Microstructures, Thermal Property And Magnetic Property Of Fe(co)-based Alloys

Among the Fe-based soft magnetic nanocrystalline systems, considerable attention isdevoted to the Fe-M-B type alloys (where M=Zr, Hf and Nb). It has large magneticpermeability, large saturation inductions Bs, low coercivities Hc, low loss, good frequencydispersion property. Fe80Zr10B10, Fe93-xZr7Bx(x=10,12,14), Fe80-xCoxZr10B9Cu1(x=0,10,20,30,40) and Fe40Co40Zr(10-x)MoxB9Cu1(x=0,2,4) alloys were prepared by melt-spinningmethod in this paper. The microstructure, thermal property and magnetic property wereinvestigated by X-ray diffraction (XRD), transmission electron microscopy (TEM),differential thermal analysis (DTA) and vibrating sample magnetometer (VSM). The mainresults are as follows:(1) The crystallization process of Fe80Zr10B10alloy changes intricately.The α-Fe phase isobserved in Fe80Zr10B10alloy annealed at550oC for1min. After annealing at600oC for1min,the α-Fe phase and the χ phases (α-Mn type phases) are observed in the Fe80Zr10B10alloy inthe initial crystallization stage. The α-Mn type phase is metastable phase. The increase ofannealing time leads to the χ phases (α-Mn type phases) transforms to α-Fe phase. The LavesC14(λ) phase is observed after annealing at650oC for1min. The increase of annealing timeleads to the Laves C14(λ) phase transforms to α-Fe, Fe3Zr and Fe2Zr phases are observed inFe80Zr10B10alloy. The coercivity (Hc) and saturation magnetization (Ms) of alloys afterdifferent annealing temperature changed with their different crystallization product.(2) The first crystallization peak temperature increases with increasing B content. Onlythe α-Fe phase is observed in the Fe83Zr7B10alloy. Both the α-Fe and Fe23B6phases areobserved in the Fe93-xZr7Bx(x=12,14) alloys. Msof three kinds of as-quenched alloys allincrease with increasing B content. After annealing at temperatures above823K, Msof threekinds of alloys decrease with increasing B content. Above773K, Hcof three kinds of alloysincrease with increasing B content.(3) On the basis of Fe80Zr10B10alloy, Fe80Zr10B9Cu1alloy is prepared. Adding Coelements instead of Fe, Fe80-xCoxZr10B9Cu1(x=0,10,20,30,40) alloys are prepared. Theapparent activation energies are318.15,304.49,226.75,386.97and267.03kJ/mol, respectively. The increase of Co content changes the crystallization process. Thecrystallization processes of Fe80-xCoxZr10B9Cu1(x=0,10,20) alloys are similar: amorphousâ†'amorphous+α-Fe(Co)â†'α-Fe (Co)+Fe3Zr+ZrFe2+Fe3B; The crystallization processes ofFe80-xCoxZr10B9Cu1(x=30,40) alloys are: amorphous+α-Fe(Co)â†'amorphous+α-Fe(Co)+α-Mn typeâ†'α-Fe+Fe(Co)3Zr+ZrFe2; amorphousâ†'amorphous+α-Fe(Co)â†'α-FeCo+ZrCo3B2+Fe(Co)3Zr, respectively.(4) Adding Mo element on the basis of Fe40Co40Zr10B9Cu1alloy, Fe40Co40Zr(10-x)MoxB9Cu1(x=0,2,4) alloys were prepared. The apparent activation energies are303.76,247.27and244.05kJ/mol, respectively. Mo addition reduces the thermal property of the alloys,inhibits the precipitation of ZrCo3B2compounds and reduces the Hcobviously.