Preparation And Magnetic Properties Of Anisotropic （Sm,Pr）Co₅/Fe Nanocomposite Particles

The data shows that the magnetic energy product of fully coupled dual-phasepermanent magnet can be twice as the sintered Nd2Fe14B, which possesses the highestmagnetic energy product in single-phase permanent magnets, so the nanocompositepermanent magnets attracted much attention in the filed of magnetism.In this article, anisotropic (Sm,Pr)Co5hard phase particles with plate-like structurewere synthesized via surfactant assisted high energy ball milling, in combination with theelectroless plating method, the (Sm,Pr)Co5powders before and after ball milling wereused as coated substrates, odium borohydride (NaBH4) and sodium citrate(C6H5Na3O7·2H2O) were used as reducing agent and complexing agent respectively, afterreduction of ferrous sulfate (FeSO4·7H2O), the soft magnetic phase iron finally depositedon the surface of (Sm,Pr)Co5, and the studies on morphology, microstructure andmagnetic properties were made by scanning electron microscopy (FE-SEM) and X rayenergy spectrum analysis (EDS) as a supplement, X ray diffraction (XRD), and vibratingsample magnetometer (VSM).SEM images show the agglomeration of (Sm,Pr)Co5powders without ball milling isserious, so it is not easy for the magnetic soft phase iron to deposit on the (Sm,Pr)Co5powders. The iron diffraction peaks could be indexed in the XRD pattern of(Sm,Pr)Co5/Fe nanocomposites after vacuum annealing at600℃for10minutes, whichproved the existence of iron. After chemical coating, the saturation magnetizationof composite powders increased from the initial65.42emu/g to73.37emu/g, but thecoercive force decreased from10.85kOe to7.63kOe.After ball milling, the size of hard magnetic particles decreased, and the degree ofagglomeration has been weakened, presenting flake-like and string structure, which isconducive to the further coating. SEM images after coating show a layer of dense, uniformsoft magnetic phase has been deposited on the surface of (Sm,Pr)Co5. With the increasecontent of soft magnetic phase, the saturation magnetization and coercive force of thecomposite powders show a trend of rise and decline respectively, however the remanenceincreases first and then decreases, it has a maximum when the content of soft magnetic phase was15%in weight, the magnetic properties of the composite magnets beforecoating and after coating are listed as follows: before coating: Hci=10.58kOe,Mr=50.70emu/g, Ms=61.73emu/g; after coating: Hci=8.89kOe, Mr=53.35emu/g,Ms=73.08emu/g.