Establishment of SPM Nanofractographic Techique and Its Application to Investigation of Damage and Fracture Mechanisms of Materials

该研究项目的重点是应用扫描隧道显微镜(STM)和原子力显微镜(AFM)，即所谓的扫描探针显微镜(SPM)，来研究材料的断裂机制和强度评估。为了建立标准的方法来观察材料的断口和受损表面，或纳米纤维摄影术，进行了循环法测试。研究小组由来自五所大学的六个研究所、一个国家研究所和两个来自私营公司的研究所组成。为了进行循环试验，制备了微机械加工的标准SPM样品，每个研究所都使用SPM测量了样品的表面。用于循环测试的SPM是在空气和/或超高真空中工作的STM、接触式AFM和敲击模式AFM。SPM是由日本和美国的几家领先的SPM开发商制造的。特别注意了SPM针尖的形状，因此，在观察前后拍摄了超高分辨率的场发射型扫描电子显微镜(SEM)图像。研究小组调查了针尖形状对SPM定量三维形状的影响，研究所之间测量的垂直和水平长度的差异，以及SPM开发人员之间的差异：小组讨论了影响SPM图像的因素。小组还讨论了应用扫描探针显微镜分析溶液中局部腐蚀损伤的原位纳米观察，如点蚀、晶间腐蚀和应力腐蚀，以及各种材料在空气中疲劳损伤的萌生和扩展：讨论了局部腐蚀和疲劳的纳米损伤机理。研究还扩展到原子力显微镜在纳米硬度测量中的应用，以及非米级SPM针尖半径测量方法的发展。

The research project focused on the application of scanning tunneling microscopy (STM), and atomic force microscopy (AFM), which are so called scanning probe microscopy (SPM), to investigate fracture mechanisms and strength evaluation of materials. In order to establish standard methods for observing fracture and damaged surfaces of materials, or nanofractography, round robin tests were conducted. The research group consisted of six institutes from five universities, one national institute, and two institutes from private companies. In order to perform round robin tests, standard SPM samples manufactured by micromachining were prepared and each institute measured the sample surface by using SPMs. The SPMs used for the round robin tests were STMs, contact mode AFMs, and tapping mode AFMs operating in air and/or ultra-high vacuum. The SPMs were manufactured by several leading SPM developers in Japan and the United States. Special attention was paid to shape of SPM tip, and therefore, the ultra-high resolution field emission type scanning electron microscope (SEM) images were taken before and after the observation. The research group investigated influences of tip shape on quantitative three dimensional shapes by SPM,the difference of vertical and horizontal length measured among the institutes, and among the SPM developers : the group discussed the affecting factors on SPM images. The group also discussed the application of SPM to analyze in situ nanoscopic observation of localized corrosion damage in a solution such as pitting corrosion, intergranular corrosion, and stress corrosion, as well as fatigue damage initiation and propagation of various kinds of materials in air : nanoscopic damage mechanisms of localized corrosion and fatigue were discussed. The research was also extended to the application of an atomic force microscope to measure nanoscopic hardness, and the development of measuring method of SPM tip radius in a nonmeter order.