Friction Stir Processing Multi-Run Modification of Cast Aluminum Alloy

Abstract

The effect of multi-run FSP modification of cast aluminum alloy AlSi9Mg are presented. The relationship between the number of trials and microstructures are shown. FSP process was performed on the typical milling machine specifically adopted for the processing trials. The microstructure was examined by light as well as scanning and transmission electron microscopy. The studies have shown that the multi-run FSP process causes decrease of the grain size and increase of the homogeneity of the microstructure. In contrast to the cast condition, the microstructure in the processed material was characterized by a relatively uniform distribution of the second phase particles. The size and aspect ratio of these particles decreased significantly. Application of FSP process resulted in a decrease of the porosity in the modified material. The modified materials achieved at perpendicular runs can be characterized by the higher dislocation density that obtained at parallel ones. The multi-run FSP process caused increase the elongation and ultimate tensile strength of modified material in comparison to properties of the cast aluminum alloy.