Fabrication of large-scale steel-aluminum components with homogenously distributed amorphous interfacial layer and enhanced bonding strength using modified friction stir additive manufacturing

Large-scale components of steel and aluminum alloys (Fe -Al) with high bonding strength are highly needed from space exploration to the fabrication of transportation systems. The formation of detrimental intermetallic compounds at the Al -Fe interface has limited the application range of the Fe -Al components. The modified friction stir additive manufacturing was developed for fabricating large-scale Fe -Al components with homogenously distributed interfacial amorphous layers rather than detrimental intermetallic compounds. The interfacial amorphous layers comprised an Mg -O rich amorphous layer < 20 nm in thickness and an Al -Fe -Si amorphous layer < 120 nm in thickness. The interfacial amorphous layers exhibited high thermal stability and did not change even after the post-processing heat treatment of heating at 500 degrees C for 20 min and aging at 170 degrees C for 7 h. The tensile strengths of the Fe -Al tensile specimens were increased from 160 to 250 MPa after the application of the post-processing heat treatment. The fracture occurred in the aluminum alloys instead of at the dissimilar metal interface, demonstrating that high bonding strength at the Al -Fe interface was enabled by the formation of homogenously distributed interfacial amorphous layers. (c) 2024 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.