Effect of gd substitution on the structural, magnetic, and magnetocaloric properties of Fe68Tb5B23Nb4 metallic glass

Abstract

The effects of adding Gd on the Curie temperature (T-c), glass-forming ability (GFA), and magnetocaloric effect (MCE) were studied in Fe68-x ,GdxTb5B23Nb4 (x = 0, 2, and 6) glassy alloys prepared by suction casting. It was shown that when Gd content was exchanged with Fe partially for x = 2, GFA was increased, whereas for x = 6, adding Gd content has reduced the GFA and amorphous structure could not be obtained. Critical diameter was found to be 3 mm for Fe66Gd2Tb5B23Nb4 bulk metallic glass (BMG). By exchanging Gd with Fe partially, T c could effectively be tuned in a quite broad temperature interval from 487 K (x = 0) to 380 K (x = 6) for which amorphous structure could not be obtained. Maximum magnetic entropy change (-Delta S-M)(max) values were found to be 1.16, 0.84 Jkg(-1)K(-1), and 0.54 Jkg(-1)K(-1) as well as, refrigeration capacity (RC) values were obtained as 116 J/kg, 84.84 J/kg, and 40.50 J/kg under a low field change of 2 T for x = 0, 2, and 6, respectively. Although T c was shifted to lower temperatures by exchanging Fe with Gd partially, -(Delta S-M)(max )decreased almost half of the base alloy and RC decreased approximately 1/3 of the base alloy.