Dislocation Structure Analyses by Surface Observation using ECCI Method and Its Application to Fatigue Damage Estimation

ECCI法表面观察位错结构分析及其在疲劳损伤估计中的应用

• 批准号: 15360372
• 负责人: HASHIMOTO Satoshi
• 金额: $ 8.58万
• 依托单位: Osaka City University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15360372/
• 关键词: Fatigue; ECCI Method; Dislocation Structure; Persistent Slip Band; Non-destructive Observation; ECCI; 疲労き裂伝ぱ

Electron channeling contrast imaging (ECCI) method has some advantages for dislocation structure observation in comparison with conventional transmission electron microscopy : we can observe the dislocations lying under free surface nondestructively at considerably wide area. With a help of such characteristics of the ECCI method, the dislocation structures formed at all the grains contained in gage part of fatigued strip specimens of stainless steel and copper We could obtained the vein structure and ladder-like PSB structure, which have been observed using TEM. It was found that the formations of the PSBs were preferred to the grains having large diameters, whereas Schmid factor seemed to have no relation to the PSB formation. It was also recognized that annealing twins played an important role on the PSB formation : the number of the PSBs generated both along and across the annealing twin boundaries were larger than that predicted statistically.Dislocation structures near fatigue cracks of polycrystalline copper specimens were also observed using the ECCI technique. Prior to the ECCI observations, optical microscope observations were conducted to classify the fatigue crack morphologies into several kinds. It was found that the dislocation structures were correlated with the slip morphologies observed using the optical microscope. The cell structure almost corresponded to the severely deformed plastic zone where the individual slip bands could not be identified. The labyrinth dislocation structure was detected at the double-slip region. Ladder-like dislocation structure was detected ahead of the Stage I type fatigue crack. Hence, it can be said that the persistent slip band (PSB) was a favorable crack path. However, the microscopic route of the crack growth was not along the PSB but along the cell structure which was developed locally in the vicinity of the crack tip.

与传统的透射电子显微镜相比，电子通道对比度成像（ECCI）方法在脱位结构观察方面具有一些优势：我们可以观察到位于自由表面不损坏下的位置在相当广泛的区域。借助ECCI方法的这种特征，在疲劳的不锈钢和铜的疲劳条样本中包含的所有谷物中形成的脱位结构，我们可以获得使用静脉结构和梯子样PSB结构，这些结构已被观察到使用tem。发现PSB的地层比具有较大直径的谷物优选，而Schmid因子似乎与PSB形成没有关系。还认识到退火双胞胎在PSB形成中起着重要的作用：沿着和跨退火双胞胎产生的PSB数量大于统计学上预测的。 ECCI技术。在进行ECCI观察之前，进行了光学显微镜观察，以将疲劳裂纹形态分为几种。发现位错结构与使用光学显微镜观察到的滑移形态相关。细胞结构几乎对应于无法识别单个滑动带的严重变形的塑料区域。在双滑动区域检测到迷宫位错结构。在阶段I型疲劳裂纹之前，检测到梯子状的脱位结构。因此，可以说持续的滑带（PSB）是一个有利的裂纹路径。但是，裂纹生长的微观途径不是沿PSB，而是沿着裂纹尖端附近局部开发的细胞结构。

项目成果

A.Vinogradov, S.Hashimoto, V.I.Kopylov: "Enhanced Strength and Fatigue Life of Ultra-Fine Grain Fe-36Ni Invar Alloy"Materials Science & Engineering. A355. 277-285 (2003)

A.Vinogradov、S.Hashimoto、V.I.Kopylov：“增强超细晶粒 Fe-36Ni 因瓦合金的强度和疲劳寿命”材料科学

A.Vinogradov, S.Hashimoto: "Fatigue Properties of Severely Deformed Materials"Metals. N1. 51-62 (2004)

A.Vinogradov、S.Hashimoto：“严重变形材料的疲劳特性”金属。

Strange Patterns in Crystals and Damages of Metallic Materials.

晶体中的奇怪图案和金属材料的损坏。

• 发表时间: 2004
• 期刊: Proc. 12th Osaka City University International Symposium
• 作者: Y.Kaneko;S.Hashimoto
• 通讯作者: S.Hashimoto

ECCI法による銅単結晶の疲労転位構造の観察

ECCI法观察铜单晶疲劳位错结构

• 发表时间: 2002
• 期刊: 日本金属学会誌 66
• 作者: 兼子佳久;橋本敏
• 通讯作者: 橋本敏

Strange Patterns in Crystals and Damages of Metallic Materials

晶体中的奇怪图案和金属材料的损坏

• 发表时间: 2004
• 期刊: The proceedings of 12th OCU International Symposium
• 作者: Y.Kaneko;S.Hashimoto
• 通讯作者: S.Hashimoto