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Full-field Strain Measurements for Microstructurally Small Fatigue Crack Propagation Using Digital Image Correlation Method
Published on: January 16, 2019
Velocity-dependent fatigue crack paths in nanograined Pt films
R A Meirom1, T Clark, R Polcawich
1Department of Materials Science and Engineering and The Materials Research Institute, The Pennsylvania State University, 202B Steidle Building, University Park, Pennsylvania 16802, USA.
Physical Review Letters
|September 4, 2008
Summary
Crack growth in nanograined platinum films is driven by dislocation slip, not just grain boundary damage. These findings challenge generalized models for nanograined metals.
Area of Science:
- Materials Science
- Mechanical Engineering
- Nanotechnology
Background:
- Previous studies suggested mechanical damage in nanograined films accumulates at grain boundaries regardless of crack velocity or loading conditions.
- Existing models for crack growth in nanostructured materials may not be universally applicable across different metallic systems.
Purpose of the Study:
- To investigate the fundamental mechanisms of crack advance in nanograined platinum (Pt) films.
- To determine the influence of crack growth rate and loading mode on crack propagation behavior in Pt.
- To compare crack growth mechanisms in Pt with those observed in other nanograined metals, such as nickel (Ni).
Main Methods:
- In-situ mechanical testing of nanograined Pt films under controlled loading conditions.
- High-resolution microscopy techniques to observe crack path evolution and deformation mechanisms.
- Analysis of crack growth rates and correlation with observed microstructural changes.
Main Results:
- Crack advance in nanograined Pt films is governed by a dislocation-slip mechanism.
- The operative mechanism is dependent on the crack growth rate and the applied mode of loading.
- Crack paths initiated at grain boundaries but transitioned to a transgranular mode before failure.
Conclusions:
- The dislocation-slip mechanism observed in Pt contradicts the assumption of purely grain boundary-dominated damage accumulation.
- Crack growth mechanisms in nanograined Pt are distinct from those previously reported for nanograined Ni.
- Generalized models for crack growth in nanostructured metals require system-specific validation.
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