## 1 Introduction  
The growth in engineering in industrial applications has led to efforts to construct cost-efficient alloys with exceptional properties, such as high strength, light weight, and ductility [1]. Despite their attractive characteristics and widespread usage, aluminum (Al) alloys require further development [2]. In this regard, confronting this obstacle is achieved by constructing Al-based alloys, which have garnered attention due to their light weight, higher strength, and toughness, as well as reusability [3]. Though other materials' properties need to be considered as corrosion resistance [4; 5], many studies tend to focus on mechanical properties [6]. Aluminum and its alloys are widely used in industry due to their low density, high specific strength, good corrosion resistance, good performance, high thermal and electrical conductivity, attractive appearance, and recyclability [7; 8; 9]. As a very light metal, magnesium and its alloys have excellent specific strength, good castability, hot formability, good shielding against electromagnetic interference, and recyclability [10]. To save weight, aluminum alloys, and magnesium alloys can be used instead of steel and iron, which are much heavier [10; 11]. There are specific programs to use more suitable metalsinstead of other metals due to the advantages of their specific characteristics, such as the damping ability of magnesium and the creep resistance of aluminum [9; 12]. It is expected that both metals, aluminum, and magnesium, will be used more for industry in the future. The combination of aluminum and magnesium in a composite structure allows the use of these alloys for more applications, which results in optimal weight savings. Among others, a dissimilar joint of Al and magnesium (Mg), labeled Al/Mg, has been found as a promising approach for reaching a high strength-to-weight ratio property [13]. Having various structural and mechanical properties makes the joining of these two alloys attractive due to the possibility of the formation of wide properties, which were inaccessible before [14]. There is quite a vast range of methods utilized for the dissimilar welding of Al/Mg; thus, choosing the joint method is of paramount importance. Considering the drawbacks of Al, namely low molten viscosity, high reflectivity, and inherent oxide layer formation, traditional welding processing resulted in hot cracking, poor joining, and potential defects [7]. Correspondingly, the formation of intermetallic compounds, brittle compounds, pores, and solidification cracks in conventional approaches, e.g., arc welding and fusion welding processes, was observed [15]. Compared to others, to overcome these shortcomings, friction stir welding (FSW) has been suggested because of its processing uniqueness and cost-efficient technique [16; 17]. It is worth mentioning that FSW prevents the formation of weld defects and reduces hydrogen solubility [18]. During FSW, the welding tool contains two different motions: rotary and linear along the joint line. The pin is plunging between the sheet workpieces with rotational motion followed by traversing along the joint causing dissimilar bonding by mixing metals at the joint zone [9]. The intermixing of two materials at the stir zone is affected by engaged processing parameters such as welding speed, tool rotation speed, and the piece position [19; 20; 21]. In this context, it is figured out that applying optimized rotational and linear speed causes the formation of stable phases in the weld zone [22]. During the welding process, the kinetic energy is turned into thermal energy due to friction at the interface between the tool and work pieces; thus, process parameters strictly impact the amount of introduced heat [9]. The tool traverse speed and rotational speed remarkably affect the heat generation. It is recommended that the heat input is directly and inversely proportional to rotational speed and tool traverse speed, respectively [7].