Enhancement of Magnetic Properties and Corrosion Resistance for Misch Metal Based RE-Fe-B Magnets Prepared by Double Main Phase Process
In order to reduce the RE-Fe-B material cost and to balance the utilization of rare earth sources,[(Pr,Nd)1-xMMx]30.3(Fe,Co)bal-M0.73B0.98(x=0.3,0.5,0.7,wt%)magnets were prepared by double main phase(DMP)and single main phase(SMP)processes.DMP magnets are superior to SMP magnets with the same nominal composition in magnetic properties and corrosion resistance.For x-0.5,the magnetic properties of DMP magnets are B,=1.308 T,Hcj=799.980 kA/m and(BH)max=325.6436 kJ/m3,which are higher than those for SMP magnets(B,=1.297 T,Hcj=746.8868 kA/m and(BH)max=317.8428 kJ/m3)with the same nominal composition,and the impro-ved RE-rich phase distribution and REs heterogeneity distribution are the main reasons.When DMP magnets are exposed to a hygro-thermal environment,there is not only RE-rich phase corrosion,but also pulverized main phase grain due to hydrogenation behavior difference between LaCe-rich and LaCe-lean shell-core within one individual grain.As a result,it is demonstrated that DMP techni-que is an effective approach to improve the permanent magnetic properties and corrosion resistance of MM-based sintered magnets.
misch metaldouble main phase processmagnetic propertiescorrosion resistanceheterogeneous distribution of rare earth