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Entropy 2014, 16(3), 1808-1818; doi:10.3390/e16031808
Article

Entropy Change during Martensitic Transformation in Ni50−xCoxMn50−yAly Metamagnetic Shape Memory Alloys

1,* , 2
,
1,3
 and
1
1 Department of Materials Science, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan 2 Department of Materials and Environmental Engineering, Sendai National College of Technology, Natori 981-1239, Japan 3 Research Institute for Engineering and Technology, Tohoku Gakuin University, Tagajo 985-8537, Japan
* Author to whom correspondence should be addressed.
Received: 12 February 2014 / Revised: 18 March 2014 / Accepted: 19 March 2014 / Published: 24 March 2014
(This article belongs to the Special Issue Entropy in Shape Memory Alloys)
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Abstract

Specific heat was systematically measured by the heat flow method in Ni50-xCoxMn50-yAly metamagnetic shape memory alloys near the martensitic transformation temperatures. Martensitic transformation and ferromagnetic–paramagnetic transition for the parent phase were directly observed via the specific heat measurements. On the basis of the experimental results, the entropy change was estimated and it was found to show an abrupt decrease below the Curie temperature. The results were found to be consistent with those of earlier studies on Ni-Co-Mn-Al alloys.
Keywords: entropy change; specific heat; thermal transformation arrest; kinetic arrest; metamagnetic shape memory alloy; martensitic transformation; Ni-Co-Mn-Al entropy change; specific heat; thermal transformation arrest; kinetic arrest; metamagnetic shape memory alloy; martensitic transformation; Ni-Co-Mn-Al
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).
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Xu, X.; Ito, W.; Kanomata, T.; Kainuma, R. Entropy Change during Martensitic Transformation in Ni50−xCoxMn50−yAly Metamagnetic Shape Memory Alloys. Entropy 2014, 16, 1808-1818.

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