Development, validation and application of a magnetic bond order potential for the Fe-C system

Fe-C 体系磁性键序势的开发、验证和应用

• 批准号: 405621081
• 负责人: Dr. Matous Mrovec
• 金额: --
• 依托单位: Interdisciplinary Centre for Advanced Materials Simulations
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/405621081?language=en
• 关键词: Development; validation; application; magnetic; bond

The iron-carbon system belongs to the technologically most important binary systems since it is the basis of steel, one of the main materials in today’s society. A great deal of progress has been made in theoretical understanding of the physical, thermodynamic and mechanical properties of this system. However, explicit modelling of atomic-scale processes in modern steels with complex chemistries and microstructures still presents a significant challenge. The reason is that most of these processes are governed by a subtle interplay between chemical and magnetic interactions.The primary objective of this research project is to develop a state-of-the-art magnetic bond-order potential (BOP) that will be capable of describing quantitatively the atomic-scale behavior of the Fe-C system. The developed BOP model shall be able to cover the whole composition range from individual elements over dilute C concentrations in the Fe matrix up to large C concentrations where diverse carbide phases are formed. Since BOPs are derived by a rigorous coarse-graining procedure from quantum mechanics they implicitly contain phenomena originating at the electronic structure level such as magnetism. At the same time, their real-space formulation in the form of many-body interatomic potentials makes them computationally efficient. This combination of physical accuracy and computational efficiency enables them to be employed in atomistic studies of complex configurations and conditions, for instance, properties of extended crystal defects or motion of phase interfaces, that govern not only the mechanisms of structural and magnetic phase transitions in the Fe-C system but also its macroscopic mechanical behavior.

铁碳系统属于技术上最重要的二元系统，因为它是当今社会主要材料之一钢的基础。对该体系的物理、热力学和力学性质的理论认识已经取得了很大的进展。然而，在具有复杂化学成分和微观结构的现代钢中，原子尺度过程的显式建模仍然是一个重大挑战。本研究的主要目的是发展一种能够定量描述Fe-C体系原子尺度行为的最先进的磁性键序势（BOP）。所开发的BOP模型应能够涵盖整个成分范围，从Fe基体中稀C浓度的单个元素到形成不同碳化物相的大C浓度。由于BOP是通过严格的粗粒化过程从量子力学中推导出来的，它们隐含着起源于电子结构水平的现象，如磁性。与此同时，它们以多体原子间相互作用势的形式在实空间中表达，使得它们在计算上是高效的。这种物理精度和计算效率的结合使它们能够用于复杂配置和条件的原子学研究，例如，扩展晶体缺陷或相界面运动的性质，不仅支配Fe-C系统中的结构和磁性相变机制，而且还支配其宏观力学行为。