Interfacial characterization of additively manufactured stainless steel to aluminium thin wall with nickel interlayer

The formation of brittle incoherent Fe–Al intermetallics at dissimilar interface makes wire arc additive manufacturing (WAAM) of stainless steel (SS)–aluminium (Al) difficult. The incorporation of nickel (Ni) interlayers between SS and Al is thought to improve structural integrity. This article provides a detailed characterization of SS–Ni and Al–Ni interfaces. The Al-Ni interface is divided into three intermetallic zones: AlNi at center, Al 3 Ni on Al side, and AlNi 3 on Ni side. The Ni 3 Fe, NiFe, and NiFe 3 intermetallics at the SS–Ni interface increase with heat input. The intermetallics at the Al–Ni interface are found to be affected by heat input as well as primary dendrite arm spacing (PDAS) and dendrite growth angle (DGA) of the Ni dendrites. With low heat input, low DGA, and high PDAS, the intermetallic thickness at the Al–Ni interface decreases. It is also discovered that as heat input increases, the hardness of both interfaces increases. Graphical abstract