On the oxygen stabilized Nd-rich phase in the Nd-Fe-B (-O) permanent magnet system

In Nd-Fe-B permanent magnets, the cubic Nd-rich phase (a=0.52 nm) is very important to the development of coercivity and to the sintering mechanism. Transmission electron microscopy shows that this Nd-rich phase is not stable under electron irradiation. An analysis of the decomposition reaction, which leads to the formation of cubic Nd/sub 2/O/sub 3/ and NdO demonstrates that the Nd-rich phase can be classified as a NdO compound which is supersaturated with oxygen and stabilized with iron. A model that takes into account the existence of a liquid miscibility gap in the Nd-Fe-B-O quaternary system is proposed to explain the formation of this phase.<
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