Understanding Transformation Superplasticity, High Temperature Deformation and Manufacturing of Entropy Stabilized Oxides

了解相变超塑性、高温变形和熵稳定氧化物的制造

• 批准号: 2029966
• 负责人: Julie Schoenung
• 金额: $ 42万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2024-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2029966&HistoricalAwards=false
• 关键词: Understanding; Transformation; Superplasticity; Temperature; Deformation

The inherent brittleness of ceramic materials often makes them difficult to form during manufacturing, limiting them to applications that do not require complex shapes. The recently discovered class of ceramics, entropy stabilized oxides (ESOs), exhibit a unique reversible phase transformation behavior that provides significant control over the properties via heat treatment, thus allowing for an efficient means of manufacturing these materials into complex shapes without fracture or failure. This award supports fundamental research to explore the mechanisms underlying transformation superplasticity and uncover new methods of manufacturing ESOs. These materials show promise as supercapacitors, battery cathodes, catalysts, and electrolytes, which impacts U.S. industry and economy. The project explores the fields of advanced manufacturing and materials science and engineering, with educational, training and outreach activities that provide exposure to interdisciplinary topics for undergraduate, graduate and K-12 students, especially those from underrepresented minorities.Entropy stabilized oxides (ESOs) are ceramic materials in which configurational disorder is compositionally engineered into a single phase with multiple cations randomly populating sublattice locations. ESOs display a reversible phase transformation behavior when heat treated within a particular temperature window. This phase transformation manifests as a controllable phase heterogeneity, giving unprecedented control over the microstructure of ESOs. Such a dramatic transformation could be leveraged to enhance ductility during high temperature deformation, allowing for efficient forming through transformation superplasticity and cyclic deformation. Transformation superplasticity allows for mechanical deformation of more than 100% due to the internal strain that arises from the mismatch between co-existing phases, which can accumulate during thermal cycling. The research involves the following tasks: 1) synthesis and consolidation of bulk ESO samples with different grain sizes; 2) heat treatment to achieve the desired phase state (amount and composition of the secondary phase(s)); 3) high temperature deformation and superplastic forming; and 4) evaluation of microstructure and properties. Experiments are complemented with theoretical modeling to analyze the influence of grain size, applied stress, pressure, strain rate and temperature on diffusion, and consequently deformation mechanisms and superplasticity. This research establishes a relationship between starting microstructure and deformation behavior, thus advancing the understanding of deformation mechanisms in ESOs and their potential for superplastic forming using techniques such as forging and extrusion.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.

陶瓷材料固有的脆性往往使它们在制造过程中难以形成，这限制了它们仅适用于不需要复杂形状的应用。最近发现的一类陶瓷，即熵稳定氧化物(ESO)，表现出独特的可逆相变行为，通过热处理对性能进行显著控制，从而允许一种有效的方法将这些材料制造成复杂的形状，而不会断裂或失效。该奖项支持基础研究，以探索转变超塑性的潜在机制，并发现制造ESO的新方法。这些材料在超级电容器、电池正极、催化剂和电解液等方面显示出良好的前景，这将影响美国的工业和经济。该项目探索先进制造和材料科学与工程领域，通过教育、培训和推广活动，为本科生、研究生和K-12学生提供跨学科主题的接触，特别是那些来自代表性较低的少数民族的学生。熵稳定氧化物(ESO)是一种陶瓷材料，在这种材料中，构型无序被组成工程化为单一相，其中多个阳离子随机地填充在亚晶格位置。当在特定的温度窗口内热处理时，ESO表现出可逆的相变行为。这种相变表现为一种可控的相异质性，对ESO的微观结构进行了前所未有的控制。这种戏剧性的转变可以用来提高高温变形过程中的延展性，从而通过相变超塑性和循环变形实现有效的成形。相变超塑性允许超过100%的机械变形，这是由于共存相之间的不匹配引起的内部应变，在热循环过程中会积累。研究内容包括：1)不同粒度ESO块体样品的合成与固结；2)达到所需相状态的热处理(S)；3)高温变形与超塑性成形；4)组织与性能评价。通过实验和理论模拟相结合，分析了晶粒度、外加应力、压力、应变速率和温度对扩散的影响，进而分析了变形机制和超塑性。这项研究建立了初始微结构和变形行为之间的关系，从而促进了对ESO中的变形机制及其使用锻造和挤压等技术进行超塑性成形的潜力的理解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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

Morphological evolution in nanostructured secondary phases in entropy stabilized oxides

熵稳定氧化物中纳米结构第二相的形态演化

• DOI: 10.1016/j.matchar.2022.112301
• 发表时间: 2022
• 期刊: Materials Characterization
• 影响因子: 4.7
• 作者: Dupuy, Alexander D.;Schoenung, Julie M.
• 通讯作者: Schoenung, Julie M.

Multiscale phase homogeneity in bulk nanocrystalline high entropy oxides

块体纳米晶高熵氧化物的多尺度相均匀性

• DOI: 10.1016/j.jeurceramsoc.2021.03.035
• 发表时间: 2021
• 期刊: Journal of the European Ceramic Society
• 影响因子: 5.7
• 作者: Dupuy, Alexander D.;Chellali, Mohammed Reda;Hahn, Horst;Schoenung, Julie M.
• 通讯作者: Schoenung, Julie M.

Hidden Transformations in Entropy-Stabilized Oxides

• DOI: 10.1016/j.jeurceramsoc.2021.06.014
• 发表时间: 2021-06
• 期刊: Journal of The European Ceramic Society
• 影响因子: 5.7
• 作者: A. Dupuy;I-Ting Chiu;P. Shafer;E. Arenholz;Y. Takamura;J. Schoenung

Microstructure, mechanical properties, and ionic conductivity of a solid-state electrolyte prepared using binderless laser powder bed fusion

• DOI: 10.1557/s43578-021-00390-4
• 发表时间: 2021-09
• 期刊: Journal of Materials Research
• 影响因子: 2.7
• 作者: Katherine A. Acord;A. Dupuy;Xin Wang;Alexandra L. Vyatskikh;O. Donaldson;T. Rupert;James J. Wu