The Al-Fe Intermetallic Compounds and the Atomic Diffusion Behavior at the Interface of Aluminum-Steel Welded Joint

The formation of intermetallic compounds (IMC) at the Al/Fe interface determined the mechanical property of steel-aluminum welded joint. To understand the interfacial microstructure evolution and relate diffusion mechanism of atoms cross the Al/Fe interface, the effect of welding parameters on the interfacial IMC was studied, and the molecular dynamics method (MD) was used to simulate the diffusion process of Al and Fe atoms. Four temperatures (950 K, 1000 K, 1050 K, and 1100 K) were selected in the simulation model. The interfacial IMC are distributed in a laminar pattern, and their physical phases are mainly composed of Fe2Al5, controlling the Al/Fe atomic ratio of 5:2 in the IMC configuration, the Embedded Atom Method (EAM) potential is used to describe the interactions between Al and Fe atoms. In the Al-Fe system IMC conformation, the mean square displacement and diffusion (MSD) coefficient of Al atoms at different temperatures were small, and the main diffusion path is the Al atoms across the IMC conformation into the Fe crystal structure. The diffusion in the IMC conformation was mainly along the direction perpendicular to the interface. The diffusion mechanisms were mainly vacancy diffusion and interstitial diffusion mechanisms.