiCp content degrades the strain-controlled fatigue properties in the low cycle regime, with a potential benefit in the high cycle regime. The relationship between elastic strain amplitude, plastic strain amplitude and reversals to failure are well described by the Basquin and Coffin-Manson equations, respectively. A comparison made between the monotonic and cyclic stress-strain curves reveals that the reinforcement amount as well as the imposed strain amplitude significantly affects the characteristics of the evolving hysteresis loops.