Melt The Pull Preparation Of Amorphous Soft Magnetic Alloy Fiber And Its Giant Magneto-impedance Effect

In 1992, Mohri and his co-workers first discovered the giant magneto-impedance(GMI) effect in FeCoSiB amorphous wires. Owing to various merits such as high sensitiveness, low saturation magnetic field, quick respondence and high stability, GMI effect shows attractive potential of application in the field of magnetic sensor and it has arose extensive attention among researchers. Considering that the wire shape amorphous alloy is one with the most notable GMI effect and its small size, low cost and high strength, it has even more enormous foreground of application.At present, the initial explanation of the physical mechanism of GMI effect has been established. Depending on the frequency of the driving AC current that flows through the samples, the GMI can be roughly separated into three different regimes:(1) In the low-frequency range of 1-10kHz, it is mainly due to magneto-inductive effect.(2)At higher frequencies up to a few MHz, the effect is basically caused by variations of the magnetic penetration depth due to strong changes of the effective magnetic permeability caused by an external magnetic field.(3)At very high frequencies of the order of GHz, strong changes of the sample's impedance occur owing to the ferromagnetic resonance.Our aim is to investigate the amorphous alloy fibers manufactured by melt-extraction method which are seldom studied. By improving existing single roller amorphous ribbon fabrication equipment, in addition to producing ribbons, we successfully produced amorphous fibers using melt extraction method which has not yet been reported in our country. XRD, TGA and DSC analysis indicate the wires have good amorphous characteristics. Low frequency GMI measurements after longitudinal AC and pulse current Joule-heat treatments indicate that the heat treatment has obvious influence on GMI effect, which showed diversified characters. We have attempted to explain the physical mechanism of some of the results, to deepen the understanding of GMI phenomena and benefit the future works on better GMI materials.