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

Abstract

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/Al 11 Ce 3 co-continuous structure, i.e., Al 11 Ce 3 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 Al 11 Ce 3 phase and Al matrix combined with nano-scale network structures provided a strong ability to hinder the propagation of microcracks formed within Al 11 Ce 3 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 Al 11 Ce 3 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 AM processing technique. • Microstructure featured extremely fine eutectic Al/Al 11 Ce 3 co-continuous structure. • Al 11 Ce 3 network is connected by nanocrystalline grains with different orientations. • The as-fabricated Al-Ce-Mg alloy displays superior strength-ductility combination. • The as-fabricated Al-Ce-Mg alloy maintains high strength at elevated temperature.