Effect of Cr Substitution on Thermal Stability of Magnetization and Oxidation Resistance of SmFeN Compounds

We investigated the effects of Cr element substitution on thermal stability of magnetic flux and oxidation resistance of SmFeN compounds by X-ray diffraction (XRD), thermogravimetry analysis (TG), and flux aging loss measurement methods. We found that with increases in Cr substitution, the irreversible flux losses of bonded magnets made from these alloys decrease remarkably. When Cr substitution reaches 2 at%, the beneficial effect reaches a maximum; the irreversible flux loss of such bonded magnets exposed to a temperature 170degC for 2 h is only 4.97%. The oxidation resistance of SmFeN magnetic powders is also notably improved with the increased Cr substitution .