Entropy change caused by martensitic transformations of ferromagnetic shape memory alloys
Fecha
2017Autor
Versión
Acceso abierto / Sarbide irekia
Tipo
Artículo / Artikulua
Versión
Versión publicada / Argitaratu den bertsioa
Impacto
|
10.3390/met7110509
Resumen
In this paper, our most recent findings on the influence of magnetic order on the main transformational caloric and elastic properties of shape memory alloys (SMAs) are reviewed. It is argued that ferromagnetic order has a strong influence on the temperature interval of martensitic transformation (MT), the characteristics of stress-induced MT, and the shear elastic modulus of SMA. The problem of ...
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In this paper, our most recent findings on the influence of magnetic order on the main transformational caloric and elastic properties of shape memory alloys (SMAs) are reviewed. It is argued that ferromagnetic order has a strong influence on the temperature interval of martensitic transformation (MT), the characteristics of stress-induced MT, and the shear elastic modulus of SMA. The problem of separation of the magnetic contributions to the entropy change ΔS and heat Q exchanged in the course of martensitic transformation (MT) of SMA is considered in general terms, and theoretical formulas enabling the solution of the problem are presented. As an example, the ΔS and Q values, which were experimentally determined for Ni-Mn-Ga and Ni-Fe-Ga alloys with different Curie temperatures TC and MT temperatures TM, are theoretically analyzed. It is shown that for Ni-Mn-Ga martensites with TM < TC, the ratio of elastic and magnetic contributions to the entropy change may be greater or smaller than unity, depending on the temperature difference TC – TM. [--]
Materias
Shape memory alloys,
Transformational properties,
Magnetic order,
Entropy change,
Elastic modulus
Editor
MDPI
Publicado en
Metals, 2017, 7, 509
Departamento
Universidad Pública de Navarra. Departamento de Física /
Nafarroako Unibertsitate Publikoa. Fisika Saila
Versión del editor
Entidades Financiadoras
Partial financial support from projects MAT2014-56116-C04-01-R and MAT2012-37923-C02-01 (AEI/FEDER, UE) is acknowledged. The financial support from project 0117U000433 of NASU and project 0117U004340 of MESU is also acknowledged.