Study On Microalloying Of Fe-Si-B Amorphous Alloy And Melt Thermodynamic Model

In recent years,Fe based amorphous alloys have developed rapidly because of their excellent soft magnetic properties.However,with the rapid development of the electronic and electric power industry,higher requirements have been put forward for the performance of Fe based amorphous alloys.Compared with the widely used silicon steel and other materials,the low saturation magnetization(Bs)of Fe based amorphous alloy is the biggest "weakness"restricting their development.However,it is not feasible to increase Bs by increasing the content of amorphous alloy Fe in the industrial process,because in Fe-based amorphous alloys,high Fe content is often accompanied by the decrease of glass formation ability(GFA),which is extremely unfavorable to industrial production.Therefore,the researchers of this project studied research on microalloying and impurity element control,and the following work has been carried out to achieve the goal of industrial production of high Bs Fe based amorphous alloys:1.The effects of ferromagnetic element Co with small atomic radius on the thermodynamic properties,GFA,soft magnetic properties,and local structure of Fe80Si9-xB11Cox(x=0-1 at.%)and Fe76Si9-xB10P5Cox(x=0-1 at.%)amorphous alloys were studied.The experimental results show that the GFA of the amorphous alloy can be slightly increased by adding proper amount of Co(≤0.4 at.%).;The coercivity(Hc)of the alloy decreases slightly when the amount of Co is less than 0.4 at.%,but increases sharply when the amount of Co is more than 0.4 at.%.;After Co doping,the Bs of the amorphous alloy increases,especially the Bs of Fe76Si8.4B105Co0.6 amorphous alloy increased by 0.07 T;Mossbauer spectroscopy test results indicate that Co doped in the alloy will form a new cluster structure with the elements in the alloy,resulting in an increase in the average coordination of Fe atoms around Fe atoms,enhanced magnetic exchange between Fe atoms,resulting in the increase of Bs.2.The effects of transition group elements with large atomic radius on the thermodynamic properties,GFA,soft magnetic properties and local structure of Fe80Si9-xB11Mx(x=0-0.5 at.%)amorphous alloys were studied by replacing Si with V/Nb.The results show that the Curie temperature(Tc)and initial crystallization temperature(Tx)of the amorphous alloy can be significantly increased when the addition of V is 0.3at.%,and the appropriate doping of V can inhibit the precipitation of α-Fe phase,while the doping of Nb can improve the thermal stability of the amorphous alloy,and the Tx is significantly increased.The addition of V or Nb can effectively improve the GFA of the amorphous alloys.;Hc decreases when the V or Nb doping is less than 0.2 at.%,especially when the doping amount of Nb is 0.2 at.%,it decreases to the minimum value of 3.63 A/m,which is about 44%lower than the Fe80Si9B11 amorphous band;When the V doping amount is 0.3 at.%,Bs reaches its maximum value,which is about 0.04 T higher than the Fe80Si9B11 amorphous band and when Nb doping amount is 0.2 at.%,Bs is about 0.03 T higher than the Fe80Si9B11 amorphous band;A simple binary model is proposed to illustrate the effect of V/Nb doping on the local structure.However,the composite doping of V and Nb is unfavorable for improving the GFA of Fe80Si8.6B11VxNb0.4-x(x=0-0.4 at.%)amorphous alloys;The maximum value of Bs is achieved when the V doping amount is 0.3 at.%and the Nb doping amount is 0.1 at.%.3.The thermodynamic calculation model was established applying the theory of ionmolecular coexistence(IMCT),and the mass action concentration of some melt components was calculated.The relationship diagram of mass action concentration with temperature and components of binary system was drawn,and the mass action concentration of some Fe-Si-BP-C alloy components was calculated.The P distribution ratio for the reaction between CaOB2O3 slag and Fe-B-P alloy melt was calculated,and previous experimental results were selected for verification.The P distribution ratio calculated using thermodynamics was consistent with the experimental results.