Constituent phases in Sm(Fe1-xCox)(11)Ti alloys with 0 <= x <= 0.3 and Sm1-yZry(Fe(0.8)Co(0.)2)(11.5)Ti-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(Fe1-xCox)(11)Ti increases the saturation magnetization (mu M-0(5)) of the ThMn12-type compound from 1.35 T to 1.52 T, while the largest magnetic anisotropy field (mu H-0(A)) of 10.9 T was achieved for x = 0.2, mu M-0(5) and Curie temperature (T-c) which were determined to be 1.43 T and 800 K, respectively. For the Sm1-yZry(Fe(0.8)Co(0.)2)(11.5)Ti-0.5 alloy with lower Ti, the phase stability of the ThMn12 structure is attained by substituting Sm with Zr. Increase of Zr in Sm1-yZry(Fe(0.8)Co(0.)2)(11.5)Ti-0.5 from y = 0.1 to 0.3 decreases mu M-0(5) from 1.61 to 1.52 T. However, the largest T-c of 830 K was found for the ThM12-type phase in the (Sm0.8Zr0.2) (Fe0.8Co0.2)(1)(1.)(5)Ti(0.5 )alloy, mu M-0(5) and mu H-0(A) of which were determined to be 1.53 T and 8.4 Tat 300K, respectively. The ThMn12-type phase in the (Sm0.8Zr0.2) (Fe0.8Co0.2)(1)Ti-1.(5)0.5 alloy has comparable intrinsic hard magnetic properties with those of Nd2Fe14B. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.