In this paper, the grain refinement of a 5052 aluminum alloy was achieved using two different fabrication approaches. In the first approach, the grains in the investigated alloy were modified and refined during the casting process by adding refining elements, namely, titanium and boron (TiB), while in the second approach, the base 5052 aluminum alloy and modified (5052 + TiB) alloy were refined by friction stir processing (FSP), a solid-state processing technique. The microstructure of the investigated alloys was examined using a high-resolution polarized optical microscope; moreover, XRD analysis was performed to identify the established phases in the investigated alloys. The impact of the modifying elements and FSP on the hardness and corrosion behavior of the 5052 alloy was evaluated. The results revealed that the (TiB) modifiers only enhanced the grain refinement of the aluminum cast alloy, while FSP improved the hardness properties and produced additional grain refinement on the surface of the processed alloy. Adding TiB as a modifier to the 5052 enhanced the corrosion resistance. In addition, the corrosion resistance of the surface of the friction stir processed alloy improved after using two passes.