Mechanical Behavior of Novel Metal-Oxide Composites with Hierachical Microstructures: Effect of Scale and Interfacial Structure

非技术描述：通常，具有纳米尺寸内部特征的材料具有显著的性能，例如高强度(与具有更大特征的相同材料相比)。然而，以负担得起的成本和大量制造出具有纳米级特征的这种材料可能是困难的。这一研究项目的重点是一条新的路线，以创造具有纳米级陶瓷和金属层的材料，这些材料可能具有不寻常的和有利的机械性能，并以合理的成本进行加工。电子显微镜技术和专门的小规模力学测试揭示了陶瓷-金属界面的作用、各相的取向和相的尺寸对力学性能的影响。这些结果提供了对这些现象的基本科学理解，这些现象可应用于陶瓷和金属的连接、制造用于承载应用的坚固材料以及防止微电子设备中的故障。此外，在这项工作中形成的广泛的科学概念正在被纳入到针对K-12儿童的推广活动中，从而鼓励他们参与科学和工程领域。技术细节：这项研究项目专注于了解陶瓷-金属复合材料的微观结构发展和力学行为，这些陶瓷-金属复合材料是通过部分还原具有氟铝石起始结构的混合氧化物陶瓷而产生的。降低这类材料以部分去除氧气可以产生具有独特陶瓷-金属复合形貌的分级结构，这是迄今为止还没有被研究过的，并且有望显示出诱人的机械性能。陶瓷/金属特征的微观结构尺度从几十纳米到几十微米，可以得到层状和球状两种形貌。一种独特的微观结构的发现可以通过还原氟磷矿材料来创建，再加上相对较新的象差校正扫描电子显微镜和原位微机械测试仪器的出现，使得首次有可能揭示陶瓷-金属纳米复合材料的微观结构尺度和片层取向对硬度、硬度和韧性的影响。这项研究的结果与连接等工艺过程有关，也与理解陶瓷-金属系统中的结垢效应有关。此外，大学水平的学生正在发展像差校正扫描电子显微镜和原位微机械测试等新兴领域的专业知识。

NON-TECHNICAL DESCRIPTION: Often, a material with nanometer-sized internal features has remarkable properties such as high strength (when compared to the same material with larger features). However, it can be difficult to create such materials with these nanometer-scale features at an affordable cost and in large quantities. This research project is focused on a new route for creating materials with nanometer-scale layers of ceramics and metals that have the potential to possess unusual and advantageous mechanical properties and to be processed at a reasonable cost. Electron microscopy techniques and specialized small-scale mechanical tests are revealing the role of the ceramics-metal interfaces, the orientation of the individual phases, and the size of the phases on mechanical properties. The results are providing a fundamental scientific understanding of these phenomena that can be applied to fields such as joining of ceramics and metals, creation of strong materials for load-bearing applications, and prevention of failure in microelectronic devices. In addition, the broad scientific concepts developed during this work are being incorporated into outreach activities that target K-12 children, thereby encouraging their participation in science and engineering fields.TECHNICAL DETAILS: This research project is focused on understanding the microstructure development and mechanical behavior of ceramic-metal composites derived from the partial reduction of mixed oxide ceramics that have a delafossite starting structure. Reducing this class of materials to partially remove oxygen yields a hierarchical structure with unique ceramic-metal composite morphologies that hitherto have not been studied and that promise to exhibit attractive mechanical properties. The microstructural scale of the ceramic/metal features range from tens of nanometers to tens of microns, and both layered and globular morphologies can be achieved. The discovery of a unique microstructure that can be created by reducing delafossite materials, combined with the relatively recent advent of aberration-corrected scanning transmission electron microscopes and in situ micro-mechanical testing instruments, make it possible for the first time to reveal the effects of ceramic-metal nanocomposite microstructure scale and lamellar orientation on stiffness, hardness, and toughness. The findings of the study are relevant to technological processes such as joining, and to understanding scaling effects in ceramic-metal systems. Additionally, university-level students are developing expertise in the emerging areas of aberration-corrected scanning transmission electron microscopy and in situ micro-mechanical testing.