New frontiers in synthesis of high-entropy transition metal borides enabled by microwave-induced plasma

非技术总结该项目的重要性在于，它解决了对先进陶瓷的需求，将其作为航空航天、国防、发电和加工工业中许多应用的关键技术，具有重大的国家影响。对设计用于恶劣条件下运行的材料的研究对于应对一系列挑战至关重要-从创造更好的涡轮机，反应堆和电池到开发未来的能源系统。该项目的实验和计算部分有助于支持国家材料基因组计划（MGI）的目标，以更快的速度和更低的成本发现，制造和部署先进材料。在该项目中开发的被称为高熵陶瓷的一类材料扩展了高温和抗生锈的范围，这是高超声速飞行器等先进材料系统所需的。调查涉及了解这些新材料是如何形成的，沿着还有它们的机械和防锈性。这些材料是使用一种高效的技术处理的，这种技术基于一种被称为等离子体的物质状态;这是一种在该领域尚未探索的处理方法。 实验和计算方法都被用来提供关于如何合成，表征和建模这些材料的新知识。该社区通过参与当地的科学中心，致力于等离子体技术的奇迹，目的是为广大观众，包括公众和K-12 students.Technical SummaryThis project investigates a novel approach for synthesis of high-entropy transition metal borides enabled by microwave-induced plasma.与主要依赖对流的传统工艺相比，这种方法的优点包括：增强扩散、降低能耗、非常快的加热速率和显著减少的加工时间、降低烧结温度以及改善物理和机械性能。等离子体放电在促进微波加热和经由高活性物质（诸如电子、离子和自由基）的化学反应方面是高效的。这种合成路线是尚未探索的高熵陶瓷，并提供了机会，研究机制有助于形成这类相对较新的材料。通过这种独特的方法导致完全相变的动力学和反应途径进行了研究，沿着与结构，硬度和抗氧化性的表征。计算工作量通过用部分占据法计算熵形成能力来指导组分选择，使用CalPhad将热力学与相图耦合来预测抗氧化性，并用特殊的准随机结构来模拟机械性能。该项目的成果包括：对微波诱导等离子体如何影响和增强高熵硼化物形成的反应途径/动力学的新认识，以及沿着实验验证的机械和抗氧化性能的新模型的开发。该项目的社区外展重点是向包括公众和K-12学生在内的广泛观众展示等离子技术的奇迹。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARYThe significance of this project is that it addresses the need for advanced ceramics as a key enabling technology for many applications in aerospace, defense, power generation, and processing industries having significant national impact. The study of materials designed for operation under harsh conditions is essential to meet a range of challenges—from creating better turbines, reactors, and batteries to developing future energy systems. The experimental and computation components of this project help support the goals of the National Materials Genome Initiative (MGI) in the effort to discover, manufacture, and deploy advanced materials faster and with less cost than ever before. The class of materials known as high-entropy ceramics developed in this project extends the range of high temperatures and resistance to rusting as needed for advanced material systems, such as hypersonic vehicles. The investigations involve understanding how these new materials form, along with their mechanical and rust resistance. The materials are processed using a highly efficient technique based on a state of matter known as plasma; a processing approach not yet explored in this field. Both experimental and computational methodologies are employed to provide new knowledge about how these materials can be synthesized, characterized, and modeled. The community are engaged about the wonders of plasma technology through involvement with a local science center, with aim for a broad viewing audience including the general public and K-12 students.TECHNICAL SUMMARYThis project investigates a novel approach for synthesis of high-entropy transition metal borides enabled by microwave-induced plasma. Compared to conventional processes that rely primarily on convection, the advantages of this approach include: enhanced diffusion, reduced energy consumption, very rapid heating rates and considerably reduced processing times, decreased sintering temperatures, and improved physical and mechanical properties. The plasma discharge is highly efficient in promoting microwave heating and chemical reactions via highly active species such as electrons, ions and radicals. This synthesis route is yet unexplored for high-entropy ceramics and presents opportunity to study the mechanisms contributing to formation of this relatively new class of materials. The kinetics and reaction pathway leading to complete phase transformation via this unique approach is investigated, along with characterization of structure, hardness and oxidation resistance. The computational effort guide component selection by computing entropy forming ability with partial occupation method, predict oxidation resistance using CalPhad to couple thermodynamics with phase diagrams, and model mechanical properties with special quasi-random structures. Outcomes from this project include: new understanding of how microwave-induced plasmas affect and enhance reaction pathways/kinetics toward high-entropy boride formation and development of new models for mechanical and oxidation resistance properties along with validation from experiment. Community outreach in this project focuses on the wonders of plasma technology for a broad viewing audience including the general public and K-12 students.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.