Aluminium Matrix Composites (AMC) reinforced by boron carbides promise mechanical performances comparable to MMCs already used in the aerospace industry ($Al-TiC$ and $Al-SiC$) for much lower relative densities. Compared to traditional ex-situ synthesis paths (stir casting, squeeze casting, etc.), in-situ synthesis of the reinforcement should allow improved interfaces and increased mechanical performances. So far, MMCs from this system have focused on the $Al-B_4C$ combination, which is produced using conventional methods. However, all of these methods face a reactivity problem during the high temperature step. In fact, $B_4C$ is not in equilibrium with the Aluminium matrix below 2177°C, which implies a risk of damages to the reinforcements due to reactions with the matrix and the appearance of weakening phases. To answer this problem, the AMC Al-τ3 ($Al_3B_{48}C_2$) has been proposed as an alternative by Dezellus et al. This material has been previously synthesized by peritectic decomposition of $AlB_2$ in a graphite crucible. 

This technique, although demonstrating the existence of the material, greatly limits the possibilities of complex parts shaping. The synthesis route explored in the present work is to combine ball-milling to produce first an $AlB_2-C$ nano-structured powder and high-shear mixing to then produce an $Al-x(AlB_2-C)$ precursor powder that facilitates and promotes the synthesis of Al-τ3 ($Al_3B_{48}C_2$) AMC during a Laser Powder Bed Fusion step following this reaction :

$24 AlB_2 + 2 C → Al_3B_{48}C_2+ 21 Al$

Different powder samples of $AlB_2-C$ and $Al-x(AlB_2-C)$ passed through ATG-DSC and Laser Powder Bed Fusion (LPBF) were analyzed by XRD and SEM-EDX. The objective is to highlight the influence of different milling-mixing and heat treatment parameters on the final phases and microstructures and to understand chemical reactions that occur during reactive synthesis.