ON THE TABLE-LIKE MAGNETOCALORIC EFFECT, MICROSTRUCTURE AND MECHANICAL PROPERTIES OF LAXFE11.6 SI1.4 SYSTEM

Abstract

The structural, microstructural, magnetic and mechanical properties of LaxFe11.6Si1.4 (x = 1.3, 1.7) alloys prepared by arc melting have been studied. The Rietveld refinement of the X-ray diffraction (XRD) patterns shows that increasing La content leads to increase in secondary phases and decrease in 1:13 phase from 88% to 71%. Thermomagnetic measurements show that there is not much change in the Curie transition, however the thermal hysteresis increases with the increase in La content. Table like magnetocaloric effect was observed from 180 K to 200 K in both the alloys. A magnetic entropy change of 19.73 J/kg-K and 15.24 J/kg-K were observed at a low field change of 1 T in La1.3Fe11.6Si1.4 and La1.7Fe11.6Si1.4 alloy respectively. The magnetic entropy change further increases to 23.48 J/kg-K at 183 K and 19.51 J/kg-K at 180 K under an applied filed change of 7 T and the effective magnetic refrigeration capacity was found to be 672 J/kg and 581 J/kg in La1.3Fe11.6Si1.4 and La1.7Fe11.6Si1.4 alloys respectively at a field change of 7 T. The adiabatic temperature was found to be 1.16 K and 2.45 K under a field change of 1 T and increases to 6.05 K and 8.13 K at an applied field change of 7 T in La1.3Fe11.6Si1.4 and La1.7Fe11.6Si1.4 alloy respectively. Increase in La content leads to increase in the mechanical strength suggesting better machinability, thus making them suitable for viable magnetic refrigeration applications.