Microstructure and magnetic properties of SmCo_(5) sintered magnets

SmCo_(5)sintered magnets with good thermal stability are mainly used in high-temperature field.In this study,two types of SmCo_(5) powders with different nominal z values were mixed and synthesized into SmCo_(5) magnets by the traditional powder metallurgy method.The magnetic properties of the SmCo_(5) sintered magnet are maximum energy product of(BH)_(max)=172.29 kJ·m^(-3),remanence of B_(r)=7.47×10^(5)A·m^(-1)and coercivity of H_(ci)=2.42 T.The results show that there are three coexisting phases in the magnet,which are SmCo_(5)phase,Sm_(2)Co_(7)phase and Sm_(2)O_(3)phase.The microstructural observation indicates that the average grain size in the magnet is about 8μm,and the high coercivity of this magnet is attributed to these fine grains.X-ray diffraction(XRD)and electron backscatter diffraction(EBSD)results indicate that the magnet has a well-aligned(00l)orientation texture.

Structure and magnetic properties of nanocrystalline dysprosium powders

In this current study,nanocrystalline Dy powders were prepared by melt-spinning and subsequent highenergy ball-milling.The effect of ball-milling time on the structure and magnetic properties of the powders was studied.The crystal structure and microstructure of the melt-spun ribbons and ball-milled powders were observed by X-ray diffraction(XRD),scanning electron microscopy(SEM)and transmission electron microscopy(TEM).Magnetic measurement of all samples was performed with vibrating sample magnetometer(VSM).XRD results indicate that the average crystal grain size of the powders decreases from 90.09 nm of the ribbons to 10.42 nm of the4-h ball-milled powders.Further TEM observation shows that the grains are fine and uniform.The Neel temperature(TN)decreases from 182 K of the ribbons to 172 K of the powders,while the Curie temperature(TC)increases from100 to 130 K,demonstrating that the grain size has substantial influence on the magnetic transition process.Moreover,at 60 K,as the ball-milling time increases,the coercivity of the powders increases first,peaking at 0.48 T for 2-h milling,then drops again,while the remanence of the powders decreases monotonic ally.As a result,the powders milled for 2 h exhibit an optimal maximum energy product of 64.0 kJ·m-3,demonstrating the good potential of these powders as a permanent magnet at low temperatures.

Low-cost Sm0.7Y0.3Co5 sintered magnet produced by traditional powder metallurgical techniques

RCo5(R=rare earth)sintered magnets have good temperature stability,so it is still widely used in high temperature field.In this paper,by the method of adding liquid phase SmCo1.7 to the main phase,Sm0.7Y0.3Co5 magnet was prepared by traditional powder metallurgical process.The results show the presence of a main phase RCo5,a minor phase R2 Co7,and a R-rich phase in the magnet.Contrasting the results of the XRD(X-ray diffraction)in random and oriented directions,the magnet has a well-aligned(00l)orientated texture,which is consistent with the result of the electron backscattered diffraction(EBSD).The Sm0.7Y0.3Co5 sintered magnet has good magnetic properties as remanence(Br)is 0.96 T,the coercivity(Hcj)is 1201.96 kA·m-1,and maximum magnetic energy product((BH)max)is 175.16 kJ m-3.