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

晶体材料暴露在中到高的同质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。这可能会导致关键部件的灾难性破裂。该学院早期职业发展(CAEREAR)奖支持实现新型微机械蠕变测试技术的基础研究，并进一步加深了对先进材料(如多主元素合金)蠕变变形机制的基本了解。这项研究有助于实现优异的抗蠕变材料，使美国社会的关键部门，如能源、交通、航空、推进和太空探索受益，对人类福祉、经济和环境可持续发展产生深远的有利影响。该奖项还通过支持各种外展活动和为代表不足的学生创造新的从事科学研究的机会，将研究和教育结合在一起。蠕变强度可以说是高温下运行的结构合金最重要的机械性能。标准的蠕变试验既昂贵又耗时，而且需要大量样品。然而，当开发新材料时，通常需要能够测试小样本的高通量技术。这在多主元素合金的情况下尤其重要，因为需要探索其广阔的组成空间。纳米压痕是一种适合于小样本的高通量测试，它已经成为筛选这些材料的蠕变、疲劳和断裂性能的主要技术。这一职业奖项资助了试图推动纳米压痕作为一种快速筛选蠕变性能的高通量技术的研究。这项研究结合了多尺度建模、在扫描电子显微镜内进行的高温微观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。这项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。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.