Effect Of Cryogenic And Magnetic Pulse Treatment On Fe-Based Amorphous Microstructure And Magnetic Properties

Iron-based amorphous alloys have special internal atomic structure and good soft magnetic properties,which have attracted wide attention from scholars at home and abroad,and iron-based amorphous materials have been applied in many fields.The iron-based amorphous alloys are obtained by rapid condensation and are in a metastable state,when external conditions change,the internal structure of the alloys will change.This paper mainly studies the effects of cryogenic and magnetic pulse pretreatment on iron-based amorphous alloys.In this paper,Fe₈₀Si₉B₁₁ amorphous alloy is used as experimental material,which is treated by cryogenic treatment and different magnetic pulse treatment,followed by crystallization annealing treatment to partially crystallization.The alloy is tested by XRD,DSC and VSM,and the experimental results are compared and analyzed.The effects of cryogenic and magnetic pulse treatment on the internal structure,thermodynamic parameters,crystallization process and magnetic properties of the alloy are investigated.XRD analysis of the cryogenically treated amorphous alloy,compared with the original quenched sample,the sample after cryogenic treatment is still amorphous,and there is a slight peak shape fluctuation in the image,but the overall variation is small.Through the DSC test,the glass transition temperature of the alloy increase about 1K,the crystallization start temperature and the crystallization peak temperature decrease about 1K.After treatment with different times and different intensity of magnetic pulse,the amorphous alloy has obvious peak shape fluctuation in XRD pattern.In DSC detection,the glass transition temperature of the alloy is increased 2-3K,and the crystallization start temperature and crystallization peak temperature are reduced 2-3K.With the increase of pulse number and pulse intensity,the trend of the peak shape fluctuation in XRD pattern and the thermodynamic parameters in DSC are more obvious.The two pretreatment methods have an effect on the internal structure of the amorphous alloy,forming a small number of atomic clusters,and have a certain effect on the crystallization process,which causes the thermodynamic parameters to change.After the crystallization annealing treatment,compared with the quenched sample,the precipitation phase of the sample after the cryogenic treatment in the XRD detection is the same,but the number of precipitated phases and the crystallization volume fraction are slightly increased,and the crystal grains are refined,the average grain size of quenching state sample is 41.2 nm,the average grain size of cryogenic sample is 35.7 nm.After the magnetic pulse treatment,the type of precipitated phase of the sample increases,and the number of precipitated phases and the crystallized volume fraction increase.After the magnetic pulse treatment with a pulse intensity of7T and a pulse number of 300,500 and 700,respectively,the average grain size of the sample is33.9 nm,31.4 nm,and 28.5 nm,respectively;After the magnetic pulse treatment with a pulse number of 700 and a pulse intensity of 6T,7T and 8T,respectively,the average grain size of the sample is29.7 nm,28.5 nm,and 27.2 nm,respectively,both of which are less than 41.2 nm.In the DSC test,both pretreatments cause the glass transition temperature of the alloy to rise,the crystallization start temperature and the crystallization peak temperature to decrease,and the exothermic peak region to decrease.The pretreatment affects the crystallization process of the amorphous alloy,the thermodynamic parameters change,the type and number of precipitated phase,the crystallization volume fraction and the grain size change.The results of VSM test after crystallization show that the saturation magnetization of the alloy after cryogenic treatment and magnetic pulse treatment increases 3-8 emu/g,and the residual magnetization,remanence ratio and coercivity decrease 7-18 emu/g、4%-11%、18-22 Oe,the soft magnetic propertie of the alloy is improved.The effect of magnetic pulse processing is more obvious in both cases,and the soft magnetic propertie of the alloy is further improved with the increase of the number and the intensity of pulses.