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Many researchers have attempted to join Aluminum Matrix Composites (AMCs) using traditional fusion welding processes resulting in the formation of porosity, segregation, coarse microstructure, brittle intermetallic compounds and corrosion of ceramic particles. Friction Stir Processing (FSP) is the latest solid-state technique to achieve the homogeneous dispersion of reinforcement particles in the friction stir processed zone of AMCs [M. Shamanian, E. Bahrami, H. Edris and M. R. Nasresfahani, Surf. Rev. Lett.25 (2018) 1950010]. The most widely used reinforcing material since the inception of FSP is inorganic (metallic) powders such as silicon carbide, titanium alloy, graphene, iron, stainless steel, nitrides and oxides, and fewer works have been reported on organic powders (i.e. bioprocessing using agro-waste powders) such as fly ash, palm kernel shell ash, coconut shell ash and rice husk ash [O. M. Ikumapayi, E. T. Akinlabi, S. K. Pal and J. D. Majumdar, Procedia Manuf.35 (2019) 935]. In this work, the effect of FSP on the changes in metallurgical characterization and mechanical properties of AA7075/(3, 6 and 9) vol.% ZrB₂in situ AMCs was observed. After performing FSP, the AMCs were characterized using Scanning Electron Microscope and the mechanical properties such as Ultimate Tensile Strength and microhardness on the processed zone of the AMCs were calculated. The effect of FSP on AA7075/ (3, 6 and 9) vol.% ZrB₂in situ AMCs was investigated. The fracture morphologies on the processed surface of the AMCs were evaluated.

Al–Si alloys are commonly utilized in the production of automobile components, including pistons and cylinders. Although this alloy offers desirable features for usage in pistons, several microstructural characteristics, such as the presence of needle-like silicones or dendrites, impair the performance of the parts produced. In this study, TiC reinforcement particulates were employed to generate matrix composites via friction stir processing (FSP) to increase the wear resistance of Al–Si alloys. The microstructural characteristics of the nugget zone of FSPed specimens were studied. The results reveal that the FSP improves the base alloy microstructural characteristics. The particle distribution and quality of the bonding between the TiC particles and the aluminum matrix were investigated using SEM. The hardness and wear tests were performed to establish the mechanical and wear properties of the particle reinforced composites. The hardness test results showed that the produced composites had a hardness of 144HV, which shows a growth of almost 220% compared to the base metal. The pin-on-disc wear test was carried out with sliding speeds of 1 and 2m/s, and loads of 5, 10 and 20N. The wear test results showed that the wear resistance of the produced particle-reinforced composite compared to the base alloy was improved by about 540%.

Friction Stir Processing (FSP) is a promising solid state method and it is developed from the Friction Stir Welding (FSW) principle. FSP was employed to enhance the surface characteristics by ceramic particulate reinforced with AA5052 aluminum alloy. Initially, the machined square grove was formed on AA5052 and packed with ceramic particulate. In this research, chromium carbide (Cr₃C₂) is a ceramic material for improving the surface characteristics of the base material. The FSP parameters such as tool rotational speed, traverse speed and axial forces were utilized in this process. The microstructure evolutions of the processed specimens were observed by optical microscope and Field Emission Scanning Electron Microscope (FESEM) with Electron Dispersion Spectroscopy (EDS). The mechanical properties like processed microhardness and tensile strength of AA5052 friction stir processed specimens were analyzed. The various microstructural zones were observed in the processed regions with dispersion of the particulates Cr₃C₂. The specimen fabricated at 1000 rpm tool rotational speed, 25 mm/min traverse speed and 7 kN axial force exhibits maximum microhardness and tensile strength with homogeneous dispersion of Cr₃C₂.

Friction stir processing (FSP) is an effective tool to produce a surface composite layer with enhanced mechanical properties and modified microstructure of as-cast and sheet metals. In the present work, the mechanical and microstructural properties of as-cast AZ91 magnesium alloy were enhanced by FSP and an AZ91/SiC surface nanocomposite layer has been produced using 30 nm SiC particles. Effect of the FSP pass number on the microstructure, grain size, microhardness, and powder distributing pattern of the surface developed has been investigated. The developed surface nanocomposite layer presents a higher hardness, an ultra fine grain size and a better homogeneity. Results show that, increasing the number of FSP passes enhances distribution of nano-sized SiC particles in the AZ91 matrix, decreases the grain size, and increases the hardness significantly. Also, changing of the tool rotating direction results much uniform distribution of the SiC particles, finer grains, and a little higher hardness.