Study On Phase Equilibrium And Magnetic Properties Of RE-Pr-Fe(RE=Ce,La) Alloys

Now the country vigorously advocates the development of clean energy such as wind power and solar energy,so as to reduce the use of high-pollution energy such as traditional coal and gasoline.The rare earth permanent magnet material is one of the important raw materials of clean energy.It has been widely used in the fields of wind power and electronic devices and so on.The magnetic devices require more and more magnetic properties of magnets with the development of the times,so it is necessary to develop and study the new permanent magnet materials.The development of new permanent magnet materials with the addition of La and Ce not only reduce cost,but also consume backlogged rare earth energy.The equilibrium phase relationship of Ce-Pr-Fe and La-Pr-Fe and the solidification structure evolution in the iron-rich region of Ce-Pr-Fe system have important theoretical guiding significance for the process design,composition optimization and magnetic regulation of permanent magnetic materials.In this paper,the equilibrium phase relationship of Ce-Pr-Fe system at 400?,600?and La-Pr-Fe system at 600?were studied by using the traditional alloy method and the diffusion couple method.In addition,the solidification structure evolution in iron-rich region of Ce-Pr-Fe ternary and the effect of Cr and Ni doping on the magnetic and absorbing properties of Pr₂Fe₁₇ alloy were also studied.?1?The equilibrium phase relation of Ce-Pr-Fe system is studied by using traditional alloy method and diffusion couple method.The equilibrium phase relationships of Ce-Pr-Fe system at 400?and 600?was constructed by phase analysis of alloys by equipment such as XRD?BSE/EDS and EPMA.Moreover,the solidification structure evolution was analyzed according to the thermal analysis curve and the BSE/EDS of the as-cast and equilibriated alloys.?2?The ternary alloys with different composition of La-Pr-Fe system were prepared by arc melting and annealing processes.The equilibrium phase relationship of La-Pr-Fe system at 600?was constructed by XRD and BSE/EDS.There is no PrFe₂ phase in Pr₂₅Fe₇₅ and Pr₄₅Fe₅₅ alloys at 600?.However,it was observed in both Ce₅Pr₅₀Fe₄₅ and La₁₅Pr₂₅Fe₆₀ ternary alloys,indicating that the ternary element aids the formation of PrFe₂phase.This is further supported by the diffusion results.No PrFe₂ phase was found in the isothermal section of Ce-Pr-Fe at 400?,while it was found in the isothermal sections of Ce-Pr-Fe and La-Pr-Fe at 600?,indicating that PrFe₂ should exist at 600?.It may be obtained by a peritectoid reaction i.e.Pr₂Fe₁₇+Pr?PrFe₂.?3?Pr₂Fe_17-xCr_x?x=0.0,0.1,0.2,0.4?and Pr₂Fe_17-xNi_x?x=0.0,0.1,0.2,0.3,0.4?alloys were prepared by melting,quenching and other processes.The effects of Cr and Ni doping on the magnetic properties and absorbing properties of Pr₂Fe₁₇ alloy were analyzed by XRD,SEM,VSM and VNA.