## 1 Introduction  
The use of lightweight materials [1; 2; 3] with high strength and stiffness [4] is becoming increasingly important in many industries, such as aerospace [5], automotive [6], and biomedical [7]. Metal foams, which are a class of lightweight materials with a unique porous structure, have shown great potential in meeting these demands [8]. Recent years have seen considerable attention focused on closed-cell aluminum foams. Their excellent mechanical and physical properties have made them conducive to various engineering applications in chemical, biological, functional, and structural sectors [9; 10]. Such foams are characterized by their lightness, high strength, and excellent energy absorption capacity [11; 12], making them attractive materials for various engineering applications such as impact energy absorbers, aerospace, and automotive components. To fully exploit the potential of closed-cell aluminum foams, it is imperative to understand their mechanical behavior and the response to different loading conditions. One of the most common methods used to evaluate the mechanical behavior of closed-cell aluminum foams is compression testing under quasi-static conditions. The method involves the application of a compressive load on the foam sample under a constant crosshead speed and measurement of the foam's response to the load in terms of the stress-strain curve. Invaluable information about the foam's compressive plateau, pseudo-elastic modulus, and energy absorption capacity can thereby be gleaned, giving us an insight into its mechanical properties [13]. A strong correlation has been observed between the morphology and compression behavior of closed cell aluminum foams. The foam's cell size, shape, and distribution significantly affect compression strength, energy absorption, and deformation behavior [14; 15] in static and dynamic conditions [16]. Smaller cell size and uniform cell distribution result in higher compression strength and energy absorption, whereas irregular cell shapes lead to reduced foam performance. Closed cell aluminum foams are a type of foam composed of aluminum with closed pores inside. They have been widely used in various industries due to their unique combination of properties. The microstructure of closed cell aluminum foams can have a major influence on their mechanical properties, and thus it is important to understand the correlation between microstructure and mechanical properties. In particular, the porosity, size, and circularity of the foam can affect the mechanical properties of the material. Generally, the higher the porosity size, the lower the stiffness and the strength of the material. This is because the porosity provides a lower reacting surface, resulting in lower stiffness and strength. Additionally, the porosity can also affect the thermal properties of the foam, as the open cells provide a greater surface area for heat transfer [17; 18]. On the other hand, the smaller the porosity size and the higher the circularity, the higher the stiffness and the strength of the material. This is because smaller cells provide a more even distribution of stress, resulting in a stiffer and higher strength material. Additionally, the circularity of the cells can also affect the thermal properties of the material, as circular cells can provide higher heat transfer coefficient [18]. Despite many papers being published during recent years, a systematic study on the correlation between microstructure and mechanical properties in compressive tests has not been carried out on closed-cell Al foams. In this work, a comprehensive study on the compression behavior of closed-cell aluminum foams is illustrated. To control the physical microstructure of cell walls and eliminate weakening phases, the Al powders must be carefully selected, additives that enhance viscosity and foaming agent must be added in the powder's mixture, and, finally, account must be taken of the thermal conditions during foam solidification [19].