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.

在高温下，非技术摘要基的超合金在服务期间具有高强度和耐腐蚀性。由于这些重要的特征，它们已被广泛用于高性能燃烧发动机，例如燃气轮机，热和核电站。为了在高温下实现出色的机械性能，降水硬化已被广泛用于增强超合金。该程序将着重于理解和控制相对于合金矩阵（即变体选择）在基于镍的超合金中的变体选择的方向。还将研究在应力辅助衰老过程中选定的变体的调制机械性能。从该计划中获得的见解将提高人们对加强机制的理解，并为相关行业提供新的指导，以改善合金的机械性能。该计划不仅将促进科学的进步，而且还将促进国家繁荣，以及由于对航空航天，热和核工业的贡献，高温燃气轮机组件的性能提高可以显着提高飞机发动机和发电厂的效率。此外，该奖项将鼓励妇女和代表性不足的工程领域，并通过创造性的学习模块和讲习班和其他大学课程来增强社区和外展活动。技术总结金属材料的机械性能与其内部微观结构密切相关。特别是，沉淀颗粒在内的形态，包括其形状，方向和分布可以批判性地确定相分开合金的特性。变体选择是指相对于合金基质的特定沉淀方向的形成。以Ni基合金为例，将研究成核和早期生长阶段的相干纳米尺寸沉淀的变体选择的形成机理，并将研究相应的调制机械性能。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处理参数来控制变体选择的启动； - 如何通过选择所需滑动系统朝着优先方向的变体来实现各向异性加强？技术工作的特征是（1）阐明材料参数在热力学处理过程中的成核和早期生长阶段在变化选择中的影响，（2）构成单晶样品，以及（3）研究在张力和蠕变变形过程中的各向异性增强。由于其广泛的应用，该程序将重点介绍基于镍的合金。但是，阐明的基本机制适用于大多数包含连贯沉淀物的合金，例如新型的难治性合金。该奖项反映了NSF的法定任务，并被认为值得通过基金会的知识分子优点和更广泛的影响标准通过评估来进行评估。

项目成果

First-Principles Calculation of Stacking Fault Energies in Ni2(Cr, Mo)

• DOI: 10.1016/j.mtcomm.2023.105447
• 发表时间: 2023-01
• 期刊: Materials Today Communications
• 影响因子: 3.8
• 作者: Jie Song;Yao Fu