Smhyphen;Fehyphen;N permanent magnets have been prepared by mechanical alloying of Sm and Fe powder and subsequently treating the material in a twohyphen;step process. Measurements of the minor hysteresis loops and of the initial magnetization curve were performed at room temperature. The reversible susceptibility (khgr;rev), the total susceptibility (khgr;tot) of the initial magnetization curve and of the demagnetization curve, and the temperature dependence of the coercive field (Hc) of a magnetically isotropic nanocrystalline Smhyphen;Fehyphen;N magnet have been measured up to a field strength of 6.4 MA/m. The anisotropy constants,K1andK2, of Sm2Fe17Nxwere deduced from the crystalline electric field calculation in the temperature range from 0 to 500 K. The critical diameter of single domain Smhyphen;Fehyphen;N particles was calculated to be 320 nm at room temperature. This leads to the conclusion that mechanically alloyed Smhyphen;Fehyphen;N is composed of singlehyphen;domain particles. The temperature dependence of the coercive field of Smhyphen;Fehyphen;N has been analyzed within the framework of the micromagnetic models. It is concluded from these results that the nucleation process controls the coercivity mechanism of mechanically alloyed Smhyphen;Fehyphen;N material. The thermostability of the Smhyphen;Fehyphen;N magnet has also been tested.
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