In Situ High-Cycle Fatigue Reveals Importance of Grain Boundary Structure in Nanocrystalline Cu-Zr

Nanocrystalline metals typically have high fatigue strengths but low resistance to crack propagation. Amorphous intergranular films are disordered grain boundary complexions that have been shown to delay crack nucleation and slow crack propagation during monotonic loading by diffusing grain boundary...

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Bibliographic Details
Published in:JOM (1989) 2019-04, Vol.71 (4), p.1221-1232
Main Authors: Schuler, Jennifer D., Barr, Christopher M., Heckman, Nathan M., Copeland, Guild, Boyce, Brad L., Hattar, Khalid, Rupert, Timothy J.
Format: Article
Language:English
Subjects:
Chemistry/Food Science
Coarsening
Copper
Crack initiation
Crack propagation
Deformation and Transitions at Grain Boundaries
Diffusion rate
Ductility
Earth Sciences
Engineering
Environment
Fatigue failure
Fracture mechanics
Fracture toughness
Grain boundaries
Grain growth
Grain size
High cycle fatigue
Low resistance
MATERIALS SCIENCE
Metal fatigue
Nanocrystals
Nucleation
Physics
Propagation
Spectrum analysis
Thin films
Transmission electron microscopy
Zirconium
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Summary:Nanocrystalline metals typically have high fatigue strengths but low resistance to crack propagation. Amorphous intergranular films are disordered grain boundary complexions that have been shown to delay crack nucleation and slow crack propagation during monotonic loading by diffusing grain boundary strain concentrations, which suggests they may also be beneficial for fatigue properties. To probe this hypothesis, in situ transmission electron microscopy fatigue cycling is performed on Cu-1 at.% Zr thin films thermally treated to have either only ordered grain boundaries or amorphous intergranular films. The sample with only ordered grain boundaries experienced grain coarsening at crack initiation followed by unsteady crack propagation and extensive nanocracking, whereas the sample containing amorphous intergranular films had no grain coarsening at crack initiation followed by steady crack propagation and distributed plastic activity. Microstructural design for control of these behaviors through simple thermal treatments can allow for the improvement of nanocrystalline metal fatigue toughness.
ISSN:1047-4838
1543-1851
DOI:10.1007/s11837-019-03361-7