Records |
Author |
Pourbabak, S. |
Title |
Influence of nano and microstructural features and defects in finegrained NiTi on the thermal and mechanical reversibility of the martensitic transformation |
Type |
Doctoral thesis |
Year |
2020 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
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Pages |
166 p. |
Keywords |
Doctoral thesis; Electron microscopy for materials research (EMAT) |
Abstract |
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Series Volume |
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Edition |
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ISSN |
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ISBN |
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Additional Links |
UA library record |
Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
Most recent IF: NA |
Call Number |
UA @ admin @ c:irua:165919 |
Serial |
6305 |
Permanent link to this record |
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Author |
Pourbabak, S.; Verlinden, B.; Van Humbeeck, J.; Schryvers, D. |
Title |
DSC cycling effects on phase transformation temperatures of micron and submicron grain Ni50.8Ti49.2 microwires |
Type |
A1 Journal article |
Year |
2020 |
Publication |
Shape memory and superelasticity |
Abbreviated Journal |
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Volume |
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Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
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Pages |
1-10 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2199-384x; 2199-3858 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
|
Times cited |
1 |
Open Access |
Not_Open_Access |
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 |
Call Number |
UA @ admin @ c:irua:169514 |
Serial |
6492 |
Permanent link to this record |
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Author |
Pourbabak, S.; Orekhov, A.; Schryvers, D. |
Title |
Twin-jet electropolishing for damage-free transmission electron microscopy specimen preparation of metallic microwires |
Type |
A1 Journal article |
Year |
2020 |
Publication |
Microscopy Research And Technique |
Abbreviated Journal |
Microsc Res Techniq |
Volume |
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Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
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Pages |
1-7 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
A method to prepare TEM specimens from metallic microwires and based on conventional twin-jet electropolishing is introduced. The wire is embedded in an opaque epoxy resin medium and the hardened resin is mechanically polished to reveal the wire on both sides. The resin containing wire is then cut into discs of the appropriate size. The obtained embedded wire is electropolished in a conventional twin-jet electropolishing machine until electron transparency in large areas without radiation damage is achieved. |
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Wos |
000567944200001 |
Publication Date |
2020-09-28 |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1059-910x |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.5 |
Times cited |
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Open Access |
OpenAccess |
Notes |
; Fonds Wetenschappelijk Onderzoek, Grant/Award Number: G.0366.15N ; |
Approved |
Most recent IF: 2.5; 2020 IF: 1.147 |
Call Number |
UA @ admin @ c:irua:171969 |
Serial |
6642 |
Permanent link to this record |
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Author |
Safdel, A.; Zarei-Hanzaki, A.; Abedi, H.R.; Pourbabak, S.; Schryvers, D.; Basu, R. |
Title |
Asymmetrical superelastic behavior of thermomechanically processed semi-equiatomic NiTi alloy in tensile and compressive modes of deformation |
Type |
A1 Journal article |
Year |
2021 |
Publication |
Journal Of Alloys And Compounds |
Abbreviated Journal |
J Alloy Compd |
Volume |
878 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
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Pages |
160443 |
Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
Abstract |
In the present work two different cold working and annealing schemes were utilized, and the asymmetric superelastic response of thermomechanically processed materials were then assessed through cyclic tensile and compressive modes of deformation. The values of transformation stress, transformation strain, and pseudoelastic strain were measured for each treated and solutionized specimens and the asymmetric response was compared. In the solution annealed state, the difference of these parameters at different deformation modes was negligible due to the weak texture of the material, while for thermomechanically treated ones, development of specific deformation and recrystallization texture components was identified to be one of the underlying reasons of intensified asymmetry. The evolved substructure during the thermomechanical processing also played a substantial role in determining the asymmetric response. The presence of fine grains and dense dislocation substructure could hinder the movement of the transformation front, thus limiting the range of transformation. In tensile mode, the transformation stress was lower, but higher transformation strain was achieved, which was discussed relying on the slip activity in specified oriented grains. The lower transformation strain in compression mode led to lower pseudoelastic strain due to the narrow transformation range which finally degraded superelastic response of the material. (C) 2021 Elsevier B.V. All rights reserved. |
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Place of Publication |
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Wos |
000660477400005 |
Publication Date |
2021-05-18 |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0925-8388 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.133 |
Times cited |
|
Open Access |
OpenAccess |
Notes |
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Approved |
Most recent IF: 3.133 |
Call Number |
UA @ admin @ c:irua:179564 |
Serial |
6855 |
Permanent link to this record |
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Author |
Montero-Sistiaga, M.L.; Pourbabak, S.; Van Humbeeck, J.; Schryvers, D.; Vanmeensel, K. |
Title |
Microstructure and mechanical properties of Hastelloy X produced by HP-SLM (high power selective laser melting) |
Type |
A1 Journal article |
Year |
2019 |
Publication |
Materials & design |
Abbreviated Journal |
Mater Design |
Volume |
