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实现广泛的重要技术。 被称为MAX相的陶瓷碳化物和氮化物材料家族具有不寻常且通常独特的一组特性，这些特性将陶瓷和金属的一些最佳属性联合收割机结合起来。这些材料重量轻、硬度高、稳定，能够像典型的陶瓷一样耐高温，但也能耐损伤，在高温下具有延展性，并且像金属一样易于加工。此外，某些MAX相在空气中加热时会形成保护层，对热冲击、热循环和化学侵蚀具有极强的抵抗力。这个设计材料革命和工程我们的未来（DMREF）奖支持基础研究，以了解MAX阶段这些保护层的形成过程。这项研究将结合计算模拟和实验合成和表征，为加速开发和设计具有出色机械性能的高温应用MAX相材料建立知识基础。该项目的成果将促进MAX阶段在发电，能源转换，运输，航空航天和国防技术中的应用。该项目还为研究生和本科生提供专业的多学科培训，将材料信息学，建模，原子计算和实验整合到材料设计中。尽管对MAX相进行了二十年的实验研究，但设计其最佳成分和微观结构仍然是一个挑战，主要是因为大量的可能成分和微观结构，以及缺乏将它们的组成和微观结构与性能相关联的可靠的物理模型。本研究计划的总体目标是克服这些挑战，促进高温应用MAX相的设计：（1）开发基于物理的氧化铝保护层的形成预测;（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）设计贝叶斯参数识别校准协议;（4）实施和部署高效全局优化协议，以有效发现具有最佳热机械性能的MAX相;（5）通过材料合成、表征和热机械测试来验证所提出的框架。这将提供指导性的基础知识和协议，以设计高温应用的MAX相的最佳组成和微观结构。

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.