Structural evolution mechanism during 3D printing of MXene-reinforced metal matrix composites

The combination of a two-dimensional morphology, hydrophilic surface, and remarkable properties makes MXene an ideal nanofiller for next-generation metal matrix composites (MMCs). However, the thermal stability of MXene during the non-equilibrium, ultrahigh-temperature consolidation process of 3D printing, is unknown. In this study, the manufacturing feasibility and structural evolution of MXene-reinforced MMCs prepared by laser powder bed fusion (L-PBF) were elucidated. High-laser-absorbing Ti₃C₂T_x MXene sheets were uniformly decorated on the surface of Al powders through electrostatic self-assembly, resulting in enhanced 3D printability. Through laser irradiation, α-Al₂O₃ particles were formed via the conversion of an amorphous alumina layer on the Al powder or the reaction between the surface functionalities of MXene and molten Al. Simultaneously, MXene was partially transformed into monocrystalline TiC nanorods through the dissolution–precipitation mechanism. Thus, a novel MXene/Al composite co-reinforced with MXene sheets, TiC nanorods and α-Al₂O₃ particles was successfully synthesized through L-PBF. This study offers a feasible approach to expand the applications of MXene, and provides new insights into fabrication of high-performance MMCs with polymorphic reinforcements.