High-resolution transmission electron microscopy observations on rapidly solidified Nd-Fe-B alloys are presented. The results show the existence of nanophases of different compositions to the nominal Nd2Fe14B as-prepared alloy, which was detected prior to the fast-quenching process. In particular, iron-enriched nanophases are commonly found among the wide variety of nanophases in the final alloy. The possible mechanisms, as well as their relevance to the understanding of the properties of these magnetic materials, are also discussed.