Open Access
Article Number 04007
Number of page(s) 5
Section Principles, Simulations, Materials: Advanced Materials
Published online 01 September 2009
ESOMAT 2009, 04007 (2009)
DOI: 10.1051/esomat/200904007

In-situ TEM straining of tetragonal martensite of Ni-Mn-Ga alloy

Yanling Ge1, Niva Zárubová1, 2, Zdeněk Dlabáček1, 2, Ilkka Aaltio1, Outi Söderberg1 and Simo-Pekka Hannula1

1  Department of Materials Science and Engineering, Helsinki University of Technology, P.O. Box 6200, FI-02015 TKK, Finlad
2  Institute of Physics, ASCR v.v.i., Na Slovance 2, 182 21 Prague 8, Czech Republic

Published online: 1 September 2009

The in-situ straining of tetragonal martensite of Ni-Mn-Ga alloy was studied in a transmission electron microscope (TEM) JEM 1200EX equipped with a double tilt straining stage. The sample was analyzed before and after the straining experiments using the conventional as well as high resolution TEM (Tecnai F20 G2 200kV FEG). Before straining, the martensitic structure of the samples consisted of thermally induced self-accommodated multivariants. During the in-situ straining, detwinning processes were recorded. The volume fraction of the twin variants preferably oriented to the applied tensile force increased at the expense of the less favorably oriented ones. The movement of the twin boundaries was followed in detail. The analysis performed after straining suggested that the detwinning processes occurred by movement of twinning dislocations. The interface between two twinned bands acted as a nucleation source for emitting the twinning dislocations.

© Owned by the authors, published by EDP Sciences 2009