Amorphous-FeCoCrZrB ferromagnets for use as high-temperature magnetic refrigerants

Abstract

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 25K intervals from 25to525K. The entropy change (ΔS) due to the magnetocaloric effect was computed by integrating the magnetic isotherms. The refrigeration capacity (RC) was computed by Wood-Potter method. At 3979kA∕m (50kOe) the FeCoCrZrB alloys have RC values of 240–320J∕kg; at 796kA∕m (10kOe) the alloys have values of 32–54J∕kg. The RC values favorably compare with values reported for other refrigerant materials. The peak ΔS temperature depends strongly on composition, varying from 200to450K. The wide flexibility in choosing amorphous alloy compositions allows them to be fine tuned for multistage high temperature refrigerators. The saturation magnetization at 25 and 300K and Curie temperatures are also reported for the five alloys.

Influence of La and Ce additions on the magnetocaloric effect of Fe–B–Cr-based amorphous alloys

“…With 5% Ce added to Fe 80 B 12 Cr 8 , T pk could be tuned near room temperature with relatively constant peak ⌬S M . Fe 79 B 12 Cr 8 La 1 exhibited enhanced RC compared to Gd 5 Si 2 Ge 1. 9 Fe 0.1 .…”

“…They offer low magnetic hysteresis, high electrical resistivity, enhanced corrosion resistance, good mechanical properties, and tunable T C by composition variation. [4][5][6] In addition, the elements involved are abundant and fabrication costs are reasonable, making them highly competitive. Fe 80 Cr 8 B 12 amorphous alloys exhibit promising MCE near RT, Cr additions enhance the corrosion resistance of the alloy.…”

A constant magnetocaloric response in FeMoCuB amorphous alloys with different Fe∕B ratios

“…8 Recently, there is a growing interest in studying the applicability of soft magnetic amorphous alloys as magnetic refrigerants. [9][10][11][12][13][14][15][16] Albeit the maximum magnetic entropy change, ͉⌬S M pk ͉, for these alloys is modest when compared to that of rare-earth-based materials, the remarkable difference in material costs is an incentive for studying their suitability as magnetic refrigerants. Besides their reduced magnetic hysteresis ͑virtually negligible͒, the high electrical resistivity ͑which would decrease eddy current losses͒, tunable Curie temperature, and, in the case of bulk amorphous alloys, [17][18][19][20] outstanding mechanical properties are beneficial characteristics for a successful application of the material.…”

Enhanced magnetocaloric response in Cr∕Mo containing Nanoperm-type amorphous alloys

“…In particular, there is a growing interest in studying the applicability of soft magnetic amorphous alloys as magnetic refrigerants [9][10][11][12][13][14][15][16][17][18][19][20] due to their reduced magnetic hysteresis ͑vir-tually negligible͒, higher electrical resistivity ͑which would decrease eddy current losses͒, and tunable Curie temperature T Curie . Among the different compositional series of soft magnetic amorphous alloys, Nanoperm-type alloys are those that currently exhibit the highest RC values, having also among the highest values of ͉⌬S M pk ͉.…”