Determining Grain Boundary Solute Segregation Specificity in Nanocrystalline Stability

确定纳米晶稳定性中的晶界溶质偏析特异性

• 批准号: 1709803
• 负责人: Gregory Thompson
• 金额: $ 49.84万
• 依托单位: University of Alabama Tuscaloosa
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-07-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1709803&HistoricalAwards=false
• 关键词: Determining; Grain; Boundary; Solute; Segregation

Non-technical Abstract: When the grain size of a material is reduced, the strength of a material increases. Unfortunately, these small grain sizes are energetically unfavorable as compared to larger sized grains. Upon heating, the smaller grains will grow to reduce this energy difference which results in the loss of strength. In recent years, the development of specific types of alloys has shown that the lower concentration atom type, or solute, can stabilize these grains against this growth. An outcome of these observations has been various models to explain the grain size stabilization. However, these models have several fundamental scientific gaps that still remain to be solved. For example, the modeled grain boundaries are considered equivalent wherein reality grain boundaries are diverse in their structure, energy, and mobility. The lack of experimental verification of this solute specific segregation to grain boundaries has hindered further model development. This research will overcome these prior limitations by combining electron microscopy and atom probe tomography to detect solute segregation to those specific boundaries. These results will then be forward fed to atomics models that explain this diversity of behavior. This research will be integrated into various outreach activities, including a summer materials camp for secondary education teachers to introduce materials science into the middle/high school classrooms. Technical Abstract:Nano-crystalline materials is an area of active research owing to their unique size dependent properties. Since interfaces (boundaries) constitute a large fraction of the entire structure, the corresponding interfacial energy from those boundaries can make these grains inherently unstable. Solute partitioning to these boundaries has been devised as a means to stabilize these grains against growth with concepts of kinetic solute drag effects and thermodynamic reduction of interfacial energy being suggested mechanisms for stabilization. To date, these models assume all the grain boundaries are isotropic and equivalent to each other; in reality grain boundaries are diverse in energy, structure, and mobility with solute partitioning being a function of that variability. Using cross-correlative precession electron diffraction and atom probe tomography, this research will elucidate the solute specificity to grain boundaries that leads to stabilization. The experimental findings will be linked to hydride Monte Carlo-Molecular Dynamics atomistic models that will elucidate the mechanisms of stabilization to specific boundary types. In addition, real-time experimental quantification of those boundaries during annealing will be measured to ascertain mobility and kinetic contributors to stability. The collective results will bridge outstanding and fundamental knowledge gaps in revealing how thermodynamic and kinetic considerations for specific grain boundaries leads to grain size stability. This research will be seamlessly integrated to various outreach activities to strengthen the STEM disciplines including a summer materials camp for secondary education teachers to introduce materials science into middle/high school classrooms.

非技术摘要：当材料的晶粒尺寸减小时，材料的强度会增加。不幸的是，与较大尺寸的谷物相比，这些小谷物尺寸在能量上是不利的。加热后，较小的谷物将生长以减少这种能量差异，从而导致强度损失。近年来，特定类型的合金的发展表明，较低的浓度原子类型或溶质可以稳定这些晶粒，以抵制这种生长。这些观察结果的结果是解释晶粒尺寸稳定的各种模型。但是，这些模型具有几个基本的科学差距，仍然有待解决。例如，建模的晶界被认为是等效的，其中现实晶界的结构，能量和迁移率都有多种多样。缺乏对这种溶质特异性分离晶界的实验验证阻碍了进一步的模型开发。这项研究将通过结合电子显微镜和原子探针断层扫描来克服这些先前的局限性，以检测到这些特定边界的溶质分离。然后，这些结果将被转发给原子学模型，以解释这种行为的多样性。这项研究将纳入各种外展活动，包括一个用于中学教师的夏季材料营地，将材料科学引入中/高中教室。技术摘要：纳米晶体材料是由于其独特的依赖性特性而进行了积极研究的领域。由于接口（边界）占整个结构的很大一部分，因此来自这些边界的相应界面能可以使这些晶粒固有地不稳定。已经设计了对这些边界的溶质分配，是一种稳定这些晶粒的一种手段，该手段是通过动力学溶质阻力效应的概念和稳定机制的热力学降低的概念。迄今为止，这些模型假设所有晶界都是各向同性的，相互等效的。实际上，晶界的能量，结构和迁移率是多样的，溶质分配是该变异性的函数。使用交叉反相关的进动电子衍射和原子探针断层扫描，这项研究将阐明导致稳定的晶界的溶质特异性。实验发现将与Hydride Monte Carlo分子动力学模型相关，该模型将阐明稳定机制与特定边界类型。 此外，将测量对退火期间这些边界的实时实验定量，以确定稳定性的迁移率和动力学贡献者。集体结果将弥合杰出和基本知识的差距，以揭示特定晶界的热力学和动力学考虑如何导致晶粒尺寸稳定性。这项研究将无缝地集成到各种外展活动中，以加强STEM学科，包括中学教育教师的夏季材料营地，将材料科学引入中/高中教室。

项目成果

Revisting Lennard Jones, Morse, and N-M potentials for metals

• DOI: 10.1016/j.commatsci.2022.111206
• 发表时间: 2022-02-02
• 期刊: COMPUTATIONAL MATERIALS SCIENCE
• 影响因子: 3.3
• 作者: Jacobson, David W.;Thompson, Gregory B.
• 通讯作者: Thompson, Gregory B.

A Comparative Investigation Between Transmission Kikuchi Diffraction (TKD) and Precession Electron Diffraction (PED)

透射菊池衍射（TKD）与进动电子衍射（PED）的比较研究

• DOI: 10.1017/s1431927620014026
• 发表时间: 2020
• 期刊: Microscopy and Microanalysis
• 影响因子: 2.8
• 作者: Sneddon, Glenn;Zhou, Xuyang;Thompson, Gregory;Cairney, Julie
• 通讯作者: Cairney, Julie

The influence of alloying in stabilizing a faceted grain boundary structure

• DOI: 10.1016/j.actamat.2020.09.085
• 发表时间: 2020-12
• 期刊: Acta Materialia
• 影响因子: 9.4
• 作者: Jonathan L. Priedeman;G. Thompson

Revealing in-plane grain boundary composition features through machine learning from atom probe tomography data

• DOI: 10.1016/j.actamat.2022.117633
• 发表时间: 2021-06
• 期刊: Acta Materialia
• 影响因子: 9.4
• 作者: Xuyang Zhou;Ye Wei;Markus Kuhbach;Huan Zhao;F. Vogel;R. D. Kamachali;G. Thompson;D. Raabe;B. Gault

Spinodal Decomposition in Nanocrystalline Alloys

• DOI: 10.1016/j.actamat.2021.117054
• 发表时间: 2021-08
• 期刊: Acta Materialia
• 影响因子: 9.4
• 作者: Xuyang Zhou;R. Darvishi Kamachali;B. Boyce;Blythe G. Clark;D. Raabe;G. Thompson