Assessing phase equilibria and atomic mobility of intermetallic compounds in aluminum-magnesium alloy system

Abstract Aluminum-magnesium (Al–Mg) binary system is the basis of many important Al and Mg alloys. The thermodynamic and atomic-diffusional behaviors of Al-rich or Mg-rich alloys have been extensively studied. However, it is not well understood for the thermodynamic and atomic-diffusional behaviors in Al–Mg intermetallic compounds (IMCs) such as Al140Mg89 (β), Al30Mg23 (e), and Mg17Al12 (γ), which significantly influence the microstructure and performance of Al and Mg alloys. In this paper, the most complete and self-consistent thermodynamic and atomic-diffusional databases have been constructed using CALculation of PHAse Diagram (CALPHAD) modeling and experimental data in literature. The following are reported for the first time: 1) the homogeneity in Al140Mg89 (β), Al30Mg23 (e), and Mg17Al12 (γ) IMCs assessed and validated using the most recent experimental results; and 2) the atomic diffusion mobility in Al140Mg89 (β), Al30Mg23 (e), and Mg17Al12 (γ) IMCs with their interdiffusion coefficients validated by experiments. The new databases have been further validated by diffusion couple experiments, demonstrating their applicability in controlling atomic-diffusion at interface, quantitative microstructure simulation, and development of engineering applications of Al–Mg and Mg–Al based alloys and systems. The present fundamental methodology and modeling principles are applicable to all materials and engineering applications.