Magnetostriction reduction and magnetic permeability enhancement of Ti added Fe0.7Co0.3 alloy

Abstract

The current work presents the study of three alloys, (1) the binary Fe0.7Co0.3 alloy (atomic fraction), (2) the addition of 3 at. % of Ti, and (3) the addition of 3 at. % of Ti and 1% of Nb. The interest is to increase the permeability of this binary alloy due to the additions of Ti and Nb, since Fe–Co alloys with Co content in the range of 27–35 at. % have much lower permeability than the commercial equiatomic alloy. The advantage of low Co Fe–Co alloys is the lower price compared to the equiatomic one. The alloys were produced by arc melting and were subsequently hot rolled and annealed in the final thickness at 1200 °C over 24 h. Microstructure characterization revealed single α-phased alloys with body centered cubic structures. Positive results were observed in the magnetic and electric properties of the (Fe0.70Co0.30)97Ti3 alloy compared to Fe0.7Co0.3, meaning the decreasing saturation magnetostriction λs, and the growth of the maximum relative permeability by 24% and of the resistivity by 63%, occurred without a change in the coercive field and in the maximum magnetic induction. The (Fe0.7Co0.3)97Ti3 alloy's maximum magnetic relative permeability is μrmax = 855 and occurs at a field of only 160 A/m, this field being more than two times lower compared to the one of the binary alloy. On the other hand, the addition of Ti + Nb has improved the deformation performance of the (Fe0.7Co0.3)97Ti3 alloy at high temperatures and did not change the magnetostriction, nor the resistivity. The quaternary alloy presents a maximum magnetic relative permeability of μrmax = 270 at 1960 A/m and a maximum magnetic induction reduced by 14% compared to the other two alloys.