Effect of Alloying and Thermo-Mechanical Processing on the Deformation of Hexagonal Close-Packed Alloys

六方密排(HCP)金属，如钛、镁和锆合金，通常用于能源、交通和生物医学技术中的结构应用，彻底了解它们的机械完整性是它们在使用中可持续发展的关键。将合金的细微结构与其在使用温度下的变形抗力相关联，将有助于对控制合金性能的机制有新的理解，并可为高强度、耐用部件的设计提供指导。该奖项支持基础科学研究，以了解锆基合金中合金成分和结构对机械性能的作用。这项研究将实验测试与计算建模相结合，基于对这些合金的成分、结构以及这些与性能和使用性能之间的关系的新知识来预测它们的行为。这项工作将带来新的科学理解，可应用于许多重要的合金系统，并将为参与研究的学生提供极好的教育机会。特别强调通过参与K-12推广计划来扩大对科学研究的参与，这将使高中生以及本科生和研究生有机会参与到研究中来。这项研究讨论了热机械处理和合金化对锆合金蠕变各向异性的影响，重点是Nb的添加和热处理。添加Nb作为合金元素已被证明具有更好的性能和耐久性，本研究旨在了解控制这一行为的现象。这些合金的蠕变各向异性将在不同的区域，如幂定律蠕变和粘性蠕变，以及在高应力下的幂定律破碎区进行研究。相应的变形微观结构将被表征，以彻底了解潜在的蠕变机制和双轴蠕变各向异性。从本研究中获得的知识可用于理解其他HCP合金在高温下的塑性变形机制，并可为预测使用中的尺寸变化提供可靠的工具。这项研究包括实验和建模两种方法，研究结果将被整合到课堂教学中，以培养下一代工程师。

Hexagonal close-packed (HCP) metals such as titanium, magnesium and zirconium alloys are commonly used for structural applications in energy, transportation and biomedical technologies, and a thorough understanding of their mechanical integrity is central for their in-service sustainability. Correlating fine-scale structure of the alloys with their resistance to deformation at service temperatures will allow for new understanding of the mechanisms that control alloy performance, and can provide guidance for design of high-strength, durable components. This award supports fundamental scientific research to understand the role of alloy composition and structure on mechanical properties in zirconium-based alloys. The research brings experimental testing together with computational modeling to predict the behavior of these alloys based on the new knowledge of their composition, structure, and how these relate to properties and performance in service. The work will lead to new scientific understanding that can be applied to a number of important alloy systems, and will provide excellent educational opportunities for students participating in the research. Particular emphasis is placed on broadening participation in scientific research through engagement in K-12 outreach programs which will allow high school students the opportunity to participate in the research, along with undergraduate and graduate students.This research addresses the influence of thermo-mechanical treatment and alloying on creep anisotropy of zirconium alloys with emphasis on niobium addition and heat treatment. The addition of niobium as an alloying element has been shown to lend better performance and durability, and this research aims to understand the phenomena controlling this behavior. Creep anisotropies in these alloys will be investigated in the different regimes such as power-law and viscous creep, as well as at high stresses in the power-law breakdown region. Corresponding deformation microstructures will be characterized for a thorough understanding of the underlying creep mechanisms and the biaxial creep anisotropy. The knowledge derived from this research can be applied to understand the plastic deformation mechanisms of other HCP alloys at high temperatures, and can provide robust tools to predict dimensional changes in service. This research involves both experimental and modeling approaches, and the findings will be integrated into classroom teaching for training the next generation of Engineers.