Study of relaxation and crystallization kinetics of NiTi made amorphous by repeated cold rolling
- Author(s)
- Martin Peterlechner, Joachim Bokeloh, Gerhard Wilde, Thomas Waitz
- Abstract
An amorphous structure of NiTi was obtained by repeated cold rolling. Relaxation and crystallization were studied applying a combination of sensitive calorimetric methods, X-ray diffraction and transmission electron microscopy. Upon deformation, a nanostructured mixture of crystalline and amorphous phase occurs. With increasing degree of RCR, the fraction of the crystalline phase decreases; at an equivalent strain of 16.8, an almost completely amorphous phase arises. Isothermal calorimetry yields a monotonously decreasing signal followed by a peak occurring by relaxation of the amorphous phase and nanocrystallization, respectively. The relaxation signal is well described by a Kohlrausch-Williams-Watts function. Crystallization kinetics agree with those expected from the Johnson-Mehl-Avrami model. The kinetic exponent agrees with three-dimensional growth and mixed nucleation or nucleation with a decreasing rate. The crystallization kinetics of NiTi made amorphous by severe plastic deformation differ from those of amorphous NiTi obtained by melt spinning or sputter deposition.
- Organisation(s)
- Physics of Nanostructured Materials
- External organisation(s)
- Westfälische Wilhelms-Universität Münster
- Journal
- Acta Materialia
- Volume
- 58
- Pages
- 6637-6648
- No. of pages
- 12
- ISSN
- 1359-6454
- DOI
- https://doi.org/10.1016/j.actamat.2010.08.026
- Publication date
- 2010
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103018 Materials physics
- Portal url
- https://ucris.univie.ac.at/portal/en/publications/study-of-relaxation-and-crystallization-kinetics-of-niti-made-amorphous-by-repeated-cold-rolling(da080e36-ff2e-4842-9126-591777e56903).html