CAREER: Enabling High-throughput Creep Testing of Advanced Materials through in-situ Micromechanics and Mesoscale Modeling

结晶材料暴露于中等至较高的同源温度下会导致渐进变形，称为蠕变，这通常决定了材料使用寿命的结束。它可能导致关键部件的灾难性破裂。这个教师早期职业发展（CAREER）奖支持基础研究，使新的微机械蠕变测试技术，它进一步在先进材料，如多主元素合金蠕变变形机制的基本理解。这项研究有助于实现上级抗蠕变材料，这有利于美国社会的关键部门，如能源，运输，航空，推进和太空探索，对人类福祉，经济和环境可持续性产生深远的有益影响。该奖项还通过支持各种外展活动，为代表性不足的学生创造新的机会，使研究和教育融为一体。蠕变强度可以说是高温下工作的结构合金最重要的机械性能。标准蠕变测试既昂贵又耗时，而且需要大量样品。然而，在开发新材料时，通常需要能够测试小样品的高通量技术。这在多主元素合金的情况下特别重要，因为需要探索其广阔的成分空间。纳米压痕是一种高通量的测试，适合于小样本，它已成为主要的技术，不仅筛选蠕变，但也疲劳，和这些材料的断裂性能。该CAREER奖资助的研究，试图推进纳米压痕作为一种高通量的技术，快速筛选蠕变性能。该研究结合了多尺度建模，在扫描电子显微镜内高温下进行的微机械测试和机器学习，以建立纳米压痕和单轴蠕变性能之间的关系。该研究还拓宽了对体心立方耐火多主元素合金高温变形机制的基本理解。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Crystalline materials exposed to medium to high homologous temperatures can result in progressive deformation, called creep, which often determines the end of a material's service life. It may result in the catastrophic rupture of critical components. This Faculty Early Career Development (CAREER) award supports fundamental research enabling novel micromechanical creep testing techniques, and it furthers the fundamental understanding of creep deformation mechanisms in advanced materials such as multi-principal element alloys. This research contributes to enabling superior creep-resistant materials, which benefit critical sectors of the U.S. society such as energy, transportation, aviation, propulsion, and space exploration, with far-reaching beneficial consequences on human well-being, economics, and environmental sustainability. This award also integrates research and education by supporting various outreach activities and creating new opportunities for underrepresented students to engage in scientific research.Creep strength is arguably the most important mechanical property for structural alloys operating at high temperatures. Standard creep tests are expensive and time-consuming, and they require bulk samples. When developing new materials, however, high-throughput techniques that are capable to test small samples are typically required. This is particularly important in the case of multi-principal element alloys, due to needs to explore their vast compositional space. Nanoindentation is a high-throughput test suited for small samples, and it has been the primary technique to screen not only creep, but also fatigue, and fracture properties of these materials. This CAREER award funds research that attempts to advance nanoindentation as a high-throughput technique for fast screening of creep properties. The research combines multiscale modeling, micromechanical tests carried out at high temperature within a scanning electron microscope, and machine learning to establish a relation between nanoindentation and uniaxial creep properties. The research also broadens the fundamental understanding of high-temperature deformation mechanisms in body-centered cubic refractory multi-principal element alloys.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.