Effect of Ti on structure and soft magnetic properties of Si-rich Finemet-type nanocrystalline Fe73.5Cu1Nb3-xSi17.5B5Tix alloys

Abstract

Fe73.5Cu1Nb3-xSi17.5B5Tix (x = 0, 1, 2, 3) amorphous alloys were prepared by the single roller melt spinning method. The effects of Ti substitution for Nb on the crystallization behavior, microstructure and soft magnetic properties were investigated. Compared to the previously reported Finemet alloy, the onset primary crystallization temperature Tx1 becomes lower which has dropped from 803K to 758K. The crystallization temperature interval ΔTx increases from 468K to 488K as the x increases from 0 to 3. However, the Curie temperature of amorphous phase shows a downward tendency with the increase of Ti content. Compared to the previously reported Finemet alloy, the μi increases obviously to more than 18,000 at x = 1, the Hc decreases from 0.59 Oe to 0.54 Oe. When Ti replaces Nb completely, the optimum annealing temperature range for precipitating single soft magnetic phase is enlarged, but the permeability at room- and high-temperature is deteriorated, the reason of which was also analysed.