Effect of Al Bronze Interlayer on Liquid–Solid Compound Interface of Sn Bronze/Steel

To address the challenges of liquid metal embrittlement (LME) cracks and low bonding strength at the Sn bronze/steel liquid–solid compound interface, an innovative Sn bronze/Al bronze/steel laminated composite is fabricated using a wire arc additive manufacturing (WAAM) process, which involved introducing an Al bronze interlayer. The microstructure of interlayer and its related interfaces, as well as the mechanical properties of the composites, are investigated. Results show that the microstructure of Al bronze is mainly composed of α-Cu and β-Cu₃Al. An interdiffused layer with a maximum thickness of 5 μm exists at the Al bronze/steel interface, which plays an important role in interface adaptation. The Sn bronze/Al bronze interface possesses a 30 μm α(Cu–Al–Fe) transition layer, and the continuous transition of α + β → α(Cu–Al–Fe) → α(Cu–Sn) from the base material to the clad layer is realized. No LME cracks are found in the steel after the Al bronze and Sn bronze deposition. The Al bronze/steel and Sn bronze/Al bronze interfaces exhibit strong bonding strengths of 395 and 361 MPa, respectively.