| Fe-based amorphous/nanocrystalline alloys as a new generation of green energy-saving materials have attracted great attention due to their excellent soft magnetic properties,which are widely used in electronics and power industries.However,on the one hand,the low Fe concentration of the alloy results in a low saturation magnetic flux density(Bs:below 1.7 T),which can not be comparable with the silicon steel(Bs?2.0 T).On the other hand,the current amorphous alloy ribbons always suffer low amorphous forming ability with high Fe content,which limits the thickness and width.In addition,there are still a lot of problems,which need to be solved,such as:the two stages of crystallization temperature is too narrow,low Curie temperature,crystallized material becomes brittle and so on.Therefore,it has important engineering application value and academic significance to develop a new type of Fe-based amorphous/nanocrystalline soft magnetic alloy system with low-cost and high-performance.In this paper,through the process of rapid quenching,we designed a new type of Fe-based amorphous/nanocrystalline soft magnetic system with low cost,high saturation magnetization and low coercivity.And we have successfully prepared the FeSiBCuC and FeSiBCuCP alloy systems.Through the addition of Si,B,P and C elements,the amorphous forming ability(GFA),thermal stability,soft magnetic properties and ductile-brittle of these two types Fe-based amorphous/nanocrystalline soft magnetic alloy systems were studied.The main results and conclusions are summarized as follows:(1)In the Fe83.5-xSi2B14Cuo.5Cx(x=0,0.1,0.2,0.3,0.4,0.5 at.%)alloys,with the increase of C content,the crystalline peak of alloys gradually weakens,when x=0.2 and 0.3 at.%,the alloys exhibit an amorphous character,while the precipitation of a-Fe phase exists in other alloys.It indicates that the addition of minor carbon can improve the amorphous forming ability of alloys.When the annealing temperature reaches at 450?×10min,the saturation magnetization(Ms)of Fe83.2Si2Bi4Cu0.5C0.3 nanocrystalline alloy achieves the maximum value of 203.4 emu/g(Bs?1.91 T),and the coercivity(Hc)is about 34.7 A/m.(2)In the Fe83.4Si2B14-xPxCu0.5C0.1(x = 0,1,2,3,4,5,6 at.%)alloys,with the substitution of P for B element inhibits the crystallization.When the x4 at.%,the alloys exhibit a completely amorphous structure,which indicates that the addition of P can effectively improve the amorphous forming ability of alloys.With the increase of P content,the temperature interval between the two crystallization peaks is greatly enlarged.When the x=5 at.%,?Tx reaches the maximum value,of about 118.3?.After the optimum heat treatment(430?×10min),the Fe83.4Si2B10P4Cu0.5C0.1 nanocrystalline alloy exhibits the maximum Ms value of about 195.8 emu/g(Bs?1.8 T)and low He of 6.7 A/m.(3)In the Fe84.2Si6-xB9PxCu0.5C0.3(x = 2.0,2.5,3.0,3.5,4.0 at.%)alloys,with the increase of P element,the crystallization peak of alloys is gradually suppressed.When x=4 at.%,the alloy transforms from nanocrystalline into a fully amorphous structure.It indicates that the substitution of P for Si improves the amorphous forming ability of alloys.The minor addition of B and C element are very sensitive to the amorphous forming ability of alloys.It contributes to the formation of amorphous alloy by effectively controlling the amount of non-metal elements.When x=4 at.%,the Fe84.2Si2B9P4Cu0.5C0.3 amorphous alloy exhibits larger the range of annealing temperature between two crystallization peaks(?Tx=Tx2-TX1),of about 132?.Through the optimal annealing treatments(430?×10min),the Fes4.2Si2B9P4Cu0.5C0.3 nanocrystalline alloy reaches the maximum Ms value of about 194.6 emu/g(Bs?1.81 T)and low Hc,of about 8.6 A/m.(4)In the Fe84.7SixB10.5-xP4Cu0.5Co0.3(x=0,0.5,1.0,1.5,2.0 at.%)alloys,with the substitution of Si for B element,the crystallization peak gradually weakens until disappears.When x=1.5 at.%,the Fe84.7Si1.5B9P4Cu0.5C0.3 alloy exhibits a completely amorphous structure.It indicates that the addition of minor Si inhibits the crystallization and improves the amorphous forming ability of alloys.With the increase of Si content,the secondary crystallization temperature(Tx2)shifts to higher temperature,which enlarges the difference of temperatures(?Tx)between Txi and T,2.With the increase of Si content(Si?1.0 at.%),the alloy annealed at 440? effectively inhibits the precipitation of Fe-(B,P)phases.Therefore,it indicates that the addition of Si can improve the thermal stability,broaden the range of annealing temperature and prevent precipitation of the secondary phase.When annealing temperature is at 440?×10min,the Fe84.7Si1.5B9P4Cu0.5C0.3 nanocrystalline alloy achieved the highest Ms of 206.5 emu/g(Bs?1.92 T)and low He of 12.5 A/m.(5)In the Fe85Si1.5-xB9Cu0.5P4Cx(x=0,0.1 0.2,0.3,0.4,0.5 at.%)alloys,under the same thickness(25 ?m)conditions,with the increase of C(0.1 at.%)content,the alloy exhibits a completely amorphous state and enlarges the maximum thickness of glassy from 19 ?m to 25 ?m.It indicates that the minor addition of C increases the amorphous forming ability of the alloys.With the increase of C content,the curie temperature(Tc)shifts to lower temperature,while the first cry stallization temperature(Tx1)shifts to higher temperature.Larger Tx1-Tc contributes to the thermal stability of alloys.After the optimum annealing temperatures(420?×10min),the Fe85Si1.4B9Cu0.5P4C0.1 nanocrystalline alloy reaches the maximum Ms,of 205 emu/g(Bs?1.93 T)and lowest He of 5.8 A/m.(6)Both of the Fe85Si1.5B9Cu0.5P4 and Fe85Si1.4B9Cu0.5P4C0.1 amorphous ribbons do not fracture after folding 180° even in the quenched state and annealing temperature,which exhibit good bending ductility.With the increase of C content(>0.1 at.%),the alloys transform into crystallization which reduces the toughness of the alloys.With the addition of C(0.1 at.%)element,the transition temperature of ductility-brittleness increases from 340? to 360?,which can effectively optimize the ductility-brittleness transition temperature point of Fe85Si1.5-xB9Cu0.5P4Cx alloys.(7)For the Fe85Si1.4B9P4Cu0.5C0.1 alloy,when the annealing temperature(Ta?420?)is low,the alloy precipitates a large amount of a-Fe grains with the increase of annealing time.With the increase of heat temperatures(Ta?>460?),the rapid thermal processing(RTP)can effectively prevent the precipitation of iron-boride/phosphorus phases.When annealed at 420? for 1 min,the Fe85Si1.4B9P4Cu0.5C0.1 nanocrystalline alloy exhibits lowest He of 5.5 A/m and higher Ms of 204.5 emu/g(Bs?1.92 T).When annealed at 420 for 30 min,the Fe85Si1.4B9P4Cu0.5C0.1 nanocrystalline alloy exhibits highest Ms of 207.9 emu/g(Bs?1.95 T)and lower He of 6.7 A/m. |
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