Magnetic properties of Sm(Co/sub bal/Fe/sub 0.31/Zr/sub 0.05/Cu/sub 0.04/B/sub x/)/sub z/ alloys and their melt-spun materials (x=0.02--0.04,z=7.5--12)
Cast alloys and melt-spun ribbons with nominal compositions of Sm(Co/sub bal/Fe/sub 0.31/Zr/sub 0.05/Cu/sub 0.04/B/sub x/)/sub z/ (x=0.02-0.04,z=7.5-12) have been synthesized and characterized in a temperature range of 10-1273 K and at fields up to 5T. The main phase in the as-cast alloys exhibited a Th/sub 2/Ni/sub 17/ type structure, with a strong uniaxial anisotropy. Minor phases with a TbCu/sub 7/ and/or CaCu/sub 5/ structure emerged as z (3d/R) decreased. As a result, the anisotropy field (H/sub A/) increased from 67 to 120 kOe, while 4/spl pi/M/sub s/ fell from 12.8 to 10.5 kG at 300 K when z was decreased from 12 to 7.5. For melt-spun ribbons, they are nano-structured in nature and magnetically hard, even in the as-spun state. By lowering the value of z(3d/R) and raising the B content, a finer microstructure and a higher H/sub ci/ were obtained. Hard magnetic properties of H/sub ci/=4.9-12 kOe, 4/spl pi/M/sub s/=9.0-12.0 kG at 300 K have been obtained from ribbon samples. Among them, Sm(Co/sub bal/Fe/sub 0.31/Zr/sub 0.05/Cu/sub 0.04/B/sub 0.02/)/sub 10/ ribbon showed the highest (BH)/sub max/ of 10.8 MGOe at 300 K. A Henkel plot analysis suggested the existence of exchange-coupling interaction between the magnetically hard and soft phases in the ribbon materials.
Effect of Fe content on structural and magnetic properties of SmCo4−xFexB alloys
Abstract The phase formation and magnetic behavior of SmCo 4 − x Fe x B ( x  = 0, 0.25, 0.5, 0.75, 1 and 2) produced by melt spinning have been investigated. At x  = 0, melt spinning resulted in the formation of the SmCo 4 B phase and an ultrahigh coercivity of 44 kOe at 300 K. Fe substitution resulted in the formation of an amorphous structure along with the Sm(Co,Fe) 4 B phase during melt spinning. A single Sm(Co,Fe) 4 B phase was observed after crystallization when x 4 B and Sm 2 (Co,Fe) 17 B y were observed when x  ⩾ 1. Hysteresis loops at x x  ⩾ 1. In the crystallized Fe-containing materials, an increase in both coercivity and magnetization with increasing Fe content was observed until x  = 1. Initial magnetization curves revealed nucleation-controlled behavior at x x  = 1 and x  = 2. The average grain size for the annealed SmCo 4 − x Fe x B samples measured from TEM micrographs was 110 nm for both x  = 0.5 and x  = 1 and 90 nm for x  = 2.
Magnetic hardening studies in sintered Sm(Co,Cux,Fe,Zr)z 2:17 high temperature magnets
Lorentz microscopy combined with conventional transmission electron microscopy were used to image the magnetic domains and microstructures of sintered Sm(CobalCuxFe0.06Zr0.03)z (0.088⩽x⩽0.128; 5.8⩽z⩽7.2) permanent magnets which were specifically designed for high temperature applications. The microstructural data were correlated with the magnetic measurements to understand the origin of coercivity. All sintered magnets showed typical cellular and lamellar microstructures. The cell size and coercivity were found to be more sensitive to z than to the Cu content. For a fixed Cu content, by increasing z from 5.8 to 7.2, the cell size was found to vary dramatically from 10 to 80 nm and the coercivity from 5.6 to 40 kOe, respectively. On the other hand, for fixed z, the cell size decreases slightly with increasing Cu content from 0.08 to 0.128 and the corresponding coercivity increases from 23.6 to 40 kOe. Both z and the Cu content show a smaller effect on the cell boundary width and lamella phase density. Doma...