Effect of Si and Al content on core loss in Fe-Si-Al powder cores

We examined the effects of Si and Al content of Fe-Si-Al alloy powders with respect to the temperature dependence of core loss in order to find an optimum composition that achieves both negative temperature dependence of core loss and good permeability. By reducing the Si content from the 9.6 mass% of conventional Sendust alloy composition to 7.9-8.9 mass%, the temperature dependence of core loss became negative and maintained the high permeability of the Sendust powder core. The optimum composition was 8.8 mass% Si and 6.0 mass% Al, yielding a core loss value of 240 kW/m³ at 373 K, about half that of the conventional Sendust powder core.