Atomistic investigation on the impact of substitutional Al and Si atoms on the carbon kinetics in ferrite

• Published in: Journal of alloys and compounds Vol. 921; p. 166031
• Main Authors: Huang, Liangzhao, Eyméoud, Paul, Maugis, Philippe
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.11.2022; Elsevier BV
• Subjects: Aluminum base alloys; Carbon; Critical temperature; Density functional theory; Diffusion rate; Fe-Al-C; Fe-Al-Si-C; Fe-Si-C; Ferrites; First principles; Interaction models; Internal friction; Iron; Monte Carlo; Saddle points; Silicon; Simulation; Size effects; Tracer diffusion; First principles; Internal friction; Monte Carlo; Fe-Si-C; Tracer diffusion; Fe-Al-C; Fe-Al-Si-C
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2022.166031

The pairwise interactions of substitutional solute atom X = Al, Si with interstitial carbon at stable (octahedral) and saddle-point (tetrahedral) positions in body-centered-cubic iron (α-Fe) are computed using density-functional theory. These pairwise interactions are used in atomistic kinetic Monte Carlo approach to simulate carbon internal friction and tracer diffusion measurements in Fe-Si, Fe-Al, and Fe-Al-Si ferritic alloys without any adjusting parameters. The good agreement between the simulated and experimental Snoek relaxation profiles validates the pair interaction model for kinetic simulations. The predicted effect of Al on slowing down carbon diffusion is consistent with previous studies. We highlight a super-cell size effect on the Si-carbon interactions obtained from first principles. Using a carefully tested database, it is shown that the introduction of Si into ferrite only decreases the carbon diffusivity below a critical temperature. •Comparing simulated and experimental internal friction profiles allows to verify the pair interaction energy database.•A good agreement between the simulated and experimental internal friction profiles for an alloying solute up to 9 at%.•A super-cell size effect on the short-range Si-C interactions resulting from first principles calculations.•Al is more efficient than Si in slowing down carbon diffusion because it leads to greater kinetic trapping of carbons.