## 1 Introduction  
One of the most important areas of interest in materials science and engineering has been the development of new generation materials with unique and tailored properties. Metal matrix composites (MMCs) represent the most innovative avenue of research in the field of materials engineering, with the potential to significantly improve aluminium alloy mechanical properties by the incorporation of high-modulus, high-strength ceramic particles into aluminium matrices [1, 2]. When compared to traditional structural materials, aluminium-based MMCs have higher specific strength and stiffness, which makes them perfect for several uses in the automotive, aerospace, marine, and recreational sectors [3, 4]. Exceptional properties that set them apart from traditional materials include high elastic modulus, outstanding resistance to corrosion, increased fatigue strength, better low coefficient of thermal expansion, and resistance to wear [5, 6]. AA5083-based composites are ideal for applications demanding lightweight, high-strength materials with excellent formability and corrosion resistance. These properties make them suitable for a diverse range of industries, including construction, marine, automotive, and aerospace [7, 8]. To fabricate composites and enhance mechanical properties, friction stir processing (FSP), a novel solid-state method, uses the principles of friction stir welding (FSW) by utilizing a rotating tool to modify surface properties and enhance mechanical performance without melting the base material [9; 10]. FSP causes microstructural change, densification, and homogeneity all at the same time by subjecting the material in the stir zone/nugget zone to plastic deformation, mixing, and heat exposure [11]. FSP also encourages shearing and even dispersion of particles inside the matrix [12]. Thus far, metal matrix composites have been successfully fabricated using FSP. Specific parameter combinations are used in FSP techniques, and each one affects how the processed surface behaves. Depending on the materials used, the desired composite properties, and the equipment available, different process parameters, such as tool geometry, tool rotation speed, traverse speed, preheating temperature, and applied pressure, will apply. Out of all the process parameters that impact FSP, it has been noted that the tool rotation speed and traverse speed [13] have an impact on the even distribution of the reinforcing particles, grain refinery, and heat production during the composites' fabrication, while the tool tilt angle has a major impact on the dispersion of reinforcing particles. In the stir zone, parameters such tool travel speed, plunge depth, tool rotation rate, and tool angle determine temperatures and microstructure properties [14]. Material flow and temperature distribution behaviour are greatly influenced by tool geometry and welding parameters, which can alter microstructure [15]. Grain size can be refined with lower heat input, but plasticization or softening of the material requires higher heat input. High traverse speeds and low rotating speeds can result in smaller grain sizes, but vice versa because defects may increase [16]. Therefore, it is essential to maximize both traverse and rotational speeds in order to produce a stir zone with fewer defects and smaller grain size. A summary of some of the most important processing parameters is given below. Rotation speed (rpm): Another significant element that controls the flow and dispersion of the workpiece material is the rotational speed. As the rotation speed of the tool increases, a higher dissolution of soluble particles is likely to occur while the insoluble particles are likely to fragment further [17]. Increasing the speed at which the tool rotates can improve the size of the grain and increase the stir zone's temperature considerably. It is important to note that the microstructural evolution of the material can be affected by the direction in which the tool rotates [18].