Magnetocaloric difference between ribbon and bulk shape of Gd-based metallic glasses

In this work, magnetocaloric properties of the as-cast rods and melt-spun ribbons for Gd-based metallic glasses are investigated. Different magnetocaloric responses in the rods and ribbons are observed and discussed. Under a magnetic field change of 5 T, maximum magnetic entropy change (-Delta S-M(max)) values of 8.7 and 9.1 Jkg(-1)K(-1) are obtained for the as-cast Gd55Co19Al24Si1Fe1 and Gd20Dy20Er20Co20Al20 rods, which are obviously larger than those of 7.8 and 7.7 Jkg(-1) K-1 for their ribbon counterparts, respectively. In addition, the as-cast rods show obviously larger exponent n values compared with the melt-spun ribbons, i.e., the -Delta S-M(max) increases faster with increasing applied magnetic field. The magnetocaloric difference is analyzed and can be mainly attributed to the effects of the demagnetizing field, the oxide existence and the microstructural differences in ribbons and rods. The glassy rods exhibiting larger magnetocaloric effect are more attractive for the application of magnetic refrigerants.