Abstract

The generation of Intermetallic Compounds (IMCs) in friction stir welding of dissimilar Al/Mg alloys is a key issue affecting the quality and mechanical properties of welding joints. Numerical simulation has become a powerful means to study the evolution mechanism of IMCs but requires knowing microscopic parameters like the Gibbs free energy density of the generated phases and the interface energy between different phases. In this study, the selected Gibbs free energy density of each phase in Al-Mg system under different temperatures from the CALPHAD database was fitted by polynomial fitting method, and a simple, effective and accurate fitting formulae of Gibbs free energy density were obtained. Using the molecular dynamics method, the interface energy calculation model was established according to the heterogeneous coherent interface relationship, and the interface energy of the heterogeneous phases at different temperatures was obtained, and the specific values were given. The determination of both Gibbs free energy density and the interface energy of the heterogeneous phases provides a data basis for the modeling and simulation of IMCs in welding dissimilar Al/Mg alloys.

Keywords:Intermetallic compounds; Friction stir welding; Dissimilar Al/Mg alloys; Gibbs free energy density; Interface energy of the heterogeneous phases