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Pourbabak, S.; Verlinden, B.; Van Humbeeck, J.; Schryvers, D. |
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Title |
DSC cycling effects on phase transformation temperatures of micron and submicron grain Ni50.8Ti49.2 microwires |
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A1 Journal article |
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Year  |
2020 |
Publication |
Shape memory and superelasticity |
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Volume |
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Issue |
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Pages |
1-10 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
The effect of thermal cycling parameters on the phase transformation temperatures of micron and submicron grain size recrystallized Ni-Ti microwires was investigated. The suppression of martensitic transformation by thermal cycling was found to enhance when combined with room temperature aging between the cycles and enhances even more when aged at elevated temperature of 100 degrees C. While aging at room temperature alone has no clear effect on the martensitic transformation, elevated temperature aging at 100 degrees C alone suppresses the martensitic transformation. All aforementioned effects were found to be stronger in large grain samples than in small grain samples. Martensitic transformation suppression in all cases was in line with the formation of Ni4Ti3 precursors in the form of < 111 & rang;(B2) Ni clusters as concluded from the observed diffuse intensity in the electron diffraction patterns revealing short-range ordering enhancement. Performing thermal cycling in some different temperature ranges to separate the effect of martensitic transformation and high temperature range of DSC cycling revealed that both high temperature- and martensitic transformation-included cycles enhance the short-range ordering. |
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Wos |
000530232800001 |
Publication Date |
2020-05-04 |
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ISSN |
2199-384x; 2199-3858 |
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UA library record; WoS full record; WoS citing articles |
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Times cited |
1 |
Open Access |
Not_Open_Access |
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Notes |
; S.P. would like to thank the Flemish Science Foundation FWO for financial support under Project G.0366.15N. ; |
Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:169514 |
Serial |
6492 |
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Author |
Pourbabak, S.; Orekhov, A.; Samaee, V.; Verlinden, B.; Van Humbeeck, J.; Schryvers, D. |
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Title |
In-Situ TEM Stress Induced Martensitic Transformation in Ni50.8Ti49.2 Microwires |
Type |
A1 Journal article |
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Year |
2019 |
Publication |
Shape memory and superelasticity |
Abbreviated Journal |
Shap. Mem. Superelasticity |
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Volume |
5 |
Issue |
2 |
Pages |
154-162 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
In-situ transmission electron microscopy tensile straining is used to study the stress induced martensitic transformation in Ni50.8Ti49.2. Two microwire samples with different heat treatment are investigated from which one single crystal and three polycrystalline TEM specimens, the latter with micro- and nano-size grains, have been produced. The measured Young’s modulus for all TEM specimens is around 70 GPa, considerably higher than the averaged 55 GPa of the original microwire sample. The height of the superelastic stress plateau shows an inverse relationship with the specimen thickness for the polycrystalline specimens. Martensite starts nucleating within the elastic region of the stress–strain curve and on the edges of the specimens while also grain boundaries act as nucleation sites in the polycrystalline specimens. When a martensite plate reaches a grain boundary in the polycrystalline specimen, it initiates the transformation in the neighboring grain at the other side of the grain boundary. In later stages martensite plates coalesce at higher loads in the stress plateau. In highly strained specimens, residual martensite remains after release. |
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Wos |
000472940200002 |
Publication Date |
2019-05-20 |
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2199-384X |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Times cited |
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Open Access |
Not_Open_Access |
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Notes |
Saeid Pourbabak likes to thank the Flemish Science Foundation FWO for financial support under Project G.0366.15N. This work was also made possible through the AUHA13009 Grant “TopSPIN for TEM nanostatistics” of the Flemish HERCULES foundation. |
Approved |
Most recent IF: NA |
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Call Number |
EMAT @ emat @UA @ admin @ c:irua:159989 |
Serial |
5177 |
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Author |
Yao, X.; Amin-Ahmadi, B.; Li, Y.; Cao, S.; Ma, X.; Zhang, X.-P.; Schryvers, D. |
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Title |
Optimization of Automated Crystal Orientation Mapping in a TEM for Ni4Ti3 Precipitation in All-Round SMA |
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A1 Journal article |
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Year |
2016 |
Publication |
Shape memory and superelasticity |
Abbreviated Journal |
Shap Mem Superelasticity |
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Volume |
2 |
Issue |
2 |
Pages |
286-297 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Automated crystal orientation and phase mapping in TEM are applied to the quantification of Ni4Ti3 precipitates in Ni–Ti shape memory alloys which will be used for the implantation of artificial sphincters operating using the all-round shape memory effect. This paper focuses on the optimization process of the technique to obtain best values for all major parameters in the acquisition of electron diffraction patterns as well as template generation. With the obtained settings, vast statistical data on nano- and microstructures essential to the operation of these shape memory devices become available. |
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Wos |
000408743700001 |
Publication Date |
2016-11-07 |
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ISSN |
2199-384X |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Times cited |
2 |
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Notes |
X. Yao gratefully acknowledges the Chinese Scholarship Council (CSC) for providing a PhD scholarship. Research support was also provided by the Key Project of the Natural Science Foundation of Guangdong Province (S2013020012805) and the Natural Science Foundation of China under Grant No. 51401081. |
Approved |
Most recent IF: NA |
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Call Number |
EMAT @ emat @ c:irua:138600 |
Serial |
4324 |
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Author |
Schryvers, D. |
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Title |
Advanced electron microscopy characterisation of important precipitation and ordering phenomena in shape memory systems |
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A1 Journal article |
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Year |
2015 |
Publication |
Shape memory and superelasticity |
Abbreviated Journal |
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1 |
Issue |
1 |
Pages |
78-84 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
The present paper discusses some important aspects of precipitation and ordering in alloy systems that show a martensitic transformation and can or are used as shape memory or superelastic metallic systems. The precipitates are investigated by a variety of conventional and advanced electron microscopy techniques, including atomic resolution, 3D slice-and-view, energy loss spectroscopy etc. Depending on the system, such secondary phases can decrease the probability of a displacive transformation by changing the phase stability in the system, such as in the case of NiAl or NiTiPd, or can mechanically hinder the passage of the transformation interface, as in NiTiNb. On the other hand, properly controlling the nucleation and growth of some precipitates can strongly improve the properties of some types of materials, as is the case for the well-known Ni4Ti3 precipitates. |
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Wos |
000432420400008 |
Publication Date |
2015-04-20 |
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ISSN |
2199-384X;2199-3858; |
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Additional Links |
UA library record; WoS full record |
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Notes |
Fwo |
Approved |
Most recent IF: NA |
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Call Number |
c:irua:127684 |
Serial |
69 |
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