LAUSR

Abstract The Fe-rich corner of the quaternary system Sm-Fe-Mo-Al is studied at isothermal conditions. The phase equilibria of ferromagnetic SmAl x Fe 10 − x Mo 2 with adjacent phases, especially Sm 2 Al x Fe 15.7 − x Mo 1.3 , are observed for 1000 °C. Existence ranges are studied by SEM/EDX on samples with various compositions. Magnetic and structural properties were obtained by VSM(PPMS) as well as Permagraph measurements while structural relations were tracked by XRD. Al can be substituted for Fe up to x = 6.5 accompanied by a decrease in high field (8 MA/m ≈ 10 T) polarization from 0.66 T (x = 0.0) to 0.44 T (x = 2.0). Respective Curie temperatures of SmAl x Fe 10 − x Mo 2 and Sm 2 Al x Fe 15.7 − x Mo 1.3 initially increase with Al content reaching a maximum of ≈ 125 °C at x = 0.5 and ≈ 135 °C at x = 1.0, respectively. Further Al substitution decreases TC. The coercive fields of optimally annealed nanocrystalline powders decrease slightly from 153 kA/m for x = 0.0–139 kA/m for x = 0.8 and drops to 38 kA/m for x = 2.0. XRD data indicates that lattice parameters of SmAl x Fe 10 − x Mo 2 continuously increase with Al content. The simultaneous refinement of X-ray and neutron diffraction patterns confirms that Mo prefers 8i sites in the ThMn12 structure and that Al occupies equally 8i and 8j in a ratio of 1:2.