Details
| Original language | English |
|---|---|
| Pages (from-to) | S219-S221 |
| Journal | Journal of alloys and compounds |
| Volume | 577 |
| Issue number | SUPPL. 1 |
| Publication status | Published - 11 Feb 2012 |
| Externally published | Yes |
Abstract
Most shape memory applications require anisotropic properties; hence the materials used for sensors and actuators display properties like shape memory or superelastic strains that are usually optimized along a certain direction. It is well known that stress-free aging of near equiatomic NiTi single crystals improves microstructural stability under cyclic loading conditions. The present study shows that aging under compressive stress applied along the [1 1 1] orientation results in the formation of precipitates perpendicular to the loading axis, which further improves fatigue resistance. So far, the dependence of the functional degradation on the crystallographic orientation has only been studied after stress-free aging or after aging under compression followed by cyclic loading along the same crystallographic direction. Therefore, the scope of this study was to investigate the dependence of superelasticity on crystallographic orientation for different angles between the normal to the habit plane of the precipitates and the loading axis. It is shown that the functional properties can be controlled by aging of the single crystals in [1 1 1] orientation under stress. It was also observed that after aging under compression, functional degradation resistance is strongly dependent on the crystallographic orientation during cyclic loading. The effect of different superimposed stress modes and the influence of crystallographic orientation on the microstructural mechanisms that govern functional degradation as well as the ramifications on the design of NiTi nanocomposites with an optimized microstructure are discussed.
Keywords
- Cyclic stress-strain response, Fatigue, Martensite, NiTi shape memory alloys, Precipitation, Single crystals
ASJC Scopus subject areas
- Engineering(all)
- Mechanics of Materials
- Engineering(all)
- Mechanical Engineering
- Materials Science(all)
- Metals and Alloys
- Materials Science(all)
- Materials Chemistry
Cite this
- Standard
- Harvard
- Apa
- Vancouver
- BibTeX
- RIS
In: Journal of alloys and compounds, Vol. 577, No. SUPPL. 1, 11.02.2012, p. S219-S221.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Dependence of functional degradation on crystallographic orientation in NiTi shape memory alloys aged under stress
AU - Weighardt, S. C.
AU - Maier, H. J.
AU - Chumlyakov, Y. I.
N1 - Funding information: Support by Deutsche Forschungsgemeinschaft is gratefully acknowledged.
PY - 2012/2/11
Y1 - 2012/2/11
N2 - Most shape memory applications require anisotropic properties; hence the materials used for sensors and actuators display properties like shape memory or superelastic strains that are usually optimized along a certain direction. It is well known that stress-free aging of near equiatomic NiTi single crystals improves microstructural stability under cyclic loading conditions. The present study shows that aging under compressive stress applied along the [1 1 1] orientation results in the formation of precipitates perpendicular to the loading axis, which further improves fatigue resistance. So far, the dependence of the functional degradation on the crystallographic orientation has only been studied after stress-free aging or after aging under compression followed by cyclic loading along the same crystallographic direction. Therefore, the scope of this study was to investigate the dependence of superelasticity on crystallographic orientation for different angles between the normal to the habit plane of the precipitates and the loading axis. It is shown that the functional properties can be controlled by aging of the single crystals in [1 1 1] orientation under stress. It was also observed that after aging under compression, functional degradation resistance is strongly dependent on the crystallographic orientation during cyclic loading. The effect of different superimposed stress modes and the influence of crystallographic orientation on the microstructural mechanisms that govern functional degradation as well as the ramifications on the design of NiTi nanocomposites with an optimized microstructure are discussed.
AB - Most shape memory applications require anisotropic properties; hence the materials used for sensors and actuators display properties like shape memory or superelastic strains that are usually optimized along a certain direction. It is well known that stress-free aging of near equiatomic NiTi single crystals improves microstructural stability under cyclic loading conditions. The present study shows that aging under compressive stress applied along the [1 1 1] orientation results in the formation of precipitates perpendicular to the loading axis, which further improves fatigue resistance. So far, the dependence of the functional degradation on the crystallographic orientation has only been studied after stress-free aging or after aging under compression followed by cyclic loading along the same crystallographic direction. Therefore, the scope of this study was to investigate the dependence of superelasticity on crystallographic orientation for different angles between the normal to the habit plane of the precipitates and the loading axis. It is shown that the functional properties can be controlled by aging of the single crystals in [1 1 1] orientation under stress. It was also observed that after aging under compression, functional degradation resistance is strongly dependent on the crystallographic orientation during cyclic loading. The effect of different superimposed stress modes and the influence of crystallographic orientation on the microstructural mechanisms that govern functional degradation as well as the ramifications on the design of NiTi nanocomposites with an optimized microstructure are discussed.
KW - Cyclic stress-strain response
KW - Fatigue
KW - Martensite
KW - NiTi shape memory alloys
KW - Precipitation
KW - Single crystals
UR - http://www.scopus.com/inward/record.url?scp=84891631997&partnerID=8YFLogxK
U2 - 10.1016/j.jallcom.2012.02.005
DO - 10.1016/j.jallcom.2012.02.005
M3 - Article
AN - SCOPUS:84891631997
VL - 577
SP - S219-S221
JO - Journal of alloys and compounds
JF - Journal of alloys and compounds
SN - 0925-8388
IS - SUPPL. 1
ER -