Investigation on mechanical properties and fracture behavior of A356 aluminum alloy based ZrO2 particle reinforced metal-matrix composites

In the present study, an investigation has been carried out on the influences of ZrO2 content and casting temperature on mechanical properties and fracture behavior of A356 Al/ZrO2 composites. A356 aluminum alloy matrix composites reinforced with 5, 10 and 15 vol% ZrO2 were fabricated at various casting temperatures, viz. 750, 850 and 950 °C via the stir casting method. Based on the obtained results, optimum amount of reinforcement and casting temperature were determined by evaluating the density and mechanical properties of the composites. Hardness and tensile tests were carried out in order to identify the mechanical properties of the composites. Fracture surfaces of the samples were also studied to identify the main fracture mechanism(s) of the composites. The results indicate that all samples fractured due to the inter-dendritic cracking of the matrix alloy. Reinforcing the Al matrix alloy with ZrO2 particles, improved the hardness and ultimate tensile strength of the alloy to the maximum values of 70 BHN and 232 MPa, respectively. Consequently, the highest mechanical properties were obtained by the specimen including 15% of ZrO2 produced at 750 °C.