Formation of Surface Metal Matrix Composites with Reinforcement Particles in Aluminium Alloys by FSP-A Review

Abstract

Friction Stir Processing (FSP) is an advanced solid-state technique developed to enhance surface properties of aluminium alloys by in-situ surface metal matrix composites (SMMCs) through the incorporation of reinforcement particles into the substrate material. In contrast to FSP, conventional techniques like powder metallurgy and surface coatings often suffer from inherent limitations, including porosity and non-uniform distribution or segregation of reinforcement particles within the metal matrix, which can compromise the mechanical and functional properties of the final composite. Different type of ceramic reinforcement particles like TiO2 (titanium oxide), SiC(Silicon carbide), Al2O3(aluminium oxide), and B4C(boron carbide) may be used to form SMMC’s of aluminium alloys. The incorporation of reinforcement particles through FSP has proven to be an effective method for enhancing the surface properties of metallic materials. These reinforcement particles are introduced into the stirred zone, where intense plastic deformation and dynamic recrystallization occur. This results in a refined grain structure and a uniform dispersion of particles within the alloy’s surface layer. As a result, significant improvements are observed in surface hardness, wear resistance, and corrosion resistance of soft aluminium alloys. The solid-state nature of FSP eliminates common defects associated with fusion-based methods, such as porosity or interfacial reactions between the matrix and reinforcement. These improvements make FSP an attractive technique for developing surface metal matrix composites (SMMCs) tailored for demanding applications in aerospace, automotive, and marine industries.