Development Of High Performance FeCoSiBPC(Cu) Amorphous/nanocrystalline Alloys

Fe-based soft magnetic amorphous and nanocrystalline alloy materials are a new type of soft magnetic functional material with high Bs,low Hc,and high magnetic conductivity.However,there are still some issues with these materials.Fe-based amorphous alloys with good glass forming ability have lower Bs,while amorphous/nanocrystalline alloys with high Bs have poor glass forming ability and require strict preparation processes with a narrow annealing temperature range.Additionally,their Bs is still lower compared to traditional silicon steel.With the increasingly developing power electronics industry,there is a growing demand for higher Bs in iron-based amorphous/nanocrystalline soft magnetic alloys.The Fe80Co3Si3B10P1C3 amorphous alloy developed and produced by Jiangsu JITRI Advanced Energy Materials Research Institute Co.,Ltd.has good magnetic properties.After annealing,its Bs can reach 1.70 T,and coercivity is around 12 A/m after annealing.However,its glass forming ability is low,requires higher copper roll speed.The composition of the alloy was optimized by adjusting the Si element content,try to enhance its glass formation ability,and the effects of substituting Si for Fe or B on its performance were compared.Additionally,Cu was added to the amorphous alloy to nanocrystalline it and investigate the effects of nano crystallization on the alloy’s properties.The main research results are as follows:(1)The glass forming ability was predicted by the values of ΔHmix and δ.The threshold value of ΔHmix and δ were determined by the formation range of Fe-B binary amorphous and Fe76Si3B5P8.7C7 amorphous alloy,which are-10.98～-29.54 kJ/mol and 11.5-16.8.The more negative the ΔHmix and the larger the δ,the stronger the glass forming ability.The effect of δon the glass forming ability is greater than that of ΔHmix.The δ value should be compared first while judging the glass forming ability of Fe-based amorphous alloy.The alloys with large δhave high glass forming ability.In the case of similar δ,the more negative the ΔHmix,the greater the glass formation ability.In addition,the addition of 0.6-1.0 at.%Cu has little effect on the glass forming ability of the alloy.(2)The addition of Si element can affect the glass forming ability and thermal stability.Adding Si element by replacing B element,the glass forming ability decreases,and the crystallization onset temperature Tx1 and crystallization peak temperature Tp1 of the amorphous alloy decrease,leading to a decrease in the thermal stability of the ribbon.However,adding Si element by replacing Fe element can significantly increase Tx1 and Tp1,and enhance the thermal stability of the amorphous alloy.The prepared Fe80-yCo3Si3+yB13P1C3(y=2,4)amorphous alloy has good glass forming ability and thermal stability,wide heat treatment range,and can obtain low coercivity after annealing,the coercivity of the y=4 sample is only 4.97 A/m after heat treated at 673 K for 10 minutes.In addition,the saturation magnetization Bs of the Fe80yCo3Si3+yB13P1C3(y=2,4)ribbons is 1.69 T(y=2)and 1.67 T(y=4),respectively.(3)0.6-1.0 at.%of Cu was added to amorphous alloys to investigate the effects of nanocrystallization on their properties.Nanocrystalline ribbons of(Fe80Co3Si3B10P1C3)100-xCux(x=0.8),(Fe80Co3Si5B8P1C3)100-yCuy(y=0.6,0.8,1.0)and(Fe78Co3Si5B10P1C3)100-zCuz(z=0.6,0.8,1.0)ribbons were prepared at different speeds.After being annealed at 633 K for 10 minutes,the Bs of the x=0.8 sample was 1.73 T,while those of the y=0.8 and y=1.0 ribbons were 1.73 T and 1.74 T,respectively.The Bs of the z samples was greater than 1.70 T,the z=0.8 sample is 1.72 T,0.03T higher than that of the corresponding amorphous alloy.The addition of Cu had a small effect on the glass forming ability of the ribbons,but caused the Tx1 and Tp1 of the alloys to shift towards lower temperatures,while Tx2 and Tp2 remained almost unchanged.The temperature difference ΔTx between Tx1 and Tx2 increased for all samples,with a maximum of 145 K(y=1).(4)The corrosion resistance of Fe80Co3SixB13-xP1C3(x=1,2,3,4,5)ribbons first increases and then decreases with the increase of Si content,and the corrosion resistance of the ribbon reachs best when x=3,4.The corrosion resistance of Fe80-yCo3Si3+yB13P1C3(y=2,4)ribbons deteriorates with the increase of Si content.When Cu is added,the corrosion current density of the ribbon is lower than that of the corresponding amorphous ribbons,and the nanocrystalline ribbon has stronger corrosion resistance than the amorphous ribbons.