Magnetism in iron alloys: thermodynamics, kinetics and defects

铁合金中的磁性：热力学、动力学和缺陷

• 批准号: 316673557
• 负责人: Professor Dr. Sergiy Divinski
• 金额: --
• 依托单位: CEA Centre de Saclay
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/316673557?language=en
• 关键词: Magnetism; iron; alloys; thermodynamics; kinetics

The project focuses on three iron-base alloys for high-temperature, high-strength and strong-magnet applications: Fe-Cr, Fe-Mn and Fe-Co. Because of the role of magnetism an innovative materials design based on advanced modeling approaches is necessary to control key properties of these materials. A design strategy requires the combination of (i) accurate methods to determine atomic features with (ii) efficient coarse-graining to access target physical properties and to perform the screening of materials compositions. For the former, density functional theory (DFT) has proven to be a highly successful tool. For Fe-based alloys, however, a critical bottleneck is the role that magnetic ordering, excitations and transitions have on thermodynamic, defect and kinetic properties. Therefore, a complete and accurate modeling of magnetism is needed to address the materials-design challenges: resistance to radiation damage related to the chemical decomposition in Fe-Cr, grain-boundary embrittlement in ferritic Fe-Mn and high-strength of austenitic Fe-Mn, and the phase ordering and the relative stability of alpha and gamma phases in Fe-Co cannot be fully understood without properly accounting for the magnetic effects. First, we approach this challenge with DFT by making use of recent progress in treating magnetism in iron to go towards an accurate modeling of magnetic multi-component systems with point/extended defects, and beyond the standard collinear approximation. Second, we will develop new methods to bridge between (i) highly accurate electronic calculations and (ii) large-scale atomistic thermodynamic and kinetic simulations for iron based alloys by - and this is decisive - fully taking into account the impact of magnetism on defect properties, diffusion and microstructural evolution. For the latter, lattice-based effective interaction models (EIMs) and tight-binding (TB) models will be developed based on DFT, including magnetic configurations, excitations and transitions. This will allow us to provide a coherent description of the role of magnetism on various properties of Fe-based alloys at finite temperature. It will further give us the ability to perform the optimization of key parameters controlling the relevant properties like phase decomposition in Fe-Cr, phase ordering in Fe-Co or decohesion of grain boundaries in Fe-Mn. Dedicated experiments in bulk alloys and along intergranular / interphase boundaries grown on demand will be performed in the project, which are essential for verifying the robustness of the theoretical predictions. The three chosen alloys exhibit a large variety of magnetic behavior. The methods developed in this proposal are transferable to the modeling of other magnetic materials. The results of our simulations will lead to the improvement of thermodynamic and diffusion databases and tools (such as DICTRA) that are nowadays routinely used in industrial R&D but that at present have difficulties in accounting for magnetism.

该项目重点研究三种用于高温、高强度和强磁应用的铁基合金：铁铬合金、铁锰合金和铁钴合金。由于磁性的作用，需要基于先进建模方法的创新材料设计来控制这些材料的关键特性。设计策略需要将（i）确定原子特征的准确方法与（ii）有效的粗粒度相结合，以获取目标物理特性并执行材料成分的筛选。对于前者，密度泛函理论（DFT）已被证明是一个非常成功的工具。然而，对于铁基合金来说，一个关键的瓶颈是磁有序、激发和转变对热力学、缺陷和动力学性质的作用。因此，需要完整而准确的磁性建模来解决材料设计挑战：与 Fe-Cr 中的化学分解相关的抗辐射损伤、铁素体 Fe-Mn 中的晶界脆化以及奥氏体 Fe- 的高强度。如果不正确考虑磁效应，就无法完全理解 Mn 以及 Fe-Co 中 α 相和 γ 相的相序和相对稳定性。首先，我们利用 DFT 来应对这一挑战，利用处理铁磁性的最新进展，对具有点/扩展缺陷的磁性多组分系统进行精确建模，并超越标准共线近似。其次，我们将开发新方法，在（i）高精度电子计算和（ii）铁基合金的大规模原子热力学和动力学模拟之间架起桥梁，这是决定性的，充分考虑磁性对缺陷的影响性质、扩散和微观结构演变。对于后者，将基于 DFT 开发基于晶格的有效相互作用模型（EIM）和紧束缚（TB）模型，包括磁构型、激发和跃迁。这将使我们能够对有限温度下磁性对铁基合金各种性能的作用提供连贯的描述。它将进一步使我们能够对控制相关性能的关键参数进行优化，例如 Fe-Cr 中的相分解、Fe-Co 中的相排序或 Fe-Mn 中晶界的脱聚。该项目将在大块合金和沿按需生长的晶间/相间边界进行专门的实验，这对于验证理论预测的稳健性至关重要。所选的三种合金表现出多种磁性行为。该提案中开发的方法可转移到其他磁性材料的建模。我们的模拟结果将导致热力学和扩散数据库和工具（例如 DICTRA）的改进，这些数据库和工具目前在工业研发中常规使用，但目前在解释磁性方面存在困难。

项目成果

Influence of crystalline defects on magnetic nanodomains in a rare-earth-free magnetocrystalline anisotropic alloy

无稀土磁晶各向异性合金中晶体缺陷对磁性纳米畴的影响

• DOI: 10.1103/physrevmaterials.5.064403
• 发表时间: 2021
• 期刊: Physical Review Materials
• 影响因子: 3.4
• 作者: D. Palanisamy;A. Kovács;O. Hegde;R. E. Dunin-Borkowski;D. Raabe;T. Hickel;B. Gault
• 通讯作者: B. Gault

Accelerated grain boundary migration in nanolaminated interstitial-free steel during chromizing

• DOI: 10.1080/21663831.2020.1827072
• 发表时间: 2021-02
• 期刊: Materials Research Letters
• 影响因子: 8.3
• 作者: S. Xie;S. Divinski;Y. Lei;Z. B. Wang

Atomic relaxation around defects in magnetically disordered materials computed by atomic spin constraints within an efficient Lagrange formalism

• DOI: 10.1103/physrevb.102.144101
• 发表时间: 2020-10-09
• 期刊: PHYSICAL REVIEW B
• 影响因子: 3.7
• 作者: Hegde, Omkar;Grabowski, Maximilian;Neugebauer, Joerg
• 通讯作者: Neugebauer, Joerg

Study of grain boundary self-diffusion in iron with different atomistic models

• DOI: 10.1016/j.actamat.2020.02.027
• 发表时间: 2020-04-15
• 期刊: ACTA MATERIALIA
• 影响因子: 9.4
• 作者: Starikov, S.;Mrovec, M.;Drautz, R.
• 通讯作者: Drautz, R.

Angular-dependent interatomic potential for large-scale atomistic simulation of iron: Development and comprehensive comparison with existing interatomic models

• DOI: 10.1103/physrevmaterials.5.063607
• 发表时间: 2021-06
• 期刊: Physical Review Materials
• 影响因子: 3.4
• 作者: S. Starikov;D. Smirnova;Tapaswani Pradhan;Y. Lysogorskiy;Harry Chapman;M. Mrovec;R. Drautz