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

Abstract

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.