| Nanocomposite two-phase Nd-Fe-B perment magnetic material has sparked widespread attention for its superior performance and lower production costs, it is a research hotspot how to prepare nanocomposite perment magnetic material of low rare earth elements and excellent performance.Because grain size can not meet the exchange coupling interaction conditions in the study of nanocomposite perment magnetic material.The main content of this paper is how to prepare nanocomposite perment magnetic material by arc melting and melt-spinning and vacuum crystallization heat treatment, and using the method of XRD, DSC, VSM to study the effect of crystallization process and alloy composition on the microstructure and properties of nanocomposite Nd-Fe-B perment magnetic material. Around the main topic I did work as follows:This paper studied the effect of addtion Cu and Nb on the structure and magnetic performance of the B-rich Nd-Fe-B based nanocomposite permanent magnetic material,and the effect of addtion Cu on the structure and magnetic performance of the Fe-rich Nd-Fe-B-based nanocomposite permanent magnetic material.(1) The master alloys were prepared by vacuum arc melting furnace, amorphous ribbons was prepared by melt-spinning technique and detected by XRD and DSC. The results show that:The ribbons were amorphous alloy, according to the results of DSC we confirmed the heat treatment process.Then we did XRD to annealed alloys ribbons and VSM to annealed alloys powder.(2) According to the DSC curve of five different component Fe-Co-Nd-Dy-B-Cu-Nb alloys shows that:The alloy system has a larger width of the supercooled liquid region.Among these alloy,the record of Fe67C08.3Nd3Dy0.5B20Cu0.2Nb1is△Tx=51K,the alloy has a lot of glass-forming ability which is expected to prepare BMG. Crystallization temperature reduce because of addtion Cu,but Combined addition of Cu and Nb increase crystallization temperature. According to DSC results,we determine to implement at the temperature of the end of the first crystallization peak(Tend1),that is615℃, crystallization treatment time is15 minutes,20minutes,25minutes and30minutes。 Then according to the result of the experiment, and the alloy Fe67Co9Nd3Dy0.5B20Cu0.5in680℃respectively crystallization treatment5-25minutes.(4)Through changing the quenching speed can affect the structure and properties of the alloy.(3) We discuss the effect of different crystallization time on the structure and permanent magnet by the result of XRD and VSM.The results show that:With the extension of the crystallization time,the amount and size of the grain is increased, and the grain refers to the soft magnetic phase which contains Fe3B and α-Fe, and the hard magnetic phase which contains Nd2Fe14B.When the grain grow too big,it will reduce the exchange coupling interaction between soft magnetic phase and hard magnetic phase, Therefore,the magnetic properties of alloy appear to reduce.There is a best crystallization time In the crystallization process of the alloy system.(4) When the Cu partial substitution of Co in the Fe67Co9.5Nd3Dy0.5B20alloy, as of Cucontent increases,the magnetic properties of alloy can be better. When the conten of Cut is0.5at%,the crystallization heat treatment time is20minutes, the alloy has the best magnetic properties:Hc=200.36kA/m, Br=0.95085T,(BH) m=46.416kJ/m3.This is because the Cu addition is belived to reduce the grain size of nanocomposite phases,and enhance the exchange coupling interaction between soft magnetic phase and hard magnetic phase.Therefore,the magnetic properties of the alloy can be improved.(5) We add Cu and Nb to replace part of Co in the nanocomposite Fe67Co9.5Nd3Dy0.5B20alloy.Combined addition of Cu and Nb into Fe-Co-Nd-Dy-B-Cu-Nb alloy reduces the magnetic properties. It is because Nb enhance the crystallization temperature and reduce the effect on crystallization kinetics, at the same time there appears intermediate phases Nd2Fe23B3, It leads to the amount of Nd2Fe14B appears decline. Therefore,the magnetic properties of alloy appear to reduce. But the addition of Nb increases the GFA of the alloy system. |
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