New Opportunities for Metallic Materials Processing with Friction Stir Alloying and Friction Stir Extrusion

The fundamental attributes of friction stir welding, which came into existence almost 30 years ago, have led to many other technologies, such as friction stir spot welding and friction stir processing (FSP). In recent years, the development of friction stir alloying (FSA) and friction stir extrusion (FSE) has been noteworthy, and both have emerged as extensions of FSP. FSA is quite promising because many alloys can be processed in small volumes at a high rate and can be used as a high-throughput alloy screening tool. FSE, on the other hand, can manufacture near-net shape products with microstructural attributes similar to those observed in friction stir processed workpieces. In this presentation, we will focus on the capabilities of FSA and FSE for processing metallic materials. Specifically, we will present results on the processing of Al-Bi, a monotectic alloy, using FSA and on the extrusion of ferrous alloys’ artifacts using powder-fed SolidStir^TM technology. SolidStir is a patent-pending friction stir-based continuous solid-state technology that facilitates making, consolidating, extruding, and depositing alloys and composites from various forms of feedstock. The microstructural characterization of these alloys was carried out using advanced characterization tools to evaluate grain size and distribution, texture, degree of recrystallization, and dispersion of the second phase(s) and their morphology. Overall, the ability to create new alloys or modify existing ones using FSA, and manufacture near-net shape products with improved microstructural control using FSE, provide new opportunities for developing advanced materials for demanding applications.