Enhanced Superalloys via Mesoscale Engineering

高温合金是理想地适用于高性能燃气涡轮机应用的关键结构材料，因为它们在高温下具有优异的抗变形性和抗环境退化性。 尽管超合金的许多固有特性可归因于基础合金化学，但在许多情况下，这些合金的性质可通过在非常精细的尺度下对结构进行工程控制来增强。 因为许多先进的涡轮机发动机现在在接近现有超合金能力极限的温度下操作，所以这些工程技术可以潜在地延长寿命并赋予许多这些超合金结构更高程度的损伤容限。 该奖项支持基础研究，以了解金属成形和加热操作过程中采用的工艺参数如何影响形态和精细结构的发展。这项研究将影响先进的燃气涡轮机技术，用于发电，空间探索和航空航天/船舶推进，具有显着的经济和环境效益，如减少燃料消耗，最大限度地减少二氧化碳和一氧化二氮的排放。该奖项还将支持当地芝加哥高中的教育推广计划，并协助美国研究生的培训和教育。该奖项资助的这项研究旨在了解在含有高比例Sigma-3孪晶界的多晶镍基高温合金中形成锯齿状晶界的基本机制，并评估它们对晶界滑动的综合影响。将在两种商用高温合金中评估共格和半共格沉淀物诱导晶界扰动的程度和有效性。 此外，双晶体样品具有受控的取向差将被制造系统量化的晶界取向差的扰动的形成和增长的影响。 最后，纳米尺度的成分和机械属性的评估沿着锯齿状的边界将结合三维微观结构表征和原位应变映射，以量化的锯齿晶界滑动的有效性。 这些研究将有助于开发创新的热机械工艺，这些工艺可以有效地用于定制或设计合金的机械性能，尽管存在介观尺度特征。

Superalloys are critical structural materials ideally suited for high performance gas turbine applications due their excellent resistance to deformation and environmental degradation at elevated temperatures. Although many of the intrinsic characteristics of superalloys can be attributed to the underlying alloy chemistry, in many instances the properties of these alloys can be enhanced through engineering control of the structure at very fine scales. Because many of the advanced turbine engines now operate at temperatures approaching the limits of existing superalloy capabilities, these engineering techniques can potentially extend the life and impart higher a higher degree of damage tolerance to many of these superalloy structures. This award supports fundamental research to understand how the process parameters employed during metal forming and heating operations effect the development of morphology and fine structure. This research will impact advanced gas turbine technologies for power generation, space exploration, and aerospace/marine propulsion, with significant economic and environmental benefits, such as the reduced fuel consumption, minimization of carbon dioxide and nitrous oxide emissions. The award will also support educational outreach programs at local Chicago high schools and assist in the training and education of US graduate students. This research funded by this award aims to understand the fundamental mechanisms that govern the formation serrated grain boundaries in polycrystalline Ni-based superalloys containing a high proportion of Sigma-3 twin boundaries, and assess their combined effect on grain boundary sliding. The extent and effectiveness of coherent and semi-coherent precipitates to induce grain boundary perturbations will be assessed in two commercial superalloys. In addition, bi-crystal samples possessing controlled misorientations will be fabricated to systematically quantify the effect of grain boundary misorientations on the formation and growth of perturbations. Finally, nano-scale assessments of the compositional and mechanical attributes along the serrated boundaries will be combined with 3D microstructural characterization and in situ strain mapping to quantify the effectiveness of the serrations on grain boundary sliding. These studies will contribute to the development of innovative thermal-mechanical processes that can be effectively used to tailor or engineer the mechanical properties of the alloy though the presence of meso-scale features.