First-principles localized cluster expansion study of the kinetics of hydrogen diffusion in homogeneous and heterogeneous Fe-Cr alloys

Journal Article · 23 January 2019 · Physical Review B

DOI: https://doi.org/10.1103/PhysRevB.99.014110 · OSTI ID:1503200

Samin, Adib J. ^[1]; Andersson, David A. ^[1]; Holby, Edward F. ^[1]; Uberuaga, Blas P. ^[1]

---

1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Metal alloys have a wide range of technological applications, from structural materials to catalysts. In many situations, the transport of hydrogen, whether intentionally for hydrogen storage and fuel cell applications or unintentionally in the case of tritium uptake in nuclear materials, is an important concern. Fe-Cr binary alloys, in particular, may be viewed as a simple model system to represent ferritic steels used in nuclear energy systems and, more generally, as a model binary alloy for examining the role of alloying elements on transport. In this work, we used density functional theory, cluster expansion, and kinetic Monte Carlo to study hydrogen kinetics in Fe-Cr alloys. In random homogeneous alloys, we observed that hydrogen diffusivity first decreased with increasing Cr content and then increased to its levels in pure Cr. Furthermore, the effects of heterogeneity, as might be induced by irradiation, were explored and it was concluded that local structural heterogeneities for the same overall Cr concentration may significantly affect the hydrogen diffusivity. The effect was attributed to the relative binding energy of hydrogen in different metals and this understanding was then utilized to predict hydrogen transport behavior in different element-segregated grain/grain boundary combinations and thus identify solute/solvent alloys where hydrogen transport might be either hindered or enhanced. Finally, we comment on the potential impact of radiation-induced segregation on hydrogen behavior in nuclear energy systems.

• Research Organization: Energy Frontier Research Centers (EFRC) (United States). Fundamental Understanding of Transport Under Reactor Extremes (FUTURE); Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: 89233218CNA000001
• OSTI ID: 1503200
• Alternate ID(s): OSTI ID: 1491781
• Report Number(s): LA-UR-19-21216; PRBMDO
• Journal Information: Physical Review B, Vol. 99, Issue 1; ISSN 2469-9950
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English