## 1 Introduction  
Magnesium-based metal matrix composites (MMCs), owing to their advantageous characteristics such as superior strength-to-weight ratio, enhanced thermal conductivity, and commendable wear resistance, have elicited significant interest, positioning them as a material of choice for advanced applications across diverse industries, including automotive, aerospace, and electronics [1, 2]. However, magnesium-based MMCs exhibit limited strength and ductility. Incorporating reinforcement particles like SiC can significantly improve these properties [3, 4]. The particle size is a critical determinant in shaping the microstructure and thereby influencing the properties of particle-reinforced magnesium matrix composites (PRMMCs) [5]. Recent research suggest micron-sized ceramic particles may reduce ductility, and nano-sized reinforcements can enhance strength and ductility in Mg-composites [6, 7]. Despite promising results, achieving uniform density distribution in green compacted parts during consolidation remains challenging, as inhomogeneous density distribution can cause nonuniform shrinkage or distortion during subsequent processes [8]. Particlesize, shape, and distribution influence the desired density distribution [9]. Mechanical milling has shown great promise as a method to attain homogeneous dispersion of nano-reinforcement particles within the matrix [4; 10]. However, mechanical milling can result in microstructural refinement and strain hardening, hindering further plastic deformation during compaction. Conventional compaction methods, such as uniaxial pressing, may need to be revised for consolidating milled powder, leading to high porosity [4]. Cold isostatic pressing (CIP) is a cost-effective method for producing green ceramic components with uniform density and high quality [10]. Optimizing process parameters such as pressure, time, and change in pressure rate is essential for achieving the desired density distribution at an affordable price [11]. However, predicting density distribution can be challenging. While various experimental methods such as Nuclear Magnetic Resonance (NMR) radioscopy [12], micro-indentation [13], X-ray tomography [14] have been used, they are not practical for predicting the densification behavior of powders before completing the experiment. Finite element method (FEM) simulations have become reliable for predicting and analyzing powder densification behavior, reducing costs and time waste [15; 16; 17; 18; 19]. Simulating powder compaction processes numerically necessitates the use of suitable continuum models capable of accurately depicting densification behaviors, which can be studied and modeled by examining powder interactions after characterizing the powder based on its size, hardness, and shap. The Modified Drucker Prager Cap (MDPC) model is frequently employed to study the densification behavior of powders, treating them as a homogeneous continuum [20; 21; 22; 23]. The MDPC model represents powders as a uniform continuum, considering input parameters encompassing elastic behavior, shear failure surface definition, cap shape determination, and the governing hardening law that prescribes alterations in material strength with plastic deformation [24]. [PERSON] et al. employed the MDPC model to characterize the densification behavior of SiC components. In the prior research [25], the MDPC model was utilized to estimate the impact of SiC nanoparticle density distribution on the compressibility of milled powder following CIP. The findings demonstrated a strong correlation between simulation and experimental outcomes for Mg-SiC nanocomposites using the MDPC model. This study investigates how the size of reinforcement particles impacts the densification behavior of milled Mg-SiC powders during CIP. The MDPC model was utilized to simulate the CIP process using FEM. Various tests were conducted, including uniaxial and Brazilian compressive tests, die compaction test, and CIP experiments, to derive the parameters for the modified Drucker-Prager Cap (DPC) model.