Oxidation of (Nd,Dy)FeB permanent magnets investigated by /sup 57/Fe Mossbauer spectroscopy

The corrosion behavior of (Nd,Dy)FeB permanent magnets has been studied in oxidizing environments by conversion electron and transmission Mossbauer spectroscopy. It is found that the Nd/sub 2/Fe/sub 14/B hard magnetic phase is not affected by ageing in 90 degrees C with 50% and 90% relative humidity. The oxidation occurs in the Nd-rich region, and the main oxidation products are Nd/sub 2/O/sub 3/ and Nd(OH)/sub 3/. At 200 degrees C in ambient atmosphere, the oxidation occurs both in the Nd/sub 2/Fe/sub 14/B and the Nd-rich phases, with the appearance of Nd/sub 2/O/sub 3/, an inhomogeneous phase close to alpha -Fe and unidentified phases, which could be beta , pi , or tau .<
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