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

用于高温应用的新材料的开发还需要了解1)负责材料机械行为的基本机制以及2)材料成分如何改变这些机制。这些位错的运动以及它们之间和与杂质之间的相互作用在基本水平上决定了金属的宏观强度、韧性和变形行为。原子尺度上的综合模拟方法，辅以电子结构计算和分子动力学（MD）模拟，将解决这种缺陷运动和铬与间隙杂质的相互作用，这限制了技术纯铬的室温延展性。提出的工作解决了杂质引起的Cr的室温脆性，并从长远的角度发展了如何克服它的前进道路。MD研究所需的原子间势将在现有和已建立的半经验势的基础上发展。MD模拟将用于探索缺陷结构，位错运动以及与静态材料参数的关联之间的相关性。结合从量子力学模拟中推导出的杂质含量对材料参数的依赖性，这项工作将增强我们对间隙杂质和化学成分对体心立方金属中位错过程的影响的理解。

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.