Crystallization behaviour, structure and magnetic properties of nanocrystalline FeZrNbBCu-alloys

Substituting Nb (2–5 at.%) for Zr in Fe86Zr7B6Cu1-alloys, the melting point and the reactivity of the melt are only weakly influenced. The window for annealing treatment (Tx2 − Tx1) is widened. The grain size D of the α-Fe-phase becomes smaller with increasing Nb content (< 10 nm). A simultaneous reduction of D and the coercivity Hc could not be observed. The first crystallization stage at about Ta = 450 °C/1 h is connected with an ascent of the coercivity Hc, which is attributed to an enhanced lattice constant a0 of the α-Fe and an increase of the magnetostriction λs. In the composition range between 3–4 at.% Nb, λs is near zero and the induction Bs is raised up to 1.52 T.