Multi-material additive manufacturing of aluminum 6061-T6 alloy with stainless steel 304: Suppression of intermetallic compounds and interface growth mechanism

Fabricating integrated aluminum-steel structures is difficult because of metallurgical incompatibilities that promote intermetallic compound (IMC) formation at their interfaces. This work introduces a practical route for additively manufacturing 6061-T6 aluminum alloy (AA6061-T6) directly onto 304 stainless steel (SS304) using a high shear strain rate-assisted interfacial bonding mechanism. Through the friction extrusion deposition-based additive manufacturing method, both single- and multi-layer deposits of AA6061-T6 were successfully fabricated on SS304, yielding a robust hybrid multi-material structure. Comprehensive analyses of deposition quality, interface porosity, and bonding performance showed that the interface achieved a tensile strength exceeding 154 MPa under quasi-static loading. Microstructural observations revealed that the deposited aluminum layers experienced severe plastic deformation, resulting in pronounced grain refinement. Importantly, the interfacial zone was found to be free of brittle IMCs, instead containing a thin amorphous layer that evolved through a non-linear reaction-zone growth law. This solid-state additive strategy establishes a promising pathway for lightweight structural systems , nuclear energy component cladding, and multifunctional engineering components, redefining how dissimilar metals can be integrated for advanced applications. • Solid-state multi-material AM and nanoscale shear localization-induced amorphization suppressing IMCs at Al Fe interface. • Melt-less deposition of AA6061 on SS304, strongly bonded interface and severe plastic deformation-induced grain refinement. Grain refinement affects the near-interface mechanical properties due to increased resistance to dislocation motion. • A nanoscale reaction zone featuring multi-element distributions (Al, Fe, Si, Mg, O, and a trace amount of Cr). The corresponding failure modes under tensile loading were ductile rather than brittle, indicating the suppression of IMCs. • Parabolic reaction-zone growth with Arrhenius-type temperature dependence for interface-interphase growth, and temperature prediction, are consistent with experimental measurements.