Microscopic mechanisms of shear band formation in bulk metallic glasses

大块金属玻璃剪切带形成的微观机制

• 批准号: 224558825
• 负责人: Professor Dr. Jürgen Horbach
• 金额: --
• 依托单位: Lehrstuhl II: Weiche Materie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/224558825?language=en
• 关键词: Microscopic; mechanisms; shear; band; formation

The mechanical properties of bulk metallic glasses (BMG) are intimately related to the formation of shear bands when these materials are deformed. In this project, large-scale Non-equilibrium Molecular Dynamics (NEMD) simulations are used to study the microscopic mechanisms of shear banding in BMG. Simple model systems are considered to understand generic scenarios of shear banding in glasses. Moreover, realistic models (in particular for Pd40Ni40P20) are developed by means of ab initio calculations. Then, by analyzing self-diffusion, strain maps and structural anisotropies inside and outside the shear bands, NEMD simulations with the realistic models allow for a direct comparison to the results obtained in the experimental project. The project’s primary focus is to give insight into the formation of shear bands via local plastic events (such as shear transformation zones). Furthermore, nucleation of fracture processes from shear banding shall be investigated. To achieve this, various parameters of the simulation are systematically changed, using different protocols of compression and shear, the consideration of simulations at constant volume and constant pressure, and the consideration of glass samples resulting from quenches at different cooling rates.

大块金属玻璃 (BMG) 的机械性能与这些材料变形时剪切带的形成密切相关。在该项目中，采用大规模非平衡分子动力学 (NEMD) 模拟来研究剪切的微观机制。 BMG 中的条带被认为可以理解玻璃中剪切条带的一般情况，并且通过 ab 开发了真实模型（特别是 Pd40Ni40P20）。然后，通过分析剪切带内外的自扩散、应变图和结构各向异性，NEMD 模拟与实际模型可以与实验项目中获得的结果进行直接比较。通过局部塑性事件（例如剪切转变区）深入了解剪切带的形成此外，应研究剪切带断裂过程的成核，使用不同的协议系统地改变模拟的各种参数。压缩和剪切的影响，考虑恒定体积和恒定压力下的模拟，以及考虑不同冷却速率下淬火产生的玻璃样品。