# Novel Composite Powders with Uniform TiB\({}_{2}\) Nano-Particle Distribution for 3D Printing
## 4 Conclusions  
Gas-atomized, TiB\({}_{2}\)-reinforced Al-3.8 Cu-1.3 Mg composite powders were synthesized by gas atomization solidification. The composite powders exhibited a fine-grained structure benefiting from the fast cooling condition and the integration of TiB\({}_{2}\) particles, which improved the nucleation rate greatly. The engulfment of TiB\({}_{2}\) particles was achieved, benefiting from the fast cooling rate and the two high-coherency orientation relationships between the particles and \(\alpha\)-Al, resulting in a relatively uniform particle distribution in the interior of the grains. The resulting Al-based composite powders with a fine grain structure and uniformly dispersed high-fraction TiB\({}_{2}\) nanoparticles provide promising candidates for nanocomposite synthesis via AM because the TiB\({}_{2}\) pre-embedded nanocomposite powders with improved laser absorptivity largely expand the powder materials palette for AM processes, since the alloy element composition can be easily modified. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline \multirow{2}{*}{**Small TiB\({}_{2}\) Particles (\(<\)200 nm)**} & \multirow{2}{*}{**Powder Size**} & \multicolumn{2}{p{113.8 pt}}{**Total Number of Recorded Small TiB\({}_{2}\) Particles**} & \multirow{2}{*}{**Orientation**} & \multicolumn{1}{p{113.8 pt}}{**Number of TiB\({}_{2}\) Particles**} & \multirow{2}{*}{**Proportion**} \\ \cline{3-3} \cline{5-6}  & & & OR1 & 24 & 92\% \\ \cline{2-6}  & \multirow{2}{*}{10 μm} & & OR2 & 1 & 4\% \\ \cline{2-6}  & & & OR1 & 27 & 79\% \\ \hline \multirow{4}{*}{Big TiB\({}_{2}\) particles (\(>\)300 nm)} & \multirow{2}{*}{**Powder Size**} & \multicolumn{2}{p{113.8 pt}}{**Total Number of Recorded Big TiB\({}_{2}\) Particles**} & \multicolumn{1}{p{113.8 pt}}{**Orientation**} & \multicolumn{1}{p{113.8 pt}}{**Number of TiB\({}_{2}\) Particles**} & \multirow{2}{*}{**Proportion**} \\ \cline{3-3} \cline{5-6}  & & & OR1 & 9 & 69\% \\ \cline{2-6}  & \multirow{2}{*}{50 μm} & & OR2 & 0 & 0 \\ \cline{2-6}  & & & OR1 & 3 & 75\% \\ \cline{2-6}  & & & OR2 & 0 & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Orientation relationship summary of all the recorded TiB\({}_{2}\) particles inside the grain by EBSD. Figure 5: The laser reflectivity and K-M absorption factor of the atomized TiB\({}_{2}\)-reinforced Al–3.8 Cu–1.3 Mg composite powder. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline \multirow{2}{*}{**Average Size of TiB\({}_{2}\) Particles**} & \multirow{2}{*}{**Powder Size**} & \multicolumn{2}{p{113.8 pt}}{**Total Number of Recorded TiB\({}_{2}\) Particles**} & \multirow{2}{*}{**Orientation**} & \multicolumn{1}{p{113.8 pt}}{**Number of TiB\({}_{2}\) Particles**} & \multirow{2}{*}{**Proportion**} \\ \cline{3-3} \cline{5-6}  & & & OR1 & 1 & 6\% \\ \cline{2-6}  & \multirow{2}{*}{50 μm} & & OR2 & 0 & 0 \\ \cline{2-6}  & & & OR1 & 0 & 0 \\ \cline{2-6}  & & & OR2 & 0 & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Orientation relationship summary of all the recorded TiB\({}_{2}\) particles at the grain boundaries by EBSD. **Acknowledgments:** This work is financially supported by the National Natural Science Foundation of China (Grant No. 51201099 and No. 51301108). Many thanks are also due to the faculty of BL14B beamline at the Shanghai Synchrotron Radiation Facility for their help on synchrotron experiments. **Author Contributions:** [PERSON] and [PERSON]: Co-organized the work, prepared the materials, characterized the materials with SEM, EBSD and Synchrotron X-ray diffraction, wrote the manuscript draft. [PERSON] and [PERSON]: Materials characterized with laser reflectivity, commented on the manuscript draft. [PERSON]: Materials characterized with SEM and TEM analysis, commented on the manuscript draft. [PERSON]: Materials prepared with casting process, commented on the manuscript draft. [PERSON]: commented on the manuscript draft.