Chemical physics

Metallurgy

Materials science

Effective diffusion coefficient

Grain boundary diffusion coefficient

Grain boundary

Radiology

Thermodynamics

Physics

Diffusion

Alloy

Microstructure

Crystallography

Medicine

Chemistry

Magnetic resonance imaging

Acta Materialia

Mg grain boundary (GB) segregation and GB diffusion can impact the processing and properties of Al-Mg alloys. Yet, Mg GB diffusion in Al has not been measured experimentally or predicted by simulations. We apply atomistic computer simulations to predict the amount and the free energy of Mg GB segregation, and the impact of segregation on GB diffusion of both alloy components. At low temperatures, Mg atoms segregated to a tilt GB form clusters with highly anisotropic shapes. Mg diffuses in Al GBs slower than Al itself, and both components diffuse slowly in comparison with Al GB self-diffusion. Thus, Mg segregation significantly reduces the rate of mass transport along GBs in Al-Mg alloys. The reduced atomic mobility can be responsible for the improved stability of the microstructure at elevated temperatures.

Atomistic study of grain-boundary segregation and grain-boundary diffusion in Al-Mg alloys