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: 2414950
• 负责人: Julie Schoenung
• 金额: $ 42万
• 依托单位: Texas A&M Engineering Experiment Station
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-12-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2414950&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通常使其在制造过程中难以成型，从而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，可以通过热处理对性能进行显着控制，从而可以有效地将这些材料制造成复杂形状，而不会破裂或失效。该奖项支持基础研究，探索相变超塑性的潜在机制，并揭示制造 ESO 的新方法。这些材料有望成为超级电容器、电池阴极、催化剂和电解质，对美国工业和经济产生影响。该项目探索先进制造和材料科学与工程领域，通过教育、培训和外展活动，为本科生、研究生和 K-12 学生，特别是来自少数族裔的学生提供跨学科主题的接触。熵稳定氧化物 (ESO) 是陶瓷材料，其中构型无序被组合设计成单相，多个阳离子随机填充亚晶格位置。当在特定温度窗口内进行热处理时，ESO 表现出可逆相变行为。这种相变表现为可控的相异质性，从而对 ESO 的微观结构提供了前所未有的控制。这种戏剧性的转变可用于增强高温变形过程中的延展性，从而通过转变超塑性和循环变形实现高效成形。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产生的内部应变，这些内部应变会在热循环过程中累积。研究内容包括以下任务：1）不同晶粒尺寸的大块ESO样品的合成和固结； 2) 热处理以达到所需的相态（第二相的数量和成分）； 3）高温变形和超塑性成形； 4）显微组织和性能评价。实验辅以理论模型，分析晶粒尺寸、施加应力、压力、应变率和温度对扩散的影响，从而分析变形机制和超塑性。这项研究建立了起始微观结构和变形行为之间的关系，从而增进了对 ESO 变形机制及其使用锻造和挤压等技术进行超塑性成形潜力的理解。该奖项反映了 NSF 的法定使命，并通过评估被认为值得支持利用基金会的智力优势和更广泛的影响审查标准。