Stress annealing effect on the piezomagnetic coefficient of Fe–Al–B alloys.

Abstract In the present work are reported the stress annealing (SA) effect on magnetic properties of Fe–Al–B alloys and the result on the piezomagnetic coefficient d 33 ⁎ = d B / d σ | H , where σ is the applied stress, B is the magnetic induction and H is the applied magnetic field. The objective is to evaluate the potential use of these alloys as smart materials of force sensors. The study comprises two alloys with compositions (Fe 0.87 Al 0.13) 98.4 B 1.6 (Al13) and (Fe 0.82 Al 0.18) 98.4 B 1.6 (Al18). The microstructure, hysteresis loops and B vs. σ | H were analyzed before and after the SA. Regarding the force sensitivity, the SA increased the piezomagnetic coefficient d 33 ⁎ due the introduction of an extrinsic anisotropy in both Fe–Al–B alloys. Moreover, the stress range, in which the piezomagnetic coefficient d 33 ⁎ is linear, is higher after the SA. Concerning the single phase (Fe 0.87 Al 0.13) 98.4 B 1.6 alloy, the force/pressure sensitivity and the linear stress range increase up to 16.8% and 47.1%, respectively. For the two phase (Fe 0.82 Al 0.18) 98.4 B 1.6 alloy, the increase was a bit higher, but the curves B vs. σ are hysteretic, spoiling the use of this material as a force sensor component. Highlights • Sensitivity of Fe–Al–B alloys for force sensor application was improved by stress annealing. • A barely linear dependence of the magnetic induction B as a function of the stress σ was obtained for small and constant magnetic field. • The single phase (Fe 0.87 Al 0.13) 98.4 B 1.6 alloy exhibits the best properties for force sensor application, since B vs. σ curves are not hysteretic. • Hysteresis on B vs. σ curves of (Fe 0.82 Al 0.18) 98.4 B 1.6 alloy is associated with a biphasic microstructure, wherein the second phase was induced by stress annealing. [ABSTRACT FROM AUTHOR]