Iron-rich (Fe1-x-yNixCoy)88Zr7B4Cu1 nanocrystalline magnetic materials for high temperature applications with minimal magnetostriction

Abstract

As inductor technology advances, greater efficiency and smaller components demand new core materials. With recent developments of nanocrystalline magnetic materials, soft magnetic properties of these cores can be greatly improved. FeCo-based nanocrystalline magnetic alloys have resulted in good soft magnetic properties and high Curie temperatures; however, magnetoelastic anisotropies persist as a main source of losses. This investigation focuses on the design of a new Fe-based (Fe,Ni,Co)88Zr7B4Cu1 alloy with reduced magnetostriction and potential for operation at elevated temperatures. The alloys have been processed by arc melting, melt spinning, and annealing in a protective atmosphere to produce nanocrystalline ribbons. These ribbons have been analyzed for structure, hysteresis, and magnetostriction using X-Ray diffraction, vibrating sample magnetometry (VSM), and a home-built magnetostriction system, respectively. In addition, Curie temperatures of the amorphous phase were analyzed to determine the best performing, high-temperature material. Our best result was found for a Fe77Ni8.25Co2.75Zr7B4Cu1 alloy with a 12 nm average crystallite size (determined from Scherrer broadening) and a 2.873 Å lattice parameter determined from the Nelson-Riley function. This nanocrystalline alloy possesses a coercivity of 10 A/m, magnetostrictive coefficient of 4.8 ppm, and amorphous phase Curie temperature of 218°C.

Nanocrystallites via Direct Melt Spinning of Fe77Ni5.5Co5.5Zr7B4Cu for Enhanced Magnetic Softness

“…It should be note that the data shown in Figure and are consistent with the XRD results of Knipling et al This is confirmed by the XRD results that all peaks are assigned to the cubic phase of α‐FeCo (Figure and ). These results indicate that the ribbon produced in this study has the same stoichiometry, as reported in the study by Knipling et al In particular, in a study by Martone et al, they investigated the effects of Ni and Co contents on the magnetic properties in Fe 77 Ni 5.5 Co 5.5 Zr 7 B 4 Cu 1 . By systematically varying Ni from 5.5 to 14.667 and Co from 5.5 to 7.333 (whereas Fe, Zr, B, and Cu contents remain the same), they found that the magnetic properties such as H c and M s are not significantly changed.…”