Abstract
In this work, aluminum piston alloy-based nano-composites of high strength and ductility with large damping capacity were produced. Ni particles and Al2O3 particles were used as reinforcing agents to produce three nano-composites by adding three mixtures of these particles to the melt of Al-Si piston alloy at 700 degrees C and application of stirring and squeeze casting. In addition, three micro-composites were produced by adding Ni particles of different percentages to the melt of the same matrix alloy and application of mechanical stirring and squeeze casting with the same conditions. The microstructures of the different materials were investigated using optical and scanning electron microscopes. Energy-dispersive x-ray analysis was carried out to analyze the elements of the reinforcing and matrix materials. Ultimate tensile strengths and engineering strains of the unreinforced and reinforced materials were evaluated by carrying out tension tests at room temperature. Modal tests were also carried out to evaluate the dynamic characteristics: natural frequency and damping ratio. The tests showed that the ultimate tensile strengths, ductility, and damping capacity of these composites were improved by the increase of both Ni and/or Al2O3 contents. A dynamic life indicator (damping ratio divided by natural frequency) is calculated for each material and showed a significant increase with the increase of nano-particles and/or micro-particles. By carrying out the experiments at different conditions, the mechanical properties, modal characteristics (such as natural frequency and damping ratio), and life indicator can be correlated. By constructing relationships between these properties and dynamic characteristics, the vibration modal analysis can be used for prediction of these properties and characteristics non-destructively.