Molecular dynamics simulations on the influence of precipitates on the strain localization in aged Al-Mg alloys

在原子水平上，金属材料中的应变局部化是由位错的传播、位错附近外来原子的运动、位错之间的相互作用以及位错与非均质性（固溶原子、析出相和晶界）的相互作用决定的。在宏观层面上，析出物对Al-Mg合金力学性能的影响表现为拉伸试验中不均匀的变形行为。这也被称为波特文-勒夏特列（PLC）效应。尽管对PLC效应有大量的实验结果和先进的模拟方法，但在原子尺度上PLC效应的基本现象仍然没有完全理解。我们打算在拟议项目的框架内系统地缩小这一差距。在分子动力学（MD）模拟的帮助下，在纳米尺度上研究了Al-Mg合金材料硬化的过程。临界分解剪切应力（CRSS），源自不同类型和尺寸的沉淀，并通过MD计算，以研究它们对材料硬化的影响。应力控制变形和应变控制变形都将进行模拟，结果将相互验证并通过文献值进行验证。

The strain localization in metallic materials is, at the atomic level, governed by the propagation of dislocations, the movement of foreign atoms in the vicinity of dislocations, the interaction of dislocations with each other and by the interaction of dislocations with inhomogeneities (solid soluted atoms, precipitates and grain boundaries). At the macroscopic level, the effect of precipitates on the mechanical properties of Al-Mg alloys can be noticed in the form of an uneven deformation behavior during tensile tests. This is also known as the Portevin - Le Chatelier (PLC) effect.Despite extensive experimental results to the PLC effect and advanced simulation methods, the basic phenomena of the PLC effect at the atomistic scale are still not fully understood. It is our intention to systematically close this gap within the frame of the proposed project. Processes contributing to the material hardening in Al-Mg alloys will be investigated at the nanoscale level with the help of molecular dynamics (MD) simulations.Critical resolved shear stresses (CRSS), originating from various precipitate types and sizes and calculated by MD in order to investigate their influence onto the material hardening. Both stress- and strain controlled deformations will be simulated, the results will be validated by each other as well as by literature values.