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域化受位错的传播、位错附近的外来原子的运动、位错之间的相互作用以及位错与非均质(固溶原子、析出物和晶界)的相互作用所支配。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过程中变形行为的不均匀。尽管对PLC效应有大量的实验结果和先进的模拟方法，但对PLC效应在原子尺度上的基本现象还没有完全了解。我们打算在拟议项目的框架内有系统地缩小这一差距。利用分子动力学(MD)模拟手段，在纳米尺度上研究Al-Mg合金的材料硬化过程，计算不同析出相类型和尺寸的临界剪切应力(CRSS)，以研究它们对材料硬化的影响。应力和应变控制的变形都将被模拟，结果将相互验证，并与文献值进行验证。

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.