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Proceedings Paper

Comparison of martensite transformation temperatures in a NiMnGa alloy determined with hot/cold stage optical microscopy and differential scanning calorimetry
Author(s): Calvin V. Hyatt; Shannon P. Farrell; Bob Armstrong; J. C. Bennett; Irv Keough; Gary Fisher; Jian Chen; Michael A. Gharghouri
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Paper Abstract

The martensite transformation temperatures of both as-grown and heat-treated specimens removed from a Bridgman grown boule of off-stoichiometric Ni2MnGa were determined by differential scanning calorimetry (DSC) and hot/cold stage microscopy. The work showed that martensite start and austenite finish transformation temperatures determined by the hot/cold stage microscope technique were in agreement with those determined by the DSC method. The hot/cold stage microscope technique was shown to be useful for characterizing variations of transformation temperature across a specimen. The results revealed that residual stress, deformation and boule composition variations produce artefacts in DSC traces which need to be identified, understood and controlled. Transmission electron microscope results suggest that the possible contribution of a premartensitic transformation to the high temperature edge of the martensite peak on DSC scans needs further investigation.

Paper Details

Date Published: 13 August 2003
PDF: 10 pages
Proc. SPIE 5053, Smart Structures and Materials 2003: Active Materials: Behavior and Mechanics, (13 August 2003); doi: 10.1117/12.484741
Show Author Affiliations
Calvin V. Hyatt, Defence Research and Development Canada (Canada)
Shannon P. Farrell, Defence Research and Development Canada (Canada)
Bob Armstrong, Defence Research and Development Canada (Canada)
J. C. Bennett, Acadia Univ. (Canada)
Irv Keough, Defence Research and Development Canada (Canada)
Gary Fisher, Defence Research and Development Canada (Canada)
Jian Chen, Dalhousie Univ. (Canada)
Michael A. Gharghouri, Dalhousie Univ. (Canada)


Published in SPIE Proceedings Vol. 5053:
Smart Structures and Materials 2003: Active Materials: Behavior and Mechanics
Dimitris C. Lagoudas, Editor(s)

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