Deformation-induced texture in nanocrystalline 2:17, 1:5 and 2:7 Sm–Co magnets

The effect of crystal structures on texture induced by hot plastic deformation was studied for Sm–Co, Sm–Zr–Co, Sm–Zr–Co–Fe and Sm–Co–Fe–Mn nanocrystalline alloys with 9–22 at% Sm. Nanocrystalline precursors were obtained via high-energy ball milling and subsequent hot consolidation; deformation was carried out at 800–1150 °C. The analysis of X-ray diffraction and magnetic measurements showed that the degree of the axial [0 0 1] texture after deformation was negligible for the ordered 2:17 structure, but became increasingly noticeable for the disordered 2:17 (“1:7”), 1:5 and 2:7 structures. Because of interplay of several factors including the [0 0 1] texture, saturation magnetization and magnetocrystalline anisotropy, there was no universal trend in the hard magnetic properties with the Sm content. Optimum compositions for the maximum energy product varied from Sm11(Co, Fe, Mn)89 in the Sm–Co–Fe–Mn series to Sm11Zr2(Co, Fe)87 in the Sm–Zr–Co–Fe series to Sm17(Co, Fe)83 in the Sm–Co–(Fe) series. Iron substitution for cobalt strongly suppresses the 1:5 structure, whereas the Fe-free magnets based on the SmCo5 compound showed by far the highest room-temperature coercivity.