Details
| Original language | English |
|---|---|
| Pages (from-to) | 7340-7355 |
| Number of pages | 16 |
| Journal | Acta materialia |
| Volume | 59 |
| Issue number | 19 |
| Publication status | Published - 23 Sept 2011 |
| Externally published | Yes |
Abstract
While previous studies have reported that nanocrystalline materials exhibit poor resistance to fatigue crack growth (FCG), the electro-deposited nanocrystalline Ni-Co alloys tested in this paper show superior resistance to FCG. The high damage tolerance of our alloy is attributed to the following: alloying with Co, low internal stresses resulting in stability of the microstructure, and a combination of high strength and ductility. The high density of grain boundaries interact with the dislocations emitted from the crack tip, which impedes FCG, as predicted by the present model and measured experimentally by digital image correlation. Further, the addition of Co increases the strength of the material by refining the grain size, reducing the fraction of low angle grain boundaries, and reducing the stacking fault energy of the material, thereby increasing the prevalence of twinning. The microstructure is stabilized by minimizing the internal stress during a stress relief heat treatment following the electro-deposition process. As a result grain growth does not occur during deformation, leaving dislocation-mediated plasticity as the primary deformation mechanism. The low internal stresses and nanoscale twins preserve the ductility of the material, thereby reaching a balance between strength and ductility, which results in a superior resistance to FCG.
Keywords
- Crack propagation, Fatigue, Grain boundaries, Irreversibility, Nanocrystalline alloys
ASJC Scopus subject areas
- Materials Science(all)
- Electronic, Optical and Magnetic Materials
- Materials Science(all)
- Ceramics and Composites
- Materials Science(all)
- Polymers and Plastics
- Materials Science(all)
- Metals and Alloys
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In: Acta materialia, Vol. 59, No. 19, 23.09.2011, p. 7340-7355.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Superior fatigue crack growth resistance, irreversibility, and fatigue crack growth-microstructure relationship of nanocrystalline alloys
AU - Sangid, Michael D.
AU - Pataky, Garrett J.
AU - Sehitoglu, Huseyin
AU - Rateick, Richard G.
AU - Niendorf, Thomas
AU - Maier, Hans J.
N1 - Funding information: Support for this work was provided primarily by Honeywell Aerospace Corporation and partially by the National Science Foundation (DMR 08-03270). The authors would like to thank Josh Kacher for his assistance with filtering the EBSD data and John Oyelakin for his assistance with the initial testing.
PY - 2011/9/23
Y1 - 2011/9/23
N2 - While previous studies have reported that nanocrystalline materials exhibit poor resistance to fatigue crack growth (FCG), the electro-deposited nanocrystalline Ni-Co alloys tested in this paper show superior resistance to FCG. The high damage tolerance of our alloy is attributed to the following: alloying with Co, low internal stresses resulting in stability of the microstructure, and a combination of high strength and ductility. The high density of grain boundaries interact with the dislocations emitted from the crack tip, which impedes FCG, as predicted by the present model and measured experimentally by digital image correlation. Further, the addition of Co increases the strength of the material by refining the grain size, reducing the fraction of low angle grain boundaries, and reducing the stacking fault energy of the material, thereby increasing the prevalence of twinning. The microstructure is stabilized by minimizing the internal stress during a stress relief heat treatment following the electro-deposition process. As a result grain growth does not occur during deformation, leaving dislocation-mediated plasticity as the primary deformation mechanism. The low internal stresses and nanoscale twins preserve the ductility of the material, thereby reaching a balance between strength and ductility, which results in a superior resistance to FCG.
AB - While previous studies have reported that nanocrystalline materials exhibit poor resistance to fatigue crack growth (FCG), the electro-deposited nanocrystalline Ni-Co alloys tested in this paper show superior resistance to FCG. The high damage tolerance of our alloy is attributed to the following: alloying with Co, low internal stresses resulting in stability of the microstructure, and a combination of high strength and ductility. The high density of grain boundaries interact with the dislocations emitted from the crack tip, which impedes FCG, as predicted by the present model and measured experimentally by digital image correlation. Further, the addition of Co increases the strength of the material by refining the grain size, reducing the fraction of low angle grain boundaries, and reducing the stacking fault energy of the material, thereby increasing the prevalence of twinning. The microstructure is stabilized by minimizing the internal stress during a stress relief heat treatment following the electro-deposition process. As a result grain growth does not occur during deformation, leaving dislocation-mediated plasticity as the primary deformation mechanism. The low internal stresses and nanoscale twins preserve the ductility of the material, thereby reaching a balance between strength and ductility, which results in a superior resistance to FCG.
KW - Crack propagation
KW - Fatigue
KW - Grain boundaries
KW - Irreversibility
KW - Nanocrystalline alloys
UR - http://www.scopus.com/inward/record.url?scp=80053174046&partnerID=8YFLogxK
U2 - 10.1016/j.actamat.2011.07.058
DO - 10.1016/j.actamat.2011.07.058
M3 - Article
AN - SCOPUS:80053174046
VL - 59
SP - 7340
EP - 7355
JO - Acta materialia
JF - Acta materialia
SN - 1359-6454
IS - 19
ER -