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17. Magnetocaloric effect of Ni-Fe-Mn-Sn microwires prepared by melt-extraction technique.

Author

Zhang, Hehe, Qian, Mingfang, Zhang, Xuexi, Jiang, Sida, Wei, Longsha, Xing, Dawei, Sun, Jianfei, and Geng, Lin

Subjects
*MAGNETOCALORIC effects, *NANOWIRES, *MAGNETIZATION, *ANNEALING of metals, *REFRIGERATION & refrigerating machinery, *MARTENSITIC transformations, *SHAPE memory alloys
Abstract

Small-sized materials with large surface to volume ratio favor heat transfer during magnetic refrigeration cycling and thus may help enhancing the refrigeration efficiency. Here, high Fe content Ni 44.9 Fe 4.3 Mn 38.3 Sn 12.5 polycrystalline microwires were prepared by a melt-extraction technique. The as-extracted microwires were annealed at 1173 K for 60 min, leading to significant grain growth and formation of a secondary Fe-rich γ phase. The annealed microwire exhibits larger magnetization difference ( ΔM ) between the austenite and martensite phases and smaller thermal hysteresis compared to the as-extracted microwire. The annealed microwire possesses a magnetic transition to austenite at 299 K, followed by a martensitic transformation (MT) from a ferromagnetic austenite to a weak-magnetic martensite at 208 K upon cooling. Under a magnetic field of 50 kOe, the annealed microwires show a maximum magnetic entropy change ΔS m of 6.9 J/kg·K and an effective refrigeration capacity RC eff of 78.0 J/kg over a broad working temperature span ΔT FWHM of 20 K around the MT. In addition, magnetic transition of the austenite gives rise to ΔS m − 3.7 J/kg·K and RC mag 232.5 J/kg with ΔT FWHM of 85 K under 50 kOe. [ABSTRACT FROM AUTHOR]

Published
2017
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