Study on the interfacial bonding behavior of dissimilar aluminum alloys via additive friction stir deposition

Conventional fusion-based additive manufacturing methods for dissimilar aluminum alloys often face low efficiency and weak interfacial bonding. The rod-feeding-based additive friction stir deposition (R-AFSD) process improves this by achieving metallurgical bonding through recrystallization without melting the material. This work fills a study gap in multilayer deposition of dissimilar aluminum alloys, focusing on bonding mechanisms and optimizing interfacial properties critical for high-performance dissimilar aluminum alloys structures in aerospace applications. This work fabricated a three-layer deposition of 6061-T6, 2024-T6, and 7075-T6 alloys, characterizing material flow and interfacial microstructure using scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD). Zn enrichment at the 7075/2024 interface resulted in an average grain size of 0.8 ​μm, enhancing interfacial strength. Shear tests showed that the 7075/2024 interface had the highest shear strength of 232 ​MPa, while the 6061/2024 interface exhibited a maximum shear strength of 155 ​MPa with greater plasticity. The multilayer structure of dissimilar aluminum alloys demonstrates superior performance by integrating the strengths of each alloy. The strategic placement of 6061 in the bottom layer provides corrosion resistance, while 2024 enhances fatigue resistance, and 7075 withstands high loads. This study offers novel insights into R-AFSD for dissimilar aluminum alloy deposition, with significant implications for aerospace applications.