Understanding the Deformation Behavior of Alumina-Forming Austenitic Stainless Steels

即使越来越多地使用可再生能源，在可预见的未来，用于发电的主要能源很可能是化石燃料。因此，出于经济原因，尽可能有效地利用这些资源至关重要。提高发电厂的运行温度可以提高其效率。高温的限制因素是材料可以在更高的温度下工作，并且在经济上可行。本项目的目的是阐明在铝形成奥氏体（AFA）不锈钢的变形机制，正在考虑用于这一应用。这项工作将训练一名博士生和几名本科生掌握最先进的技术。该项目将确定与晶界（GB）析出强化相关的变形机制，并试图了解在含有无析出区（PFZ）和多种类型的析出物的合金中的基本变形行为，每种类型的析出物都可以对变形行为做出不同的贡献。这项工作将在AFA不锈钢Fe-20Cr-30Ni-2Nb-5Al模型上进行。在机械测试前后，通过透射电子显微镜（TEM）和扫描电子显微镜（SEM）进行详细的微观结构和缺陷表征。在室温和750℃下进行的TEM原位应变和SEM原位应变研究将检查位错/沉淀和位错/GB的相互作用，包括了解PFZ沿GB的作用。这项工作将训练一名博士生和几名本科生掌握最先进的技术。

NON-TECHNICAL SUMMARYEven with the increasing use of renewable energy, the primary energy sources for the foreseeable future for power generation are likely to be fossil fuels. Thus, for economic reasons, it is critical to use these resources as efficiently as possible. Increasing a power plant's operating temperature increases its efficiency. The limiting factor for higher temperature is materials that can operate at higher temperatures, and are economically viable. The aim of this project is to elucidate the deformation mechanisms in alumina-forming austenitic (AFA) stainless steels that are being considered for this application. The work will train both a Ph.D. student and several undergraduates in state of the art techniques.TECHNICAL SUMMARYThe project will ascertain the deformation mechanisms associated with grain boundary (GB) precipitation strengthening, and attempt to understand the fundamental deformation behavior in alloys containing both a precipitate free zone (PFZ) and multiple types of precipitates in both the GBs and the matrix each of which can contribute differently to the deformation behavior. The work will be performed on the model AFA stainless steel Fe-20Cr-30Ni-2Nb-5Al. Detailed microstructural and defect characterization by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) wlll be performed before and after mechanical testing. TEM in-situ straining and SEM in-situ straining studies performed at both room temperature and 750C will examine both dislocation/precipitate and dislocation/GB interactions, including understanding the role of the PFZ along the GBs. The work will train both a Ph.D. student and several undergraduates in state of the art techniques.