Atomistic simulations of deuterium irradiation on iron-based alloys in future fusion reactors. (December 2016)

• Record Type: Journal Article
• Authors: Safi, E.; Polvi, J.; Lasa, A.; Nordlund, K.
• Is Part Of: Nuclear materials and energy. Volume 9(2016)
• Page Start: 571
• Page End: 575
• Publication Date: 2016-12
• Subjects: Nuclear energy -- Periodicals; Nuclear fuels -- Periodicals; Nuclear reactors -- Materials -- Periodicals; Radioactive substances -- Periodicals; 621.4833
• DOI: 10.1016/j.nme.2016.08.021
• Languages: English
• ISSNs: 2352-1791

Abstract

Highlights: MD method to study the effect of D irradiation on iron-based alloys, was used. In Fe3 C, due to preferential sputtering of C during the bombardment, the surface was enriched with Fe. The initial lattice structure was observed to become completely amorphised at the D implantation zone. In general, our results show that if steels are used as a plasma-facing material, the presence of C in them will lead to chemical sputtering of carbon-containing molecules. Abstract: Iron-based alloys are now being considered as plasma-facing materials for the first wall of future fusion reactors. Therefore, the iron (Fe) and carbon (C) erosion will play a key role in predicting the life-time and viability of reactors with steel walls. In this work, the surface erosion and morphology changes due to deuterium (D) irradiation in pure Fe, Fe with 1% C impurity and the cementite, are studied using molecular dynamics (MD) simulations, varying surface temperature and impact energy. The sputtering yields for both Fe and C were found to increase with incoming energy. In iron carbide, C sputtering was preferential to Fe and the deuterium was mainly trapped as D2 in bubbles, while mostly atomic D was present in Fe and Fe–1%C. The sputtering yields obtained from MD were compared to SDTrimSP yields. At lower impact energies, the sputtering mechanism was of both physical and chemical origin, while at higher energies (>100 eV) the physical sputtering dominated.