The Study Of SmCo-Based Amorphous Magnets

Recently amorphous hard magnetic alloys attracted general interests due to their uniquemechanical, physical, chemical properties and corrosion resistance ability. Crystalline SmCobasedand SmFeC-based alloys possess good magnetic properties, but reports of theiramorphous systems are still rare. This paper mainly studied the relationship among glassforming ability, phase composition, microstructure and magnetic properties in high-energyball milling alloying method through XRD, TEM and VSM.Samples adding CNTs in SmCo_6.9Hf_0.1 alloys whose nominal compositions areSmCo_6.9Hf_0.1, SmCo_6.9Hf_0.1+CNTs0.05 and SmCo_6.9Hf_0.1+CNTs_0.2 have been prepared by highenergy ball-milling technology for 4¹00h followed by crystallized annealing. It has beenfound that the addition of CNTs can change the milling efficiency and decrease the oxidizingtendency of powder. The magnetic properties of all powder have been changed via highenergy ball milling for 4 hours. With the increasing of CNTs, the coercivity increased.Simultaneous addition of elements such as Fe, Zr, Nb, Al, B and Si in Sm-Co alloys canincrease its glass forming ability. It is found that the addition of Si decreases the glass formingability of melt-spun ribbons while obviously improve the hard magnetic properties thatcompared with as-cast alloys the coercivity and remanence of ribbons increase from 0.9 kOeand 8.5 emu/g to 11.1 kOe and 14.7 emu/g respectively. It is also found that the content ofamorphous phase in Sm_11.3Co_56.6Fe_7.5Zr_4.7Nb_4.7Al_5.7B_3.8Si_5.7 approached to maximum at thespeeds of 25 m/s in melt-spinning while the coercivity and remanence ratio reaches to 8.7 kOeand 0.74 respectively. At 40 m/s, the remanence ratio exceeds 0.73 and the coercivity is 11.1kOe.Sm_11.6Co_38.9Fe_38.9Zr_6.2Cu_0.9B_3.5 and Sm_9.1Fe_73.6Si_3.2B_12.3C_1.8 alloys have been prepared byannealing, water-quenching and melt-spun method. The phases compositions of annealed andwater-quenched Sm11.6Co38.9Fe38.9Zr6.2Cu0.9B3.5 alloys are Sm₂(Co, M)17 main phase and Fe-Cowhile Sm_9.1Fe_73.6Si_3.2B_12.3C_1.8 alloys are composed of Sm-Fe(mainly Sm₂Fe₁₇, a -Fe and Fe2B. Both samples have a large number of amorphous phases after melt-spinning. Themagnetic properties of as-cast, annealed, water-quenched and melt-spun alloys are not good.