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Study on Effect of Environment on Strength and Life of Micromaterials in Fatigue

环境对微材料疲劳强度和寿命的影响研究

基本信息

批准号：
12650087
负责人：
NAKAI Yoshikazu
金额：
$ 2.43万
依托单位：
Kobe University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650087/
关键词：
Micromaterial Fatigue Environment Thin Film Natotechnology AFM Fractography Crack initiation 交流電位差法

项目摘要

Fatigue test systems were developed to study the fatigue mechanisms in metallic micro-materials. This system has an electro-dynamic actuator or an audio speaker as a loading device. Fatigue tests were conducted with commercially pure iron, or pure aluminum either in air or in sodium chloride solution, and fatigue life and fracture morphologies were observed. In either materials, and in either environment, scattering of fatigue lives were very large compared with conventional size specimens, and they were larger for smaller specimens. The effect of environment was not observed for short life region, and they were appreciable in long life region. Two types of fracture morphologies were observed.For monitoring fatigue damage of micro materials, an A.C. potential method was developed. In iron, the value of potential were almost constant during fatigue process except for just before final fracture, while they continuously increased up to final unstable fracture in aluminum.Fatigue test system for pure aluminum thin film was also developed in the present study. Two types of fatigue test specimen were made by electrolytic polishing and mechanical machining from aluminum foil whose thickness was 12 urn. The strength of specimen made by mechanical machining was larger than that of specimen made by electrolytic polishing. The variation in fatigue life of specimen made by electrolytic polishing was large compared with specimen made by mechanical machining. Both before and after the fatigue tests, slip-bands were observed by using optical microscopy and AFM. The spacing of slip bands in the thin film was found to be much larger than that of the bulk specimen.

疲劳试验系统是为研究金属微材料的疲劳机理而开发的。该系统具有电动致动器或音频扬声器作为加载装置。对工业纯铁和纯铝分别在空气和氯化钠溶液中进行了疲劳试验，观察了疲劳寿命和断口形貌。在任一种材料中，在任一种环境中，疲劳寿命的分散性与常规尺寸试样相比非常大，并且对于较小的试样，它们更大。在短寿命区未观察到环境因素的影响，而在长寿命区则有明显的环境因素影响。为了监测微材料的疲劳损伤，提出了一种新的疲劳损伤监测方法--交流阻抗法。电位法。铁在疲劳过程中，除最终断裂前外，电位值几乎恒定，而铝在疲劳过程中，电位值不断增加，直至最终不稳定断裂。本研究还开发了纯铝薄膜疲劳测试系统。采用电解抛光和机械加工两种方法对厚度为12 μ m的铝箔进行疲劳试验。机械加工试样的强度大于电解抛光试样的强度。与机械加工试样相比，电解抛光试样的疲劳寿命变化较大。在疲劳试验前后，通过光学显微镜和原子力显微镜观察到滑移带。薄膜中滑移带的间距远大于块状试样。