Interfacial Microstructure and Mechanical Properties of Ti‐6Al‐4V/Ni‐Ti Bimetallic Structures Fabricated by Multi‐Wire Arc Additive Manufacturing

Conventional fabrication of Ti‐6Al‐4V/Ni‐Ti bimetallic structures is both costly and impractical for complex geometries. In this study, to resolve these difficulties, multi‐wire arc additive manufacturing (M‐WAAM) with in situ alloying is used. The results show that NiTi 2 phase reduces ductility and induces stress concentration due to lattice mismatch with the NiTi phase, further accelerating crack formation. The as‐built wall consists of NiTi 2 and NiTi layers, formed through element diffusion, with the interface evolving from a basket‐weave microstructure to a eutectic α‐Ti + NiTi 2 phase and ultimately a planar NiTi 2 structure. Besides, as‐built wall exhibits a peak microhardness of 692.2 HV, a compressive strength of 1137.5 ± 31 MPa, and a fracture strain of 6.7% ± 2%. This study presents an efficient strategy for fabricating complex bimetallic structures, providing insights into integrated manufacturing of dissimilar metals for aerospace and related applications.