Low-Frequency Magnetic Pulsing Effect As Well As EET Study Of Amorphous Alloy Fe₄₃Co₄₃Hf₇B₆Cu₁

FeCo-based nanocrystalline soft magnetid materials have perfect magnetics, such as high permeability, high magnetic induction intensity, low coercive force, low dissipation, high Curie temperature and so on. Therefore, the research on the formation and properties of the FeCo-based nanocrystalline soft magnetid materials has attracted widespread attention in recent years and become a focus in high temperature soft magnetid materials.Firstly, chemical constituents of Fe(Co)-Hf-B-Cu alloys were designed in this paper, and then Fe43Co43Hf7B6Cu1 alloy ribbons were prepared by melt spinning of single roll casting method. The obtained thin tape in 30～40μm, width in about 3 mm. The composite characterization of prepared sample by XRD, Mossbauer spectrum and DSC. The results indicate that alloy ribbons are amorphous state, Tg=379.80℃, TX=472.99℃,Tp1=509.95℃, Tp2=620.72℃,Tp3=712.03℃etc.The amorphous thin ribbons were treated by low-frequency magnetic pulsing:pulse magnetic field from 148Oe to 379Oe, pulse frequency from 10-40Hz and processing time from 60-240s. Experimental results showed that the maximum temperature risingΔt in the LFPMF treatment process is no more than 10℃, and the internal and external temperature rising did not show significant difference. There did not exist high temperature or transient high temperature and temperature uniformity was good. The microstructures of treated samples were examined by XRD and Mossbauer spectra:The low frequency magnetic pulse can lead to the initial crystallization of Fe43Co43Hf7B6Cu1 amorphous alloys, The crystallized quantity varied from 2.249～10.969%. With the increasing of the pulse magnetic field or the processing time the amount of the crystallization present increasing trentency, There is not linear relationship between the crystallized quantity and pulse frequency, but is increasing at beginning then reducing. Preliminary research on the soft magnetic property of the treated and untreated alloys by LFPMF indicate thatσs and Hc of the treated alloys were pushed compared with as-quenched, Mr of the treated alloys were reduced, The soft magnetid properties of samples treated by LFPMF were improved. The soft magnetic property is optimum when crystallized quantity is 5.057%, corresponding H=222Oe, f=40Hz, t=240s.The covalence electronic structures of amorphous and crystalline phases before and after LFPMF treatment were calculated using the bond length difference (BLD) method in the empirical electron theory (EET). According to the atoms proportions and the contribution of each cell iron and cobalt atoms to the magnetic moment of the Fe43Co43Hf7B6Cu1 alloy. The magnetic moment per unit mass of amorphous phase was calculated as 159.7978emu/g, and that of crystallized phase was 184.2174emu/g. Then the magnetic moment of the double-phase alloys after the crystallization by LFPMF treatment was calculated, and compared with experimental values. The error of these two is less than 10%.