Intrinsic magnetic properties of Sm(Fe1-xCox)11Ti and Zr-substituted Sm1-yZry(Fe0.8Co0.2)11.5Ti0.5 compounds with ThMn12 structure toward the development of permanent magnets

Constituent phases in Sm(Fe_1-xCo_x)₁₁Ti alloys with 0 ≤ x ≤ 0.3 and Sm_1-yZr_y(Fe_0.8Co_0.2)_11.5Ti_0.5 alloys with 0 ≤ y ≤ 0.3 and the intrinsic magnetic properties of the ThMn₁₂-type phases in these alloys were investigated for discussing the potential as permanent magnet material. The increase of Co substitution for Fe from x = 0.1 to 0.3 for Sm(Fe_1-xCo_x)₁₁Ti increases the saturation magnetization (μ₀M_s) of the ThMn₁₂-type compound from 1.35 T to 1.52 T, while the largest magnetic anisotropy field (μ₀H_A) of 10.9 T was achieved for x = 0.2, μ₀M_s and Curie temperature (T_c) which were determined to be 1.43 T and 800 K, respectively. For the Sm_1-yZr_y(Fe_0.8Co_0.2)_11.5Ti_0.5 alloy with lower Ti, the phase stability of the ThMn₁₂ structure is attained by substituting Sm with Zr. Increase of Zr in Sm_1-yZr_y(Fe_0.8Co_0.2)_11.5Ti_0.5 from y = 0.1 to 0.3 decreases μ₀M_s from 1.61 to 1.52 T. However, the largest T_c of 830 K was found for the ThM₁₂-type phase in the (Sm_0.8Zr_0.2) (Fe_0.8Co_0.2)_11.5Ti_0.5 alloy, μ₀M_s and μ₀H_A of which were determined to be 1.53 T and 8.4 T at 300 K, respectively. The ThMn₁₂-type phase in the (Sm_0.8Zr_0.2) (Fe_0.8Co_0.2)_11.5Ti_0.5 alloy has comparable intrinsic hard magnetic properties with those of Nd₂Fe₁₄B.