The effects of nitriding on the magnetic properties of Sm–Fe- and Sm–Fe–Ta-based materials

• Published in: Journal of alloys and compounds Vol. 433; no. 1; pp. 256 - 260
• Main Authors: Podmiljšak, B., McGuiness, P.J., Rožman, K. Žužek, Novosel, B., Pejovnik, S., Kobe, S.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.05.2007; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Diffusion; Domain effects, magnetization curves, and hysteresis; Exact sciences and technology; Gas–solid reactions; Magnetic measurements; Magnetic properties and materials; Magnetization curves, magnetization reversal, hysteresis, barkhausen and related effects; Nitride materials; Permanent magnets; Physics; Studies of specific magnetic materials; Magnetic measurements; Permanent magnets; Gas–solid reactions; Nitride materials; Diffusion; Samarium alloys; Tantalum alloys; Magnetization; Thermomagnetic effects; Gas solid reaction; Differential thermal analysis; Iron alloys; Gas-solid reactions; Nitrides; Coercive force; Nitridation; Nitrogen additions; Magnetic properties
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2006.06.054

Interstitial Sm–Fe-based nitrides with compositions close to that of Sm 2Fe 17N 3 are an interesting class of hard magnetic materials. In this series of experiments we characterised the nitrogenation process using a vibrating-sample magnetometer (VSM) and a thermogravimetric differential thermal analyser (TG/DTA). The VSM was fitted with a high-temperature furnace tube and a system for varying the atmosphere around the sample with different gases between 10 −2 mbar and 1 bar. The experiments involved two alloys, with the compositions Sm 13.7Fe 86.3 and Sm 13.8Fe 82.2Ta 4.0, and three different particle sizes, <2 mm, <200, and <15 μm. The results show that the nitriding process is very sensitive to the composition and the particle size, and that nitriding at higher temperatures can result in a nitrogen disproportionation and a loss of the Sm 2Fe 17 phase.