In-Field Heat Treatment Effect on Nitridation of Sm₂Fe₁₇

抄録

An in-field heat treatment furnace utilized for a magnet with a 50 mm room-temperature bore was made to study magnetic field effect on gas-solid reaction. Using this furnace, nitridation of Sm₂Fe₁₇ powder was performed under a 5-T magnetic field and a 0.1-MPa nitrogen gas pressure for the temperature range 623 to 743 K. Applying a magnetic field of 5 T promoted nitridation by approximately 0.6 nitrogen atoms per formula unit compared with zero-field nitridation, and almost fully nitride Sm₂Fe₁₇N_2.9 was obtained at 743 K.

Fig. 3 Temperature dependence of the magnetization for Sm₂Fe₁₇N_x prepared by the zero-field heat treatment (ZFHT) and 5 T in-field heat treatment (IFHT-5T) at the nitriding temperature T_n of 623 K (a) and 743 K (b). For comparison, the data of Sm₂Fe₁₇ and Sm₂Fe₁₇N₃ are also shown.