This project will explore the synthesis of metal-matrix nanoparticle composites using solidification processes, including stir mixing technique. In the synthesis of the composites using the stir mixing process, there will be uncertainties such as difficulty in the introduction and dispersion of nanosize particles, increase in viscosity in melts due to high surface area of nanosize particles, and flotation/sedimentation velocities of nanosize particles. The incorporation of nanoparticles can lead to metal-matrix nanocomposites with improved mechanical properties, including high strength, high fatigue and high creep properties.
In this research, mixing technologies will be developed to mix nanosize particles in aluminum melts, and optimum solidification process will be identified for obtaining a uniform distribution of nanosize particles in cast materials. Mixing conditions, including feeding rate of nanosize particles, stirrer speed, particle volume fraction, wetting agent, ultrasonic energy, and melt temperature will be optimized for a uniform distribution of nanosize particles. The fluidity of a melt containing nanosize particles and velocities of flotation or settling of nanosize particle will also be determined from the final distribution of the particles in the melt and in the matrix. The solidified microstructure and the distribution of nanoparticles in the matrix will be analyzed to understand nucleation and growth behavior in the presence of nanosize particles. Selected properties, including the density, modulus and compressive properties will be measured related to processing variables. It is anticipated that the results of this work can lead to technology transfer for nanocomposite castings.
