Paper Title:
Martensitic Transformations and Functional Stability in Ultra-Fine Grained NiTi Shape Memory Alloys
  Abstract

Martensitic transformations in NiTi shape memory alloys (SMAs) strongly depend on the microstructure. In the present work, we investigate how martensitic transformations are affected by various types of ultra-fine grained (UFG) microstructures resulting from various processing routes. NiTi SMAs with UFG microstructures were obtained by equal channel angular pressing, high pressure torsion, wire drawing and subsequent annealing treatments. The resulting material states were characterized by transmission electron microscopy and differential scanning calorimetry (DSC). The three thermomechanical processing routes yield microstructures which significantly differ in terms of grain size and related DSC chart features. While the initial coarse grained material shows a well defined one-step martensitic transformation on cooling, two-step transformations were found for all UFG material states. The functional stability of the various UFG microstructures was evaluated by thermal cycling. It was found that UFG NiTi alloys show a significantly higher stability. In the present work, we also provide preliminary results on the effect of grain size on the undercooling required to transform the material into B19’ and on the related heat of transformation.

  Info
Periodical
Materials Science Forum (Volumes 584-586)
Edited by
Yuri Estrin and Hans Jürgen Maier
Pages
852-857
DOI
10.4028/www.scientific.net/MSF.584-586.852
Citation
J. Burow, E. Prokofiev, C. Somsen, J. Frenzel, R. Valiev, G. F. Eggeler, "Martensitic Transformations and Functional Stability in Ultra-Fine Grained NiTi Shape Memory Alloys", Materials Science Forum, Vols. 584-586, pp. 852-857, 2008
Online since
June 2008
Export
Price
$32.00
Share

In order to see related information, you need to Login.

In order to see related information, you need to Login.

Authors: M. Kolář, Vladivoj Očenášek, J. Uhlíř, Ivana Stulíková, Bohumil Smola, Martin Vlach, V. Neubert, K. Šperlink
Abstract:The influence of plastic deformation and heat-treatment on the precipitation of Al3(Sc, Zr) particles and the effect of these precipitates...
357
Authors: Sergey Kozyukhin, Alexey A. Sherchenkov
Abstract:Phase change memory materials of Ge-Sb-Te system [(GeTe)m(Sb2Te3)n (m : n = 1:1; 1:2; 2:1)] were studied during thermal cycling by...
22
Authors: Dalibor Vojtěch, Alena Michalcová
Abstract:Nearly equi-atomic Ni-Ti alloys (nitinol) show shape memory behavior, superelasticity, high strength, excellent corrosion resistance and...
471
Authors: N.I. Vlasova, V.S. Gaviko, A.G. Popov, N.N. Shchegoleva, L.A. Stashkova, Dmitriy Gunderov, Xavier Sauvage
Abstract:Equiatomic FePd alloy in the ordered state has been processed by means of high-pressure torsion deformation (HPTD) and then annealed. X-ray...
392
Authors: Katarzyna Bałdys, Grzegorz Dercz, Łukasz Madej
Abstract:The ferromagnetic shape memory alloys (FSMA) are relatively the brand new smart materials group. The most interesting issue connected with...
171