Magnetic Hardening of CeFe11Ti and the Effect of TiC Addition

We report the magnetic hardening of CeFe₁₁Ti by melt spinning and compare ribbons prepared with and without TiC additions for grain refinement. X-ray diffraction indicates that samples melt-spun at surface wheel speeds between v_s = 10 and 35 m/s are multiphased. However, CeFe₁₁Ti with a major ThMn12-type phase has been successfully obtained either by directly melt spinning at the optimum wheel speed v_s = 10 m/s or by annealing the overquenched ribbons melt spun at v_s = 35 m/s. To restrain the grain growth during annealing, 3 and 6 at% TiC have been added to the starting ingots, which were subsequently melt spun in the same range of wheel speed. For as-spun samples, adding TiC leads to much finer grains as well as much greater phase separation compared with samples without TiC. However, upon annealing, multiphased TiC added samples can be fully converted to the desired CeFe₁₁Ti phase with ThMn₁₂type crystal structure together with TiC precipitates. Because of the grain refining effect played by TiC, samples with TiC are subject to less grain growth during the heat treatment, and hence feature an enhanced H_ci =1.3$ kOe and energy product (BH)_max = 0.87$ MGOe that are 18% and 22% higher, respectively, compared with the best annealed samples without TiC.