Magnetocaloric effect in amorphous and nanocrystalline Fe81−xCrxNb7B12 (x = 0 and 3.5) alloys

The magnetocaloric effect in series of amorphous and nanocrystalline Fe81−xCrxNb7B12 (numbers indicate at.%, x = 0 and 3.5) samples has been studied by evaluating the magnetic entropy changes, ΔSm, from magnetization data. The addition of chromium to the ternary Fe81Nb7B12 alloy results in a decrease of the Curie temperature of amorphous sample, Tc(am), from 363 to 279 K, which makes this Cr containing alloy an interesting material for potential magnetic refrigeration applications near room temperature. Upon magnetic field change from 0 to 0.7 T, the maximum entropy change located at the Tc(am) of non-crystallized ribbons has been found to be about 0.7 J kg−1 K−1. The progressive nanocrystallization of amorphous samples results in a more diffuse ferro-/paramagnetic transition, which causes a decrease of the magnetic entropy changes and at the same time the ΔSm peak becomes broadened. The observed ΔSm values compare favorably with other amorphous Fe-based alloys.