Records |
Author |
Somsen, C.; Kästner, J.; Wassermann, E.F.; Boullay, P.; Schryvers, D. |
Title |
Microstructure of quenched Ni-rich Ni-Ti shape memory alloys |
Type |
A1 Journal article |
Year |
2001 |
Publication |
Journal de physique: 4
T2 – 8th European Symposium on Martensitic Transformations (ESOMAT2000), SEP 04-08, 2000, COMO, ITALY |
Abbreviated Journal |
J Phys Iv |
Volume |
11 |
Issue |
Pr8 |
Pages |
445-449 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
Microstructural investigations with transmission electron microscopy were carried out on quenched Ni-Ti alloys with 52 and 54.5 at% Ni. For the Ni52Ti48 specimen long time exposed diffraction patterns of a single grain show besides the expected reflections of the B2-phase, two sets of extra reflections in different zones. The first type of spots is explained by lattice displacement waves, which are regarded as precursors of the martensitic Ni-Ti phases, B 19' and R-phase, respectively. The second set of reflection with more diffuse intensity than the other reflections is related to Ni4Ti3 precipitates in an early state of formation. For the Ni-richer Ni54.5Ti45.5 alloy only Ni4Ti3 precipitates in an early state of formation are found but no precursors of the B 19'- and R-phase. |
Address |
|
Corporate Author |
|
Thesis |
|
Publisher |
E d p sciences |
Place of Publication |
Les ulis cedexa |
Editor |
|
Language |
|
Wos |
000173253800075 |
Publication Date ![sorted by Publication Date field, ascending order (up)](img/sort_asc.gif) |
2007-09-14 |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
1155-4339; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
|
Times cited |
2 |
Open Access |
|
Notes |
|
Approved |
Most recent IF: NA |
Call Number |
UA @ lucian @ c:irua:104187 |
Serial |
2073 |
Permanent link to this record |
|
|
|
Author |
Somsen, C.; Wassermann, E.F.; Kästner, J.; Schryvers, D. |
Title |
Precursor phenomena in a quenched and aged Ni52Ti48 shape memory alloy |
Type |
A1 Journal article |
Year |
2003 |
Publication |
Journal de physique: 4
T2 – 10th International Conference on Martensitic Transformations, JUN 10-14, 2002, ESPOO, FINLAND |
Abbreviated Journal |
J Phys Iv |
Volume |
112 |
Issue |
Part 2 |
Pages |
777-780 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
We measured the electrical resistivity R(T) and specific heat C-p(T) between room temperature (RT) and 4.2 K as well as the microstructure by transmission electron microscopy (TEM) of a Ni-52 Ti-48 SMA quenched from 1000degreesC (B2-Phase range) to RT and then annealed for 1h at T=380degreesC, 550degreesC and 650degreesC. In the “as quenched” and the “650degreesC annealed” state no martensitic transformations (MT's) occur. The diffraction patterns show faint reflections originating from coherent Ni4Ti3 precipitates in an early state of formation. Additional reflections of the type 1/2 <110>, 1/2 <111> and 1/3 <110> result from various lattice displacement waves, which are precursors of the MT's to the B19' and R-phase, respectively. Indeed, high resolution TEM micrographs of the [001] zone of the “as quenched” sample reveal transverse 1/2 <110> <110> lattice displacement waves, precursors of the B19' martensite. The coherent Ni4Ti3 precipitates, homogeneously distributed on a small length scale, binder the MT's in the “as quenched” and the “650degreesC annealed” state, and thus only the precursors appear. When annealed at T=380degreesC, however, coherent Ni4Ti3 precipitates with a length of 10nm are clearly visible in TEM. These precipitates trigger the NIT from the B2 to the R-phase on cooling, as evidenced also by anomalies in R(T) and C-p(T). Annealing at T-550degreesC leads to the well known two step MT's from the B2 to the R-phase and then into the B19'-phase. These martensitic transitions are clearly seen as additional peaks in the specific heat and anomalies in the resistance, while the “as quenched” and 650degreesC annealed samples show weak features in R(T) and C-p(T). |
Address |
|
Corporate Author |
|
Thesis |
|
Publisher |
|
Place of Publication |
Les Ulis |
Editor |
|
Language |
|
Wos |
000186503400036 |
Publication Date ![sorted by Publication Date field, ascending order (up)](img/sort_asc.gif) |
2008-08-19 |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
1155-4339; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
|
Times cited |
2 |
Open Access |
|
Notes |
|
Approved |
Most recent IF: NA |
Call Number |
UA @ lucian @ c:irua:102791 |
Serial |
2694 |
Permanent link to this record |