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Title: Martensitic transformation of NiTi nanocrystals embedded in an amorphous matrix

Abstract

The influence of the size on the martensitic phase transformation of spherical NiTi nanocrystals embedded in an amorphous matrix was studied by transmission electron microscopy. The transformation from B2 austenite to B19' martensite is suppressed by a transformation barrier that increases with increasing transformation strains and decreasing diameter of the nanocrystals. Minimizing the strain and interface energy yields a two step transformation from B2 to the R-phase and finally to B19'. The transformation starts at the crystalline/amorphous interface by heterogeneous nucleation. In the case of the R-phase to B19' transformation large strains occur causing after a certain point fine compound twinning during growth that finally leads to a complete transformation right up to the interface. In the isolated nanocrystals a lack of collective transformation effects yields larger transformation barriers and causes larger critical diameters than those observed in the grains of nanocrystalline NiTi.

Authors:
 [1];  [1]
  1. Institute of Materials Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna (Austria)
Publication Date:
OSTI Identifier:
20634800
Resource Type:
Journal Article
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 52; Journal Issue: 19; Other Information: DOI: 10.1016/j.actamat.2004.08.003; PII: S1359-6454(04)00470-7; Copyright (c) 2004 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1359-6454
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AUSTENITE; CRYSTALS; INTERFACES; MARTENSITE; NANOSTRUCTURES; NICKEL ALLOYS; PHASE TRANSFORMATIONS; STRAINS; TITANIUM ALLOYS; TRANSMISSION ELECTRON MICROSCOPY; TWINNING

Citation Formats

Waitz, T, and Karnthaler, H P. Martensitic transformation of NiTi nanocrystals embedded in an amorphous matrix. United States: N. p., 2004. Web. doi:10.1016/j.actamat.2004.08.003.
Waitz, T, & Karnthaler, H P. Martensitic transformation of NiTi nanocrystals embedded in an amorphous matrix. United States. https://doi.org/10.1016/j.actamat.2004.08.003
Waitz, T, and Karnthaler, H P. 2004. "Martensitic transformation of NiTi nanocrystals embedded in an amorphous matrix". United States. https://doi.org/10.1016/j.actamat.2004.08.003.
@article{osti_20634800,
title = {Martensitic transformation of NiTi nanocrystals embedded in an amorphous matrix},
author = {Waitz, T and Karnthaler, H P},
abstractNote = {The influence of the size on the martensitic phase transformation of spherical NiTi nanocrystals embedded in an amorphous matrix was studied by transmission electron microscopy. The transformation from B2 austenite to B19' martensite is suppressed by a transformation barrier that increases with increasing transformation strains and decreasing diameter of the nanocrystals. Minimizing the strain and interface energy yields a two step transformation from B2 to the R-phase and finally to B19'. The transformation starts at the crystalline/amorphous interface by heterogeneous nucleation. In the case of the R-phase to B19' transformation large strains occur causing after a certain point fine compound twinning during growth that finally leads to a complete transformation right up to the interface. In the isolated nanocrystals a lack of collective transformation effects yields larger transformation barriers and causes larger critical diameters than those observed in the grains of nanocrystalline NiTi.},
doi = {10.1016/j.actamat.2004.08.003},
url = {https://www.osti.gov/biblio/20634800}, journal = {Acta Materialia},
issn = {1359-6454},
number = 19,
volume = 52,
place = {United States},
year = {Mon Nov 08 00:00:00 EST 2004},
month = {Mon Nov 08 00:00:00 EST 2004}
}