ICAMS / Interdisciplinary Centre for Advanced Materials Simulation
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C, N and H binding energies in Fe2Nb Laves phases

Date: 31.03.2014
Place: DPG Spring Meeting 2014, Dresden, Germany

Alvin Noe Ladines
Thomas Hammerschmidt
Ralf Drautz

The family of Laves phases are interesting from a technological point of view because of their capability for hydrogen storage and their strengthening effect in steel. Although their bulk properties are well understood, the solubility of light elements in these compounds is still unclear. This is due in part to their complex defect structure and the limitations of current experimental techniques for light elements. In this study, we use density functional theory (DFT) to calculate the solubility of C, N and H at the different interstitial sites in the Fe2Nb C14 Laves phase. Our results suggest that the light elements prefer the voids centered at the triangles shared by two adjacent tetrahedral elements over the centers of these tetrahedra due to the slightly larger volume. Moreover, the binding energies are also dependent on the number of Nb nearest neighbors which is consistent with the high affinity of C, N and H to Nb. Our results suggest a considerable solubility of N and H in Fe2Nb. For C, we observe a weaker solubility which we attribute to the increased strain that is apparent as increased bond lengths.

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