High-performance co-continuous Al-Ce-Mg alloy with in-situ nano-network structure fabricated by laser powder bed fusion

A novel Al-Ce-Mg alloy with an in-situ nano-network structure and improved tensile properties was fabricated using laser powder bed fusion (LPBF). The microstructure of the as-fabricated alloy exhibited an extremely fine eutectic Al/Al₁₁Ce₃ co-continuous structure, i.e., Al₁₁Ce₃ intermetallics with an in-situ nano-network surrounding the interconnected Al matrix. It forms an equiaxed grain in the scanning direction (SD) and columnar grain in the building direction (BD). The yield strength (YS) and ultimate tensile strength (UTS) in SD and BD are 300 ± 11.5 MPa, 438 ± 6.9 MPa, and 303 ± 5.0 MP, 442 ± 3.3 MPa, about three times higher than those of as-cast alloy. The elongations (El) are 9.3 ± 0.7% and 6.2 ± 1.2% in SD and BD, respectively, exhibiting anisotropy. The perfect interfacial bonding between the Al₁₁Ce₃ phase and Al matrix combined with nano-scale network structures provided a strong ability to hinder the propagation of microcracks formed within Al₁₁Ce₃ particles. Besides, the alloy retained outstanding strength at elevated temperatures with 200 MPa at 300 °C and 100 MPa at 400 °C, which may be attributed to the heat resistance of nano-network Al₁₁Ce₃ intermetallics and the extremely low diffusion coefficient of Ce in the Al matrix. This work provides a new idea for developing heat-resistant aluminum alloys with a good combination of strength and ductility via additive manufacturing (AM) processing technique.