Effect of Zener-Hollomon Parameter on Microstructure of Aluminum Based Nanocomposite Layers Produced by Friction Stir Processing

For more than a decade, there has been considerable interest in the fabrication of metal matrix composites by employing Friction Stir Processing (FSP). In this study a new model based on Zener-Hollomon (Z) parameter has been developed, which is believed to be the first of its kind, to accurately predict microstructural characteristics of Al-based composites Additionally, the processing window of composite fabrication determined and revealed that sound samples achieve within the range of 2.42 to 24.61 rev/mm for the ratio of rotation speed to travel speed (ω/ν). Recording the peak temperatures during processing beside the optical and Scanning Electron Microscopic (SEM) studies showed that increasing the number of FSP passes and the ratio of ω/ν have a remarkable influence on bolstering the role of nanoparticles in grain refinement. Results also indicated that the mean grain size of FSPed samples and matrix of nanocomposites decreases with an increase in the Z parameter. Finally, particular equations for various numbers of passes developed, which make a correlation between the grain size of Al-based composites and the FSP parameters via Z parameter.