DMREF: Collaborative Research: Accelerated Development of Damage Tolerant and Oxidation Resistant Alumina-Forming MAX Phases

能够承受恶劣环境的材料有可能使一系列重要技术成为可能。一系列被称为MAX相的陶瓷碳化物和氮化物材料具有一系列不寻常的、往往是独特的特性，这些特性结合了陶瓷和金属的一些最佳属性。它们轻、硬、稳定，能够像典型的陶瓷一样耐高温，但也具有耐损性，在高温下具有延展性，像金属一样易于加工。此外，一些MAX相在空气中加热时形成保护层，极耐热冲击、热循环和化学攻击。这项旨在革新和设计我们未来的设计材料奖(DMREF)支持基础研究，以了解这些处于最大阶段的保护层的形成过程。这项研究将结合计算模拟和实验合成与表征，为加速开发和设计高温应用中具有优异力学性能的MAX相材料建立知识库。该项目的成果将促进MAX阶段在发电、能源转换、交通、航空航天和国防技术方面的应用。该项目还为研究生和本科生提供了集成材料信息学、建模、原子计算和材料设计实验的专门的多学科培训。尽管对MAX相进行了20年的实验研究，但设计其最佳成分和微观结构仍然是一个挑战，主要是因为可能存在大量的成分和微观结构，并且缺乏将其成分和微观结构与性能联系起来的可靠的物理模型。本研究计划的总体目标是克服这些挑战，促进高温应用中MAX相的设计，具体做法如下：(1)开发用于形成保护性氧化铝层的物理预测器；(2)开发微观力学模型，并确定控制固有热机械性能的成分/结构参数；(3)设计用于参数识别的贝叶斯校准协议；(4)实施和部署高效的全局优化协议，以高效发现具有最佳热机械性能的MAX相；以及(5)通过材料合成、表征和热机械测试对建议的框架进行验证。这将为设计高温应用的MAX相的最佳成分和显微组织提供指导性的基础知识和方案。

Materials capable of withstanding harsh environments have the potential to enable a wide range of important technologies. A family of ceramic carbide and nitride materials referred to as MAX phases possess unusual and often unique sets of properties that combine some of the best attributes of ceramics and metals. These are light, stiff, stable and able to resist high temperatures like typical ceramics, but also damage tolerant, ductile at high temperatures and as readily machinable as metals. In addition, some of the MAX phases form protective layers when heated in air, that are extremely resistant to thermal shock, thermal cycling and chemical attack. This Designing Materials to Revolutionize and Engineer our Future (DMREF) award supports fundamental research to understand the process by which these protective layers in MAX phases are formed. This research will incorporate computational simulations and experimental synthesis and characterization to build the knowledge base for the accelerated development and design of MAX phase materials with outstanding mechanical properties for high temperature applications. Results of this project will foster application of MAX phases in power generation, energy conversion, transportation, aerospace and defense technologies. This project also provides specialized multidisciplinary training for graduate and undergraduate students on integrating materials informatics, modeling, atomistic computations and experiments in materials design.Despite two decades of experimental studies on MAX phases, designing their optimal composition and microstructure has remained a challenge mainly because of the large number of possible compositions and microstructures, and a lack of robust physical models that relate their composition and microstructure to properties. The overall goal of this research program is to overcome those challenges and foster design of MAX phases for high temperature applications by: (1) developing physics-based predictors for the formation of protective alumina layers; (2) developing micromechanical models and identifying compositional/structural parameters that control intrinsic thermomechanical properties; (3) designing Bayesian calibration protocols for parameter identification; (4) implementing and deploying Efficient Global Optimization protocols for the efficient discovery of MAX phases with optimal thermomechanical properties and; (5) validating the proposed framework through material synthesis, characterization and thermomechanical testing. This will provide guiding fundamental knowledge and protocols to design optimal compositions and microstructures of the MAX phases for high temperature application.