## 5 Discussion  
This study aimed to investigate the effect of SiC particle size on the densification behavior, specifically the homogeneity of density distribution in Mg-SiC nanocomposites following the CIP process, which is critical for achieving uniform density distribution. To meet this, a modified Drucker-Prager Cap (DPC) elastoplastic continuum finite element method (FEM) model was employed, previously utilized and validated for analyzing the impact of SiC volume fraction on the Mg-SiC nanocomposites' density distribution homogeneity after cold isostatic pressing [27]. The previous study's results demonstrated that as the SiC volume fraction increased, the Mg-SiC nanocomposites' density distribution homogeneity decreased. The densification process occurs in three distinct stages. Initially, there is a rearrangement of powder particles, leading to an increase in packing density [23]. In the second stage, elastic-plastic deformation takes place at the contact areas between particles, resulting in a higher coordination number and a reduction in porosity as pressure is applied [28]. As the pressure further increases, the phenomenon of cold welding and/or mechanical interlocking becomes prominent. This causes brittle powder particles to fracture and rearrange, contributing to enhanced densification [21]. The process of densification is influenced by several factors, including material properties such as hardness, work-hardening, and cold-welding response, as well as geometric characteristics like particle shape, size, and  
Figure 5: **(a)** the contour plots of pressure distribution for M105\(\mu\) and M105n after the CIP process under different applied pressures of 100, 300, 500, and 700 Mpa, **(b)** the contour plots of Relative density distribution for M105\(\mu\) and M105n after CIP under 100, 300, 500 and 700 MPa. distribution [23]. The higher maximal relative density and improved compressibility observed in the Mg-SiC nanocomposite containing submicron-sized SiC particles, as estimated through FEM calculations under various pressures, can be attributed to the input model parameters used in the simulation. Higher values of cohesion of material (_d_) and friction angle (\(\beta\)) for M10S\(\upmu\) compared to M10 Sn (see Table 3) indicated enhanced interlocking of M10S\(\upmu\) constituent particles [29; 30], which can be traced back to the microstructural characterization of the powder composite. M10 Sn exhibited finer and equiaxed morphology after 25 h of mechanical milling (Figure 6a), while M10S\(\upmu\) powder particles displayed a more irregular, flake-like morphology (Figure 6b) [31]. The presence of flakes and irregular-shaped particles creates an asymmetrical local stress field characterized by a significant shear component. This shear component contributes to the entanglement and cohesion of the material [32]. The size and shape of the powder particles also influence the friction angle (\(\beta\)) of a powder composite. Powder composites with fine and equiaxed particles, such as M10 Sn, tended to have a lower friction angle and reduced interlocking between the powder particles [33]. The cap eccentricity (R) in the MDPC model reflects the propagation of plastic flow among particles and their resistance to deformation or deflection under applied loads. It provides information about how the particles resist deformation or deflection under the given load [29]. The significantly lower cap parameter value for M10 Sn, 0.53, compared to M10S\(\upmu\), 1.77, reveals the lower deflection and higher stiffness, i.e., higher resistance to permanent plastic deformation [30] of the composite containing the nanoparticles under the same load. Although the volume fraction of SiC reinforcement in both M10S\(\upmu\) and M10 Sn is the same at 10%, the smaller grains in M10 Sn containing nanosized SiC compared to M10S\(\upmu\) containing submicron-sized SiC result in an increase in grain boundaries, thereby increasing resistance to plastic deformation and densification of M10 Sn [34].