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

The mechanism of stress induced magnetic anisotropy is an important basic science problem which has been investigated extensively.The researchers tried to solve the problem by using different experimental methods to establish different theoretical models.Design and preparation of stress annealing in situ observation device.According to the longitudinal giant magneto-impedance effect curve of Fe73.5Cu1Nb3Si13.5B9 ribbon samples which has been annealed and tempered we get the magnetic anisotropy field,at the same time monitoring ribbon elongation under applied stress.Gather the micro data By using Shanghai Synchrotron Radiation Facility(SSRF)BL14B—Hard X-ray micro focus and applied the beam line station.Analysis of the magnetic anisotropy induced by stress,the elongation data,and the change rule of microstructure,get the conclusion as follows:1.The character of magnetic anisotropy induced by stress annealing for Fe-based alloy ribbon(1)The annealing stress σ has a linear relationship with the induced magnetic anisotropy H and satisfy the equation:H=13.1σ + 3 87.(2)The induced magnetic anisotropy field can be reduced by tempering,but can’t completely eliminate the magnetic anisotropy field.The residual magnetic anisotropy field is hard to eliminate,which makes up 25.1%of the induced magnetic anisotropy field.The residual magnetic anisotropy field has a exponential attenuation relation with tempering and satisfy the relation:α = 19.0e-n/2.9 +25.1.(3)Annealing at 200Mpa、540 ℃,the magnetic anisotropy field of the stress annealing samples are taken from the amorphous initial state is 1.68 times than the magnetic anisotropy of the stress annealing samples are taken from nanocrystalline initial state.The ratio of the residual magnatic field is 2.12 after multiple tempering.2.The flexibility of Fe-based alloy ribbon during the process of stress annealing and tempering (1)A linear relationship with annealing stress σ and the elongation of ribbon l,satisfy the equation:l = 0.021 σ-1.16.(2)Tempering can not make the ribbon back to before,plastic deformation section of amorphous creep part can not be eliminated,many times after tempering the residual creep into 74.4%,the residual creep and tempering times has the relation:β = 24.9e-n/5.9 + 74.4.3.The synchrotron radiation research of stress annealing(1)Lattice anisotropy induced by stress annealing,the difference of parallel and vertical is 0.00895A after stress annealing at 200MPa and 540℃.(2)Lattice anisotropy induced by stress annealing decrease after tempering.For the first time after tempering the residual lattice anisotropy is 51%,the second residual lattice anisotropy was 42%.(3)Annealing at 200MPa、540 ℃,the lattice anisotropy of the stress annealing samples are taken from the amorphous initial state is 1.35 times than the lattice anisotropy of the stress annealing samples are taken from nanocrystalline initial state.4.The mechanism of magnetic anisotropy induced by stress annealingThe magnetic anisotropy of stress annealing is composed of two parts,one(74.4%)is lattice anisotropy of anelastic deformation that can be reduced by tempering.The other part(25.1%)is transverse magnetic couping induced by nanocrystalline distribution anisotropy that can not reduced by tempering.