Competing accommodation mechanisms of the martensite in nanocrystalline NiTi shape memory alloys

Author(s)
Thomas Waitz, Wolfgang Pranger, Thomas Antretter, Franz Dieter Fischer, Hans-Peter Karnthaler
Abstract

Two competing mechanisms that compensate the transformation strains of the martensite are observed by transmission electron microscopy studies of nanocrystalline NiTi alloys. A single variant of compound twinned martensite forms below a critical grain size of about 100nm. In larger grains, a herringbone morphology of two different twinned variants of the martensite is observed. Calculations show that homogeneous transformation strains are reduced by the self-accommodating arrangement of different martensitic variants. This takes place at the expense of the formation of additional interfaces causing local strain concentrations. It is concluded that the size dependence of the martensitic morphology is caused by a different scaling behavior of the homogeneous and interfacial strain energies.

Organisation(s)
Physics of Nanostructured Materials
External organisation(s)
Montanuniversität Leoben
Journal
Materials Science and Engineering A: Structural Materials: Properties, Microstructures and Processing
Volume
481-482
Pages
479-483
No. of pages
5
ISSN
0921-5093
DOI
https://doi.org/10.1016/j.msea.2007.03.122
Publication date
2008
Peer reviewed
Yes
Austrian Fields of Science 2012
103018 Materials physics
Portal url
https://ucris.univie.ac.at/portal/en/publications/competing-accommodation-mechanisms-of-the-martensite-in-nanocrystalline-niti-shape-memory-alloys(4d009fc0-9399-4d7d-9140-dc3a10c3eec9).html