Effect Of Trace Element Addition On Structure And Properties Of Fe-Base Amorphous Alloys

With the development of the times,the industrial sector has increasingly high requirements for the performance of magnetic materials,especially in the fields of power,electronics,and communication,which require excellent properties such as high magnetic permeability,low hysteresis,and low losses.In these fields,iron-based amorphous materials have attracted attention due to their high saturation magnetization and low losses.However,their saturation magnetization is relatively low,and their price advantage compared to traditional silicon steel products is not obvious.Therefore,it is urgent to develop iron-based amorphous alloys that are both economically practical and have excellent saturation magnetization.Although iron-based amorphous alloys with high iron content already have high saturation magnetization,they still cannot fully meet the demands of high-power electronic devices.Additionally,excessively high Fe content in amorphous alloys will inevitably cause a decrease in their amorphous forming ability,posing a challenge for large-scale production.Therefore,this study focuses on slight composition regulation of Fe₈₀P₁₂C₈ and Fe₈₃B₉C₈ alloys with a relatively high Fe content（≥80 at.%）,aiming to seek amorphous ribbons with both excellent amorphous forming ability and soft magnetic properties that are economically practical.Firstly,we investigated the effect of Si element doping on the structure,thermodynamic properties,soft magnetic properties,and mechanical properties of Fe₈₀P₁₂C₈ alloy using various analytical techniques.Five ingots and ribbons,namely Fe₈₀P₁₂C₈（Si₀）,Fe₈₀P₁₁C₈Si₁（Si₁）,Fe₈₀P₁₀C₈Si₂（Si₂）,Fe₈₀P₉C₈Si₃（Si₃）,and Fe₈₀P₈C₈Si₄（Si₄）,were prepared using the meltspinning method.Our results showed that all five ribbons maintained a completely amorphous state,and the addition of Si significantly improved the glass-forming ability and stability of the iron-based amorphous ribbons.We found that the addition of Si reduced the nearest-neighbor atomic distance（r1）in the ribbons,resulting in a transformation of the FCC cluster structure to the BCC cluster structure.As a result,the saturation magnetization（B_s）and Curie temperature（T_C）of the ribbons increased gradually with increasing Si content,while the coercivity（H_C）decreased.Nanohardness testing showed that the Young’s modulus,hardness,and wear resistance of the iron-based amorphous ribbons were significantly improved by Si doping.Furthermore,the fracture morphology of the ribbons changed from ductile dimples to periodic stripes with increasing Si content.Secondly,we systematically investigated the effect of doping with different atomic amounts of Group IV elements on the structure and properties of Fe-B-C alloys.Four ingots and ribbons,Fe₈₃B₉C₈（FeBC）,Fe₈₃C₆Si₂（FeBCSi）,Fe₈₃B₉C₆Ge₂（FeBCGe）,and Fe₈₃B₉C₆Sn₂（FeBCSn）.were prepared using a melt-spinning method.X-ray diffraction（XRD）and transmission electron microscopy（TEM）analyses showed that the Fe-B-C alloy ingots mainly consisted of striped α-Fe phase and Fe——3C phase,while the addition of Sn with excessively large atomic weight resulted in a morphological change to particle-like α-Fe phase and Fe₂₃（C,B）₆ phase.The crystal characteristics were preserved by rapid cooling,which led to a dramatic increase in the nearest-neighbor atomic distance of the ribbons.As for ribbons,all ribbons except for FeBCSi remained in the amorphous state.The room temperature saturated magnetization（B_s）,Young’s modulus（E_Y）,and degradation efficiency（η）of the Fe-B-C amorphous ribbon system all showed significant improvements with increasing atomic weight of the doping elements.and reached the optimal value at FeBCGe.while the addition of Sn with excessively large atomic weight caused the deterioration of BS and η.Moreover,the Bs of FeBCGe amorphous ribbons increased significantly after annealing near the crystallization peak temperature.