165 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
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Pages |
107598 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
In order to increase the production rate during selective laser melting (SLM), a high power laser with a large beam diameter is used to build fully dense Hastelloy X parts. Compared to SLM with a low power and small diameter beam, the productivity was increased from 6 mm3/s to 16 mm3/s, i.e. 2.6 times faster. Besides the productivity benefit, the influence of the use of a high power laser on the rapid solidification microstructure and concomitant material properties is highlighted. The current paper compares the microstructure and tensile properties of Hastelloy X built with low and high power lasers. The use of a high power laser results in wider and shallower melt pools inducing an enhanced morphological and crystallographic texture along the building direction (BD). In addition, the increased heat input results in coarser sub-grains or high density dislocation walls for samples processed with a high power laser. Additionally, the influence of hot isostatic pressing (HIP) as a post-processing technique was evaluated. After HIP, the tensile fracture strain increased as compared to the strain in the as-built state and helped in obtaining competitive mechanical properties as compared to conventionally processed Hastelloy X parts. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000458259300020 |
Publication Date |
2019-01-09 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0264-1275 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
4.364 |
Times cited |
15 |
Open Access |
OpenAccess |
Notes |
This research was supported by the ENGIE Research and Technology Division. The authors acknowledge ENGIE Research and Technology Division for the use of the SLM280HL machine. S.P. likes to thank the Flemish Science Foundation FWO for financial support under Project G.0366.15N. |
Approved |
Most recent IF: 4.364 |
Call Number |
EMAT @ emat @UA @ admin @ c:irua:157469 |
Serial |
5176 |
Permanent link to this record |
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Author |
Pourbabak, S.; Montero-Sistiaga, M.L.; Schryvers, D.; Van Humbeeck, J.; Vanmeensel, K. |
Title |
Microscopic investigation of as built and hot isostatic pressed Hastelloy X processed by Selective Laser Melting |
Type |
A1 Journal article |
Year |
2019 |
Publication |
Materials characterization |
Abbreviated Journal |
Mater Charact |
Volume |
153 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
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Pages |
366-371 |
Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
Abstract |
Microstructural characteristics of Hastelloy X produced by Selective Laser Melting have been investigated by various microscopic techniques in the as built (AB) condition and after hot isostatic pressing (HIP). At sub-grain level the AB material consists of columnar high density dislocation cells while the HIP sample consists of columnar sub-grains with lower dislocation density that originate from the original dislocation cells, contradicting existing models. The sub-grains contain nanoscale precipitates enriched in Al, Ti, Cr and O, located at sub-grain boundaries in the AB condition and within the grains after HIP. At some grain boundaries, micrometer sized chromium carbides are detected after HIP. Micro hardness within the grains was found to decrease after HIP, which was attributed to the decrease in dislocation density due to recovery annealing. |
Address |
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Corporate Author |
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Thesis |
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Place of Publication |
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Editor |
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Language |
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Wos |
000472696900040 |
Publication Date |
2019-05-21 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1044-5803 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.714 |
Times cited |
2 |
Open Access |
Not_Open_Access |
Notes |
S.P. likes to thank the Flemish Science Foundation FWO for financial support under Project G.0366.15N. The authors acknowledge ENGIE Research and Technology Division for the use of the SLM280HL machine and financial support. This work was also made possible through the AUHA13009 grant “TopSPIN for TEM nanostatistics” of the Flemish HERCULES foundation. |
Approved |
Most recent IF: 2.714 |
Call Number |
EMAT @ emat @UA @ admin @ c:irua:159974 |
Serial |
5178 |
Permanent link to this record |
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Author |
Pourbabak, S.; Wang, X.; Van Dyck, D.; Verlinden, B.; Schryvers, D. |
Title |
Ni cluster formation in low temperature annealed Ni50.6Ti49.4 |
Type |
A1 Journal article |
Year |
2017 |
Publication |
Functional materials letters |
Abbreviated Journal |
Funct Mater Lett |
Volume |
10 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
10 |
Pages |
1740005 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab |
Abstract |
Various low temperature treatments of Ni50.6Ti49.4 have shown an unexpected effect on the martensitic start temperature. Periodic diffuse intensity distributions in reciprocal space indicate the formation of short pure Ni strings along the <111> directions in the B2 ordered lattice, precursing the formation of Ni4Ti3 precipitates formed at higher annealing temperatures. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000395164100006 |
Publication Date |
2017-01-10 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1793-6047 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
1.234 |
Times cited |
4 |
Open Access |
Not_Open_Access |
Notes |
The authors like to thank the Flemish Science Foundation FWO for financial support under project G.0366.15N “Influence of nano- and microstructural features and defects in fine-grained Ni-Ti on the thermal and mechanical reversibility of the martensitic transformation and the shape memory and superelastic behavior”. We are also very grateful to Prof. Dr. Jan Van Humbeeck for initiating this work, for his continuous support and inspiring discussions. |
Approved |
Most recent IF: 1.234 |
Call Number |
EMAT @ emat @ c:irua:142545 |
Serial |
4619 |
Permanent link to this record |
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Author |
Shi, H.; Pourbabak, S.; Van Humbeeck, J.; Schryvers, D. |
Title |
