High entropy effects from variable chemical order in multi-principal element solution alloys

多主元素溶液合金中可变化学顺序的高熵效应

• 批准号: 1804320
• 负责人: Mingwei Chen
• 金额: $ 40.2万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-01 至 2022-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1804320&HistoricalAwards=false
• 关键词: entropy; effects; variable; chemical; order

Non-technical Abstract:This project advances the field by answering a fundamental materials science question, the structure (in this case, the local chemical order, LCO)-property relationship in the emerging high entropy alloys (HEAs, where multiple elements are mixed in equal amounts and the resulting alloy retains a single atomic structure). The focus is on the signature 'high entropy effect' that sets these HEAs apart from traditional solid solutions. The research highlights the wide variety of local chemical order on the atomic-to-nanometer level and therefore 'plenty of room at the bottom' for rich property possibilities. It will also deliver a powerful toolset (realistic interaction potentials) for the atomistic modeling community working on HEAs to gain atomistic insight into the underlying deformation mechanisms. This work also offers niche benefits for society and education. First, from the application standpoint, the LCOs in HEAs open a vast playground to tailored properties in solution alloys. For example, a random solution is amenable to extensive shaping at room temperature. After shaping, the part can be heated to an intermediate temperature to develop LCO over an extended period of time, gaining strength for load-bearing applications. Second, this research will improve the understanding of closely-related concentrated alloys, such as the very popular stainless steels. Third, the new alloys with partial chemical order will enrich the basic courses in materials science, such as Thermodynamics and Phase Transformations, so that future students can practice a real-world example of 'solution' in their hands, one that can be manipulated to go all the way from chemically random to highly ordered, and see for themselves what various enthalpy and entropy terms do to the starting random solution. The findings of new alloys and new properties will be broadly disseminated at international conferences and in first-class journals.Technical Abstract:Configurational entropy has been perceived as the key factor in stabilizing multi-principal element single-phase solid solutions (SS), the so-called "high entropy alloys" (HEAs). However, the role of entropy in phase selection was overrated, as these concentrated alloys have complex chemical interactions, such that the random SS is only metastable except at very high temperatures. The goal of this project is to highlight a hitherto less-noticed, and arguably more important, trait of 'high entropy', and illustrate its impact on the defect behavior and mechanical properties. It will be illustrated that HEAs are not really chemically disordered, but rather have large variability of local chemical order (LCO) of the various species on the lattice sites. This, while precluding the hypothetical extreme of ideal random solution, represents a vast range of possible structural arrangements that can be tailored to change HEA properties, beyond traditional solutions and intermetallics. Molecular dynamics simulations will be conducted with realistic empirical interatomic potentials developed specifically for HEAs, to systematically i) map out the LCOs possible in HEA at a given composition and its strong dependence on the processing temperature; ii) demonstrate that the partial chemical order sensitively and drastically changes generalized planar fault energy, not only in terms of its sample-average, but also its spatial variation; and iii) unveil how the different LCOs influence the behavior of dislocation, in particular its energy landscape and the activation parameters that govern the mechanical strength.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术摘要：该项目通过回答基本的材料科学问题，结构（在这种情况下为局部化学顺序，LCO） - 新兴高熵合金中的属性关系（HEAS，其中多个元素相等的含量和合金合金保留单个原子结构）。重点放在签名的“高熵效应”上，该效果使这些HEAS与传统的实心解决方案不同。该研究突出了原子能至纳米级上各种各样的当地化学秩序，因此“底部有足够的空间”，以实现丰富的财产可能性。它还将为在HEAS上工作的原子建模社区提供强大的工具集（现实的交互潜力），以获得对基本变形机制的原子洞察力。这项工作还为社会和教育提供了利基利益。首先，从应用程序的角度来看，HEAS中的LCO打开了一个宽敞的操场，可在溶液合金中量身定制特性。例如，随机解决方案可以在室温下进行大量塑形。成型后，可以将零件加热到中等温度，以在很长的时间内发展LCO，从而获得负载应用的强度。其次，这项研究将提高人们对密切相关的浓缩合金的理解，例如非常流行的不锈钢。第三，具有部分化学顺序的新合金将丰富材料科学中的基本课程，例如热力学和相变，以便未来的学生可以练习他们手中的“解决方案”的真实示例，可以通过化学随机进行操纵，从化学随机到高度有序，并为自己的各种感觉和胚胎术语提供对开始的随机解决方案。新合金和新特性的发现将在国际会议和一流的期刊中广泛传播。技术摘要：构型熵已被视为稳定多原则单相固体解决方案（SS）的关键因素（SS），即所谓的“ Higheroy Alloys”（Heas）。但是，熵在相选择中的作用被高估了，因为这些浓缩合金具有复杂的化学相互作用，因此除了非常高的温度外，随机SS仅是可稳定的。该项目的目的是突出显示“高熵”的迄今为止较小的，可以说更重要的特征，并说明了其对缺陷行为和机械性能的影响。可以说的是，HEAS并不是真正的化学混乱，而是晶格部位上各种物种的局部化学秩序（LCO）的差异很大。这在排除理想随机解决方案的假设极端的同时，代表了许多可能的结构排列，可以量身定制，以改变传统解决方案和金属间质量。分子动力学模拟将以专门为HEAS开发的现实经验性原子间潜能进行，以系统地i）在给定组成的HEA中绘制可能的LCO及其对加工温度的强烈依赖； ii）证明部分化学秩序不仅在其样品平均方面，而且在空间变化方面都敏感和巨大地改变了普遍的平面断层能。 iii）揭示了不同的LCO如何影响错位的行为，特别是其能量格局和控制机械强度的激活参数。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识优点和更广泛的影响审查标准通过评估来进行评估的。

项目成果

Universal scaling law of glass rheology

• DOI: 10.1038/s41563-021-01185-y
• 发表时间: 2020-08
• 期刊: Nature Materials
• 影响因子: 41.2
• 作者: Shuangxi Song;F. Zhu;Mingwei Chen

Unusual dislocation behavior in high-entropy alloys

• DOI: 10.1016/j.scriptamat.2020.02.021
• 发表时间: 2020-05-01
• 期刊: SCRIPTA MATERIALIA
• 影响因子: 6
• 作者: Ma, Evan

Strengthening in multi-principal element alloys with local-chemical-order roughened dislocation pathways

• DOI: 10.1038/s41467-019-11464-7
• 发表时间: 2019-08-08
• 期刊: NATURE COMMUNICATIONS
• 影响因子: 16.6
• 作者: Li, Qing-Jie;Sheng, Howard;Ma, Evan
• 通讯作者: Ma, Evan

3D Continuously Porous Graphene for Energy Applications

• DOI: 10.1002/adma.202108750
• 发表时间: 2022-02-25
• 期刊: ADVANCED MATERIALS
• 影响因子: 29.4
• 作者: Han, Jiuhui;Johnson, Isaac;Chen, Mingwei
• 通讯作者: Chen, Mingwei

Decoupling between Shockley partials and stacking faults strengthens multiprincipal element alloys

• DOI: 10.1073/pnas.2114167118
• 发表时间: 2021-12
• 期刊: Proceedings of the National Academy of Sciences
• 作者: Zongrui Pei;Siyuan Zhang;Yinkai Lei;Fan Zhang;Mingwei Chen