| Due to its excellent soft magnetic properties,such as high initial permeability(?i),]ow coercivity(Hc),high saturation magnetization(Ms)and low loss(W),the Fe-rich amorphous/nanocrystalline alloys have been used widely as the magnetic materials for designing reacter,transformer,inventer,sensor,filter,inductor and so on.In the electric area,these alloys have successfully attracted an extensive attention by its potential possibility of substituting Si steels.However,these alloys are kept in its initially developing stage,it dues to the high content of Fe and the lack of big size metal atoms,the former which makes the fabrication of the amorphous ribbons becomes more difficult,while the later leads to a difficult control of the a-Fe crystallization and which further could easily induce the precipitation of Fe-B or Fe-(B,P)compounds.Therefore,it is meaningful for academic research and industrial application to develop some new-style Fe-rich amorphous/nanocrystalline alloys,with a aim that the alloys will be easily formatted,easily controlled of the a-Fe crystallization and easily obtained the excellent magnetic properties.In the paper,based on the theories of Inoue,the new-style Fe-rich amorphous alloys were designed by elements substituting and micro alloying,such as Fe-B-Cu system with adding Hf,Fe-B,Cu-Hf system with adding Si,Fe-B-Cu-Hf system with adding P and Fe-B-P-Cu-Hf with adding P.Then,the ribbons were fabricated by the single roller melt-spinning equipment,and the effects on glass forming ability(GFA),thermal stability,crystallization behaviors,precipitation phases and soft magnetic properties of the casting ribbons were investigated by X-ray diffraction(XRD),differential scanning calorimetry(DSC),vibrating sample magnetometer(VSM)and so on.Major conclusions as follow:(1)For Fe86B13Cu1 alloys,the addition of Hf is beneficial for improving the glass forming ability(GFA)and thermal stability simultaneously.The Fe86B13Cu0.5Hf0.5 and Fe86B13Cu0.4Hf0.6 casting ribbons show an entirely amorphous matrix,which exhibit a two-step crystallization process and a big initial crystallization temperature range of ?-Fe and Fe-B crystallization peaks.For both Fe86+a(B13Cu0.5Hf0.5)14-a and Fe86+b(B13Cu0.4Hf0.6)14-b system alloys,by increasing more content of Fe,the Fe86.2(B13Cu0.5Hf0.5)13.8 and Fe86.8(B13Cu0.4Hf0.6)13.2 casting ribbons can still keep an entirely amorphous matrix,and the Fe86B13Cu0.4Hf0.6 alloy shows a better GFA,compared to Fe86B13Cu0.5Hf0.5.(2)Annealing by Ta = 798K × 10min,the Fe86B13Cu0.5Hf0.5 alloy begins to precipitate Fe-B compounds,while the Fe86B13Cu0.4Hf0.6 alloy still keeps on the crystallization of a-Fe phase steadily.Both casting ribbons show a relative lower Ms,after annealing,Ms values show a fast increase and reach to the maximum approximately 206.3emu/g and 208.2emu/g as Ta = 723K,respectively;by the second annealing with magnetic field(1000Gs/673K),the alloys show a low Hc values about 2.8A/m and 2.3A/m,respectively.The Fe86B13Cu0.4Hf0.6 amorphous alloy shows a more easily control of a-Fe crystallization and is easy to get an excellent magnetic properties.(3)For the Fe86B13-cSicCu0.4Hf0.6 alloys,as c = 0.25,0.5,0.75,the casting ribbons show an entirely amorphous matrix and the alloys exhibit a good GFA.By adding minor Si,the amorphous matrix shows a lower crystallization temperature of a-Fe phase and a higher crystallization temperature of Fe-B phase,indicating the decrease of the crystallization temperature range,later,which show an increase trend by adding more Si.The Ms values of the casting ribbons are relative lower,but which increase quickly by the subsequent annealing and reach to the maximum approximately 207.3emu/g,208.5emu/g and 207.7emu/g,respectively,as the annealing temperature near Tpl;after the second annealing with magnetic field(1000Gs/673K),the alloys show a low H,values about 2.3A/m,2.5A/m and 2.8A/m,respectively.(4)For the Fe86B13-dPdCu0.4Hf0.6 alloys,as d = 0.5,1.0,the casting ribbons can easily get an entirely amorphous structure,the initial crystallization temperature range of ?-Fe and Fe-B crystallization peaks are 143K and 146K,respectively.During annealing,the amorphous matrix precipitates a-Fe phase first,and then the precipitation temperature of Fe-(B,P)phase shows a decrease trend to the increasing content of P.the Ms values of the casting ribbons are relative lower,but which also show an fast increase by the subsequent annealing and reach to the maximum about 208.1 emu/g and 206.3emu/g,respectively,as the annealing temperature near Tpl;after the second annealing with magnetic field(1000Gs/673K),the alloys show a low H,about 3.1A/m and 3.7A/m respectively.(5)For the Fe86B12SieP1-eCu0.4Hf0.6 alloys,as e = 0.25,0.5,0.75,the casting ribbons show an entirely amorphous structure.By adding minor Si,the amorphous matrix shows a lower a-Fe crystallization temperature and a higher Fe-B crystallization temperature,with adding more Si,the annealing temperature range of both crystallization phases are stably kept approximately 160K.For these amorphous alloys,by Kissinger equation,the apparent activation energy of a-Fe crystallization peak is double to that of Fe-(B,P)crystallization peak.The Ms values of the casting ribbons are relative lower,but which increase rapidly by the subsequent annealing and reach to the maximum approximately 212.3emu/g,214.2emu/g,214.9emu/g,respectively,as the annealing temperature near Tp1;by the second annealing with magnetic field(1000Gs/673K),the alloys show a low Hc about 2.9A/m,2.5A/m and 2.4A/m.(6)In these new-style Fe-rich amorphous/nanocrystalline alloys,based on the key points of the stability of a-Fe crystallization and the soft magnetic properties,the good compositions of each system are Fe86B13Cu0.4Hf0.6,Fe86B12.5Si0.5Cu0.4Hf0.6,Fe86B12.5P0.5Cu0.4Hf0.6 and Fe86B12Si0.75P0.25Cu0.4Hf0.6 alloys,respectively.But the perfect composition is Fe86B12Si0.75P0.25Cu0.4Hf0.6,which shows a good control of a-Fe crystallization and can easily get an excellent magnetic properties. |
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