OXYGEN ABSORPTION BY THE FE17SM2 PHASE

The results of oxygen absorption in temperatures ranging from 200 to 5 00 degrees C are reported. It was observed that the oxygen saturation limit is temperature dependent, being of 3 atoms per formula unit (at/ fu) at 200 degrees C, 12.8 at/fu at 300 degrees C, 20.3 at/fu at 400 d egrees C and 28.5 at/fu at 500 degrees C. This implies that above 200 degrees C the phase is deeply altered by oxygen absorption. Samples wi th absorption at 200 degrees C were studied as prepared and heat treat ed at 500 degrees C/40h. The results show that the heat treated sample s consist of Fe17Sm2, Fe and Sm2O3. Metallographic examination and sus ceptibility data support the hypothesis that the as prepared samples c onsist of a mixture of Fe17Sm2 and interstitial Fe17Sm2O3.