## 2 Review Available Literature
### AA5052-Based MMCs  
[PERSON] et al. [35] studied process factors concerning the mechanical properties and microstructure of an AA5052-SiC composite made by FSP. AMMC was created on the surface of 5052 aluminium sheets using FSP and 5-micrometre and 50-nanometre silicon carbide particles. Between passes, the impact of the traverse speed and rotational direction shifts was investigated. To determine the tool's rotational and traverse speeds that produced the best powder dispersion, experiments were carried out utilizing all possible combinations of the three traverse speeds of 40 mm/min, 80 mm/min, and 125 mm/min and the three rotational speeds of 700 rpm, 1120 rpm, and 1400 rpm. Investigations were conducted on the impacts of tool rotational speed and particle size on the distribution of SiC particles, FSP passes, and the specimen's microstructure, wear, and microhardness characteristics. The findings indicate that the hardness and wear qualities were enhanced by increasing the number of passes, reducing the size of the SiC particles, and changing the tool's rotational motion between FSP passes. FSP and nano-sized SiC particles were used to produce an ultrafine microstructure. The use of SiC powder significantly improved the hardness. The microhardness increased by up to 55% over the parent material, and the rate of wear was reduced by 9.7 times. [PERSON] et al. [36] employed FSP to create an AA5052-Al\({}_{2}\)O\({}_{3}\) nano-ceramic particle reinforced composite. After many FSP passes, the microstructural and mechanical characteristics of AA5052-Al\({}_{2}\)O\({}_{3}\) surface composites were studied. FSP was conducted with varied tool-rotation speed to travel rate ratios (\(\omega\)/\(\upsilon\)) ranging from eight revolutions per minute to 100 revolutions per minute and a pin-tilting angle (\(\varphi\)) ranging from 2.5\({}^{\circ}\) to 5\({}^{\circ}\) to determine the best FSP conditions for the manufacture of stir zones without macroscopic faults. As the number of FSP passes increased, the stir zone's grain size decreased, and the surface composite created by four passes had a submicron mean grain size. The development of a nanocomposite with a mean cluster size of 70 nanometres after four passes and uniform Al\({}_{2}\)O\({}_{3}\) particle dispersion in the base material were other benefits of increasing the FSP pass. Tensile testing showed that all FSP samples had more elongation than the base metal and that composites formed in three and four passes had greater UTS and yield strengths and lower elongation than FSPed materials prepared without powder under comparable conditions. Under good conditions, the four-pass composite's UTS and percentage elongation of the parental material increased to 118 and 165 percent, respectively. [PERSON] et al. [37] created a high-strength ultra-fine-grained Al-Mg-SiC nanocomposite through a multi-step friction-stir-processing procedure. An ultra-fine-grained Al-matrix nanocomposite with improved tensile and indentation hardness was created using multi-pass FSP in this study. Using up to five cumulatively overlapping FSP operations, SiC nanoparticles of around 3.5 vol% were incorporated into an Al-Mg alloy matrix. Using scanning and electron backscattered electron microscopy, the nanoparticle dispersion in the stirred zone and their interfaces with the aluminium matrix were investigated. As a result of dynamic recrystallization during FSP, the grain and sub-grain structures of the SZ were refined to around 1.4 \(\upmu\)m and less than 1 \(\upmu\)m, respectively. The distribution and orientation of grains were considerably affected by the presence of SiC nanoparticles during FSP. Based on the Orowan looping and grain-refining processes, SiC nanoparticles showed both direct and indirect effects on the strengthening of the Al matrix. During FSP, the distribution and shape of the precipitates were partially dissolved.