In-situ synergistic strategy for achieving high strength 2024 Al alloys with long-term thermal stability over 900 h via laser powder-bed fusion

Additively manufactured (AM) Al alloys for elevated-temperature applications face the critical challenge of balancing ambient-temperature strength with thermal stability. Herein, crack-free Ni- and V-co-modified 2024 Al alloys (AA2024-xNi-yV) are fabricated by laser powder-bed fusion (L-PBF). The molten pool morphology, microstructures, mechanical properties and thermal stability of the as-built alloys are systematically investigated. A pronounced synergistic enhancement arises from via Al 2 Cu 2 Ni eutectic cellular networks and high-density Mg 3 (Al 9 V) 2 precipitates, yielding a high ambient-temperature ultimate tensile strength (UTS) of 535.51±3.09 MPa and superior elevated-temperature UTS values of 306.61±2.30 MPa (200 °C), 213.69±12.57 MPa (250 °C), and 134.40±4.95 MPa (300 °C). Long-term thermal stability is also demonstrated for over 500 h at both 200 °C and 250 °C, with retained UTS of 376.56±3.06 MPa (70.3% retention) and 353.03±2.84 MPa (65.9% retention), respectively. Furthermore, even after 900 h at 250 °C, the UTS remained 349.19±13.42 MPa (65.2% retention). These results demonstrate the effectiveness of the synergistic strategy, which involves co-introduction of a low-solubility eutectic element (Ni) and a slow-diffusing peritectic element (V). This approach provides a versatile route to developing L-PBF-compatible Al alloys with robust mechanical properties at both ambient and elevated temperatures. Through in-situ co-modification with Ni and V, a high-strength 2024 Al alloy with excellent thermal stability was fabricated. The formed Al 2 Cu 2 Ni eutectic networks and Mg 3 (Al 9 V) 2 nanoprecipitates jointly contribute to superior mechanical performance, reaching ultimate tensile strength (UTS) of 535.5 MPa and exceptional thermal stability (349.2 MPa after 900 h at 250 °C, UTS retention of 65.2%). • 2024 Al alloy is co-modified with low-solubility Ni and slow-diffusing V. • Synergy effect with Ni-rich networks and Mg 3 (Al 9 V) 2 precipitates is proved. • Excellent comprehensive mechanical properties are achieved. • UTS retains 349.2 MPa after 900 h at 250 °C, showing outstanding thermal stability.