Preparation of (Sm_0.8Zr_0.2)_1.05–1.10(Fe_0.9Co_0.1)_11.3Ti_0.7 Magnets by the Spark Plasma Sintering Method

Abstract

An amorphous powder of starting compound (Sm_0.8Zr_0.2)_1.05–1.10(Fe_0.9Co_0.1)_11.3Ti_0.7 was directly sintered in a carbon die under a pressure of 50 MPa using the spark plasma sintering (SPS) method. This is the first result showing the possibility of using this compound to prepare bulk magnets that have comparatively high magnetic properties. Typical sintered magnets with a density of 6.2 and 6.5 g cm⁻³, which are about 80% and 84% of the theoretical density, exhibited a coercivity of about 430 and 370 kA m⁻¹ and (BH)_max of 50.6 kJ m⁻³ (= 6.32 MGOe) and 57.2 kJ m⁻³ (= 7.15 MGOe) at room temperature, respectively. The crystal structures of the samples with high magnetic properties prepared by the SPS method were a mixture of the 1-9 and 1-12 phases, which is the same result as reported for powder samples prepared by annealing of the same starting compound.

Fig. 7 (a), (b) Hysteresis loops, (c), (d) enlarged demagnetization and (BH)_max curves of SPS sample A and B, respectively, measured using a VSM with H_max = 12 MA m⁻¹ (HFLSM, IMR, Tohoku University). ^*Demagnetizing field corrected.