Microstructure and soft magnetic properties of (Fe0.9Co0.1)(73.5)Si13.5B9-xNb3Cu1Gex nanocrystalline alloys

The nanocrystalline (Fe0.9Co0.1)(73.5)Si13.5B9-xNb3Cu1Gex, alloys were obtained by partial devitrification of their amorphous precursors. The influence of partial substitution of B by Ge on the microstrucural evolution of these alloys was studied by means of X-ray diffraction (XRD) and differential scanning calorimeter (DSC). The temperature dependence of initial permeability (mu(i)-T curves) for (Fe0.9Co0.1)(73.5)Si13.5B6Nb3Cu1Ge3 alloys heating cooling cycled at 450-650 degrees C was mainly measured. It was found that the Ge doping into (Fe0.9Co0.1)(73.5)Si13.5B9Nb3Cu1 alloy can reduce the onset primary crystallization temperature (T-x1), enlarge the interval temperature (Delta T-x) from 129 degrees C to 180 degrees C and improve the high temperature soft magnetic properties, especially for (Fe0.9Co0.1)(73.5)Si13.5B6Nb3Cu1Ge3 alloy. After annealed at 450-650 degrees C for the alloy with x = 3, the optimum high temperature magnetic softness was observed in 600 degrees C-annealed sample, the mu(i) above 1000 at 10 kHz can be kept up to 550 degrees C, which is due to the higher crystallization phase volume fraction and the thinner amorphous layer thickness and an enhancement of the exchange stiffness in the intergranular region.