Study on the effects of Nb-substitution for Fe in Sm2Fe17 alloy on the formation and disproportionation characteristics of Sm2Fe17Nx-type interstitial materials

In the present study, the Sm2Fe17Nx-type interstitial materials have been prepared by reaction between Nb-free or Nb-substituted Sm2Fe17-type alloy and N-2 gas. Nitrogenation behaviour of the Sm2Fe17-type materials has been studied by means of thermopiezic analysis (TPA) and differential thermal analysis (DTA). Magnetic properties of the produced Sm2Fe17Nx-type interstitial materials were characterised in vibrating sample magnetometer (VSM) or thermomagnetic analyser (TMA). It has been found that nitrogenation kinetics of the Sm2Fe17-type alloy is improved significantly by the Nb-substitution for Fe in the alloy. Nitrogen content in the Sm2Fe17Nx-type interstitial materials has been found to be substantially increased by the No-substitution. It was suggested that the high nitrogen content in Sm-2(Fe,Nb)(17)N-x may possibly be explained by the possibility that the Nb-substitution may influence the site occupancy of nitrogen atoms: The Nb-substitution may possibly lead to 18g site occupancy of the nitrogen atoms in addition to the 9e site. The Nb-substitution was also found to enhance thermal stability of the Sm2Fe17Nx-type interstitial material. A slight degradation of hard magnetic properties of the Sm2Fe17Nx-type interstitial material due to the Nb-substitution was found to take place; it was, however, insignificant in practical point of view.