Improving magnetocaloric properties of Fe_68–xCr_xTb₅B₂₃Nb₄(x= 0, 2, 4, 6 and 8) metallic glasses having high glass-forming ability with tunable Curie temperature

The impacts of adding Cr on the Curie temperature (TC), glass-forming ability (GFA), and magnetocaloric effect were studied in Fe68−xCrxTb5B23Nb4 (x = 0, 2, 4, 6 and 8) metallic glasses prepared by suction casting. GFA depends on Cr content in the composition. For Fe68−xCrxTb5B23Nb4 bulk metallic glasses (BMGs), with critical diameters up to ~3 mm can be produced by suction casting and maximum value of GFA was found for x = 6. By exchanging Cr with Fe partially, TC could effectively be adjusted in a quite broad temperature interval from 487 K for x = 0 to 267 K for x = 8, whereas maximum magnetic entropy change decreased from 1.16 to 0.53 Jkg−1 K−1 and refrigeration capacity (RC) changed from 116 to 45.05 J/kg under a low field change of 2 T. Though TC is shifted to room temperature, maximum magnetic entropy change and RC decreased almost half of the base alloy. To enhance these properties (Fe0.62Cr0.06Tb0.05B0.23Nb0.04)100−yCuy (y = 0.75, 1), metallic glasses are prepared. By the help of small addition of Cu, magnetocaloric properties can be effectively increased without changing the TC. These findings show that the successful synthesis of the Fe-based Fe62Cr6Tb5B23Nb4 and (Fe0.62Cr0.06Tb0.05B0.23Nb0.04)100−yCuy (y = 0.75, 1) BMGs near room temperature, could be considered as promising candidates as magnetic refrigerant materials.