Tailoring of magnetoimpedance effect and magnetic softness of Fe-rich glass-coated microwires by stress- annealing

Abstract

There is a pressing need for improving of the high-frequency magneto-impedance effect of cost-effective soft magnetic materials for use in high-performance sensing devices. The impact of the stress-annealing on magnetic properties and high frequency impedance of Fe-rich glass-coated microwires was studied. Hysteresis loops of Fe-rich microwires have been considerably affected by stress- annealing. In stress-annealed Fe- rich microwire we obtained drastic decreasing of coercivity and change of character of hysteresis loop from rectangular to linear. By controlling stress-annealing conditions (temperature and time) we achieved drastic increasing (by order of magnitude) of giant magnetoimpedance ratio. Coercivity, remanent magnetization, diagonal and of-diagonal magnetoimpedance effect of Fe-rich microwires can be tuned by stress-annealing conditions: annealing temperature and time. Observed experimental results are discussed considering relaxation of internal stresses, compressive “back-stresses” arising after stress annealing and topological short range ordering.

Direct Magnetoelectric Effect in a Sandwich Structure of PZT and Magnetostrictive Amorphous Microwires

“…The saturation magnetostriction λ s increased by an order of magnitude after glass removal. This could be explained by stress-dependence of λ s [21] and substantial decrease in the internal stress when the thermoelastic stress caused by glass coating was released. When the glass was removed after the as-cast wire was annealed (S4) the bi-stability was restored but the rotational portion of the magnetization loop was still present.…”

“…We will further demonstrate that the ME effect increases when the annealed wires without glass are used (although quite similar for wires annealed either before glass removal or after). The wire magnetic behavior could be further refined by changing the post-production treatments [20,21].…”

Stress-Induced Magnetic Anisotropy Enabling Engineering of Magnetic Softness and GMI Effect of Amorphous Microwires

“…Different values of mechanical loads allowed us to apply tensile stresses during the annealing, σ a , up to 900 MPa. The stress value during the annealing, σ a , within the metallic nucleus and glass shell was evaluated, as described elsewhere [38,39].…”

“…Besides these technical features, the overall cost should be also considered for applications (e.g., smart composites with wire inclusions) where substantial amounts of wires are required.Excellent soft magnetic properties with enhanced GMI effects are usually reported for as-prepared Co-rich [11][12][13][14][15] and nanocrystalline Fe-rich magnetic microwires [36,37]. The latter are often accompanied with an inherent brittleness of samples over the course of the nanocrystallization process, and therefore alternative stress-annealing approaches have been proposed, to enhance the GMI effect retaining the amorphous structure [38,39]. Stress-annealing can be performed in a temperature range well below the crystallization onset.…”

Магнитная Анизотропия И Сверхвысокочувствительный Стресс-Магнитоимпеданс В Микропроводах С Положительной Магнитострикцией

“…В случае цилиндрической геометрии проводника при токовом отжиге одновременно действуют тепловой и магнитный факторы, причем магнитное поле способствует магнитному упорядочению в циркулярном направлении. Так, например, токовый отжиг и отжиг в присутствии растягивающих напряжений использовались авторами [16,17] для изменения легкой оси анизотропии в проводах на основе Fe с положительной магнитострикцией с целью усиления эффекта МИ в этих недорогих материалах.…”