Issue |
ESOMAT 2009
2009
|
|
---|---|---|
Article Number | 02032 | |
Number of page(s) | 6 | |
Section | Principles, Simulations, Materials: Background | |
DOI | https://doi.org/10.1051/esomat/200902032 | |
Published online | 01 September 2009 |
DOI: 10.1051/esomat/200902032
3D strain fields surrounding Ni4Ti3: direct measurement and correlation with the R-phase.
W. Tirrya1, 2 and D. Schryvers1, 21 EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp, Belgium
2 COBO, KMS, Renaissancelaan 30, B-1000, Brussels, Belgium
wim.tirry@ua.ac.be
Published online: 1 September 2009
Abstract
Strain fields introduced by coherent Ni4Ti3 precipitates in
austenitic Ni-Ti are believed to be a possible origin of why the R-phase transformation is
introduced as an extra step before transforming to the B19'. The presence of this strain
field was already confirmed in the past by conventional transmission electron microscopy
(TEM) techniques and measured quantitatively by high resolution TEM (HRTEM). This time
the geometrical phase method is applied on HRTEM micrographs to measure the full 3D
strain tensor of the strain fields. Since each atomic resolution micrograph
only results in a 2D measurement of the strain, observations in two different zone orientations
are combined to retrieve the 3 × 3 strain tensor. In this work observations in a
[1-1 1]B2 and [1 0-1]B2 zone orientation are used and this in case of
precipitates with a diameter of around 50nm. In a next step the measured strain tensor is
compared to the calculated eigenstrain of the R-phase in reference to the B2 matrix. This
comparison shows that the introduced strain is very similar to the eigenstrain of one R-phase
variant. Since for both structures, Ni4Ti3 and Rphase, four orientation variants are possible,
each variant of the R-phase is thus able to accommodate the strain field of one of the
Ni4Ti3 variants.
© Owned by the authors, published by EDP Sciences 2009