Effects Of Zirconium On The Magnetic Properties In Pr₂Fe₁₄B/α-Fe Nanocomposite Permanent Magnets

Permanent magnets are very important for the development of electronic technology enterprises.Because of its high theoretical energy product(144 MGOe),nano two-phase magnets have become one of the research hotspots.However,recent experimental studies have found that the microstructure of the samples obtained is far from theoretical requirements,resulting in low coercivity and magnetic properties.Improving the microstructure of materials by adding trace elements is an effective way to improve coercivity.This work reports the effects of Zirconium on magnetic properties of nanocomposite permanent magnets Pr2Fe14B/α-Fe prepared at various wheel speeds.The ingot of nominal composition Pr9.5Fe84-xB6.5-yZrxPy(x=0,1,2,3;y=0,0.1)was prepared in an Electric Arc Furnace.The melt spinning technique was employed to prepare the ribbon.The ribbons of various thicknesses(40-66)μm have been obtained at various wheel speeds of 18,24 and 30 m/s.The results showed that 1 at.%Zr addition in master alloy composition of Pr9.5Fe84B6.s improved the magnetic properties largely as compare to Zr-free alloy.The maximum energy product was largely improved addition of 1 at.%Zr,from 9 kJm-3(Zr-free alloy)to 80 kJm-3(Zr-rich alloy),the intrinsic coercivity was increased enormously from 89 kAm-1(Zr-free alloy)to 886 kAm-1(Zr-rich alloy),and the remanence polarization also improved from 0.51 T to 0.75 T.The powder X-ray diffraction technique was employed to analyze the phase constituent of the as-spun ribbon.The XRD result confirmed the existence of hard 2:14:1,and soft a-Fe and Fe3B phases in Pr9.5Fe84B6.5 alloy ribbon.The XRD analysis performed after addition of 1 at.%Zr revealed that addition of Zr in master alloy reduces the content of soft phase.The result showed some traces of hard phase 2:14:1and the peak of Fe3B(only at 30 m/s).The SEM technique was performed to study the microstructure of the spun ribbon alloy.The morphology of the master alloy Pr9.5Fe84B6.5 showed protrusion regionconfirmed the crystalline nature of the as-spun ribbon.The morphology of the Zr-added alloy at 30 m/s showed the uniform microstructure,small grain size,and absence of fracture.Thenature reduced after addition of 3 at.%Zr implies that Zr addition shifts the structure crystalline to amorphous phase.The highest coercivity value of 937 kAm-1(3 at.%Zr)at 18 m/s been reported in this study.The melt spun ribbon has been prepared with the addition of 0.1 at.%P in the master alloy,the XRD results showed that with the P addition crystallinity of the ribbon alloy increased.Further,1 to 3 at.%Zr was added in the same alloy Pr9.5Fe84B6.4P0.1,the maximum energy product of 80 kJm-3(3 at.%Zr)at 18 m/s and largest coercivity of 945 kAm-1(2 at.%Zr)at 30 m/s has been achieved.This coercivity value is the highest so far in this poor rare earth nanocomposite magnets.The SEM result showed the uniformity in the microstructure owing to high magnetic properties.