| Fe-based soft magnetic amorphous alloy exhibits excellent soft magnetic properties due to its unique structure,which makes it have great application potential in energy saving and consumption reduction.However,the saturation flux density(Bs)of Fe-based amorphous is lower than silicon steel sheets,which is not conducive to promote the high efficiency and miniaturization of electromagnetic conversion devices.To obtain high Bs,it is necessary to increase the Fe content,but the excessively high Fe content will deteriorate amorphous forming ability(AFA).Although it is not necessary to prepare soft magnetic amorphous into a bulk in the field of soft magnetic applications,it is reported that a thick strip of 50?100 ?m is used to form a core,which exhibits the lager effective area and smaller iron loss.Besides,the influence of impurity elements in the low-purity raw materials on the amorphous properties is also obvious,and there is a gap between the industrial level and the laboratory level.Therefore,we can't ignore AFA while paying attention to soft magnetic performance.Firstly,in order to predict the formation ability of iron-based amorphous,the classical Fe-Si-B alloy system is selected carry out regression analysis on mixed enthalpy,mixed entropy and electron concentration value(e/a).According to the results,we choose the(e/a)as the main reference for the design of Fe-based amorphous.The relationship between clusters and(e/a)is established by the concept of ideal atomic alignment model(IPA)and is demonstrated by the thermodynamic behavior of the alloy strips.We found that ?-Fe are easily precipitated,when the Fe content reaches a certain value,which always corresponds to a relatively fixed(e/a)value called the critical(e/a).Theoretically,the alloy composition with critical(e/a)can maintain high Bs and relatively high AFA.According to this idea,we designed Fe-B-C components and successfully prepared them into amorphous,which farther verified the existence of critical(e/a).Meanwhile,we also found that the defects predicting AFA only by(e/a)values.Therefore,other factors affecting AFA were explored through the substitution of multiple transitional elementsSecondly,the critical(e/a)is applied to the composition of quaternary Fe-based amorphous.Sn element was added to classical Fe-Si-B alloy,and the Fe-Si-B-Sn amorphous strips exhibit excellent soft magnetic properties.The annealing process was also studied and finally found:the AFA is closely related to(e/a)for Fe-Si-B-Sn amorphous and there is a critical(e/a)that sharply reduces AFA indicating the critical(e/a)phenomenon is also relatively common;the amorphous forming ability tends to increase first and then decrease with the substitution of Sn when the(e/a)is not change;the addition of Sn element can significantly reduce initial crystallization temperature(Tx1)and coercive force(Hc);when the content of Sn is greater than 2%,the Bs is significantly lowered;clamping copper on both sides of the amorphous ribbon is beneficial to suppress the growth of crystal grains,which is of great significance for the preparation of amorphous nanocrystals.Finally,in order to explore the sensitivity of Fe-Si-B-Sn amorphous ribbon to impurities in industrial raw materials and the suitability of melt purification processes(fluxing)in this system,we compared various properties of strips prepared from industrial Fe-Si and high-purity Si materials respectively.The following conclusions are drawn:the use of industrial grade raw materials to prepare Fe-Si-B-Sn-based amorphous ribbons will reduce the amorphous forming ability and this problem can be solved by fluxing to some extend;the use of industrial raw materials for the preparation of Fe-Si-B-Sn-based amorphous ribbons will reduce Bs and this problem cannot be solved by fluxing;some impurity element in the industrial raw material can improve the thermal stability of the strip,and the fluxing treatment can retain the favorable side of the impurity and remove the harmful side. |
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