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Amorphous FeCoCrZrB Ferromagnets for Use as High-Temperature Magnetic Refrigerants



Freemon Johnson, Robert D. Shull


Magnetic metallic glasses, having large magnetic moments and high Curie Temperatures (TC), have not been widely studied as magnetic refrigerants. In this study, we report on the magnetocaloric effects of five FeCoCrZrB amorphous alloys ((FexCoyCrz)91Zr7B2, with Fe:Co:Cr ratios of 100:0:0, 90:15:5, 85:5:10, and 75:15:10 chosen for efficiently surveying the high TC metallic glass composition surface. Magnetic isotherms were measured at 25 K intervals from 25 to 525 K. The entropy change (?S) due to the magnetocaloric effect was computed by integrating the magnetic isotherms. The refrigeration capacity (RC) was computed by the Wood and Potter method. At 5 Tesla the FeCoCrZrB alloys have RC values of 240-320 J/kg; at 1 Tesla the alloys have values of 32-54 J/kg. The RC values favorably compare with values reported for other refrigerant materials. The peak ?S temperature depends strongly on composition, varying from 200 to 450 K. The wide flexibility in choosing amorphous alloy compositions allows them to be fine tuned for multi-stage high temperature refrigerators. The saturation magnetization at 25 and 300 K and Curie temperatures are also reported for the five alloys.
Journal of Applied Physics


amorphous magnets, magnetic measurements, magnetic refrigeration, magnetocaloric effect


Johnson, F. and Shull, R. (2006), Amorphous FeCoCrZrB Ferromagnets for Use as High-Temperature Magnetic Refrigerants, Journal of Applied Physics, [online], (Accessed April 17, 2024)
Created April 26, 2006, Updated October 12, 2021