Microstructure and Phase Transformations of HPT NiTi

  1. Prof. Dr. Michael Zehetbauer3 and
  2. Prof. Ruslan Z. Valiev4
  1. T. Waitz1,
  2. V. Kazykhanov2 and
  3. H. P. Karnthaler1

Published Online: 28 JAN 2005

DOI: 10.1002/3527602461.ch6e

Nanomaterials by Severe Plastic Deformation

Nanomaterials by Severe Plastic Deformation

How to Cite

Waitz, T., Kazykhanov, V. and Karnthaler, H. P. (2004) Microstructure and Phase Transformations of HPT NiTi, in Nanomaterials by Severe Plastic Deformation (eds M. Zehetbauer and R. Z. Valiev), Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, FRG. doi: 10.1002/3527602461.ch6e

Editor Information

  1. 3

    Institut für Materialphysik, Universität Wien, Boltzmanngasse 5, 1090 Wien, Austria

  2. 4

    Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, 12 K. Marks Str., Ufa, 450 000, Russia

Author Information

  1. 1

    Institute of Materials Physics, University of Vienna, Wien, Austria

  2. 2

    Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, Ufa, Russia

Publication History

  1. Published Online: 28 JAN 2005
  2. Published Print: 25 FEB 2004

ISBN Information

Print ISBN: 9783527306596

Online ISBN: 9783527602469

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Keywords:

  • microstructure;
  • phase transformation;
  • intermetallic shape memory alloy NiTi;
  • nanocrystalline NiTi alloys;
  • mechanical amorphization;
  • severe plastic deformation;
  • high pressure torsion (HPT);
  • electron microscopy

Summary

The intermetallic shape memory alloy NiTi is of considerable interest from both a scientific and technological point of view. The shape memory properties are caused by a martensitic phase transformation. The transformation occurs from the cubic B2 austenite to the monoclinic B19′ martensite; depending on the composition of the alloy, the trigonal R-phase can occur as a transition structure. Nanocrystalline NiTi alloys can be processed by mechanical amorphization followed by a suitable heat treatment [1]. In the present investigation, Ni-50.3 at.% Ti, completely transformed to martensite in a single step, was subjected to severe plastic deformation by high pressure torsion (HPT) followed by annealing, yielding a nanocrystalline structure. It is the aim of the present paper to investigate the impact of the grain size on the martensitic phase transformation.