Interaction of interstitial solid-solution impurities and dislocation motion in body-centered cubic metals

• Applicant: Dr. Christian Brandl
• Subject Area: Thermodynamics and Kinetics as well as Properties of Phases and Microstructure of Materials ; Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 271954546

The development of novel materials for high-temperature applications also entails the knowledge of 1) the fundamental mechanisms responsible for materials mechanical behavior and 2) how does the materials composition modify these mechanisms. The motion of these dislocations and the mutual interaction of dislocations amongst themselves and with impurities govern the macroscopic strength, toughness and deformation behavior in metals on the fundamental level. An integrated simulation approach at the atomic scale, which complementary uses electronic-structure calculations and molecular dynamics (MD) simulations, will address such defect motion and interaction in chromium with interstitial impurities, which limit the room-temperature ductility of technical pure chromium. The proposed work addresses the impurity induced room-temperature brittleness of Cr with the long-term perspective to develop a path forward how it can be overcome. The required interatomic potentials for the MD studies will be developed on the basis of existing and established semi-empirical potentials. MD simulations will be used to explore the correlations between the defect structures, dislocation motion and association with static materials parameters. Together with the dependence of the material parameters on the impurity content deduced from quantum-mechanical simulation, this work will enhance our understanding on the effect of interstitial impurities and chemical composition, in general, on the dislocation processes in body-centered cubic metals.

• DFG Programme: Research Grants