Berlin 2012 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 54: Computational Materials Modelling VIII - Mechanical Properties and Strain

MM 54.1: Talk

Thursday, March 29, 2012, 15:45–16:00, TC 006

Which alloying element can make tungsten ductile: Insight from density-functional theory — •hong li^1,2, lorenz romaner², claudia ambrosch-draxl², and reinhard pippan¹ — ¹Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Jahn-Straße 12, A-8700 Leoben, Austria. — ²Chair of Atomistic Modelling and Design of Materials, University of Leoben, Franz-Josef-Straße 18, A-8700 Leoben, Austria.

Based on density-functional theory (DFT), the influence of alloying elements on the 1/2⟨111⟩ screw dislocation in tungsten is investigated to find alloying candidates that make tungsten ductile. The interaction between the alloying atom and the dislocation is calculated by varying the distance between the position of the alloying atom and the center of the dislocation. Positions near the dislocation center turned out to be energetically more favorable for alloying elements with a higher occupation of d-electrons. When Mn, Fe, Os or Ir is placed outside the inner most dislocation core, the dislocation starts moving towards this alloying atom. Furthermore, the change of dislocation core symmetry via alloying is determined using both DFT and the inter-row potential approach. A transition from a symmetric to an asymmetric core is revealed for Re, Os, and Ir. Our results implicate that these elements have similar effects on the 1/2⟨111⟩ screw dislocation in tungsten, and therefore, provide atomistic insights to the development of new tungsten materials.