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Atomistic modelling of zirconium and silicon segregation at twist and tilt grain boundaries in molybdenum

Lenchuk, Olena and Rohrer, Jochen and Albe, Karsten (2015):
Atomistic modelling of zirconium and silicon segregation at twist and tilt grain boundaries in molybdenum.
In: Journal of Materials Science, pp. 1873-1881, 51, ISSN 0022-2461,
[Online-Edition: http://dx.doi.org/10.1007/s10853-015-9494-y],
[Article]

Abstract

We investigate the influence of Zr and Si seg- regation on the cohesive strength of grain boundaries (GBs) in molybdenum using density functional theory calcula- tions. A tilt Sigma 5(310)[001] and twist Sigma 5[001] GB in bicrystal geometry are chosen as structural models. We determine the site preference of Zr and Si for segregation in these GBs and define the segregation energy. We quantify the effect of solutes on the stability of the GBs against brittle fracture by means of the Griffith criterion (work of separation). Additionally, the intrinsic bond strength of the GB containing a solute is quantified by means of the the- oretical strength. The results show that Zr and Si tend to segregate at the GBs if the low-energy insertion sites are available. However, the work of separation is decreased by the presence of Zr and Si and even in the presence of oxygen, there is no increase of the Griffith energy. Con- tributions of strain and chemical energy are analysed in order to explain our findings

Item Type: Article
Erschienen: 2015
Creators: Lenchuk, Olena and Rohrer, Jochen and Albe, Karsten
Title: Atomistic modelling of zirconium and silicon segregation at twist and tilt grain boundaries in molybdenum
Language: English
Abstract:

We investigate the influence of Zr and Si seg- regation on the cohesive strength of grain boundaries (GBs) in molybdenum using density functional theory calcula- tions. A tilt Sigma 5(310)[001] and twist Sigma 5[001] GB in bicrystal geometry are chosen as structural models. We determine the site preference of Zr and Si for segregation in these GBs and define the segregation energy. We quantify the effect of solutes on the stability of the GBs against brittle fracture by means of the Griffith criterion (work of separation). Additionally, the intrinsic bond strength of the GB containing a solute is quantified by means of the the- oretical strength. The results show that Zr and Si tend to segregate at the GBs if the low-energy insertion sites are available. However, the work of separation is decreased by the presence of Zr and Si and even in the presence of oxygen, there is no increase of the Griffith energy. Con- tributions of strain and chemical energy are analysed in order to explain our findings

Journal or Publication Title: Journal of Materials Science
Volume: 51
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Materials Modelling
Zentrale Einrichtungen > University IT-Service and Computing Centre (HRZ) > Hochleistungsrechner
Zentrale Einrichtungen > University IT-Service and Computing Centre (HRZ)
Zentrale Einrichtungen
Date Deposited: 23 Oct 2015 11:35
Official URL: http://dx.doi.org/10.1007/s10853-015-9494-y
Identification Number: doi:10.1007/s10853-015-9494-y
Funders: The research was supported by the German Research Foundation (DFG) through Project AL 578/9-1 within the Research Unit FOR 727 ‘‘Beyond Nickel-Base Superalloys’’. The authors gratefully acknowledge the computing time granted by, the John von Neumann Institute for Computing (NIC) and provided on the supercomputer JUROPA at Jülich Supercomputing Center (JSC). Computational time was also made available by the HRZ (Lichtenberg-Cluster) at, TU Darmstadt. The authors would like to thank Prof. M. Heilmaier for scientific discussions.
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