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.

陶瓷材料的固有脆性通常会使它们在制造过程中很难形成，从而将它们限制在不需要复杂形状的应用中。最近发现的一类陶瓷类，熵稳定的氧化物（ESO）表现出独特的可逆相变行为，通过热处理为性质提供了重大控制，从而可以有效地将这些材料制造成不裂缝或故障的复杂形状。该奖项支持基础研究，以探讨转化巨大性的基本机制，并发现了制造ESO的新方法。这些材料显示出影响美国工业和经济的超级电容器，电池阴极，催化剂和电解质的希望。 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.当在特定温度窗口内进行热处理时，ESO显示出可逆的相变行为。这种相变表现为可控的相位异质性，从而对ESOS的微观结构进行了前所未有的控制。可以利用这种巨大的转化来增强高温变形期间的延展性，从而通过转化的超塑性和环状变形来有效形成。转化的质超塑性可以使机械变形超过100％，这是由于共存阶段之间的不匹配而产生的，这些阶段可以在热循环过程中积累。该研究涉及以下任务：1）具有不同晶粒尺寸的散装ESO样品的合成和合并； 2）热处理以达到所需的相状态（次级的数量和组成）； 3）高温变形和超增塑形成； 4）评估微观结构和特性。实验与理论建模相辅相成，以分析晶粒尺寸，施加的应力，压力，应变速率和温度对扩散的影响，从而分析了变形机制和超塑性。这项研究建立了启动微观结构和变形行为之间的关系，从而促进了对ESO中的变形机制的理解及其使用诸如锻造和挤压等技术的超塑性形成的潜力。该奖项反映了NSF的法定任务，并被认为是通过基金会的智力优点和广泛的影响来评估CRETERIA的智力，并被认为是值得通过评估的支持。