Low-frequency core losses of zero-magnetostriction nanocrystalline soft-magnetic Fe-Zr-Si-B alloys

The development of nanocrystalline alloys showing soft-magnetic properties, such as high saturation magnetization (B-s), high permeability (mu), low coercivity (H-c), and very small magnetostriction (lambda(s)), is the subject of an increasing interest. Materials showing both high saturation magnetization and near-zero magnetostriction are very attractive for applications in particular for microelectronics and power transformers. Recently, it has been shown that rapidly quenched Fe-Zr-B-Si and Fe-Zr-B-Al alloys with subsequent thermal annealing have many of these magnetic properties[1]. In this paper, we present results on the microstructure and magnetic properties of Fe-Zr-Si-B metallic glasses produced using the melt-spinning technique. The best magnetic properties (B-s = 1.54 T, H-c = 38 A/m, and lambda(s) = 0) are obtained for annealing temperatures in the range between 550 degrees C, where a nanocrystalline bcc-Fe phase is first formed, and 700 degrees C, which is near the onset of crystallization of the remaining amorphous phase.