Strength of Low-dimensional Materials in Detrimental Environment

2015 Fiscal Year Final Research Report

• Project/Area Number: 25630014
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Materials/Mechanics of materials
• Research Institution: Kobe University
• Principal Investigator: Nakai Yoshikazu 神戸大学, 工学(系)研究科(研究院), 教授 (90155656)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 薄膜 / ナノ結晶 / 環境強度 / 疲労

Outline of Final Research Achievements

In the present project, the effect of grain size on the mechanical strength of electrodeposited nickel thin film was studied. By EBSD analysis, grain boundaries in the material were found to be large twist angle boundaries. In the measurement of grain size by EBSD, the step size should be less than tenth part of grain size.
Either relation between 0.2% proof strength, tensile strength, or fatigue limit and grain size of electro deposited nickel thin film is different from that of bulk nickel plate with conventional grain size, and this difference is large for smaller grain size thin film. This is considered to come from the fact that grain boundary has area with volume, not a face with no thickness. For the consideration of Hall-Petch relationship, mean free path of dislocation should be considered, that is actual grain size minus grain boundary area size.

Free Research Field

材料力学