Nanoparticles reinforced joints produced using friction stir welding: a review

Fusion welding processes do not find attention due to their restriction to use for certain grades of materials and alloys. Friction Stir welding (FSW) or the solid-state joining process has proven to be a more efficient process for the welding of metal-matrix reinforced composite butt joints by employing various combinations of reinforcement particles and base matrices compared to the fusion welding process. Due to the solid-state nature of the FSW process, no melting of base material would occur which leads to no toxic fumes, low energy consumption, environmentally friendly, and ease of operation that makes FSW a more versatile welding process for aerospace, automobile, and transportation industries. However, the challenges in joining metal matrix reinforced composites remain even with a substantial advancement in the process made during current years. This review article outlines a brief overview of the state of art of metal matrix reinforced welds joined using FSW. More emphasis with critical evaluation has been done on the (a) macrostructural and microstructural characteristics of a metal matrix reinforced welds which merely depend on the plasticized material flow and reinforcement particles behavior and its difficulty for uniform distribution of reinforcement particles in the weld zone based on the combination of reinforcement particles and the metal matrix materials, (b) assessment of mechanical properties of the metal matrix reinforced welds those are directly interdependent on the selection of process parameters by which the grain refinement and their reinforcement particles distribution depend that leads to changes in such properties, and (c) fracture and wear properties of the metal matrix reinforced welds which again depends on the reinforcement particles and the metal matrix materials combination. The conclusions of this review are ended up with recommendations for the directions for future research.