A Fundamental Investigation of Threshold Stress in Dispersion-Strengthened Materials

该项目旨在通过整合位错解离和正爬升概念，开发弥散强化铝合金（Al-Sc-Mg-Zr-SiC）高温蠕变的定量模型。一个创新的蠕变试样的几何形状将阐明的门槛应力机制和蠕变变形过程中的微观结构演变。了解颗粒尺寸和分布对门槛应力和蠕变动力学的影响，可以通过微观结构设计来开发高温铝合金。基于位错基本参数的定量模型的发展是迫切需要的。本研究的主要目的是：（1）研究简单合金系统（Al-Sc，Al-Zr等）的变形特性，以系统地了解其力学行为;（2）进行原位透射电子显微镜（TEM）应变实验，以确定位错在滑移和攀移运动中的速度;（3）利用实验确定的参数建立定量模型。这项工作涉及到大学-工业-政府实验室-国家用户设施的组合。%这项研究对弥散强化的基本机制有了新的认识，超越了现有技术水平。研究结果旨在开发各种技术中高温应用的抗蠕变材料。*

The project is aimed at developing a quantitative model for high temperature creep of dispersion strengthened aluminum alloys (Al-Sc-Mg-Zr-SiC) by integrating the dislocation dissociation and positive climb concepts. An innovative creep specimen geometry will elucidate the threshold stress mechanisms and the microstructural evolution during creep deformation. An understanding of the influence of particle size and distribution on threshold stress and creep kinetics can lead to development of high temperature aluminum alloys by microstructural design. The development of quantitative model based on fundamental dislocation parameters is in dire need. Major goals of the study are: (1) to investigate the deformation characteristics in simpler alloy systems (Al-Sc, Al-Zr, etc) for a systematic understanding of their mechanical behavior; (2) to perform in-situ transmission electron microscope (TEM) straining experiments for determining dislocation velocities during their glide and climb movements; and (3) to develop quantitative model using the experimentally determined parameters. The work involves a combination of university-industry-government laboratory-national user facility.%%%This research develops new understanding of the fundamental mechanisms of dispersion strengthening beyond the current state of the art. The results are aimed at the development of creep-resistant materials for high-temperature applications in various technologies.***