Microstructure Characteristics and Strength–Ductility Mechanisms of a Novel Neutron Shielding Al‐6Mg‐5Gd Alloy Fabricated by Laser Powder Bed Fusion

Al‐based neutron shielding materials suffer from poor laser powder bed fusion (LPBF) processibility, hindering their simultaneous achievement of good printability and exceptional mechanical properties. In this work, the newly developed rare‐earth Al alloy (i.e., Al‐6Mg‐5Gd) was processed by LPBF technique to meet the printability, mechanical properties, and neutron shielding property all at once. Initially, a hot crack was rarely observed in as‐LPBFed alloy within the printing parameters. The main defects were gas pores and lack of fusion pores, while the related formation mechanisms were discussed. At the optimal parameters, the relative density of alloy was 99.1%. Correspondingly, the finer cell structure (τ(C36) phase) was formed in melt pool, and the coarsened cell structure was found in the melt pool boundary. Similar to the 30 wt%B 4 C/Al composite, the as‐LPBFed Al‐6Mg‐5Gd alloy exhibited excellent neutron shielding property ( Σ = 21.5 cm −1 ). Meanwhile, the as‐LPBFed alloy had improved mechanical properties, while the yield strength and ultimate tensile strength were 269 ± 2 and 465 ± 4 MPa, respectively, and the elongation was 12.9% ± 0.3%. The underlying strengthening and ductilizing mechanisms were discussed in combination with microstructure features, in which the cell structure claimed its critical role. Finally, the good printability was confirmed in as‐LPBFed Al‐6Mg‐5Gd alloys, and the related excellent comprehensive properties can satisfy the practical application of high‐performance neutron shielding structural components using this advanced rare‐earth Al alloy.