Effect of heat treatment procedure on magnetic and magnetocaloric properties of Ni₄₃Mn₄₆In₁₁ melt spun ribbons

Abstract

The effect of heat treatment on the structural, magnetic and magnetocaloric properties of Ni₄₃Mn₄₆In₁₁ melt-spun ribbons was systematically investigated using X-ray powder diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), magnetic force microscope (MFM) and magnetic measurements. From the XRD studies, tetragonal and cubic phases were detected at room temperature for as-spun, quenched and slow-cooled ribbons. Furthermore, it was observed, upon annealing martensite transition temperatures increased when compared to the as-spun ribbon. To avoid magnetic hysteresis losses in the vicinity of the structural transition region, the magnetic entropy changes-ΔS _m of the investigated ribbons were evaluated from temperature-dependent magnetisation-M(T) curves on cooling for different applied magnetic fields. The maximum ΔS _m value was found to be 6.79 J kg⁻¹ K⁻¹ for the quenched ribbon in the vicinity of structural transition region for a magnetic field change of 50 kOe.

Keywords:

• Heusler alloys
• magnetocaloric effect
• structural phase transition

Acknowledgements

Authors acknowledge the help of Ankara University Electron Microscopy Unit for SEM experiments.