Study of Microstructure and Mechanical Behavior of Aluminum/Garnet/Carbon Hybrid Metal Matrix Composites (HMMCs) Fabricated by Chill Casting Method

Abstract

HMMCs are significantly influenced by the reinforcements. Composites with two or more reinforcements and finer grain structures are extensively used due to improved mechanical and tribological properties. The evolution of finer and uniform microstructures is strongly dependent on the cooling rate during solidification. In this investigation stir cast hybrid composites of aluminum alloy LM13 was fabricated with garnet and carbon particulate reinforcements. Chills of various materials such as copper, steel, iron and silicon carbide was used to accelerate the solidification. Combination of dispersoid varies from 3 wt% to 12 wt% in steps of 3 wt% garnet and 3 wt% carbon particulates. Microstructure characterization and mechanical properties such as hardness and ultimate tensile strength of reinforced hybrid composites were examined. The test specimens are prepared and tested as per American society for testing and materials (ASTM) standard. Vickers hardness measurement was carried out to study the hardness of the composite. The effect of chill and reinforcement characteristics was presented and compared with the hybrid composite without chill material. The results confirm the positive relationship between mechanical behavior and the dispersiod content. The copper chill cast composite with 9 wt% garnet and 3 wt% carbon was found to increase mechanical properties.