Effects of Nb content on the microstructure and magnetic properties of Fe-6.5wt.%Si alloy

The effects of adding different contents of Nb on microstructure and magnetic properties of Fe-6.5wt.%Si alloy were investigated. The results show that the addition of a suitable amount of Nb to Fe-6.5wt.%Si alloys has improved the ductility of the alloy by precipitating Nb-Fe-Si intermetallics. The precipitated Nb-Fe-Si particles have refined the grains and lowering the Si content in the matrix, the latter effect has resulted in the reduction of the ordered phases or the degree of long range order in the alloy. However, when the Nb content is 2.0wt.%, the numbers of precipitates are too high and starting to pin the movement of dislocations, which has an adverse effect on the processability of the alloy. Though the Fe-6.5Si-1.5Nb (wt.%) alloy showed better magnetic properties than the Fe-6.5Si-2.0Nb (wt.%) alloy, the addition of Nb would deteriorate the magnetic properties of Fe-6.5wt.%Si alloy. Thus, the addition of Nb should be less than 1.5 wt.% to balance the processability and magnetic properties of Fe-6.5wt.%Si alloy.