CAREER: High temperature strengthening via solute-enhanced stacking faults in structural alloys

第一部分：非技术性SUMMARY高温合金是一类重要的金属高温结构材料，它由镍和其他金属的复杂混合物组成，用于交通、国防和能源发电的燃气轮机发动机。这些高温合金的高温强度最近被观察到是由复杂的原子级过程控制的，由于高温合金化学的性质，这些过程还没有被很好地理解。这一职业奖项所带来的基础研究将揭示管理模型金属材料高温强度的基本原子级工艺。将开发计算方法和理论来提供对这些原子化过程的预测能力，先进的表征方法将验证这些预测。这项研究将使更高强度的高温合金成为可能，这可能会提高涡轮发动机的效率和功率，同时减少污染排放。从该计划中获得的基本见解将适用于许多行业使用的广泛陶瓷、金属和半导体材料，并可能实现新技术。作为该计划的一部分，外展工作将包括对当地高中生的指导以及与材料工程相关的学习模块的开发和传播。第2部分：技术总结尽管有晶体材料中溶质偏析到堆叠缺陷的知识，但这种现象尚未被用作大多数结构合金材料的强化机制。最近的文献和PI的工作表明，镍基高温合金中复杂的位错相互作用和微小的成分差异控制着层错处的溶质偏析行为，这种偏析行为可以用来提高镍基高温合金的高温蠕变强度。然而，由于先进高温合金中复杂的成分，控制溶质偏析的驱动力还没有被很好地理解。该职业奖支持的基础研究试图揭示简单合金成分中溶质偏析到层错的基本热力学驱动力。这项工作的目标是预测和量化镍基高温合金成分高温变形过程中层错处的溶质偏析，以便利用铃木偏析进一步加强这一重要类别的结构材料。该奖项反映了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。

PART 1: NON-TECHNICAL SUMMARYSuperalloys, which are comprised of nickel with complex mixtures of other metals, are an important class of metallic high temperature structural materials used in gas turbine engines for transportation, defense, and energy generation applications. The high temperature strength of these superalloys has recently been observed to be controlled by intricate atomistic-level processes that are not well understood due to the nature of the superalloy chemistry. The basic research enabled by this CAREER award will uncover the fundamental, atomistic-level processes governing high temperature strength in model metallic materials. Computational methods and theory will be developed to provide predictive capability of these atomistic processes, and advanced characterization methods will verify those predictions. This research will enable higher strength superalloys, which could increase turbine engine efficiencies and power while decreasing pollution emissions. The fundamental insights garnered from this program will be applicable to a wide range of ceramic, metallic, and semiconductor materials used across numerous industries and could enable new technologies. Outreach efforts as part of this program will include mentoring of local High School students and materials engineering-related learning module development and dissemination.PART 2: TECHNICAL SUMMARYDespite knowledge of solute segregation to stacking faults in crystalline materials, this phenomenon has yet to be utilized as a strengthening mechanism in most structural alloy materials. Recent works in the literature and by the PI have suggested that complex dislocation interactions and minute composition differences in Ni-based superalloys control the solute segregation behavior at stacking faults, and that this segregation behavior can be utilized to increase the high temperature creep strength in Ni-based superalloys. However, due to the complex compositions in advanced superalloys the driving forces governing solute segregation are not well understood. The basic research supported by this CAREER award seeks to uncover the fundamental thermodynamic driving forces for solute segregation to stacking faults in simple alloy compositions. The objective of this work is then to predict and quantify solute segregation at stacking faults during high temperature deformation in Ni-based superalloy compositions in order to utilize Suzuki segregation to further strengthen this important class of structural materials.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.