Processing and Properties of Entropy-Stabilized Boride Ceramics.

熵稳定硼化物陶瓷的加工和性能。

• 批准号: 1902069
• 负责人: William Fahrenholtz
• 金额: $ 40.64万
• 依托单位: Missouri University of Science and Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1902069&HistoricalAwards=false
• 关键词: Processing; Properties; Entropy; Stabilized; Boride

In order to make advances in hypersonic flight, nuclear fusion, ballistic impact protection, and concentrated solar power, materials are needed that can withstand temperatures far above the melting point of typical high performance materials. This project investigates the effects of composition and microstructure on the properties of complex transition metal boride ceramics which have melting temperatures above 3000 C and are among the highest melting points for any known materials. This class of materials is known as ultra-high temperature ceramics. Entropy stabilization, a concept whereby at least four other elements in approximately equal ratios are added to a binary compound, has been used to produce stable, high entropy borides. Initial studies using this approach focused on synthesis and densification without analyzing properties. Hence, this research addresses a gap in knowledge of fundamental composition-microstructure-property relationships for boride ceramics. The scientific outcomes of the project will include identification of relationships among processing conditions, microstructures, and properties to enable design selection of compositions and microstructures that will yield properties desired for demanding applications. The broader impacts will include increased inter-campus collaboration between a doctoral university with higher research activity and a public university that offers terminal M.S. degrees. This collaboration will include expanding distance methods to extend curricular offerings at both schools, and establishing stronger research links between both to enhance student recruitment and increase access to research infrastructure.The research will use an integrated experimental and computational approach to provide an unprecedented level of knowledge about the atomic structure, microstructure development, and composition-microstructure-property relationships for boride ceramics containing multiple transition metals. The main goals of the project are to: 1) utilize the entropy stabilization effect to produce new boride compositions containing metals that do not typically form borides; 2) control microstructure development by manipulating densification kinetics through changes in composition; and 3) establish ultra-high temperature structure-property relationships in this emerging class of materials. Computational methods will be used to investigate solution formation behavior, thermodynamic properties, and defect formation energies. Complementary experimental studies will focus on processing and properties of entropy stabilized boride ceramics. Reactive hot pressing will be used to produce ceramics with controlled compositions ranging from highly pure borides with containing one transition metal to entropy-stabilized compositions containing five transition metals in roughly equal proportions. In addition, reactive hot pressing offers the ability to control microstructure development to enable studies of microstructure-property relationships. The project will utilize advanced characterization tools to quantify metal distributions in boride ceramics with complex compositions, which will help elucidate densification kinetics, and measure intrinsic mechanical, thermal, and electrical properties of high entropy boride compositions. This project will lead to unprecedented knowledge of the thermochemical stability and inherent properties of entropy stabilized ceramics.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.

为了在高超音速飞行、核聚变、弹道撞击防护和集中太阳能发电方面取得进展，需要能够承受远高于典型高性能材料熔点的温度的材料。 该项目研究了组成和微观结构对复杂过渡金属硼化物陶瓷性能的影响，该陶瓷的熔化温度高于3000 ℃，并且是任何已知材料的最高熔点。 这类材料被称为超高温陶瓷。 熵稳定化是一个概念，其中至少有四种其他元素以近似相等的比例添加到二元化合物中，已被用于生产稳定的高熵硼化物。使用这种方法的最初研究集中在合成和致密化，而不分析性能。 因此，这项研究解决了硼化物陶瓷的基本组成-显微结构-性能关系的知识的差距。 该项目的科学成果将包括确定加工条件，微观结构和性能之间的关系，以实现组合物和微观结构的设计选择，从而产生要求苛刻的应用所需的性能。 更广泛的影响将包括增加具有更高研究活动的博士大学和提供终端MS的公立大学之间的校园间合作。度这项合作将包括扩大远程方法，以扩大两所学校的课程设置，并在两者之间建立更强的研究联系，以提高学生的入学率和增加对研究基础设施的访问。这项研究将使用综合实验和计算方法，以提供有关原子结构，微观结构发展，以及含多种过渡金属硼化物陶瓷的组成-组织-性能关系。 该项目的主要目标是：1）利用熵稳定效应生产新的硼化物组合物，其中含有通常不会形成硼化物的金属; 2）通过改变组合物来操纵致密化动力学来控制微观结构的发展;以及3）在这类新兴材料中建立超高温结构-性能关系。 计算方法将被用来研究解决方案的形成行为，热力学性质，和缺陷形成能。补充的实验研究将集中在熵稳定的硼化物陶瓷的工艺和性能。 反应热压将用于生产具有受控成分的陶瓷，其成分范围从含有一种过渡金属的高纯硼化物到含有大致相等比例的五种过渡金属的熵稳定成分。 此外，反应热压提供了控制微观结构发展的能力，从而能够研究微观结构-性能关系。 该项目将利用先进的表征工具来量化具有复杂成分的硼化物陶瓷中的金属分布，这将有助于阐明致密化动力学，并测量高熵硼化物成分的固有机械，热和电气性能。 该项目将导致对熵稳定陶瓷的热化学稳定性和固有特性的前所未有的了解。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。

项目成果

Local structure in high-entropy transition metal diborides

• DOI: 10.1016/j.actamat.2022.118294
• 发表时间: 2022-08
• 期刊: Acta Materialia
• 影响因子: 9.4
• 作者: M. Gaboardi;F. Monteverde;F. Saraga;G. Aquilanti;Lun Feng;W. Fahrenholtz;G. Hilmas

Effect of Nb content on the phase composition, densification, microstructure, and mechanical properties of high-entropy boride ceramics

• DOI: 10.1016/j.jeurceramsoc.2020.08.058
• 发表时间: 2021-01-01
• 期刊: JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
• 影响因子: 5.7
• 作者: Feng, Lun;Fahrenholtz, William G.;Monteverde, Frederic
• 通讯作者: Monteverde, Frederic

Measurement of the melting temperature of ZrB 2 as determined by laser heating and spectrometric analysis

• DOI: 10.1111/jace.17634
• 发表时间: 2021-02
• 期刊: Journal of the American Ceramic Society
• 影响因子: 3.9
• 作者: A. Stanfield;D. Manara;D. Robba;G. Hilmas;W. Fahrenholtz

Superhard high-entropy AlB2-type diboride ceramics

• DOI: 10.1016/j.scriptamat.2021.113855
• 发表时间: 2021-03-14
• 期刊: SCRIPTA MATERIALIA
• 影响因子: 6
• 作者: Feng, Lun;Monteverde, Frederic;Hilmas, Gregory E.
• 通讯作者: Hilmas, Gregory E.