Influence of substitutional impurities on hydrogen diffusion in B2-TiFe alloy |
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Authors: | AV Bakulin SS Kulkov SE Kulkova S Hocker S Schmauder |
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Affiliation: | 1. Institute of Strength Physics and Materials Science of SB RAS, pr. Akademichesky 2/4, Tomsk 634021, Russia;2. National Research Tomsk State University, pr. Lenina 36, Tomsk 634050, Russia;3. Institute for Materials Testing, Materials Science and Strength of Materials, University of Stuttgart, Pfaffenwaldring 32, 70569 Stuttgart, Germany |
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Abstract: | The hydrogen diffusion pathways were studied in B2-TiFe alloy within density functional theory (DFT) using the plane-wave pseudo-potential method. Our results confirm that the hydrogen diffusion between octahedral interstices where it is surrounded by two Fe and four Ti atoms along 10-1] direction is most preferential in TiFe bulk. The estimated hydrogen diffusion barrier of 0.62 eV differs insignificantly from values of barriers in pure Ti. The influence of substitutional transition and simple metal impurities on the energy barriers is discussed. It was found that impurities such as V, Cr, Mn decrease the hydrogen diffusion barriers along both considered pathways whereas Pd impurity decreases considerably the barrier along 00-1] direction that leads to the change of the diffusion mechanism. In general, the competition of structural and electronic factors strongly influences the hydrogen diffusion barriers. The present results provide a deep understanding of H behavior in TiFe bulk. |
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Keywords: | Ab-initio calculations Hydrogen Absorption Diffusion Substitutional impurities |
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