Creation of high-fatigue-resistant thin-film structures by controlling nano-crystalline microstructure and fatigue-life prediction

2014 Fiscal Year Final Research Report

• Project/Area Number: 24360049
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Materials/Mechanics of materials
• Research Institution: Meijo University
• Principal Investigator: TANAKA Keisuke 名城大学, 理工学部, 教授 (80026244)
• Co-Investigator(Kenkyū-buntansha): KIMACHI Hirohisa 名城大学, 理工学部, 教授 (30324453) ; FUJIYAMA Kazunari 名城大学, 理工学部, 教授 (20410772) ; FUJII Tomoyuki 静岡大学, 工学(系)研究科, 助教 (30377840)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 機械材料・材料力学 / 疲労 / 破壊力学 / 薄膜 / ニッケルナノ結晶 / 電着法 / X線プロフィル解析

Outline of Final Research Achievements

Multilayer thin films were produced to have a core layer of ultrafine crystals sandwiched by nano-crystalline surface layers, where the surface layers improve the resistance to crack nucleation resistance and the core layer blocks crack propagation. The fatigue strength was improved by nano-crystalline surface layers, unless no inter-layer separation did not take place. Intermediate layers will be required to achieve high resistance against fatigue. Various notched specimens made of nanocrystals were produced by UV-LIGA process. The reduction of fatigue strength due to notches was predicted by the point stress model. Nano-crystallization can improve the fatigue strength of notched samples, while, at the same time, increases the notch sensitivity. Nano-crystalline samples are very much sensitive to micro defects. Bulk samples with millimeter thickness produced by long-period electrodeposition will be useful for further detailed investigations of fatigue mechanisms of nano-crystals.

Free Research Field

工学