A review of recent progress in the fabrication of surface composites through friction stir processing

The development of surface composites is an effective tool to encounter surface-related issues, and during the recent past, friction stir processing has been developed as an energy-efficient process to fabricate surface composites effectively. FSP is an evolving thermo-mechanical surface modification technology that removes casting defects locally, refines micro-structures, improves various mechanical properties like hardness, wear resistance, strength, etc., without affecting the bulk properties. Nowadays, besides low strength metal systems, i.e., aluminum and magnesium-based alloys, FSP has been reported for making surface composites of high strength alloys like steel and titanium-based alloys. The effect of process variables and tool geometry on surface composites of different alloys have been reviewed largely, but presently we are away from obtaining desired composites. For the whole understanding of FSPed surface composites, this review consolidates different aspects of fabricated surface composites, effects of process parameters, different reinforced particles, number of passes during fabrication of surface composites, tool wear and tool materials, strengthening mechanisms for of FSPed surface composite including gaps in recent works and possible suggestions for obtaining cost-effective and defect-free FSPed composites. Copyright (C) 2022 Elsevier Ltd. All rights reserved.