Metastable and quasiperiodic phases in rapidly quenched Fe–B–Si–Nb(Cu) alloys

The formation of metastable phases as a result of devitrification of amorphous iron‐based alloys, in particular at the initial stages of the process, was investigated. Compositions with 4–14 at% B, 3–10 at% Nb, 13–15 at% Si, 0–1 at% Cu were studied by means of transmission electron microscopy, X‐ray diffraction, and differential thermal analysis. The following metastable phases were observed: bcc phase with α‐Mn‐type structure; quasiperiodic structure with cubic symmetry; hexagonal phase (rhombohedral distortion of α‐Mn structure); and Laves C14 phase. Some of these phases are also observed in “Finemet” alloys with 1% Cu: cubic quasiperiodic phase and α‐Mn‐type phase after laser annealing of amorphous phase, and the hexagonal phase at the late stages of crystallization. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)