Vacuum hot pressing of Fe–Si–B–Nb-based amorphous powder cores and their high-frequency magnetic properties

Abstract

FeSiBNb amorphous powder was prepared by gas atomization and subsequently consolidated into bulk amorphous cores by hot pressing after creating an oxide layer on the surface of the powder. FeSiBNb amorphous powders exhibiting a saturation magnetization of 127emu∕g and a coercivity of 0.34 Oe were successfully obtained by gas atomization. Hot pressing enabled consolidation of the FeSiBNb amorphous powder core within the supercooled liquid region. The core prepared from the FeSiBNb amorphous powder covered with an oxide layer of 1μm thickness showed excellent high-frequency characteristics with a stable permeability over 10 MHz and a core loss of 400mW∕cm3 at 50 kHz for Bm=0.1T. The oxide layer formed on the FeSiBNb amorphous powder was effective in improving the frequency dependence of magnetic properties and in reducing the core loss for the FeSiBNb amorphous powder cores.