Study On Microstructure And Properties Of Fe₆₄Ni₁Al_4.5Cu_0.5Ga₂P_9.65B_9.6Si₃C_5.75 Under Magnetic Field Treatment

The unique atomic structure of amorphous alloy makes it superior to traditional materials in some properties.Fe-based amorphous alloys have been widely used for their excellent soft magnetic properties.Amorphous alloys obtained by quench cooling at a critical cooling rate has a large number of local stress and vacancy,which need to be treated in a relatively stable state.The magnetic pulse processing technology is simple and has obvious influence on the performance of the material.But under pulse magnetic field as a condition of amorphous processing research is not comprehensive.In-depth study is necessary.This article adopts Fe₆₄Ni₁Al_4.5Cu_0.5Ga₂P_9.65B_9.6Si₃C_5.75 Amorphous alloy thin belt prepared by rapid melt quenching on the rotating drum.Pulsed magnetic field treatment for it under different pulse times and different magnetic field intensity,and then subjected to crystallization treatment.The effects of different intensity and frequency of pulsed magnetic field on the microstructure and properties of Fe based amorphous alloys were studied using XRD,DSC,VSM and other materials testing and analysis methods.Respectively for Fe₆₄Ni₁Al_4.5Cu_0.5Ga₂P_9.65B_9.6Si₃C_5.75 amorphous alloy 300 times,500 times and 700 times magnetic pulse processing.The results show that the alloy still maintains the amorphous state,but the XRD figure shows the amorphous diffuse scattering peak intensity is lower than that of quenched,and some smaller peak position are raised.The thermodynamic parameters of DSC have been changed,The results show that the microstructure of the alloy has been changed after pulse magnetic field treatment.After the sample was crystallized,the average grain sizes of the pretreated samples 28.1nm,25.8nm and 23.9nm,respectively,less than the size of the sample without pretreatment 31.8nm.The types of crystallization phase are also different.With the increase of the number of magnetic pulses,the kinds of precipitates and the area of crystallization increased and the grain refinement.With different magnetic field processing on the alloy under 6T,7T and 8T,studies have shown that simply increase the intensity of magnetic field have not lead amorphous alloy crystallization.But,after magnetic field enhancement,the structural relaxation of amorphous alloy is more obvious.Alloy glass transition temperature Tg increases after pretreatment,crystallization start temperature Tx and peak temperature Tp decreased.After partial crystallization,specimen crystallization precipitation phase of different magnetic field strength is the same.But,the XRD analysis shows the inside of the specimen under high magnetic field treatment microscopic structure and organization is more complicated.The sample average grain size are 23.9nm,21.0nm and 19.5nm respectively,less than untreated sample.DSC test shows that the stronger of the magnetic field intensity,sample crystallization area is larger,which illustrate that nano grain size is smaller under the strong magnetic field treatment.VSM test results show that compared with the pretreated sample,the saturation magnetization Ms of the sample treated by the pulsed magnetic field is obviously increased,and the remanence ratio Mr/Ms and coercive force Hc decreased obviously.The results show that the pulsed magnetic field pretreatment improves the soft magnetic properties of amorphous /nanocrystalline alloys.With the increase of the number of magnetic pulses or the increase of the magnetic field strength,Ms and Hc showed an increasing trend,but the Mr/Ms was decreased.It show that the magnetic pulse pretreatment with increasing the magnetic field intensity or increasing the number of treatment is beneficial to improve the soft magnetic properties of the alloy.