Effect of Friction Stir Processing on Microstructure and Hardness of Cast Hypo-Eutectic and Hyper-Eutectic Al-Si Alloys

Abstract

The objective of this study was to ascertain the impact of Friction Stir Processing (FSP) on the microstructure and hardness of Al-Si alloys of hypo-eutectic (AlSi8) and hyper-eutectic (AlSi16) composition, with a particular focus on thermomechanical alterations in the microstructure. Microstructural studies were conducted on cross-sections using light microscopy and scanning electron microscopy techniques, in conjunction with an analysis of the chemical composition in the micro-areas. Furthermore, electron backscatter diffraction analyses and analyses of the hardness distributions in the stirred zone after FSP were conducted. The utilisation of FSP to modify both AlSi8 and AlSi16 alloys was demonstrated to facilitate microstructural refinement. Based on the results, the remodelling and dynamic recrystallisation of the microstructure associated with the application of FSP treatment were identified.