Unraveling the corrosion behavior and enhanced strength-ductility synergy mechanism of a novel Al–Ce/GNPs composite fabricated by selective laser melting

A novel Al-9.5Ce-0.6Mg/0.7GNPs (wt. %) composite with a network co-continuous Al/(Al, Mg)₁₁Ce₃ eutectic structure was fabricated using laser powder bed fusion. Mg mainly exists in the Al₁₁Ce₃ phase rather than the Al matrix. The as-built composite achieved superior ultimate tensile strength (UTS) of ∼452 ± 3 MPa and an elongation of ∼5.6 ± 0.3 %. Heat treatment enhanced elongation (13.2 ± 0.3 %) while maintaining high UTS (406 ± 6 MPa), ∼4 and ∼5 times higher than as-cast Al–Ce alloy, respectively. High strength is ascribed to grain refinement, Orowan strengthening, and load transfer strengthening. The breakage of the (Al, Mg)₁₁Ce₃ network was key to obtaining excellent ductility. The HT composite exhibits excellent corrosion resistance that is an order of magnitude higher than that of as-cast Al–Ce alloy in 3.5 wt % NaCl solution, Additionally, the galvanic corrosion between α-Al and (Al, Mg)₁₁Ce₃ as well as the preferred corrosion of the melt pool boundary (MPB) was inhibited. This work provides a new idea for developing high strength-ductility synergy and corrosion resistance via additive manufacturing (AM) processing technique.