Effect of niobium addition on the martensitic transformation and magnetocaloric effect in low hysteresis NiCoMnSn magnetic shape memory alloys

The effect of Nb substitution for Ni in Ni45Co5Mn40Sn10 magnetic shape memory alloys on their magnetic properties, martensitic transformation characteristics, transformation hysteresis, and magnetocaloric properties was studied using wavelength-dispersive X-ray spectroscopy, differential scanning ca...

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Bibliographic Details
Published in:Applied physics letters 2014-12, Vol.105 (23)
Main Authors: Emre, Baris, Bruno, Nickolaus M., Yuce Emre, Suheyla, Karaman, Ibrahim
Format: Article
Language:English
Subjects:
Applied physics
AUSTENITE
CALORIMETRY
COBALT ALLOYS
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
CURIE POINT
Curie temperature
DIFFERENTIAL THERMAL ANALYSIS
DOPED MATERIALS
ENTROPY
Heat of transformation
HYSTERESIS
Latent heat
MAGNETIC FIELDS
MAGNETIC PROPERTIES
Magnetism
MAGNETIZATION
MANGANESE BASE ALLOYS
Martensitic transformations
NICKEL BASE ALLOYS
Niobium
NIOBIUM ADDITIONS
PHASE TRANSFORMATIONS
REFRIGERATION
Shape effects
SHAPE MEMORY EFFECT
Temperature
Temperature dependence
TEMPERATURE RANGE 0273-0400 K
X ray spectra
X-RAY SPECTROSCOPY
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Summary:The effect of Nb substitution for Ni in Ni45Co5Mn40Sn10 magnetic shape memory alloys on their magnetic properties, martensitic transformation characteristics, transformation hysteresis, and magnetocaloric properties was studied using wavelength-dispersive X-ray spectroscopy, differential scanning calorimetry, and the temperature and field dependence of the magnetization. Ni45Co5Mn40Sn10 alloy has a very low transformation hysteresis; however, the martensitic transformation temperatures are notably above room temperature, which is not desirable for magnetic refrigeration applications. In this study, small quantities of Nb substitution were shown to drastically shift the transformation temperatures to lower temperatures, at a rate of 68 K/at. % Nb, which is needed for household refrigeration. The austenite Curie temperature also decreased with increasing Nb content. However, a decrease in the latent heat of the martensitic transition was observed, which negatively affects the magnetic field-induced adiabatic temperature change capability. Still, the relatively large transformation entropy and the low transformation hysteresis make the Nb-doped Ni45Co5Mn40Sn10 alloys potential candidates for solid state refrigeration near room temperature.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4903494