【摘要】 扫描电子显微镜(Scanning Electron Microscope,SEM)是科学研究中的重要观察设备,在过去的几十年,人们一直致力于借助SEM从微尺度层面对热端部件所涉及的关键合金材料和构件的力学性能进行原位高温测量和表征.这一研究对认识合金材料微结构损伤演化物理机制、理解其高温失效和破坏机理、提取力学表征参数和提高寿命预测方法的准确性等有重要的理论意义和工程价值.本文首先介绍了SEM环境下原位高温力学实验的困难和挑战,综述了近年来国内外在SEM环境下发展的原位高温变形测量技术,涉及扫描环境下的原位高温测量设备、高温成像技术、高温变形测量方法等.在此基础上,介绍了作者近年来对镍基合金材料在高温变形、蠕变、以及疲劳与断裂方面的研究工作.最后,论文对该领域进一步的研究工作进行了展望.更多还原

【Abstract】 Scanning Electron Microscope(SEM) is an important observational device in scientific research. Over the past decades,scientists have been working on the high temperature deformation measurement and characterization of the critical alloy materials and components in hot sections by in situ observations with SEM. The in situ observations have both important theoretical and high engineering significance in understanding the mechanisms of the microstructure damage evolution of the alloys, understanding their high temperature failure mechanisms, extracting mechanical parameters and improving the accuracy of life prediction methods. However, in situ high temperature measurements in a SEM environment pose major challenges in high efficiency heat source design, establishment of stable high contrast microscopic images, and quantitative measurement of the deformation fields in high temperature environment. New methods and approaches must be therefore developed for measurement of mechanical properties in such harsh environment. In the study presented here,the major difficulties and challenges associated with high temperature experiments implemented in situ SEM are introduced firstly, especially the imaging failure at high temperature. The developments of high temperature in situ SEM technology in recent years are then reviewed, including high temperature in situ test instruments, high temperature imaging technology, and high temperature deformation measurement methods. On this basis, some new research results achieved by our group in the field of creep, fatigue and fracture of nickel based alloy materials at high temperature are introduced, such as the fatigue small and long crack growth behaviors at different temperature as well as in different crystallographic orientations. Nickel based alloy is the critical material for gas turbine and aero-engine due to their excellent creep, fatigue and corrosion resistance at high temperature. Finally, some conclusions of current development in this research field are presented, meanwhile works that need to be further extended in the future are also pointed out.更多还原