Electron microscopy study of Nb-rich nanoprecipitates in NiTiNb and their influence on the martensitic transformation |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Scripta materialia |
Abbreviated Journal |
Scripta Mater |
Volume |
67 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
12 |
Pages |
939-942 |
Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
Abstract |
Nb-rich nanoprecipitates in the matrix of an annealed commercial NiTiNb alloy are investigated by scanning and transmission electron microscopy, including slice-and-view and chemical analysis. The precipitates have a diameter of around 100 nm, are faceted and have a cube-on-cube relation with the B2 matrix. In situ TEM cooling shows that the martensitic transformation is hampered by the presence of these precipitates. The latter could explain the increase in hysteresis when compared with the binary system. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Oxford |
Editor |
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Language |
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Wos |
000311135000005 |
Publication Date |
2012-08-27 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1359-6462; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.747 |
Times cited |
29 |
Open Access |
|
Notes |
Fwo |
Approved |
Most recent IF: 3.747; 2012 IF: 2.821 |
Call Number |
UA @ lucian @ c:irua:101486 |
Serial |
971 |
Permanent link to this record |
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Author |
Pourbabak, S.; Orekhov, A.; Samaee, V.; Verlinden, B.; Van Humbeeck, J.; Schryvers, D. |
Title |
In-Situ TEM Stress Induced Martensitic Transformation in Ni50.8Ti49.2 Microwires |
Type |
A1 Journal article |
Year |
2019 |
Publication |
Shape memory and superelasticity |
Abbreviated Journal |
Shap. Mem. Superelasticity |
Volume |
5 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
2 |
Pages |
154-162 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Language |
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Wos |
000472940200002 |
Publication Date |
2019-05-20 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2199-384X |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
|
Times cited |
|
Open Access |
Not_Open_Access |
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 |
Call Number |
EMAT @ emat @UA @ admin @ c:irua:159989 |
Serial |
5177 |
Permanent link to this record |
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Author |
Radi, A.; Khalil-Allafi, J.; Etminanfar, M.R.; Pourbabak, S.; Schryvers, D.; Amin-Ahmadi, B. |
Title |
Influence of stress aging process on variants of nano-N4Ti3precipitates and martensitic transformation temperatures in NiTi shape memory alloy |
Type |
A1 Journal article |
Year |
2018 |
Publication |
Materials & design |
Abbreviated Journal |
Mater Design |
Volume |
262 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
262 |
Pages |
74-81 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
In this study, the effect of a stress aging process on the microstructure and martensitic phase transformation of NiTi shape memory alloy has been investigated. NiTi samples were aged at 450 degrees C for 1 h and 5 h under different levels of external tensile stress of 15, 60 and 150 MPa. Transmission electron microscopy (TEM) was used to characterize different variants and morphology of precipitates. The results show that application of all stress levels restricts the formation of precipitates variants in the microstructure after I h stress aging process. However, all variants can be detected by prolonging aging time to 5 h at 15 MPa stress level and the variants formation is again restricted by increasing the stress level. Moreover, the stress aging process resulted in changing the shape of precipitates in comparison with that of the stress-free aged samples. Coffee-bean shaped morphologies were detected for precipitates in all stress levels. According to the Differential Scanning Calorimetry (DSC) results, the martensite start temperature (M-s) on cooling shifts to higher temperatures with increasing the tensile stress during the aging process. This can be related to the change ofaustenite to martensite interface energy due to the different volume fractions and variants of precipitates. (c) 2018 Elsevier Ltd. All rights reserved. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
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Publication Date |
2018-01-04 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0264-1275 |
ISBN |
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Additional Links |
UA library record; ; WoS full record; WoS citing articles |
Impact Factor |
4.364 |
Times cited |
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Open Access |
OpenAccess |
Notes |
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Approved |
Most recent IF: 4.364 |
Call Number |
UA @ lucian @ c:irua:149854 |
Serial |
4938 |
Permanent link to this record |
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Author |
Cao, S.; Pourbabak, S.; Schryvers, D. |
Title |
Quantitative 3-D morphologic and distributional study of Ni4Ti3 precipitates in a Ni51Ti49 single crystal alloy |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Scripta materialia |
Abbreviated Journal |
Scripta Mater |
Volume |
66 |
Issue ![sorted by Issue field, ascending order (up)](img/sort_asc.gif) |
9 |
Pages |
650-653 |
Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
Abstract |
The size, shape and distribution of Ni4Ti3 precipitates in Ni51Ti49 single crystals annealed under stress-free and 〈1 1 1〉B2 compressive conditions are studied via focused ion beam/scanning electron microscopy slice-and-view. The precipitates in the stress-free material grow in autocatalytic pockets with larger size, lower number density, flatter shape and larger inter-particle distance than in the compressed material. Nevertheless, a new quantification method called water penetration reveals that, due to the precipitate alignment, martensite can grow more easily in the compressed material perpendicular to the compression direction. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Oxford |
Editor |
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Language |
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Wos |
000302425100010 |
Publication Date |
2012-01-30 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1359-6462; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.747 |
Times cited |
8 |
Open Access |
|
Notes |
Fwo |
Approved |
Most recent IF: 3.747; 2012 IF: 2.821 |
Call Number |
UA @ lucian @ c:irua:97387 |
Serial |
2743 |
Permanent link to this record |