Microstructure evolution and tensile fracture behavior of AZ91/GWZ831K laminated heterostructured material fabricated via wire arc directed energy deposition

In this study, the AZ91/GWZ831K laminated heterostructured material (LHM) were successfully fabricated using wire arc directed energy deposition (WA-DED) technology. The microstructure, mechanical properties, and tensile fracture behavior of the fabricated composite were systematically investigated. The results indicate that a transition zone, consisting of blocky Al 2 Gd and branched (Mg, Al) 3 Gd phases, formed at the heterogeneous interface. The grain structure exhibited alternating coarse and fine grain distributions. The tensile properties showed significant anisotropy, with the ultimate tensile strength (248.5 ± 2.7 MPa) and elongation (14.5 ± 0.42 %) along the traveling direction (TD) were 16 % and 63 % higher, respectively, than those along the building direction (BD). This improvement is primarily attributed to the effective heterogeneous deformation-induced strengthening effect. In-situ X-ray computed tomography (XCT) tensile tests were conducted to evaluate the damage evolution and failure mechanisms of the laminated heterostructured. The defects in the as-deposited specimens were mainly concentrated on the AZ91 alloy side near the interface. Damage evolution under tensile deformation primarily involved the coalescence of micro-voids and the merging of cracks with adjacent pores, while the brittle Al 2 Gd phase acted as the preferential nucleation site for cracks. This study elucidates the synergistic effect of interface characteristics and stress state on the damage behavior in laminated heterostructures, providing valuable insights for the fabrication of heterostructured Mg alloy components by WA-DED.