An Investigation On The Mechanism Of Magnetic Anisotropy Induced In Fe-based Ribbons During Current Stress Annealing

Fe-based soft magnetic alloy which is known as the best synthetic material.Because of its excellent soft magnetic properties which with high magnetic permeability and conductance,coercivity and loss is low.So is widely used in the power electronic field.The most representative application is in the transformer and motor.Theory predicts,compared with the traditional soft magnetic materials such as silicon steel,the Fe-based soft magnetic alloy should have significant advantages.But in practical application,transformer and motor which is prepared by Fe-based soft magnetic alloy is not reach the theory predict.Fe-based alloy soft magnetic alloy is sensitive to stress,the magnetic anisotropy will be induced effectivly when annealing under stress.But the stress inducing magnetic anisotropy mechanism hasn't been understood very well.The macro-strains of the Fe-based ribbons measured by tracing observation on the samples with gaosuo video in-situ monitoring systemduring during the joule heat stress annealing and multiple joule heat tempering.The micro-elongation and the lattice anisotropy of the a-Fe(Si)nanocrystaline in Fe-based ribbons during joule-heat stress annealing and multiple tempering measured with synchrotron radiation in situ measuring technology in Shanghai Synchrotron Radiation Facility(SSRF).The magnetic impedance of the samples was measured using an HP4294 impedance instrument and the magnetic anisotropy field was calculated from the giant magnetic impedance curve.Finally,The mechanism of stress induced magnetic anisotropy in Fe-based ribbons is analyzed.The results of the study are as follows:1.The significantly magnetic anisotropy induced after joule heat stress annealing.(1)The magnetic anisotropy induced during stress annealing the ribbons in the starting structure of cast amorphous(amorphous stress annealing)is linear with the annealing stress.The relationship is ?H? = 21? + 179.Elongation and stress is linear relationship ?l = 0.03?-0.045.(2)The magnetic anisotropy induced during the stress annealing ribbons in the starting structure of nanocrystalline,which is formed by free annealing in the cast amorphous,is linear with stress.The relationship is ?H? = 9.58? + 266.Elongation and stress is linear relationship ?l = 0.003?-0.24.2.Magnetic anisotropy field induced by stress annealing is difficult to eliminate use limited times of tempering.(1)In The same conditions,magnetic anisotropy field induced by amorphous stress annealing is 2.1 times than that induced by nanocrystalline stress annealing.Residual magnetic anisotropy field in the ribbons,which after amorphous stress annealing and tempering many times,is 2.5 times than that in the ribbons after nanocrystalline stress annealing and tempered many times.(2)The magnetic anisotropy field induced during amorphous stress annealing has been removed 73%and remains 27%after tempered many times.The magnetic anisotropy field induced during nanocrystalline stress annealing has been removed 78%and remains 22%after many times tempered.(3)The magnetic anisotropy induced during stress annealing can't be eliminated completely by meens of tempering.(4)The micro-elongation of amorphous stress annealing ribbons has been removed 2.9%after many times tempered and remains 97.1%.The micro-elongation of the nanocrystalline stress annealing ribbon has been removed 38.9%and remains 61.5%after many times tempered.3.Decline rate of Magnetic anisotropy field induced by stress annealing with tempering current.(1)the relationship of sidual magnetic anisotropy and tempering current,After fitting obtain ?= ? + be-n/c.(2)In the case of excess crystallization is not appear,The greater tempering current,the smaller the residual magnetic anisotropy field.But magnetic anisotropy field is not eliminate by tempering completely.(3)Tempering current less than annealing current,residual magnetic anisotropy field which is stable after tempering is 94.3%than the magnetic anisotropy field induced by stress annealing.Tempering current is greater than the annealing current,residual magnetic anisotropy which is stable after tempering is 26.5%than the magnetic anisotropy field induced by stress annealing..(4)When the tempering current density in 35.2?J?37.5,the greater release speed of the magnetic anisotropy.Tempering effect is the best.(5)When tempering current J ? 38.5.Excess crystallization occurred.4.The mechanism of stress induced magnetic anisotropy.Magnetic anisotropy induced after joule heat stress annealing is due to anelasticity and plastic deformation.Anelasticity induced lattice anisotropy can eliminate by tempering,Nanocrystalline lattice anisotropy by amorphous basal plastic deformation can not eliminate by tempering.Because of stress in nanocrystalline residual stress accounted for 78%,Creep(22%).Using tempering method to eliminate the stress have flaws.Induced magnetic anisotropy in the process of inhibition of amorphous soft magnetic properties.Need to develop new production process,this article research results have important guiding significance.