Influence of oxide layers on plastic properties of metals: From atomistic to mesoscopic scale

由于在富氧化环境中金属表面会形成氧化层，因此需要考虑氧化对位错成核的影响。这对于具有高表面体积比的材料（如多孔物质）和轻质材料（如铝）尤其重要。对于后者，即使在高真空条件下，也可以在几秒钟内形成氧化层。这将影响材料的机械性能，因为由于激活体积的增加和位错位置数量的增加，导致纳米晶金属的延展性增强，从而增加了位错成核。氧化对金属力学性能的影响将使用分子动力学进行研究，因为在富含氧化的环境中，考虑到氧浓度和温度的基本依赖性，模拟将形成氧化层。本研究的重点将主要放在氧化金属位错的成核上。从细观尺度观察到的开裂行为到纳米尺度观察到的辅助延性行为的转变将被分析。原子模拟将使用随机模型来实现在薄膜中尺度位错动力学中考虑氧化层的位错成核。因此，在实验可及的时间尺度上，为氧化表面的位错动力学模拟提供了一个物理上可靠的模型。

Since in oxidation-rich environments an oxide layer will form on metallic surfaces, the influence of oxidation on dislocation nucleation needs to be considered. This is particularly important for materials with high surface-to-volume ratio as porous matter and lightweight materials as aluminum. For the latter, even under high vacuum conditions, an oxide layer may form within seconds. This will influence the mechanical properties of materials because of increased dislocation nucleation due to increased activation volume and increased number of dislocation sites leading to enhanced ductility of nanocrystalline metals. The influence of oxidation on the mechanical properties of metals will be studied using molecular dynamics Since in oxidation-rich environments an oxide layer will form onsimulations considering the fundamental dependencies on oxygen concentration and temperature. The focus of this study will be primarily on the nucleation of dislocations for oxidized metals. The transition from the cracking behavior observed at the mesoscale, to the assisted-ductility behavior observed at the nano-scale will be analyzed. The atomistic simulations will be used to implement dislocation nucleation considering oxide layers in mesoscale dislocation dynamics of thin films using a stochastic model. Therewith, a physically reliable model for dislocation dynamics simulations of oxidized surfaces will be available acting on time scales accessible to experiments.