## 3 Results and Discussion
### Structural and Morphological Properties of the Power Particles
#### 3.1.3 Scanning Electron Microscopy
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{\begin{tabular}{c} **Milling** \\ **Times (h)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Average** \\ **Particle** \\ **Size (imm)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Std. Dev. \(\sigma\)** \\ **(imm)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **SEM** \\ **Micrograph** \\ **Figure** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **\% Reduction in** \\ **Average Particle** \\ **Size \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Phases in XRD** \\ **Patterns** \\ **of (002)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Graphite Peak** \\ **Energy** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Ball Mill** \\ **Energy** \\ \end{tabular} } \\ \hline \multirow{2}{*}{0} & \multirow{2}{*}{13.54 \({}^{*}\)} & C = 2.8583 & \multirow{2}{*}{5a, b, and c} & \multirow{2}{*}{-} & \multirow{2}{*}{C + Mo + W} & \multirow{2}{*}{150,000} & \multirow{2}{*}{-} \\  & & & & W = 5.1682 & & & \\ \multirow{2}{*}{75} & \multirow{2}{*}{9.32} & \multirow{2}{*}{2.6867} & \multirow{2}{*}{6a and b} & \multirow{2}{*}{31.18} & \multirow{2}{*}{
\begin{tabular}{c} C + MoW + \\ MoWC \\ \end{tabular} } & \multirow{2}{*}{1761} & \multirow{2}{*}{Low} \\  & & & & & C + MoW + \\ \multirow{2}{*}{125} & \multirow{2}{*}{4.86} & \multirow{2}{*}{1.5124} & \multirow{2}{*}{6e and f} & \multirow{2}{*}{64.10} & \multirow{2}{*}{MoWC} & \multirow{2}{*}{3791} & \multirow{2}{*}{High} \\  & & & & & & MoW + MoWC & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Morphological evolution parameters of the powder particles milled at high-energy MA. the milling process repetitively exfoliates and reintegrates the powder particles, producing a thin plate morphology of about 1.3 \(\upmu\)m. The W element's role is to harden the material and then make it brittle during the process of substitution of Mo by W atoms during MA [33]. Table 3 summarizes the evolution of particle sizes related to 75, 125, and 150 h of milling. The table shows the average particle size of the powder particles until a value of 4.8 \(\upmu\)m for 150 h of milling, which was equal to a 56% reduction compared to the average size of non-milled powder particles (0 h) given by the commercial Mo, W, and C raw materials. Table 3 also shows the intensity variation of C (002) which is related to introduction of C into the metal lattice and the microstructural evolution at different milling stages. A decrease in the (002) peak was observed from 0 until 75 h of milling, but it showed an increase between 75 and 125 h. This phenomenon was associated with a partial decomposition of graphite from the MoW alloy caused by the presence of a high density of crystalline defects, mainly, for example, dislocation and grain boundaries [17]. Then, when the milling process was continued to 150 h, this peak vanished indicating the complete introduction of graphite into the MoW alloy to produce the MoWC solid solution. However, at 150 h, the MoW alloy and MoWC solid solution coexisted with a composition of 27.7% and 71.3%, respectively, according to XRD-Reference Intensity Ratio method (RIR) calculations [35; 36]. According to SEM images, the raw materials showed a severe plastic deformation caused by mechanical impacts between media milling and the powder particles with repetitive fracturing during the MA process, which was the reason of the decrease in the particle size [37]. In addition, the formation of the nanostructured MoWC bimetallic carbide (Table 3) contributed to the reduction of the particle size since the existence of micro-sized carbides, that can act as grinding agents and lead to the refinement of the particle size, creates a great amount of tension energy during the milling process [38]. Figure 6: SEM micrographs of the powder particles milled at 75 (**a**,**b**), 125 (**c**,**d**), and 150 (**e**,**f**) hours, showing 1000\(\times\) magnification for (**a**,**c**,**e**) and 5000\(\times\) magnification for (**b**,**d**,**f**).