Microstructure and Mechanical Properties of a Hybrid Graphene–Aluminum Carbide Reinforced Aluminum Nanocomposite Fabricated by Laser Powder Bed Fusion

This work presents the synthesis and characterization of an Al-8 wt.% Ce-10 wt.% Mg nanocomposite reinforced with 0.6 vol.% multilayer graphene, fabricated by laser powder bed fusion (LPBF). During rapid solidification, a small amount of in-situ aluminum carbide (Al4C3) formed, producing a hybrid graphene-Al4C3 reinforcement. The composite exhibited a relative density exceeding 99% and an ultrafine microstructure of Mg-rich α-Al cells, an Al11Ce3 intermetallic network with a cell size of less than 300 nm, and dispersed Al13Mg6Ce precipitates. The LPBF composite tested at room temperature achieved a UTS of 538 MPa, representing a 15% improvement over the LPBF base alloy processed under identical conditions. The enhanced mechanical performance is attributed to the combined effects of solid-solution strengthening, grain and cellular refinement, load transfer from graphene and Al4C3 nanorods, and Orowan strengthening from the Al11Ce3/Al13Mg6Ce intermetallic skeleton. These results demonstrate the potential of hybrid Al-Ce-Mg alloy composites for high-performance, high-temperature lightweight applications.