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MM: Fachverband Metall- und Materialphysik

MM 3: Computational Materials Modelling I

MM 3.6: Vortrag

Montag, 14. März 2011, 12:15–12:30, IFW B

Ab initio study of effect of non-magnetic impurities on the structure and properties of grain boundaries and free surfaces in nickel — •Monika Všianská^1,2 and Mojmír Šob^1,2 — ¹Department of Chemistry, Faculty of Science, Masaryk University, Brno, Czech Republic — ²Istitute of Physics of Materials, Academy of Sciences of the Czech Republic, Brno, Czech Republic

We have studied segregation of sp-elements of the 3rd, 4th and 5th period (Al, Si, P, S, Ga, Ge, As, Se, In, Sn, Sb and Te) at the Σ5(210) grain boundary (GB) and (210) free surface (FS) in fcc nickel. We analysed the geometric configuration and the distribution of magnetic moments at the GB and FS without and with impurities. Whereas there is a slight enhancement of magnetization at the clean GB with respect to bulk nickel, the studied impurities entirely kill or strongly reduce ferromagnetism at the GB and its neighbourhood. We also determined the embrittling energy and its chemical and mechanical part from the difference between the GB and FS binding energies on the basis of the Rice-Wang model. We predict interstitially segregated Si as a GB cohesion enhancer, substitutionally segregated Al and interstitially segregated P with none or minimal strengthening effect and interstitially segregated S, Ge, As, Se and substitutionally segregated Ga, In, Sn, Sb and Te as GB embrittlers in Ni.