## 1 Introduction
Traverse speed (mm/min): Traverse speed is responsible for moving the material from the front end of the workpiece to the end. The grain size in the FSPed zone of the material being processed may increase when the tool traverse speed is decreased. As a result, it barely affects how much the tool wears. Research also indicates that increasing the traversal speed can enhance the surface composite microhardness of the FSPed zone by increasing the dispersion of the reinforcement particles [19]. Tilt angle (deg): The tilt angle of the FSP tool ensures that the substance that has been stirred stays in the tool shoulder and is propelled to the back of the tool shoulder. The processing temperature may rise when the tool tilt angle is increased [20]. Higher tilt angles can result in larger grain and particle sizes, while lower tilt angles may cause defects in the processed zone [21]. Optimizing AMMCs' microstructure and properties to meet the demanding needs of many sectors is crucial to achieving all their full potential. Approaches to optimization issues range from traditional to unconventional [22]. Conventional optimization techniques can be widely divided into two categories: mathematical search techniques (e.g., linear programming, nonlinear programming, dynamic programming) and experimental techniques such as statistical design of experiments (e.g., response surface design approach, or Taguchi method). Non-conventional metaheuristic search methods, like genetic algorithms, tabu search, and simulated annealing, have become more and more popular among scholars in recent years. While alternative optimization methods like mathematical search techniques, RSM, and metaheuristic methods offer their own advantages, they also have limitations that can hinder their practical application in optimizing processes like FSP. The Taguchimethod's efficiency, robustness, and simplicity make it a particularly attractive choice in such scenarios. The Taguchi method is a robust engineering approach, pioneered by [PERSON], which aims to enhance product and process quality through structured experimentation. By employing experimental design called orthogonal array design, signal-to-noise ratio, and analysis of variance, this method optimizes factor settings and minimizes variability, resulting in improved product performance and manufacturing efficiency [23; 24]. Researchers have used the different design of experiments and FSP in order to determine optimum process parameters for aluminium metal matrix composites utilizing different grades and reinforcements [25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35]. The novelty of this research lies in its comprehensive comparison of AA5083/Silicon carbide and AA5083/Coal composites using identical FSP parameters. Previous studies have often focused on individual reinforcements, but this research addresses a gap by examining multiple reinforcements under identical conditions. Employing a Taguchi L9 design to optimize process parameters for both composites, the study focuses on ultimate tensile strength, microhardness, and percentage elongation. The results will contribute to a deeper understanding of how different reinforcements respond to FSP, guiding the development of more cost-effective and high-performance aluminium metal matrix composites. By acknowledging and addressing the limitations of prior studies, this research offers a more comprehensive and rigorous analysis, making it a valuable contribution to the field of FSP and composite materials fabrication.