Active control of strength-plasticity matching for in-situ fabricated Ti2AlNb alloy by dual-wire arc-directed energy deposition

Ti2AlNb intermetallic alloys hold great promise for lightweight aerospace structural applications, yet their widespread implementation is constrained by the high cost and prolonged lead times associated with conventional manufacturing routes. In our previous study, a dual‑wire arc‑directed energy deposition process is established for the in‑situ synthesis of Ti2AlNb alloy, integrating the low‑cost advantages of elemental wires with high deposition efficiency into wire-based additive manufacturing. However, the complex and inherent thermal history leads to microstructural heterogeneity, necessitating post heat treatment to achieve uniform and tailorable mechanical properties. This work systematically investigates the effects of solution treatment and aging treatment on the microstructure and mechanical properties of the as‑deposited alloy. The results demonstrate that solution treatment within three‑phase region promotes the dissolution of lath O‑phase into the B2 matrix, inducing solid-solution strengthening yet leading to a reduction in tensile strength relative to the as-deposited condition. Subsequent aging treatment triggers the precipitation numerous fine acicular secondary phases, substantially elevating tensile strength up to ∼1200 MPa——comparable to forged counterparts—while inevitably reducing ductility due to stress concentration for the ST 990 ℃ + AT 720 ℃ sample (ST: solution treatment at 990 ℃, AT: aging treatment at 720 ℃). Through tailored solution‑aging strategies, the accessible window for strength–ductility matching is substantially broadened and systematically clarified for in-situ fabricated Ti2AlNb alloy by dual-wire arc-directed energy deposition. The findings provide a viable pathway for customizing the mechanical performance of wire‑arc additively manufactured Ti2AlNb alloys to meet diverse engineering requirements.