Fundamental Mechanisms in Stress-Aided Variant Selection of Nanoscale Precipitation

纳米级沉淀的应力辅助变体选择的基本机制

• 批准号: 2104941
• 负责人: Yao Fu
• 金额: $ 42.52万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-10-01 至 2024-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2104941&HistoricalAwards=false
• 关键词: Fundamental; Mechanisms; Stress; Aided; Variant

NON-TECHNICAL SUMMARYNickel-based superalloys possess combined high strength and corrosion resistance during service at elevated temperatures. Due to these important characteristics, they have been widely used in high-performance combustion engines, such as gas turbines, thermal and nuclear power plants. In order to achieve superior mechanical properties at high temperatures, precipitation hardening has been widely employed to strengthen superalloys. This program will focus on understanding and controlling the orientation of precipitates with respect to the alloy matrix, i.e., variant selection, in a nickel-based superalloy. The modulated mechanical properties by selected variant during the stress-assisted aging process will be also investigated. Insights gained from the program will advance the understanding of strengthening mechanisms as well as provide related industries with new guidance to improve the mechanical properties of alloys. The program will not only promote the progress of science but will also advance the national prosperity, and welfare due to the contribution to the aerospace, thermal and nuclear industry, where the enhanced performance of high temperature gas turbine components can significantly increase the efficiency of aircraft engines and power plants. In addition, this award will encourage women and underrepresented groups in engineering and enhance community and outreach activities through creative learning modules and workshops among other university programs. TECHNICAL SUMMARYThe mechanical properties of metallic materials are closely related to their internal microstructure. In particular, the morphology of precipitate particles including their shape, orientation and distribution can critically determine the properties of phase-separated alloys. Variant selection refers to the formation of a particular precipitate orientation with respect to the alloy matrix. Using Ni-based alloys as an example, the formation mechanisms of variant selection of coherent nanometer-sized precipitates at the nucleation and early growth stage, and the corresponding modulated mechanical properties will be investigated. We aim to answer the following fundamental questions: -How can one control the initiation of variant selection through varying important materials and processing parameters; -How to achieve anisotropic strengthening by selecting variants of which the desirable slip systems are in the preferential direction? The technical effort is featured by a closely integrated computational and experimental approach to (1) clarify the effect of materials parameters in variant selection at the nucleation and early growth stage during thermomechanical treatment, (2) fabricate single-crystalline samples, and (3) investigate the anisotropic strengthening during tensile and creep deformation. This program will be focused on nickel-based alloys due to its wide-spread applications. However, the fundamental mechanism elucidated is applicable to most alloys that contain coherent precipitates, e.g., novel refractory 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.

非技术概要镍基高温合金在高温下使用时兼具高强度和耐腐蚀性。由于这些重要特性，它们已广泛应用于高性能内燃机，例如燃气轮机、火力发电厂和核电厂。为了在高温下获得优异的机械性能，沉淀硬化已被广泛用于强化高温合金。该计划将重点了解和控制镍基高温合金中析出物相对于合金基体的方向，即变体选择。还将研究应力辅助时效过程中选定变体所调节的机械性能。从该计划中获得的见解将增进对强化机制的理解，并为相关行业提供提高合金机械性能的新指导。该计划不仅将促进科学进步，还将因对航空航天、热力和核工业的贡献而促进国家繁荣和福利，其中高温燃气轮机部件的增强性能可以显着提高飞机的效率发动机和发电厂。此外，该奖项还将鼓励工程领域的女性和代表性不足的群体，并通过其他大学项目中的创意学习模块和研讨会加强社区和外展活动。技术概要金属材料的力学性能与其内部微观结构密切相关。特别是，沉淀物颗粒的形态，包括其形状、取向和分布，可以关键地决定相分离合金的性能。变体选择是指相对于合金基体形成特定的析出物取向。以镍基合金为例，研究成核和早期生长阶段相干纳米尺寸析出物的变体选择的形成机制以及相应的力学性能调节。我们的目标是回答以下基本问题： -如何通过改变重要材料和加工参数来控制变体选择的启动； -如何通过选择所需滑移系统处于优先方向的变体来实现各向异性强化？该技术工作的特点是采用紧密结合的计算和实验方法，以（1）阐明材料参数对热机械处理过程中成核和早期生长阶段变体选择的影响，（2）制造单晶样品，以及（3）研究拉伸和蠕变变形过程中的各向异性强化。由于镍基合金的广泛应用，该计划将重点关注其。然而，阐明的基本机制适用于大多数含有相干沉淀物的合金，例如新型耐火合金。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Variant selection of intragranular Ni2(Mo,Cr) precipitates (γ′) in the Ni-Mo-Cr-W alloy

Ni-Mo-Cr-W 合金中晶内 Ni2(Mo,Cr) 析出物 (γ-) 的变体选择

• DOI: 10.1016/j.actamat.2018.11.063
• 发表时间: 2019-02-15
• 期刊: Acta Materialia
• 影响因子: 9.4
• 作者: Jie Song;R. Field;A. Clarke;Yao Fu;M. Kaufman
• 通讯作者: M. Kaufman

First-principles calculation of stacking fault energies in Ni2(Cr, Mo)

Ni2(Cr, Mo)堆垛层错能的第一性原理计算

• DOI: 10.1016/j.mtcomm.2023.105447
• 发表时间: 2023-03
• 期刊: Materials Today Communications
• 影响因子: 3.8
• 作者: Song, Jie;Fu, Yao
• 通讯作者: Fu, Yao